| John L |
As I had mentioned before I have decided to construct a Hexagon(six sided Enclosure) in which to mount the Pioneer B20FU20, along with the Parts Express ND20FA Dome Tweater.
I first got this idea from two places. First from here with the discovery of the Chang horn enclosure, in which the Pioneer and a slightly different dome tweater from Parts Express. However, I wanted to do something a little bit different.
About that time someone, either here or over at the Parts Express forum, started a thread on the Duevel Venus. It was so different and downright beautiful that I decided then and there to make my enclosure like that one, and a slightly modified dispersion horn on top.
There are several different pictures showing this Duevel Venus, but the one above, with the Santos Rosewood, is the best looking to me. Santos is my favorite veneer material, and the surrounding sap wood contrasting with the heart wood really set off the veneer.
Unfortunately I could not find any examples of Santos like that, but did find a nice bit of walnut, along with sap wood, so I decided to use it instead.
The first thing I did was practice on the table saw in order to ensure a 30% cut with each piece of plywood, and have them come out exact. My Craftsman saw did not cut exactly on the mark for 30%, but was one graduation below that number. Then I finally got the right angle, and after several attempts came up with the sample below.
Each side is exactly 8 inches across.
Following this, yesterday I cut the pieces to size and set up my Dado blade combination, which I had just purchased for this job. I have always used my router to make rabbets and dado cuts, but never cared to pay in excess of $100 for a Dado blade set, not that I could not afford it. I just never thought it worth the money.
However, I was at Harbor Freight, looking at their 10 inch, 80 tooth carbide blade, which was less than $15, and happened to see the dado set in the blade bin. I asked a worker how much it was selling for just out of curiosity. When he came back with a $26 price tag, I finally decided that the price was more then right. I practically ran to the counter with it before they had a chance to change the price.
Naturally my blade guard would not work with a dado blade set up, so I had to fabricate one to go on the Craftsman saw. I did this by using a piece of 1/4" plywood, and removing the belt clip from an old, worn out, tape measure. The clip was for holding down the back end, and a hole drilled in the front end to secure it and I was ready to go.
I have a vacuum system attached to the saw, so I turned it on, along with the saw, and slowly raised the blade until it had cut through the homemade blade guard, to the point I wanted it to go, and that way there would be no saw dust flying around. The dust would be collected in the system and larger debris would not get sucked into the machine through any rough holes. I tried it out and Voila!, perfection.
Here are the cut pieces for one of the enclosures. As you can see on one of the top pieces, the knot hole makes the plywood a reject, but the fact that it is cabinet grade is what I was looking for.
To figure out the braces, I took the origional test case above, set it down on some craft paper, traced the inside dimensions on to the paper, and then added 1/4" to the sides. I figure that if it is slighely smaller than the dado cuts, it will still be fine, as I will be glueing it and also using heavy duty staples to secure the pieces.
Once I had cut the pieces on the table saw, I cut 9" holes in three of the braces with my plunge router and the Jasper jig, which was pretty straight forward.
So, this is where I have gotten tonight. I had earlier taken two cutout pieces from OSB and lightly brad nailed the pieces together with the OSB inside the cut out pieces, as a preliminary test, and they seemed to work alright. Tomorrow I will try to put the one cabinet together, using the three braces with 9" holes, by glueing, using finishing brads, and also staples, and see if I can get it all together and look somewhere professional in the process.
If I can get it to work, I will use it, and make the second one the same way. If not, and things have this strange habit of meeting Mr Murphy, I will use it as a test and apply what I have learned with two new sets of cabinet material.
As a note, I chose to go with cabinet grade plywood in this case, rather than MDF, because I found a special at Home Depot, where Birch plywood seconds were acquired on special sale. They were going for $26 and I purchased four of them for use in my business and with this project. The plywood is a bit lighter and once glued and fastened together tightly, there should be no worry about resonance whatsoever. that is one of the real advantages of a Hexagon. the sides are not wide and the brace and support each other. With the added inner bracing, they should be rock solid.
Anyway, here is the project. I will be adding on as I go along. If you have any suggestions, question, or comments, please feel free to give us the benefit of your extensive knowlege. I have never made a six sided speaker enclosure before, and to me this is brand new ground. It looks quite daunting, and indeed it may well be. And on that I can see two real problems.
First, getting all these pieces of wood to cooperate and stay in line and even, as I attempt to glue, attach and align them all together, is going to be a real job and probably very frustrating. All the sides are straight, and I can now see the need to obtain a special router bit that will cut an interlocking groove for each surface. I'll have to look around and see what I can come up with, but until then, I will have to settle for smooth angle cuts of 30% with each side. If anyone knows where I can get a bit that will make this cut for me, I would love to know about it.
And Secondly, I am still trying to come up with a way to make the top horn dispersion piece. A member offered to help ne with the job by making them on his lathe, but I have not heard from him lately. I'll have to contact him soon, and see if he is still up to contributing to my project. I have looked into purchasing a wood lathe, but really don't have all that much need for a power tool that will take up added space and not be used to it's potential.
So, here I am just getting started, and only at stage one, with most of the planning complete(I'm certain that I overlooked a great deal already) and the pieces cut to size. Next will be that of trying to get the parts to work with me and allow me to put them all together and have it look respectable. I have a long way to go here, I'm sure. So please look at this as your project too, since my success here also depends on your interest and keeping the thread alive and interesting. |
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| Kensai |
Well, I love B20s, and I love nice walnut like you've got there, even before finishing. Sorry I don't have any advice on the carpentry aspects of things, but I am very interested in your project. What sort of cabinet will this turn out to be? With a cabinet this size, sealed or vented would be viable, though I would vote for sealed. It just sounds better, IMO. Besides, low bass is omnidirectional, just like your intent with these speakers, so a sub to fill out the bottom shouldn't change directivity.
Some things I'd like to note for you . . . stock, the B20 is pretty dull off axis. When I modded mine with phase plugs, that changed dramatically. If you're intending to make reflectors styled after Duevels', possibly you could have the point of the reflector flair back out till it is proper width and length to fill the cavity over the B20s pole piece. Removing the dust cap in order to install a phase plug or my proposed extended reflector also improves the driver's response by removing the airmass under the dust cap which compresses, especially at higher levels which you'll need to compensate for using it as omnipole like this. Another point in favor of phase plugging the B20s is the fact that these small tweeters don't like to be crossed very low, and that far off axis, even with the reflectors, I'm afraid you would have to cross them too low.
I look forward to seeing you work through this project. The potential for a wonderful sound system, not to mention some wonderful looking cabinets, is huge with this.
Kensai |
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| MPM |
| Would it be possible to make the horn dispersion piece as an extension of the phase plug? Or would that affect the sound of the b20 to much? |
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| John L |
| quote: | Originally posted by Kensai
What sort of cabinet will this turn out to be? With a cabinet this size, sealed or vented would be viable, though I would vote for sealed. It just sounds better, IMO. Besides, low bass is omnidirectional, just like your intent with these speakers, so a sub to fill out the bottom shouldn't change directivity. |
It's going to be fairly big. I calculated it very close, and I come up with almost exactly 2.79 cubic feet. I could have come up with something smaller, but think the BOFU works well in just about any environment.
Another reason for going with a cabinet of this size is that it would be interchangable with other larger drivers. A 12" could easily fit on the top of the cabinet, and it is conceivable that a good quality High Compression Horn could work with a 12" driver and have a smooth transition in the 1000-1250 hz range. If you look at the higher costing Duevel models, the Bella Luna, and the Jupiter, all three models use a high compression horn. and with the Jupiter, it is used with a 12" driver.
Also something else.If the above scenerio is not doable, in a reasonable alternative, it is also possible to set up the enclosure to accomodate a low frequency driver, firing out of the bottom of the cabinet, and using an 8" on top as a midrange, and a coaxal tweater mounted in front of it, instead of having to come up with a high compression horn siting on top of the array.
I know that using a down firing low end driver is not difficult, because It appeared in the Dunleavy Aletha, which was also a Hexagon unit. Unfortunately the Dunleavy and Duevel are the only ones that I know of which are six sided speakers. It's something that may be a bit daunting to most designers. And that is not really fair for the design, because it is actually the most efficient enclosure for space utalization, other than the Octagon. It's just quite a bit more difficult to make.
Here is what the Aletha looks like.
| quote: | Originally posted by Kensai
Some things I'd like to note for you . . . stock, the B20 is pretty dull off axis. When I modded mine with phase plugs, that changed dramatically. If you're intending to make reflectors styled after Duevels', possibly you could have the point of the reflector flair back out till it is proper width and length to fill the cavity over the B20s pole piece. Removing the dust cap in order to install a phase plug or my proposed extended reflector also improves the driver's response by removing the airmass under the dust cap which compresses, especially at higher levels which you'll need to compensate for using it as omnipole like this. Another point in favor of phase plugging the B20s is the fact that these small tweeters don't like to be crossed very low, and that far off axis, even with the reflectors, I'm afraid you would have to cross them too low. |
Doing what you suggested would be very interesting. The only problem is that I have planed to locate the small tweater, like what is used with the Chang horn, right in the center of the BOFU, like that of a coaxial. That is the only thing I can come up with. I think using the upper dispersion horn as with the Venus is biting off more than I can chew. In other words, I should be able to come up with the cone shape for the bottom part, but I would be over challenged to come up with the cone for top AND bottom. I had planned to just slightly round the top asthetically so as to have it blend with the general shape. Somehow, I find all those compression horns a bit too much for my eyes, but I fully understand the reason for them and why they are made the way they are.
| quote: | Originally posted by Kensai
I look forward to seeing you work through this project. The potential for a wonderful sound system, not to mention some wonderful looking cabinets, is huge with this.
Kensai |
I suspect this will be a very interesting project. Once I learn how to make a nice Hexagon, I may want to make all sorts of them. Making these sort of puts you in a different category.
So what do you think of the 2.5 cu ft size? Incitentially, the Aletha above is 51" high finished. The ones I am making will be somewhere close to that, once the base and the dispersion horn is attached. Currently the body is exactly 40" high in their raw form. Of course I can still cut them down a little bit, since I have not assembled the walls yet. All I would have to do would be to recut a new rabbett joint at the bottom of each piece. |
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| John L |
| quote: | Originally posted by MPM
Would it be possible to make the horn dispersion piece as an extension of the phase plug? Or would that affect the sound of the b20 to much? |
I'm not sure how that would affect the sound. Perhaps Planet 10 can ride in and give us some idea. |
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| Kensai |
The 2.5 ft^3 volume is perfect for sealed and is very workable for vented for the B20. Shouldn't be any problem designing an alignment to fit your setup since you have so much volume to play with.
Having the tweeter sitting on something (like a length of dowel) that's sitting on the B20's pole piece (yes, with the dust caps removed) with whatever you come up with as reflector suspended above should be a fine design. Just as long as you remove the dust cap and have something acting as a phase plug (plugs don't have to be bullet shaped; cylindrical should be fine for this application), you should get much better off axis performance from the B20.
If you decide to put a low frequency driver downfiring,you could still use the B20 as your mid. You would simply design the volume for the sub driver (I could recommend the Dayton SD215 which is a very flexible 8" dual voice coil sub driver that can work well in sealed or vented enclosures), then use the remaining enclosure volume as a sealed enclosure for the B20. The smaller chamber will act as a high pass filter for the B20. Then you would install a sub plate amp with a variable low pass filter for your sub driver, and you'll be able to very easily mate everything up.
Kensai |
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| John L |
| quote: | Originally posted by Kensai
The 2.5 ft^3 volume is perfect for sealed and is very workable for vented for the B20. Shouldn't be any problem designing an alignment to fit your setup since you have so much volume to play with. |
That's great! I had pretty much thought so, but it is nice to have someone else confirm it. The size I am using is pretty much perfect for many applications, and this will be very important when coming up with just one radiator at the top. "One size fits all" makes it really nice to use for making them on a lathe. Now, if only I can get access to a wood lathe.
| quote: | Originally posted by Kensai
[B]Having the tweeter sitting on something (like a length of dowel) that's sitting on the B20's pole piece (yes, with the dust caps removed) with whatever you come up with as reflector suspended above should be a fine design. Just as long as you remove the dust cap and have something acting as a phase plug (plugs don't have to be bullet shaped; cylindrical should be fine for this application), you should get much better off axis performance from the B20. |
That's a great idea. We had discussed this on another thread last month. The only logistical problem was in routing the wiring without causing problems to the driver specs. A vented pole piece would allow the wire to pass through it, but the B20 has no vented pole piece. This means I would have to make a hole through the cone and run the wire out that way.
| quote: | Originally posted by Kensai
[B]If you decide to put a low frequency driver downfiring,you could still use the B20 as your mid. You would simply design the volume for the sub driver (I could recommend the Dayton SD215 which is a very flexible 8" dual voice coil sub driver that can work well in sealed or vented enclosures), then use the remaining enclosure volume as a sealed enclosure for the B20. The smaller chamber will act as a high pass filter for the B20. Then you would install a sub plate amp with a variable low pass filter for your sub driver, and you'll be able to very easily mate everything up.
Kensai |
Funny you should recommend this line of woofers. What I really had in mind was the larger sibling, the 12" SD315, which is very efficient. Or the 10" SD270 would be nice too.
I have more than my share of tube receivers and amps, so I have to keep efficiency in mind. I'm into 60s and early 70s vintage units, such as the Sansui 1000A, or 2000/5000 series
As for the mid range, I had been considering the PA 165, but again you are bringing me back to the B20, which has an even better efficiency, and would go along easily with the subwoofer. Amazing how versatile the B20 really is. ;)
I think we may be coming up with a great future project, once this one is complete.
Oh, I have the first enclosure glued, and stapled together. I have all the pictures ready to go into the computer, and I will upload them to Photobucket soon. Then I will post them here.
I was concerned that the entire carcus would not fit well, but it went great. It is not a perfect hexagon, because the precut brace leaves some opening at one end of the carcus. But I can custom cut another piece and make it fit nicely. And it really wasn't all that difficult. However it does help to have a table saw, with dado blade set, and also a compressor for using air tools. :D |
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| John L |
Now that I have put together one of the carcuses, I have found that it is not all that difficult as I had anticipated. What I did was start with two of the three internal braces, then glue and line them up with one of the walls. Once that was done, I used my brad gun to nail them in place. Then I did the same with the third internal brace.
Next I turned the carcus over one turn and glued the end of the braces and the first wall. Then I lined up a second wall, and starting from the center brace,shot the aligned walls with brads into both walls, and continued down to the ends of each side.
Here is what it looks like turned face up. I used a pretty good bit of glue, so I needed a wet clothe to wipe off the excess.
Click on pic for larger shot.
And here is the inside shot.
Here is what the seam looks like.
2/3s of the carcus done.
And a closer look at the inside seams.
Here is the carcus put together. Once I completed attaching the six walls, I liberally used the finishing brads and then used my Duo-Fast stapler, and shot the braces in place with 1 1/4" long 1/4" wide staples. Once the carcus dries it will take a lot of force to get the walls loose, because i shot everything full of brads and staples.
Here is an inside shot. And note that I really lucked up and got the cuts to match pretty well. Looks almost professional. I'm not going to count on the next one to look that clean. :)
Next up is to fill in all the small holes and then sand everything down smooth. I found that some of the outside veneer had come off on the corners, so I will have to fill in there too. |
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| Kensai |
Fantastic stuff.
As for routing the wiring for the tweeters, you've got some options. Most invasive would be venting the pole piece by drilling through it. That way you could also drill through whatever you end up mounting the tweeter to and the wires would be 100% hidden. I doubt this would have any real effect on the B20, unless you were unlucky enough to get metal shavings into the voice coil. Simpler and safer would be to simply string the wire (which could be 30ga magnet wire, no problem) from the phase plug/tweeter mount to the edge of the basket or beyond, letting it enter the cabinet someway other than through the cone. You won't be able to see that if you orient the wire toward the back of the cabinet, once the reflector is in place, and it won't effect the sound of the B20.
I mentioned the 8" Dayton simply because it seems to sim better than either of its larger siblings in that line. WinISD pro shows it behaving slightly better in BR than the 10" or the 12", even though it needs a 1.6 cu ft enclosure and the 10" and 12" need about twice that. Just a quick look with the B20 in .9 cu ft sealed at the top adn the SD-215 in 1.6 cu ft BR tuned to 29Hz at the bottom, shows that the B20 will start rolling off around 120Hz and you should run the SD-215 on a plate amp that will let you move the crossover point at least down to 50Hz so you'll have enough room to play with it and get them optimized. The plate amp won't have to be too beefy, though since the B20 should peak about 1dB higher than the SD-215 in this configuration. And just for discussion's sake, this sim shows the SD-215's F3 at about 26Hz.
If you like the omnipole sound (which I do, second only to good dipole like OB or planar/electrostat), this should be a good and cheap (well, driver wise, anyway), not to mention almost text book "full range" speaker.
Kensai |
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| John L |
| What does "BR" mean? I'll probably slap my forehead when told, but I can't think of it at this moment?:) |
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| Kensai |
Bass Reflex
sorry about that
Kensai |
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| Fast1one |
John L, I forgot to mention that for my Chang cabinet I am using the exact tweeter with good results. I stepped up to that one for the slightly more power handling then the one Gychang used and it has done well for me :)
Good luck!
Edit: I also have the Dayton SD215! How curious, currently it is in a TL, but it will be in a back loaded pipe horn (ala BIB) for HT duty...Its a great subwoofer for the money... |
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| Godzilla |
These are coming out really great! I can't wait to hear them!
Godzilla |
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| John L |
Thanks guys.
First, I forgot to include this above. It is the carcus completely enclosed. The Duo-Fast on top of the cabinet is what I used to fasten the braces to the walls. They put in a nice staple and hold things together quite well.
Here is the carcus, after I have filled in all the brad and staple holes and sanded them smooth. I left the walls a bit rough, since they will hold glue better.
My next step will be to make the top panel, where the driver will be held, and the base portion. Once that is complete, I will start on the second cabinet, and finish it before starting the veneering. |
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| defect9 |
I gotta say, since watching you plan this project from nearly the get-go, I'm impressed. Not a clue how it'll sound, but just in the fact that you don't give up. IF nothing else, you're going to learn a lot, and if everything goes according to plan, you'll end up with a rockin' set of speakers to boot. I really hope they turn out well.
-Jared |
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| John L |
Now that the holidays are over, and Mother has left, I can get back to the project. Before Christmas, I had sanded down the one carcus that I had put together. Then I went about trying to concoct something for the base stand. I thought about using MDF, but since I was already using cabinet grade plywood, I decided to continue with the same material.
After several attempts I came up with this one. I still have not beveled the edges yet, and can't make up my mind whether to make the bevel a straight angle, or use a round over bit. I am thinking roundover because the top difraction will be rounded, and everything else will be straight lines. Some rounding may be necessary to give it a smoother apearance.
Yesterday, I started on the second carcus, by taking the 24 inch wide cut of plywood, and cutting it in half, so each piece would be approximately 48" in length. The hand cut side would be rough, and since I do not have room for a nice radial arm saw, I considered how to use my skill(Porter Cable) saw on the back decking.
I realized that the initial carcus was done one piece at a time, in custom fashion, and that took a great deal of time. So this time, I wanted to use the fruits of my learning and make things go a little bit faster.
So, I placed the two pieces on the portable saw horses, and pretty much lined them up. Here you can see the rough ends, with the top piece pushed back some.
Here I have the pieces clamped down, and marked out to the 40 inches length, just as the first one. Then I measured out the distance of cut from the edge of my saw, and got ready to make the cut.
Opps, my first mistake of the day. I measured from the wrond side of the saw. Because when I went to cut it out, the motor got in the way of the clamp holding down the level straight edge. Since I am left handed, I naturally try to do things with the left hand, and almost everything made for anything is made strictly for righties. It's simple discrimination, but life in general. :xeye:
Once I made the remeasurement, I relocated the edge, and set it up for the cut.
In order to prevent needless chipping, I applied a strip of painter's tape across the surface needing to be cut outl It really wasn't necessary, because I intended to trim off the ends of both sides in the end, but it is a very good habit to do in all cuts with a skil saw.
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| John L |
Once I had the two pieces of plywood cut evenly at 24" X 45 inches, I took them down to the basement workshop, and started setting them up for cutting at 30% angles. I can get three nice cuts with each 24 inch wide section and some left over for margin by flipping the stock 180% after each cut. This will work well, as long as the angle is correct, so I will always get a 30% cut regardless which side of the material I use. And since I had already set up a template to start, and cut the first set, this did not take all that long to do.
One thing that bothers me with making such cuts is the sawdust that it generates. I have a special vacuum set-up on my Craftsman saw, as you can see in the next picture. But in order to make all the cuts at the necessary angle, I was forced to remove the guard and it's attachment. This left me with a lot of sawdust in the shop and all over myself.
The origonal rip fence that came with the saw, back in 1981, was terrible. About ten or twelve years ago, I upgraded to the Alignarip fence, and it really makes the difference in making a great cut with the saw. The motor is a 2 hp belt drive, and I converted it to 230 volts a couple of years after purchasing it. The 230 volt change has made all the difference in the world. No matter what I run through it, it will never burn the motor out.
My next upgrade will be to get rid of the blade guard, which is too open and dangerous. I just never got around to it. BTY, I am president of Procrastinator's International, Cary Branch. :D
One of the things I always do is make a test cut, until it comes out exactly as I want it to be. I went through several cuts until I got the exact 8 inch width I was looking for.
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| John L |
One of the big advantages of using a dado blade set is that you can make custom dados on the table saw, and it makes your life much easier, instead of having to mark, clamp, and make individual passes with the router. For years I did this, and this project finally convinced me that it was past time to go out and invest in this expensive(or so I thought) investment.
The reason why I use the "or so I thought" phrase is because I know that dado blade sets almost always cost over $100 and can run up to $300 with some of the high dollar name brands. But after checking up on the Harbor freight web site, I found their dado set to be far less in cost. In fact the total cost, at your local store, is the same as on the web site, $26.99 . Believe me, this is indeed a Steal!, and anyone owning a table saw should be on the way out the door to get one as I speak. Granted, it may not be as good as a Freud, but since I don't use it day in and day out, It is more than good enough for my purposes.
Here is another thing, concerning dado blades. With them mounted on the table saw, you can no longer use your present blade guard. This means that you must make one of your own custom guards. And this is to your advantage, because with a custom blade guard you can raise the rotating blade, cutting into it, and removing only that part that is necessary to allow the blade to stick above the table.
The distinct advantage is that small pieces of wood do not get sucked into the body of the table saw, blocking up the vacuum hose underneath, and the amount of saw dust is cut to a bare minimum. If you have your saw hooked up to a vacuum, then it will suck almost all the dust into the vacuum attachment, and it will not go all over the room. And by adding a custom plastic fence guard, which has a hose sticking out the top, it will also suck up any dust that fails to make it into the body of the saw. That way you get absolutely no dust floating loose, or almost no dust. That is another reason why I need to get rid of my current blade guard and make a custom one.
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| Eva |
| Why not an odd number of faces to avoid standing waves due to parallel surfaces? :confused: |
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| John L |
| quote: | Originally posted by Eva
Why not an odd number of faces to avoid standing waves due to parallel surfaces? :confused: |
Come again? I am not following you here. |
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| John L |
After setting up the dado blade for width and depth, I got started on making the necessary cuts for inserting my ribbing while attaching all the pieces together. For my first carcus I had painstakenly made each and every cut individually and by line of sight. I had marked each place for the cuts with all six facings, and allowed for any mismeasurement by allowing the dado cut to be slightly wider than the thickness of the plywood.
This time I decided to do things differently. Instead of eyeballing all the cuts, and praying for the powers that be to make everything right on the money, I decided to automate this process.
Because the carcus needed to be 40 inches long, and I had 45 inches to work with, I allowed for one inch on one end of the pieces. By making the cuts at 1", 11", and 21", I could make three cuts, only having to move the rip fence each time I finished making my six cuts at each distance. This worked out quite well.
then I changed the direction of the six sides, and measured out to make the final two dado cuts. I figured I would need to make a 3 3/4", and 13 3/4" pass for each of the six pieces. Man, I was really on a roll here. So I quickly made my passes and made sure that all the dado cuts lined up neatly.
Then I decided to make the necessary cuts to trim off the excess length of each of the six boards. And here is where I made my second, and biggest mistake of the day. How I did this I have no idea, but they say Hubris is the mother of failure, and I can readily believe it. Somehow I got three of the panels turned around 180% from the others, and since I was on a roll, I made all my passes in short order, with no further delays.
Or so I thought. After making my last pass, I took the six panels and placed them on my work table, and started attempting to line up all the dado cuts.
What the "you fill in the blank" here. :xeye: Three of the pieces worked fine, but the other three? All the dados were off line, and the ends were not neatly made into a rabbet as they were supposed to be. This was terrible! $%##!!!##. I couldn't believe that I had made such a foolish mistake as this. And after doing things so well from the start.
What to do? Rather than recut the three panels, as I could have done were I a true perfectionist, I decided to go ahead and use them as before. This meant that I would have to recut the three to match the other three, which I did. And I did this with heavy heart. SIGH.
Now, once I finished the cuts, laid them out, and confirmed that the dado cuts all matched, I took a measurement of the length of the sides. I was 1/8" off with each piece. The original carcus is 40" long exactly, and this second one is 39 7/8" long. Not perfect, but still not worth starting over.
The process of putting the pieces together were exactly the same as with the first one, and while I was listening to the Discovery Channel tell me all about how Global Warming was in danger of destroying the Great Barrier Reef, I attached all six sides together, and used some choice four letter words, directed at the brain dead announcer for his Herd Mentality. Irritation at something can always get you moving when complacity cannot. ;)
After putting the carcus together, wiping off all the excess glue, and finally finishing things up by using my heavy duty Duo-Fast stapler, driving 1 1/2" quarter inch staples into each internal ribbing, I was almost through. Next I cut 3/8-1/2" thick strips of 7 1/4" long cuts to use to fill in the dado cutaways that were mistakes. Then I liberally applied glue within each dado cut, inserted the filler, and stappled them into place. Once the glue dried, the brace should be every bit as strong as the original plywood. The only thing to suffer would be my pride. ;)
I don't have a picture of this 'gaff', but if you wish to see it, I will sheepishly take a shot or three for you, so you can get a good laugh at me and my hubris. :xeye:
And lastly, last night, I filled in all the staple and brad holes, and also the bad parts of the exteriour plywood. This plywood was 'Seconds' and it had some facing issues, so I also filled in their mistakes. Here is the carcus with all the filler.
And here is a shot of the first cabinet, with base, along side the second one.
I originally had plans of finishing up the sanding of the second carcus and then applying the veneer, one at a time to one side of each cabinet together. But it is raining here and I can not take the second cabinet out and give it a good sanding. In fact, it is a mess outside, and that is wonderful, because we are in the middle of a severe drought, so all the rain we can get is more than nice.
Consequently I will go down stairs and begin setting up the veneer for going on to the first cabinet. When it stops raining, I will sand it and then try to play 'catch up' with the first one. The reason why I intended to do one side of each, all together, is because I want to make certain that all sides are exactly matching, all around the cabinets. I'll just have to be more careful now, and make certain that Mr. Hubris is upstairs and out of the way. :)
I'll keep everyone posted as to how the veneering is coming along. |
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| Kensai |
And I can't even make boxes worth a darn, let alone well braced hex tubes with stands and reflectors. You may be having some issues and working hard, but you're making alot of the rest of us envious. Beautiful work so far. I'm also envious that I'm not likely to get a chance to hear them when they're done.
Kensai |
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| John L |
| quote: | Originally posted by Kensai
And I can't even make boxes worth a darn, let alone well braced hex tubes with stands and reflectors. You may be having some issues and working hard, but you're making alot of the rest of us envious. Beautiful work so far. I'm also envious that I'm not likely to get a chance to hear them when they're done.
Kensai |
If you have a decent table saw you can do this as well, without too much trouble. and not only do you need the proper tools, but the right steps and technique are important to make it easier.
that is why I am trying to make the explanations as detailed, but concise, as possible. It's really not all that bad. It's just daunting the first time around.
My greatest challenge now is to find someone who will be able to turn the upper diffraction piece for the top. Anyone, who uses a lathe, I could use some recommendations, or help here. |
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| John L |
I managed to get somewhat distracted over getting supper made, so I did not get around to the veneer until later. However, I did go down stairs and start setting up the pieces to be adhered to the panels of each cabinets.
I started off by deciding just how big I wanted each piece of veneer to be before I applied the glue to the underside of the veneer and the target wall of each cabinet. Since each side was exactly 8 inches wide, I figured I could overlat each side by 1/8 inch and with a nice cut, I would have little to trim off each side. As for the length, I decided on 1 inch overlap, because I would be taping the ends with masking tape to prevent any tearing of the veneer while working with it. And too, when all was finished, I could easily trim everything off with a trim bit on my router. so the overall size of each piece of veneer would be 42 inches long, by 8 1/4 inch wide.
Next I needed some form of ability to actually see what I wanted to to be included in the veneer, and how I wished for it to run. what I needed was some king of plastic sheet where I could easily see through it and mark the boundries. I did not have any scrap piece sitting around. But I did have several pieces that I use in my business, which is making beautiful things for the interior design business. I took down one of my plastic templates for swag patterns, and use it as a template for the veneer sheets. When I finish, I will take some solvent and remove the lines.
If you look below, you can see at the top of the swag template a 42 inch line by 8 1/4 inch width. It is not easy to see, but it is there. Also, at the corners of the inner part of the template, I drilled a small hole where I could use a black velt pen as a corner marker. Sometimes you just have to use a field expedient when you can't come up with the real thing.
After that I gathered my tools, and a scrap piece of plastic laminate that was laying around. I used the back side of it as a cutting base for cutting the veneer. I have three types of veneer saws, but the one I like the best is the French Veneer Saw. If you closely examine the teeth of the blade, they are pointing one way on one side, and the other way on the other side.
Traditional veneer saws are set up for right handed people and they either come with a set of teeth that are pointed downward, or some now come with the teeth pointing back toward the person pulling the blade.
The French veneer saw is set up for both left handed and right handed people. Naturally, being left handed, I like that up front. But the blade comes already sharpened and it allows you to make the initial starter cut with the teeth going one way, and then making the real cuts on the teeth going the other way. And regardless which hand you use, it is the same arangement. Neat huh? ;)
Here are the pieces of veneer laid out on the work table. It consists of two groupings of six pieces of walnut veneer, including the sap wood. The veneer came to me in lengths of over 90 inches long, so I cut them in half. That gives me a pretty frugel use of the veneer, and leaves me more than enough todo another hexagon enclosure if I wished. and then some of this magnificant pattern left over.
I'm not real big on walnut because it is dark and about as "Blaah" as it gets. I never really understood the industry getting into walnut, with so much wonderful material out there. Cherry is far better in character IMO. But there is a world of material there that beats walnut, hands down. The only reason why I went with this walnut was because it had a wonderful pattern, and the sapwood just brought out the pattern in the wood to a degree that most other woods, short Santos Rosewood, which is really my favorite material. But for the money and the pattern, it would be hard to beat this veneer. And there was so much of it for less than $30 plus S/H. |
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| John L |
Sorry for breaking this up, but the "Submit" and " Review" buttons are backwards from other forums I use, and I accidentially hit the wrong button. Opps. :xeye:
Normally I would not mark out the boundaries of each piece, especially if I was going to bookmatch the veneer. But in this case, it does not matter, since I am going to trim off the 1/8 inch overlap anyway. After marking the bounderies, I began sawing the veneer, by making the cross cut of the ends first.
Here is what I did.
I used a 36" straight edge level and began by pulling the veneer saw carefully and using light pressure to establish a straight groove into the veneer. Then I made continuing slow passes with the saw until the excess veneer came off. Then I turned the veneer around and did the other side, the same way.
Next, I laid out a 72 inch straight aluminum measure, and secured one end, and repeated the process. However ripping is a different proposition from cross cutting. It is really important to make the initial groove precise and then begin applying pressure to the saw. And usually it only takes about three or perhaps four passes when ripping length wise. That French Veneer Saw is really nice for this Leftie. ;)
Here is what the first piece looks like after I have trimmed it down to size.
And here are more cuttings being made to the veneer. Note the clamp at the bottom of the picture. I used it to keep the measure rock steady at that end, and only had to rely on one hand to keep the other end of the measure still, while I cut with my left hand.
Here are two sequential cuts of one half of the long pieces of veneer.
And here are two sequential pieces from the other end of the veneer. If you compare the pieces you can note that even being sequential, there are still differences in the pattern. Unfortunately, it is not possible to get the pieces exactly alike, but it is vitally important to make them as close as possible. That is why one piece of veneer will go on one wall of one cabinet, and the other piece will go on the same wall of the other cabinet. And then it will be repeated for each of the six walls of each cabinet. This is why it is important to switch back and forth, so as not to get things mixed up.
Also, if you will notice on the last picture, I have already taken masking tape and taped the ends, on each side of the veneer, to keep any of the dry and brittle veneer from tearing or ripping. Nothing is more frustrating than having this happen, and then have to use veneer tape, when it wasn't needed in the first place.
This is as far as I have gotten tonight. tomorrow I will take the second carcus outside, and sand it down nicely. then I will start veneering one wall of each cabinet. I'm not certain how I am going to trim off the edge of the veneer, because doing it this way is different from trimming from a 90% corner. I guess the best way to do this is very carefully. |
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| sjetski71 |
Very nice looking design OP, and good progress. Can't wait to see the finished product.
Looks like we share tastes in veneer :). I was also looking for Santos rosewood but ended up purchasing a similar looking walnut, got it from ebay merchant thinwoodandoldtools. That project has been shelved for now since i'm in the middle of a 7 speaker project using the aura NS3 and some 3/4" eastern red cedar. The aura's will run fullrange and the tweeters will be crossed with 2.0 or 2.2uf caps. They'll be for nearfield 7.1 multimedia, and will use an 8" Dayton SD215-88 DVC (or two) to fill the lows.
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| John L |
| quote: | Originally posted by sjetski71
[B]Very nice looking design OP, and good progress. Can't wait to see the finished product. |
I'm not sure what I am going to do with the speakers once I have completed them. I will probably make some other hexagon cabinets and refine the process further. There is something about the hexagon shape that I really like. It appears to be difficult to the untrained eye, but it really isn't if you have the proper tools, and a little bit of experience.
the real challenge is in the veneering and finishing, to my way of thinking. getting the edges, on a six sided edge, finished neatly is going to be worrisome for me since it is the first time I have tried this approach.
I am of two minds here on applying the veneer, and aplying a water based glue. If you apply the glue to one side of the veneer, and don't spray the other side with water, it will curl up and ripple on you. So, anytime you work on a nice veneer, what you do to one side must also be done in like manner to the other, or you can end up with a mess.
I can either apply the glue, spray the other side with water, and wait for everything to dry before applying to the surface. OR, I can apply a shellac seal to both sides at the same time. The advantage to using the shellac up front is that the wood will already be sealed prior to my applying the glue. The distinct advantage here is that it will already be sealed, which will tend to keep any melted glue, once pressed with the hot iron, from bleeding through any cracks.
Another advantage with sealing, up front, is that should any of the glue melt and flow over to an already applied side, it will not soak up into the wood of the applied veneer. I can just wipe it off, or wait for it to dry, and scrape it away. The wood will already be sealed and the tone of the stain will be already imprinted into the finish.
I like the later way best, but will probably try it both ways and record it to see which works best for speaker building.
| quote: | | Looks like we share tastes in veneer :). I was also looking for Santos rosewood but ended up purchasing a similar looking walnut, got it from ebay merchant thinwoodandoldtools. |
When I first got started in buying veneer from E-
bay, I bought quite a bit from him. I recently went up to the storage room and pulled out all my veneers that I have stored there, and I was surprised at the amount I fell in love with and bought from him. I have a wonderful cherry, with little cluster burls present, that I got from him about five years ago. I meant to use it on a project, but never got around to it.
He is a good vendor. But I have since discovered some other fine ones there, such as Lepkowski. he is the vendor from whom I purchased this young walnut. Normally he is a little bit more expensive than others, but his quality is second to none.
I also like Steven/GreatDane6, over at Veneer Artistry, Ron Fritz(he sells a lot of short orders, and loves to talk to customers on the phone. He's a real nice fellow), RoseBudVeneer(he sells some very exotic veneers, and in quantity). there are a few others I like to do business with, but those above are quality vendors, and you will not be cheated, or sandbagged, like happens in the audio department. They are long time sellers and like to please the buyer, like you and me. ;) |
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| MJL21193 |
Hi John,
Nice progress. These will be truly fine looking speakers when finished!
Did you find a source for the top horn section? Seems everything from the sixties and seventies had something with that shape on it - lamps, swivel chair bases, planters...
If your stuck for a source, consider making it yourself like this:
A series of disks, each smaller than the previous one, stacked up and glued together. These would have to be cut to the correct diameter.
You could use 1/4" MDF or hardboard for the clean stepped edge (like we see on some horns), or you could go the extra distance and fill these smooth.
Also the disks could be rings, to have the centre of the horn hollow. This has the side benefit of being able to use the centre cut outs as more disks. The hollow centre could be filled with dry sand to damp resonances.
Not especially hard to layout either. Use some 1/4" graph paper (grid), joining 2 or three together to get the right width. Draw the arcs and measure each piece.
Here's just a rough sketch of what I mean: |
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| John L |
Here is the latest thing. I finally got the second cabinet sanded, as today was nice and sunny.
Before I start working on the veneer, I thought I would perform an experiment by using water base glue, which will work well by being ironed on. Titebond II will do this, as well as what I am currently using, Better Bond Heat Lock veneer glue. It is nice to be able to just apply glue to the bottom of the veneer, and substrate, and then just iron it on permanently.
However, there are potential problems associated with this process. If using glue and then applying it to the substrate, all that is necessary is to apply pressure evenly until the glue dries. But this can be complicating and time wasting.
However the problem is that if you apply glue or sealer to one side of the veneer, without using a like substance on the other side, the veneer will curl and wrinkle when it dries. this will tend to cause more problems that it solves.
So I decided to test the use of glue and shellac sealer to see how it affects the veneer. First I cut up some spare pieces of walnut, which were of the same tree as what I am using to cover the cabinets. Here is the picture of them in raw form.
Highlight and activate the picture to see larger image.
As can be seen, the veneer is quite flat and with only a very slight curling length wise. In other words a great veneer to work with.
I took two of the pieces of plywood outside, and opened both jars of my different shellacs. One is Orange unwaxed shellac, approximately a two pound cut. The other one is Super Blond unwaxed shellac, approximately a one pound cut. With both of them lying flat, I applied two coats of the Suber Blond, and one coat of the Orange, to make them pretty much even in sealer. I coated both sides of the veneer and allowed them to dry. Denatured alcohol evaporates quickly, so make sure and do this outside. Below is a picture of what the two look like pretty much dry.
There is a slight curl against the grain, but the wood is very pliable and easy to straighten out. Plus it is also sealed, so glue will not get soaked into the veneer should there be spillover.
Also, note the difference in color and shade of the two types of shellac. The Super Blond is very close to what the wood looks like without any stain. The Orange has a decided redish brown tint. with more coats, it will get darker. Also, you can find shellac that is even darker than this, so it is not necessary to use a dedicated stain, if you use shellac, because it automatically does it for you.
Now, on to the water based glue. Here is a shot of two pieces, one glued on one side only, and the other with glue on one side, and water sprayed on the other side.
And here is the side I sprayed with just plain H2O.
It is incredible how the veneer rolls around itself with nothing done to the other side. But on the sample that is glued on one side and sprayed with water on the other, the veneer is even flatter than by using the shellac samples.
I have just gone back to the basement and inspected the samples. It has been about two hours since I laid out the samples, and the glue has completely dried. the sample that has water sprayed on the other side, is still the flatest sample, and the two samples sealed with shellac are still very pliable and soft. In fact, almost as soft as with nothing done to it.
while I really like the best sample, the one with the water glue, I will probably seal the veneer with shellac, allow it to dry and then apply glue to one of the sealed side. And then when it dries I will iron it on to the body of the cabinet.
Anyway, I thought I would pass this little information along to everyone. |
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| John L |
| quote: | Originally posted by MJL21193
Hi John,
Nice progress. These will be truly fine looking speakers when finished!
Did you find a source for the top horn section? Seems everything from the sixties and seventies had something with that shape on it - lamps, swivel chair bases, planters...
If your stuck for a source, consider making it yourself like this:
A series of disks, each smaller than the previous one, stacked up and glued together. These would have to be cut to the correct diameter.
You could use 1/4" MDF or hardboard for the clean stepped edge (like we see on some horns), or you could go the extra distance and fill these smooth.
Also the disks could be rings, to have the centre of the horn hollow. This has the side benefit of being able to use the centre cut outs as more disks. The hollow centre could be filled with dry sand to damp resonances.
Not especially hard to layout either. Use some 1/4" graph paper (grid), joining 2 or three together to get the right width. Draw the arcs and measure each piece.
Here's just a rough sketch of what I mean: |
Hi John, No I haven't yet. I did have a member here contact me and offer his services. We corresponded, but I haven't gotten back to him yet. I was waiting until I got far enough along with the project to show how serious I was.
There is also another thing I can do. I can go to a couple of the specialty woodworkers stores here in Raleigh, and ask around for someone who has a wood lathe that will swing out for larger work. I need the disc to be at least 13" in diameter, so most lathes will not be able to to this job for me.
And too, I have pretty much figured out how to make this work best. Instead of trying to do the entire dispersal horn in one piece it may be best to to it in two pieces.
Here is how Duevel does it.
It's all in one piece like that. But it means that one end will be raw where the lathe plate is attached to the wood. I don't know how they finish the part where the plate was attached.
Note that the outer edge of the disc is about 1" thick. If I was to make two layered blanks and each one was worked on the lathe, with the outer 3/4" lower layer barely cut, and rounded, I could take the two pieces and glue them together and get a single piece of wood that is 1" thick at the outer rim and curved both top and bottom.
I would think this to be far easier for a person to turn on a lathe. And if the two pieces don't exactly fit with the same diameter, I could use a belt sander and finish the outside by hand. Then I can fill in any blanks, if any, and paint the finished product.
What do you think of that idea? |
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| MJL21193 |
| quote: | Originally posted by John L
I would think this to be far easier for a person to turn on a lathe. And if the two pieces don't exactly fit with the same diameter, I could use a belt sander and finish the outside by hand. Then I can fill in any blanks, if any, and paint the finished product.
What do you think of that idea? |
Yes, that works if you have access to a lathe (which I assumed you didn't).
Would you be using MDF or solid wood for the turning? Either is possible, with the MDF being easier to cut on the lathe and more dimensionally stable
I think I'd like it better if it were stepped, with just the widest ring rounded. It's your creation though.
Happy new year. |
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| John L |
You know, if worse comes to worse, I could indeed step it all the way around. In the end, it would most likely deflect the sound waves well. It would not look as nice as a finely flowing and polished horn though.
I had thought I would go ahead with the same material throughout, which is cabinet grade plywood. I even used that for the base.
Oh, I forgot, I can even use the spare pieces of plywood that I get from making my circular cuts with the router. I forgot about that way to use scraps. What is wrong with me. :xeye: |
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| MJL21193 |
| quote: | Originally posted by John L
You know, if worse comes to worse, I could indeed step it all the way around.
Oh, I forgot, I can even use the spare pieces of plywood that I get from making my circular cuts with the router. I forgot about that way to use scraps. What is wrong with me. :xeye: |
Or, while turning, you cound cut in some "steps". Maybe just a few near the middle.
That plywood is poplar veneer core? Could be a finishing challenge as this core will soak up a lot of primer. |
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| John L |
Ahh, but I don't have that problem because I use shellac for a sealer. Obviously you are not a user of shellac. Shellac is the ultimate sealer, or finisher that is available. You even eat shellac when you eat M&Ms. ;)
The only real limitation with it is that water and alcohol tend to ruin it's finish if left there for an extended amount of time. Table tops would work best if finished in a poly finish, or shellac with a glass top.
I always seal my wood with shellac before doing anything to it. It stores very well in flakes, and is very inexpensive to mix and apply. I simply cannot sing it's praises loud enough. And anyone who knows finishing will tell you the same thing.
Once I have sealed the wood in shellac, it will take any finish and take it well. |
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| MJL21193 |
| quote: | Originally posted by John L
Ahh, but I don't have that problem because I use shellac for a sealer. Obviously you are not a user of shellac. Shellac is the ultimate sealer, or finisher that is available.
And anyone who knows finishing will tell you the same thing.
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I used to like shellac, in my youth. Shellac is a decent sealer, but it has limitations. You can't use it as a sealer for a polyurethane finish.
Speaking of polyurethane, that is the real ultimate sealer. It's solvent stable, meaning it will not separate when applied to a very absorbent substrate like the edge of MDF (or that poplar core ply). When it cures (it cures, it doesn't dry like shellac), it's completely inert, and there isn't anything that you can't overcoat it with. |
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| John L |
| quote: | Originally posted by MJL21193
I used to like shellac, in my youth. Shellac is a decent sealer, but it has limitations. You can't use it as a sealer for a polyurethane finish. |
But that is only partially true. You are thinking about waxed shellac in it's natural form. Dewaxed shellac has none of those problems.
I have never used shellac with wax, so I don't know how it works, or doesn't work. I only use dewaxed shellac. The dewaxed variety will work on anything to the best of my knowledge. I have never had any problems with it.
Another thing, all finishes have their limitations and poly finishes are no exceptions. if the surface is damaged, you cannot spot repair it. You have to take the entire surface down and start all over.
If shellac is damaged, all you have to do is either sand away the damage, using wet sandpaper, or sandpaper and denatured alcohol. Then once the damage is gone, you can recover the damaged area with another coat of shellac, and it will blend in with the rest of the finish. |
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| MJL21193 |
| quote: | Originally posted by John L
But that is only partially true. You are thinking about waxed shellac in it's natural form. Dewaxed shellac has none of those problems.
If shellac is damaged, all you have to do is either sand away the damage, using wet sandpaper, or sandpaper and denatured alcohol. Then once the damage is gone, you can recover the damaged area with another coat of shellac, and it will blend in with the rest of the finish. |
Hi John,
Yes, it's the wax content that affects adhesion. This is a natural part of the shellac though, and it's removal diminishes it's quality.
Shellac can make a beautiful finish on a piece that will not see much abuse. It should be protected with wax though. I've done the classic French polish on a few things, but to maintain the beauty, it needs constant maintenance.
A point well made about repair being easier with the shellac finish.
There are many ways of fixing damage to pieces done with modern finishes though, such as coloured wax sticks for filling dents that will buff to a near perfect match.
I only use solvent based polyurethane as a sealer, either over solvent based stains (I don't use waterbased stains), or for MDF before priming it for paint.
Using the solvent based poly over the stain brings up the colour and highlights the grain.
I then use waterbased polyurethane clear finish on my wood projects and waterbased urethane paint for the painted projects. This is the best, most durable 1 part coating available IMHO.
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| planet10 |
| quote: | Originally posted by Kensai
Having the tweeter sitting on something (like a length of dowel) that's sitting on the B20's pole piece (yes, with the dust caps removed) |
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| OzMikeH |
Make the top part out of plaster. cast it in sand.
scrub it with a nailbrush, then coat it with gloss black paint. that will secure any remaining sand and give it a pretty cool looking surface.
Use the first one as a pattern, then shove it into the sand to make 2 more so they will be identical. |
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| John L |
| quote: | Originally posted by OzMikeH
Make the top part out of plaster. cast it in sand.
scrub it with a nailbrush, then coat it with gloss black paint. that will secure any remaining sand and give it a pretty cool looking surface.
Use the first one as a pattern, then shove it into the sand to make 2 more so they will be identical. |
Oz, that's an excellent idea! I'm wondering why I didn't think of this earlier. But that is the purpose of a thread, such as this. Imput is great isn't it. :D
Thanks a lot Oz! You're a real Pal! |
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| OzMikeH |
No wuckers. :D
It's the least I could do in thanks for such a useful thread. I've been terrified of using veneer until now.
Would be wise to use some wire mesh for reinforcement. Perhaps cement might be more durable than plaster. |
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| John L |
| quote: | Originally posted by OzMikeH
No wuckers. :D
It's the least I could do in thanks for such a useful thread. I've been terrified of using veneer until now.
Would be wise to use some wire mesh for reinforcement. Perhaps cement might be more durable than plaster. |
Tell me more about this. Please. I am serious about this, but am completely new to the process.
If I use a sand method, I will need to do it in two parts: an upper and lower, and then adhere them together.
Please explain completely and tell me what type of plaster I will need and the steps. I did some checking on plaster and there are different types.
PS: is that the same thing as "No wucking forries"? :D |
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| OzMikeH |
Yep, an abbreviation of an already cryptic figure of speech.
I've just made a model with my kid using plaster of paris. That is what gave me the idea.
You only need the hole in the ground, make the top flat. you can round the edge of the top over with a scraper while the plaster is still "green"
You carve the hole out of damp sand, I suggest making something like a giant spade drill bit out of thin plywood. If you get the right sort of sand with the right moisture content it will hold the shape well. You'll need a small trowel to scoop the "drilled" sand away. maybe a vacuum cleaner with a small hose.
If you do this in a flower pot of appropriate size the edges of the pot will be the sides and self-centre the "drill"
mix up too much plaster of paris, fill the flower pot moulds to overflowing and scrape the top off like they do with beer in belgium.
Let cure, wont take very long. then shape the top edge. |
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| MJL21193 |
This is ten times easier (and more fun) than my method!
Nice idea Mike. |
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| John L |
Here is something else we must keep in mind. Let's go back to the picture for a moment. And remember there will be no top compression horn to be erected above the horn, as in the picture
Remember, I will need to drill six holes into the dispersion horn so as to affix six supporting rods above the driver and tweater combination. Will I be able to do any precision drilling, and then tighten down the screws/bolts without cracking or breaking anything? |
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| OzMikeH |
1/3rd of a cubic foot of plaster will be rather heavy.
I'd let them rest on three legs made of flat material. No need to drill or machine it, the legs will form a cradle.
Maybe some 3mm brushed aluminium plate with various sized holes for that Lost In Space, flying saucer look.
If it was me I'd file the holes into hexagons. |
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| lousymusician |
| quote: | Originally posted by John L
Here is something else we must keep in mind. Let's go back to the picture for a moment. And remember there will be no top compression horn to be erected above the horn, as in the picture
Remember, I will need to drill six holes into the dispersion horn so as to affix six supporting rods above the driver and tweater combination. Will I be able to do any precision drilling, and then tighten down the screws/bolts without cracking or breaking anything? |
Random thoughts:
Cast the rods right into the diffusor.
Cast some coupling nuts into the diffusor, then screw the rods into those.
Cast in metal or plastic tubes, and secure the rods into them afterwords with epoxy. Make the tubes big enough to allow you to align the rods on installation, in case the tubes are a bit off vertical.
Plaster alone would be heavy and not too strong, especially if the rods must attach to a thin rim. You might find that some variation on hypertufa (a lightweight concrete made of Portland cement, peat and perlite, generally used for casting garden pots and such - Google it for more info than you could ever want) would be lighter and stronger. I don't know how easy it would be to get a smooth enough surface on it, it might need a skim coat of plaster to serve as a base for finishing.
Casting resin would be another option, but you'd need a good mold for that.
See if a local potter can spin your diffusors on a pottery wheel. A fired glazed finish could make these into works of art. Probably cost a bit, but might be worth it. Is there a college with an art department near by?
Bill |
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| John L |
I'm not quite understanding what you mean by making hexagon holes. Let me get some pictures so we can take a closer look at things.
Here is a cross section of the Venus.
In my project, the top of the horn really doesn't need to be rounded as with this Duevel, since the high compression horn on top will not be mounted there. I could even have the top completely flat. However, I don't think it would look all that pleasing since there are already too many straight lines and it needs some breaking up of this to give it a more pleasing set of lines. So, I think a slight rise/rounded top would look best, but certainly nothing like is shown here on the commercial products.
But if you look at the supporting rods in the cut-away, they are drilled into the material (wood/plaster/clay/etc) and affixed/glued/screwed to it so it will be a permanent fixture. Then is is secured to the top of the cabinet, around the cabinet's corners, next to the driver. I would think that six round rods, perhaps aluminium, would be best to work for this arrangement. That way I could use a screw or bolt to secure it to the cabinet too. And if I could not find a hollow aluminium rod, I can always use a tap and create my own threadings there for a long screw.
But a flat material on top would totally defeat the asthetics AND radiating ability of the horn effect. In fact a flat surface would not have a horn effect at all. It really needs to have a curved horn effect, or it will not work properly.
I am worried that the plaster may weigh a good bit. That is why it would have to be very secure.
Another thing: is there anything that can be used in the plaster mix that would make the mold lighter. Something such as Vermiculite, which is used in granulated form in potting soils? The vermiculite is lightweight, porous, light in color, and absorbs water. If it was mixed within the plaster cement, it would act as an aggregate to lessen the weight. |
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| John L |
| quote: | Originally posted by lousymusician
See if a local potter can spin your diffusors on a pottery wheel. A fired glazed finish could make these into works of art. Probably cost a bit, but might be worth it. Is there a college with an art department near by?
Bill [/B] |
I hate to sound like "Everyman", but I have some decent experience on the potter's wheel. When I was in the service I used to go with a friend to the Fort Jackson main craft shop. There I met a Tom Turner. I believe his first name was Tom. He had an MFA in ceramics and ran the ceramics section as a way to work out his time in service. He had been drafted right out of college into the army.
Through him I learned how to properly wedge the clay, center it on the wheel and throw a pretty good cylinder. I even made a large umbrella stand out of three cylinders. If you have never thrown clay and pulled up a cylinder, you have no idea how hard it is. The key is in centering the clay on the moving wheel. If it is off center, the cylinder will not go up in a stable wall.
I have made a lot of vases and pots, many which have been gifted and broken, and my Mother has a few. I even have some left. Here is one, a hanging basket that I still have around the house.
Anyway, because of this I fell in love with ceramics, and seriously thought about entering graduate school and major specialize in ceramics. But my BA was in history and I would have had to practically start all over. I gave up, and became an anthropologist instead. :xeye:
Anyway, doing this in ceramics was my first thought, but I realized the logistical problems doing this. I have not been on a wheel in over thirty years, so I would be very rusty. And furthermore, the community craft shop manager told me that I would have to take a cource first to prove that I could be trusted on the equipment. It's part of the standardized rules.
I may still fall back on this avenue, because it really would produce a nice piece of work.
Now there are problems doing it with clay. first off, you would have to order special clay, because the normal clay used in pottery shops and crafts centers are usually a combination of Georgia Kaolin, at least some form of fire or ball clay, perhaps some porcelain, and last but not least "Grog". Grog is a rough material that is added to the premix, and it adds roughness and body to the clay. It is not all that good for making shapes that are smooth and silky. It's also rough on the fingers, and will eat up your fingers until you have developed enough callouses. :xeye:
Anyway, I thought about it and considered it as potentially a last resort, because the next class at the craft center was on some Kooky thing that did not interest me at all. But I will think about it if I cannot come up with something more desirable.
But yes, I have seriously considered a ceramic dispersion horn.:) |
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| OzMikeH |
plates would be oriented like spokes, producing less obstruction than round legs.
not exactly what I mean but you get the general orientation and holes are what I was talking about.
If you have access to a potter's wheel that could be used to shape the sand mould. |
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| Secips |
Nice work.
Just my 2 cents.
I'd be careful in selecting the material for the diffuser as it would affect the sonic character of the speaker. That Dado set is indeed inexpensive, are the bottoms of the dado cuts flat?
You seem to be very much into your wood. A lathe is a very useful tool for woodworking. I'm surprise that with your interest in pottery and woodworking that you haven't gotten into turning bowls. Most regular wood lathes can turn 14 to 16 inches over the bed. My lathe swivels to accommodate even larger diameters. |
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| John L |
| quote: | Originally posted by Secips
Nice work.
Just my 2 cents.
I'd be careful in selecting the material for the diffuser as it would affect the sonic character of the speaker. |
I totally agree. I would suspect wood would be the best because it tends to be inert, and will not vibrate like stiff objects will. In other words, the entire energy of the sound wave will be radiated, and not absorbed by the wall and vibrate.
Ceramics may have that problem, unless the walls are made thick enough. Also, the inside would have to be filled with expandable insulation, which you can purchase at just about any hardward section. That way, the insulation would absorb any vibrations of the ceramic material. I think that would solve that problem.
| quote: | | That Dado set is indeed inexpensive, are the bottoms of the dado cuts flat? |
If you think THAT is in expensive, you should see what it is going to cost from their Dollar Days Sale, coming January12th to January 22st of this month. I just received their sales flyer in the mail yesterday, and I turned through the pages of neat buys. Suddenly, in front of my eyes, there was the same dado set , on page 5. Would you like to know how much it is selling for? Try $19.00 even! Amazing! It is so amazing that I am going to pick up another set, just in case something happens, OR as a present for someone else. $19.00 is just like giving these things away. But you probably already know that.
Does it cut flat? If I take my time and don't push it through as I would with ripping, it is not a perfect cut, but then again NO dado sets cut evenly by doing that. The moving parts are just the same as with the "Be-Pop Delux" dado sets. While I realize that Harbor Freight tools are not at the top of the heap, those tool that are not used constantly by the woodworker are Super Buys. Were I to use any expensdive dado set, on a daily basis, first I would make certain I used it in my business, so as to get a tax write-off, and secondly I would get the 'best for the least' money. And even with this, it is probably Still the best 'Cost to Use' value. After all, Dado cuts are not exposed on the outside of the woodwork, are they?
| quote: | | You seem to be very much into your wood. A lathe is a very useful tool for woodworking. I'm surprise that with your interest in pottery and woodworking that you haven't gotten into turning bowls. Most regular wood lathes can turn 14 to 16 inches over the bed. My lathe swivels to accommodate even larger diameters. |
The reason for this is self-explanatory. There are simply only so many things that one person can have the time of day to do. I just don't have the time for all the things I would love accomplish. My priorities go something like this.
My self-employed business
reading and learning things. I'm a prodigious reader.
enjoying my considerable music collection
Following politics
running the political forum I own.
BTY, did I mention politics? :D
I am self-employed, in which I make beautiful things for the interior design business. Currently, I am in the process of making a detailed swag and jabot set for a rich client, to go in her large multi-walled/windowed sun/livingroom. this requires a certain amount of woodworking ability. But most of all it requires my manual dexterity, in which I use my compressor, staple guns, and my hand and eye coordination. In other words, I am in the top 1-2% of those who have mechanical minds. When I look at Everything, I am mentally taking them apart and trying to figure out how they go back together.
But I just don't have the time to pursue a lathe, although I would love to. Also, my basement is exclusively set up for my decoration making shop, which includes my table saw/vacuum setup, and drill press, shop cabinets, and four industrial sewing machines/blind stitcher/serger. I also have a 12 foot long Gammill quilting machine for making custom bed spreads. I also have a 144" x 60" work table. Oh, I forgot, my desk unit. This takes up considerable space, and I just don't have room for a nice lathe. If I got it, I would have to make room by removing something else.
But next on my list of new things to do would be to make my own tube amplifier, make another pair of hexagon speakers,.............................
I have recently purchased some wonderful wooden pens turned on a lathe, and would love to take up that too, but where do I find the time?
Anyway, that is my problem. Oh, and I have two other underlying problems that are hard to overcome. First, when I do something, I try to to the best job possible, and can be a bit too fussy, so it takes me longer than normal to complete. And second, I have this thing about finishing things. I'm a great thinker/starter, but not the best finisher. I have to keep my nose to the grindstone, or I will think up some other new project that I just absolutely have to do, put down the current project, and be on to the next one. it's something I have to keep trying to overcome, if you understand what I mean.
Incidentially, would you be interested in contributing to my project by helping me out on the lathe end of things? I will give you the credit AND I will even pay you for your effort? How does that suit you?:) |
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| Ed LaFontaine |
John,
Just for giggles, let me know when you settle on a profile. I would need a cross-section. |
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| John L |
| quote: | Originally posted by Ed LaFontaine
John,
Just for giggles, let me know when you settle on a profile. I would need a cross-section. |
Hi Ed. The funny thing is that you and I don't cross paths here, and I was wondering just who you were, and what your avatar looked like. Now I can place you with it(as Alex Karis in Blazing saddles :D) , and I won't have any problem in the future.
I'll get in touch with you, most likely in a week. It may be a little slow going for me on the veneering job, getting it right the first time. I am taking my time and doing only one strip, on each cabinet, at a time, and then trimming, and cleaning that application before moving on to the next application. After I do this job once, I should be able to cruise through the next hexagon project. And I fully intend to do just that. In fact I already have a smaller one, with just the right veneer, lined up. But I may decide to make a seven-sided enclosure instead
I still have a little ways to go before I need the upper horn. |
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| Ed LaFontaine |
| That's fine, when you're ready. Don't overlook the lead time necessary to assemble the blank...or answer to the whims of the real boss. |
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| John L |
| quote: | Originally posted by Ed LaFontaine
That's fine, when you're ready. Don't overlook the lead time necessary to assemble the blank...or answer to the whims of the real boss. |
Right you are sir. |
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| John L |
Yesterday the weather was a little better than the day before. The temperature here in Raleigh reached a balmy 38 degrees F. So with it being so warm, and thanking my lucky stars for all this Anthropogenic Global Warming, I decided to take two of the pieces of veneer out on the back deck and seal them with three coats of Super Blond shellac.
Here I have coated one side of the veneer with the first application of shellac. It's nice and wet, and went on without a hitch. After the first doat, the second one used less shellac, and the last coat was smooth as silk. I actually wound up using almost half of that jar of shellac on these two pieces, which is quite a bit IMO.
And here I have it turned over, for the application to the back of the sheet. Note how the shellac/denatured alcohol mixture has already soaked up and actually gone all the way through to the back.
And here are the first two pieces, after I have applied three coats to front and back of both and allowed them to dry. After the wood dries, it does tend to turn a bit, so it is always best to turn the veneer over, like in the picture, so as to cut down on any more curling.
Once I let it pretty much dry outside, I brought the two in and let them finish curing, until last night. At that time I applied Heat bond glue to the sides you saw facing upward on the previous photo. That way, if there is any further curling, it will be counter to the already curled veneer. Here is what it looks like with the glue rolled liberally on to the veneer.
And here are the two carcasses with one wall of each also liberally glued. By the time for bed, the glue had still not dried completely, so I let them dry further overnight.
Then next morning, today, I checked the veneer, and found them completely dry. With them placed on top of the glued walls, they looked like this.
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