Sigh, I know. I'm terrible here. I just have so many things in my life, that have been taking up my time. I really want to get them finished. I really do. Honest.
Alright, I promise: I'll get started on the reflector's molds, so I can pour a pair and get them finished.
If I don't go fast enough, raise hell, and keep me going.
Alright, I promise: I'll get started on the reflector's molds, so I can pour a pair and get them finished.
If I don't go fast enough, raise hell, and keep me going.
>>> If I don't go fast enough, raise hell, and keep me going.
I want to see pictures!
Godzilla
http://www.zillaaudio.com/b20-mod.htm
I want to see pictures!
Godzilla
http://www.zillaaudio.com/b20-mod.htm
I just discovered this thread. Your design is close to what I was thinking of. I was going to use a bowling ball as the reflector with a smaller full range upward facing driver. Rather then a hex cabinet, I was thinking of using a round cylinder.
For everyone who has been patiently waiting for me to finish this project, I must offer my heartfelt apologies. I realize it has been a long time, and I promised to complete it, but until now have just been unable to gather the proper attitude to move forward. Well, I am finally going to give this another try.
But first, let me offer some sort of explanation about this. In a short sentence, I just lost total interest in the project. And there were several reasons. One of them was that I felt swamped over the project and thought I might never come up with a successful conclusion. The diffraction lens part is not something that is easliy accomplished. Another reason was that I had failed at producing a lens on a large lathe, and then screwed up on a casting attempt.
And another reason was that the cabinet was not the ideal size for the drivers I wanted to use. An 8" driver was just a bit small for the size of the cabinet. And yet, a 12" was just a hair too big to fit at the top . I could have made the cabinet just a bit smaller in diameter, or just a little bit larger in diameter, and it would have been near perfect. On the other hand, a 10" would work fine, but the truth is that 10" drivers are the 'bastard child' of the speaker family. Its too big to make into a two way system, and too small to be attractive when a 12" is almost the same price, and will get you more bang for the buck.
But the last reason was that I just lost interest. Perhaps it was depression, or too many things in my life at the time, but the truth is that I just couldn't bring myself to restart the project. I had left one of the cabinets at the lathe instructor's shop, which was miles away in Durham county, and the other one was in my basement shop. I had set the remaining one out of the way, but still in plain sight, just to remind me that I had a project in need of finishing. And "flaevor" is a participating member of my political/economic forum, so his presence reminded me of my responsibilities. He has been very good in not nagging me, but in the back of my mind, I can't help but feel guilt for quitting and not starting again. And the sole cabinet, left in plain sight, had this way of mentally getting lost to me. I just learned to overlook it, and not think about it.
Well, lately I have been slowly building up for another attempt at this thing, because my conscience won't leave me be. One day I was looking directly at the cabinet, and for once in a long time I actually saw it standing all alone and in need of attention. So I started thinking of how I could possibly come up with a way to make a pair of lenses and get this project done and over with. Then one night, lying in bed, I started thinking about the project and couldn't go back to sleep. When I do that I am getting intellectually serious about something. This hasn't happened to me since I spent several nights thinking about the feasibility and implementation of a Space Elevator. I know, don't ask me why I would lose sleep over a Space Elevator. It just happened because I am a big believer in getting into space and not having all of our eggs in one basket.
So now I began obsessing over this long and twisted journey. Well, to make a long story short, I went looking for my former lathe instructor, who lives in the country. But somehow I had forgotten how to find his house. I spent about three hours going along US 70 north of the 540 outer loop of Raleigh, and every road I tried, nothing looked familiar. And so I couldn't find it, no matter what I did. Things just didn't look right to me. The point is that one has to make the correct turn off US 70, travel a certain distance along a twisted road, make a left turn and then go another distance until coming to the correct gravel road on the left side of the road. Once I got there, I would have no problem making it waaaay back down the gravel road. But I had to find that gravel road first. I'm usually great with directions, but I just plain couldn't remember the way out there.
I started worrying about dementia, and my advancing age, and it was bothersome to say the very least. How could I forget something so simple and something I had visited several times? Holy Cow, how embarrassing.
Then one day last month, I was doing a job for one of my designer clients, and actually finished the job early. On the way home, I started to cross US 70, and had nothing pressing for the rest of the day. So I thought about my last attempt, and said to myself "What the Hell, let's try it again." So I got off 540 and turned toward Durham and started the process again. But I only gave cursory time to the first roads, because I had tried them several times before. I just kept driving toward Durham, trying all the roads leading to the right, and following each and every one.
I Must have tried a dozen, and kept telling myself that the road was not an intersection with a red light, so I paid more attention to the roads without a light. Next thing I knew I was into Durham County and still nothing. "Jesus, am I losing my mind" I kept thinking. I tried a few more right turns and nothing. Then I came to another red light which was red at the time. I slowly turned on to the road, and started moving out and away from US 70, but it still didn't register with me, because it was a red light interchange. But after a mile, I began noticing one or two familiar things that really weren't all that familiar, but just kinda clicked. I tried the next left and it led me to.........nothing. So I went back to the road and went further out, until I came to another left hand road. Again I turned left and went about three quarters of a mile and there was a gravel road on the left, which had several mailboxes across the road to my right. There was also a street name, but I remember there was never a street name there before, so I entered it with caution. Almost immediately I knew I had found the correct road. Eureka!!
Celebrating my success I pulled up to his home and shop, but there was nobody there. I went to the shop, peeked into the shop at several places, trying to see my long lost speaker, hoping he had not discarded it,but seeing nothing. Finally I opened the gate to the front of the house, and after trying the doorbell, I went back to the van, gathered a pad and pen, and wrote him a note. I gave him my telephone number, and left the folded note wedged in his front door. Somehow I knew he might not use the front door very much, but left it there anyway.
A couple of weeks went by, and I finally got a call from a strange name entered in my phone's CID screen. I answered and it was him. He had just found my note and wanted to tell me that yes he still had the speaker and would be more than happy for me to come and take it off his hands. I told him I would call him now that I had his number again, and waited until I had made up my mind on what to do. Then I spent several attempts to get hold of him, but Tuesday he answered the phone and we set up a time for the exchange. And that afternoon I went and picked it up on my next trip to North Raleigh. So I have both of them in my possession again.
And I finally figured out why I had forgotten how to get to his house. I was keying on the lack of a red light on US 70. But since I was out there several years ago, the county government installed a light at that intersection and mentally I had dismissed red light intersections.
Anyway, I have come up with what I believe may work. I'll explain that on the next post.
But anyway, I'm going to start work on this thing again, and work on a set of diffraction lenses. But everything is going to depend on my success in coming up with a lense that is 13.5 inches in diameter, and both match each other. Let's just cross our fingers, and hope for the best.
I've decided that if and when I finish this project, I'm going to give it to my grandson. He's a little young for this, but he just started on a saxophone, and will be interested in music. The cabinets really look nice, but they aren't perfect due to my applying the veneer after assembling the cabinet. If I do another one, I'll veneer the cabinet grade plywood, cut the pieces to measure, finish the veneer and then glue them together. I'll also make the cabinet about five inches shorter, with the diameter bigger, so as to accommodate a 12" driver with ease. And the veneer will not be a dark walnut. I don't even like walnut, and only did this because I liked the sap wood, and it reminded me of my favorite wood, Santos Rosewood. The next one will be either this one, or this one.
Again, I apologize for the extra long delay. Really.
But first, let me offer some sort of explanation about this. In a short sentence, I just lost total interest in the project. And there were several reasons. One of them was that I felt swamped over the project and thought I might never come up with a successful conclusion. The diffraction lens part is not something that is easliy accomplished. Another reason was that I had failed at producing a lens on a large lathe, and then screwed up on a casting attempt.
And another reason was that the cabinet was not the ideal size for the drivers I wanted to use. An 8" driver was just a bit small for the size of the cabinet. And yet, a 12" was just a hair too big to fit at the top . I could have made the cabinet just a bit smaller in diameter, or just a little bit larger in diameter, and it would have been near perfect. On the other hand, a 10" would work fine, but the truth is that 10" drivers are the 'bastard child' of the speaker family. Its too big to make into a two way system, and too small to be attractive when a 12" is almost the same price, and will get you more bang for the buck.
But the last reason was that I just lost interest. Perhaps it was depression, or too many things in my life at the time, but the truth is that I just couldn't bring myself to restart the project. I had left one of the cabinets at the lathe instructor's shop, which was miles away in Durham county, and the other one was in my basement shop. I had set the remaining one out of the way, but still in plain sight, just to remind me that I had a project in need of finishing. And "flaevor" is a participating member of my political/economic forum, so his presence reminded me of my responsibilities. He has been very good in not nagging me, but in the back of my mind, I can't help but feel guilt for quitting and not starting again. And the sole cabinet, left in plain sight, had this way of mentally getting lost to me. I just learned to overlook it, and not think about it.
Well, lately I have been slowly building up for another attempt at this thing, because my conscience won't leave me be. One day I was looking directly at the cabinet, and for once in a long time I actually saw it standing all alone and in need of attention. So I started thinking of how I could possibly come up with a way to make a pair of lenses and get this project done and over with. Then one night, lying in bed, I started thinking about the project and couldn't go back to sleep. When I do that I am getting intellectually serious about something. This hasn't happened to me since I spent several nights thinking about the feasibility and implementation of a Space Elevator. I know, don't ask me why I would lose sleep over a Space Elevator. It just happened because I am a big believer in getting into space and not having all of our eggs in one basket.
So now I began obsessing over this long and twisted journey. Well, to make a long story short, I went looking for my former lathe instructor, who lives in the country. But somehow I had forgotten how to find his house. I spent about three hours going along US 70 north of the 540 outer loop of Raleigh, and every road I tried, nothing looked familiar. And so I couldn't find it, no matter what I did. Things just didn't look right to me. The point is that one has to make the correct turn off US 70, travel a certain distance along a twisted road, make a left turn and then go another distance until coming to the correct gravel road on the left side of the road. Once I got there, I would have no problem making it waaaay back down the gravel road. But I had to find that gravel road first. I'm usually great with directions, but I just plain couldn't remember the way out there.
I started worrying about dementia, and my advancing age, and it was bothersome to say the very least. How could I forget something so simple and something I had visited several times? Holy Cow, how embarrassing.
Then one day last month, I was doing a job for one of my designer clients, and actually finished the job early. On the way home, I started to cross US 70, and had nothing pressing for the rest of the day. So I thought about my last attempt, and said to myself "What the Hell, let's try it again." So I got off 540 and turned toward Durham and started the process again. But I only gave cursory time to the first roads, because I had tried them several times before. I just kept driving toward Durham, trying all the roads leading to the right, and following each and every one.
I Must have tried a dozen, and kept telling myself that the road was not an intersection with a red light, so I paid more attention to the roads without a light. Next thing I knew I was into Durham County and still nothing. "Jesus, am I losing my mind" I kept thinking. I tried a few more right turns and nothing. Then I came to another red light which was red at the time. I slowly turned on to the road, and started moving out and away from US 70, but it still didn't register with me, because it was a red light interchange. But after a mile, I began noticing one or two familiar things that really weren't all that familiar, but just kinda clicked. I tried the next left and it led me to.........nothing. So I went back to the road and went further out, until I came to another left hand road. Again I turned left and went about three quarters of a mile and there was a gravel road on the left, which had several mailboxes across the road to my right. There was also a street name, but I remember there was never a street name there before, so I entered it with caution. Almost immediately I knew I had found the correct road. Eureka!!
Celebrating my success I pulled up to his home and shop, but there was nobody there. I went to the shop, peeked into the shop at several places, trying to see my long lost speaker, hoping he had not discarded it,but seeing nothing. Finally I opened the gate to the front of the house, and after trying the doorbell, I went back to the van, gathered a pad and pen, and wrote him a note. I gave him my telephone number, and left the folded note wedged in his front door. Somehow I knew he might not use the front door very much, but left it there anyway.
A couple of weeks went by, and I finally got a call from a strange name entered in my phone's CID screen. I answered and it was him. He had just found my note and wanted to tell me that yes he still had the speaker and would be more than happy for me to come and take it off his hands. I told him I would call him now that I had his number again, and waited until I had made up my mind on what to do. Then I spent several attempts to get hold of him, but Tuesday he answered the phone and we set up a time for the exchange. And that afternoon I went and picked it up on my next trip to North Raleigh. So I have both of them in my possession again.
And I finally figured out why I had forgotten how to get to his house. I was keying on the lack of a red light on US 70. But since I was out there several years ago, the county government installed a light at that intersection and mentally I had dismissed red light intersections.
Anyway, I have come up with what I believe may work. I'll explain that on the next post.
But anyway, I'm going to start work on this thing again, and work on a set of diffraction lenses. But everything is going to depend on my success in coming up with a lense that is 13.5 inches in diameter, and both match each other. Let's just cross our fingers, and hope for the best.
I've decided that if and when I finish this project, I'm going to give it to my grandson. He's a little young for this, but he just started on a saxophone, and will be interested in music. The cabinets really look nice, but they aren't perfect due to my applying the veneer after assembling the cabinet. If I do another one, I'll veneer the cabinet grade plywood, cut the pieces to measure, finish the veneer and then glue them together. I'll also make the cabinet about five inches shorter, with the diameter bigger, so as to accommodate a 12" driver with ease. And the veneer will not be a dark walnut. I don't even like walnut, and only did this because I liked the sap wood, and it reminded me of my favorite wood, Santos Rosewood. The next one will be either this one, or this one.
Again, I apologize for the extra long delay. Really.
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Your grandson is a lucky guyI can't wait to see your progress on these
I feel your pain on stopping projects near completion, I have a few of those hanging around
In all honesty, I'm really worried that I won't be able to finish it. The problem is that the two pieces for the lenses are unfired green ware. And in order to make a mold I'm going to have to pour plaster around each piece.
I never showed what they look like, but here they are together.
An externally hosted image should be here but it was not working when we last tested it.
I'm only going to get one shot at this, because the plaster, when it sets up, will expand, rather than shrink like everything else. And the force is going to crack each clay piece and ruin them. If it doesn't work out right, I'm screwed.
But lets say I get the two molds to work, what am I going to do then? I already have pictures of the two completed mold frames but haven' had time to post them here. So if they do work, what am I going to use to pour inside the mold? And how much is this going to cost?
And here is where I will need some help. If I use an epoxy resin, its going to cost a good bit. Each mold will be just a one piece mold, with the inside open. I will use something to help fill up the space, but it will still require a whole lot of resin. And resin is really expensive. It will most likely require 2 gallons too, one for each diffusion lens.
Of course there is another approach. I could use a fiberglass application. It would be less expensive, but come with all the bad fumes and headaches.
So I will need to see if there is anyone who has worked with epoxy resins, fiberglass, or both. If so, perhaps that someone can give me some expert advice, because I have never worked with either of the products.
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John,
I have SOME experience with epoxy and fiberglass having built a cedar-strip canoe and a few other smaller projects. Ask away (here or PM) and I'll see if I can help. If it's fumes you're worried about, check out MAS epoxies (MAS Epoxies - Easy Epoxy Resin & Adhesives. Marine Epoxy for Boat Repair & Boat Building; Automotive Epoxy; Epoxy for Woodworking, Signs, Surfboards, Other. New: Eco-Friendly Acetone Replacement, Non-Skid Repair).
Also, I don't really understand your process here. You have green moulds to use for casting the diffraction lenses? So there's a cavity inside these moulds into which you want to pour plaster? Or are you forming around the outside of these and somehow using that? Are you concerned that if you fire the greenware it'll change dimensions? Sorry for being dense, but I just don't get it. A little more explanation would help.
Thanks
I have SOME experience with epoxy and fiberglass having built a cedar-strip canoe and a few other smaller projects. Ask away (here or PM) and I'll see if I can help. If it's fumes you're worried about, check out MAS epoxies (MAS Epoxies - Easy Epoxy Resin & Adhesives. Marine Epoxy for Boat Repair & Boat Building; Automotive Epoxy; Epoxy for Woodworking, Signs, Surfboards, Other. New: Eco-Friendly Acetone Replacement, Non-Skid Repair).
Also, I don't really understand your process here. You have green moulds to use for casting the diffraction lenses? So there's a cavity inside these moulds into which you want to pour plaster? Or are you forming around the outside of these and somehow using that? Are you concerned that if you fire the greenware it'll change dimensions? Sorry for being dense, but I just don't get it. A little more explanation would help.
Thanks
I've been studying this eposy resin product more closely since my last post on it, and I think I understand a little bit more on the cost factor. And I also lay awake last night, wasting sleep.....again, but came up with a way to cut down on my need for a lot of epoxy resin.
Here's how I can do this. If I am successful with the plaster cast, I will turn the cast upside down and the base will become the top. Instead of trying to anticipate how to create an insert which would be attached to the underside of the top lid, there is a better way.
I could take some thin plastic kitchen cellophane, and work it around the inside of the cast. Then get a bunch of clay and fill every nick and cranny of the inside with all the clay until I have it totally filled up.
Then just remove the clay by turning the cast upside down and let gravity cause it to come out. Once I have the contoured clay out I can place it on the cover and sculpt/remove the amount of clay I want gone. I can make the walls of the diffraction lens just thick enough to make it rigid and durable, yet light weight and easy to work with.
I also won't have to use so much of that expensive resin. Then I can set up the lid, drill holes for pouring the resin into the mold, and do it that way. When it sets up, just remove the lid, and pull the resin shell out of the mold.
Once it is removed, I can glue the two halves together. And if I need to, I can make a small hole and fill the cavity with styrofoam, in order to give it more strength. Then just fill up the holes and finish.
Here's how I can do this. If I am successful with the plaster cast, I will turn the cast upside down and the base will become the top. Instead of trying to anticipate how to create an insert which would be attached to the underside of the top lid, there is a better way.
I could take some thin plastic kitchen cellophane, and work it around the inside of the cast. Then get a bunch of clay and fill every nick and cranny of the inside with all the clay until I have it totally filled up.
Then just remove the clay by turning the cast upside down and let gravity cause it to come out. Once I have the contoured clay out I can place it on the cover and sculpt/remove the amount of clay I want gone. I can make the walls of the diffraction lens just thick enough to make it rigid and durable, yet light weight and easy to work with.
I also won't have to use so much of that expensive resin. Then I can set up the lid, drill holes for pouring the resin into the mold, and do it that way. When it sets up, just remove the lid, and pull the resin shell out of the mold.
Once it is removed, I can glue the two halves together. And if I need to, I can make a small hole and fill the cavity with styrofoam, in order to give it more strength. Then just fill up the holes and finish.
Thanks for the link. I'll check it out in a few minutes.
As for the mold, I am going to use the plaster only to make the mold. I have constructed a plywood frame for both halves already. Let me go get some pictures. But first I will have to upload them into my Webshots account.
Here are some pictures.
Bottom section base
I just keep building up the inner portion, so as not to waste so much plaster.
And I just do the same thing for the upper section.
I know things look a little bit rough, but I figured that would made the plaster frame more secure inside the plywood. I'm thinking about adding some screws to the inside of each shelf in order to keep everything in one piece. If this works out right, I can store them when they are finished and possibly make more when/if I want to build another pair.
I really don't particularly like walnut, for some reason, and wish I had gone with a nicer veneer, that had burls.
Bottom section base
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I just keep building up the inner portion, so as not to waste so much plaster.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
And I just do the same thing for the upper section.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I know things look a little bit rough, but I figured that would made the plaster frame more secure inside the plywood. I'm thinking about adding some screws to the inside of each shelf in order to keep everything in one piece. If this works out right, I can store them when they are finished and possibly make more when/if I want to build another pair.
I really don't particularly like walnut, for some reason, and wish I had gone with a nicer veneer, that had burls.
Is this the same type of epoxy as that at " masepoxies.com "? They both look close to the same thing.
Glad to see you back at work on this project.
Another source of high quality epoxy, at reasonable prices is Raka (Raka, Inc. 772-489-4070, Epoxy-Fiberglass-Carbon-Kevlar) If you are looking for a local supplier check the phone directory, there should be a supplier locally in an area as large as yours...
You can also stretch epoxy resins by adding material to the mix. the material only needs to be granular in nature, and non-reactive to the epoxy. An example would be the Kenwood Turntables like my KD-500 made back in the early '70's with quartz or granite in an epoxy matrix. I believe some of the modern countertop materials like Corian are a similar matrix.
You may want to consider a vibratory table with the molds you are constructing. You may end up with unwanted voids from air bubbles otherwise...
Is this the project in which you'll use the Pioneer " Coax's " you built?
Another alternative to plaster would be to make a mold negative with Fiberglass, or FRP, and then make a positive mold cast from the mold negative. I've experience with building Race Car bodies by a couple of different methods using glass mesh with both epoxy and styrene monomer resins. It's possible to reproduce quite complex shapes when properly applied. I'd be glad to help if I can.
Keep going while you've got traction! I'm anxious to see this project completed too.
John
Another source of high quality epoxy, at reasonable prices is Raka (Raka, Inc. 772-489-4070, Epoxy-Fiberglass-Carbon-Kevlar) If you are looking for a local supplier check the phone directory, there should be a supplier locally in an area as large as yours...
You can also stretch epoxy resins by adding material to the mix. the material only needs to be granular in nature, and non-reactive to the epoxy. An example would be the Kenwood Turntables like my KD-500 made back in the early '70's with quartz or granite in an epoxy matrix. I believe some of the modern countertop materials like Corian are a similar matrix.
You may want to consider a vibratory table with the molds you are constructing. You may end up with unwanted voids from air bubbles otherwise...
Is this the project in which you'll use the Pioneer " Coax's " you built?
Another alternative to plaster would be to make a mold negative with Fiberglass, or FRP, and then make a positive mold cast from the mold negative. I've experience with building Race Car bodies by a couple of different methods using glass mesh with both epoxy and styrene monomer resins. It's possible to reproduce quite complex shapes when properly applied. I'd be glad to help if I can.
Keep going while you've got traction! I'm anxious to see this project completed too.
John
Thanks for the encouragement. And yes, its the one with the Pioneer BOFU.
Regarding filler/aggregate I have done considerable reading on related things, and one of the recommended fillers what seems to have special qualities is crushed pecan shells. I love pecans and may want to go buy a bag of pecans in their shell, just to use them. I can see one advantage to them in that if you needed to sand the product, that could be done easier. I'll want to do that anyway, since I will want to paint the finish and rough surfaces will make for a better adherence.
I don't honestly know as neither provides much in the way of chemistry. MAS had developed a very unusual (at the time, early 1990s) epoxy resin which had low off-gassing and didn't form an amine blush (which with other systems had to be cleaned with acetone!). It was a boon to boat-builders who didn't want to use acetone and often developed sensitivity to other resins. I met the chemist who developed the resin and the company as they were doing their initial marketing and he convinced me to try it. I cleaned my boat with acetone after the fiberglass layup (he said it wouldn't hurt but wasn't needed) and my next layer failed to cross-link with the layer beneath, causing peeling. He and I had some discussions which, I think, led to some reformulations which, because I had all I needed of the first formulation and haven't done any projects since, I didn't look into it further.
BTW, my brother in law does some plaster casting, and he often casts with multiple thin coatings where expansion and heating might cause a problem. He applies the plaster, shakes it vigorously while it does it's initial cure to coat evenly, then lets it cure a little more before adding more plaster. I can ask him about how it might be done if that's of interest.
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