That's right: West Systems epoxy (resin = 105 and hardener = 205), not polyester resin. I wanted the strength of epoxy and read that the epoxy fumes are far less problematic. That's not to say they're not problematic at all, of course, but I used polyester resin to fix a canoe once, and I don't miss it. Also, since I used the West Systems epoxy with some talc as filler to fill the kerfs in the mdf, it was convenient not to have to worry about compatibility issues when laying on the fiberglass.
Few
Few
John: I know you've had success spraying the ARMORSEAL 1K Waterbased Urethane Floor Enamel, as you described in the high gloss finishing thread, but I wondered if you had ever tried applying it with a brush or roller. An air compressor and spray gun are on my list of "things to acquire" but not yet on my list of "stuff I own but don't have room to store." If spraying is the only hope for a decent finish I might consider accelerating the purchase process, but I'd probably have to sneak the equipment into the house in the dead of night to avoid spousal backlash. I don't have a good place to spray, either, although I guess I could limit myself to good weather conditions and do it outside. Anyway, do you see any hope for a nice speaker finish with the Armorseal without spraying? I'm worried that the curved surfaces of my baffles would make it harder to just lay on a heavy coat and let it self-level---if that would even be an appropriate approach.
Few
Few
Hi Few,
I have tried that approach, and I detailed the results in this thread using the Armorseal with a foam roller. TBH, the time and effort required would not be worth it. The Armorseal dries too fast, and that leaves it too rough.
I have tried it before with solvent based urethane paint - it dries slower and therefore runs out smoother. The results were better, but it's a long wait for the paint to dry.
In the end, you can't beat a decent spray job.
I've been experimenting lately and have changed up again. I am back to the solvent based paint, but as a base coat. I then spray on lots of clear urethane, about 10 coats. This is the surface that will get sanded and polished. I'm seeing better colour (the Armorseal was black but not as black as I'd like) and reflectivity. The clear is also less messy to sand and when left to cure for a couple weeks, is very hard and scratch resistant.
You could try this method without a sprayer. Use a roller to put on a couple of coats of paint, sand between coats and then roll on several layers of clear, enough so that when you sand it, you don't burn through. Worth a try, for sure.
Here's the speaker now, 3 coats of black Tremclad and 10 coats of Varathane clear polyurethane.
I have tried that approach, and I detailed the results in this thread using the Armorseal with a foam roller. TBH, the time and effort required would not be worth it. The Armorseal dries too fast, and that leaves it too rough.
I have tried it before with solvent based urethane paint - it dries slower and therefore runs out smoother. The results were better, but it's a long wait for the paint to dry.
In the end, you can't beat a decent spray job.
I've been experimenting lately and have changed up again. I am back to the solvent based paint, but as a base coat. I then spray on lots of clear urethane, about 10 coats. This is the surface that will get sanded and polished. I'm seeing better colour (the Armorseal was black but not as black as I'd like) and reflectivity. The clear is also less messy to sand and when left to cure for a couple weeks, is very hard and scratch resistant.
You could try this method without a sprayer. Use a roller to put on a couple of coats of paint, sand between coats and then roll on several layers of clear, enough so that when you sand it, you don't burn through. Worth a try, for sure.
Here's the speaker now, 3 coats of black Tremclad and 10 coats of Varathane clear polyurethane.
Attachments
Thanks for bringing that thread to my attention. I hadn't seen it. Thanks also for including the photo of your latest paint job. Looks great! You're providing a moving target for the rest of us, though. I had just nailed down a local source for the Armorseal paint and now you've forged a different path for me to follow!
Fortunately or unfortunately, I can't decide which, this all provides one more nudge in the direction of a compressor and paint spraying set up. It's too bad it seems a pretty good sized compressor ($$) would be required. I'd want to be able to use it for Venturi vacuum press duties as well. One example of those systems requires at least a five gallon tank and 4.8 cfm @ 80 psi. Would satisfying those criteria also put me in good shape for spraying paint or do I need to look at the cfm delivered in some other pressure range? I guess a related question is whether an HVLP type gun is the way to go. Reading the "high gloss finish" thread I wasn't able to draw a clear conclusion on that point.
I've taken a couple more steps on the curved baffle. I applied one more layer of fiberglass to ensure everything would be stiff enough. It's certainly a helluva lot stiffer now that before the fiberglass was applied. Pretty impressive. I'll be interested to see what a layer of fiberglass on the back side (of the baffle, that is) does to the stiffness.
I also added a coating of epoxy to fill the weave of the fiberglass. I didn't get the weave absolutely filled in all spots but I'm thinking I might do some spot filling with Bondo, lots of sanding, more Bondo, lots of sanding... until I get to the point where I can slap some high fill primer on the result. Anyway, here are some photos of the baffle after one coating of epoxy to fill the weave.
As you can probably see, there are pinholes where small bubbles found their way into my epoxy coating. I probably could or should have exercised more care, but I figured I had a bunch of sanding ahead of me to tweak the shape of the surface and the bubbles would be taken care of in that process. Time will tell whether that was a good decision. I'll need to sand the surface before going to the Bondo---or one more layer of epoxy---stage anyway, so I'm hoping that will make it clear what the next step ought to be.
Few
Fortunately or unfortunately, I can't decide which, this all provides one more nudge in the direction of a compressor and paint spraying set up. It's too bad it seems a pretty good sized compressor ($$) would be required. I'd want to be able to use it for Venturi vacuum press duties as well. One example of those systems requires at least a five gallon tank and 4.8 cfm @ 80 psi. Would satisfying those criteria also put me in good shape for spraying paint or do I need to look at the cfm delivered in some other pressure range? I guess a related question is whether an HVLP type gun is the way to go. Reading the "high gloss finish" thread I wasn't able to draw a clear conclusion on that point.
I've taken a couple more steps on the curved baffle. I applied one more layer of fiberglass to ensure everything would be stiff enough. It's certainly a helluva lot stiffer now that before the fiberglass was applied. Pretty impressive. I'll be interested to see what a layer of fiberglass on the back side (of the baffle, that is) does to the stiffness.
I also added a coating of epoxy to fill the weave of the fiberglass. I didn't get the weave absolutely filled in all spots but I'm thinking I might do some spot filling with Bondo, lots of sanding, more Bondo, lots of sanding... until I get to the point where I can slap some high fill primer on the result. Anyway, here are some photos of the baffle after one coating of epoxy to fill the weave.
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.
As you can probably see, there are pinholes where small bubbles found their way into my epoxy coating. I probably could or should have exercised more care, but I figured I had a bunch of sanding ahead of me to tweak the shape of the surface and the bubbles would be taken care of in that process. Time will tell whether that was a good decision. I'll need to sand the surface before going to the Bondo---or one more layer of epoxy---stage anyway, so I'm hoping that will make it clear what the next step ought to be.
Few
Few said:
This is a cheap paint job compared to the automotive paint that I was considering using. The results are a compromise only on the final hardness of the finish. Solvent based clear urethane cures pretty hard though and definitely hard enough for the intended use.
Few said:
An investment that pays for itself , if you do a lot of the old DIY. Paint spraying, venturi vacuum pump, nail guns, inflating your car tires, blowing dust out of things, the list goes on...
As far as paint guns go, it's probably best to get a standard gravity feed non-HVLP gun. If your projects are small, the paint wasted to overspray won't amount to much anyway.
I have a Cambell Hausfeld DH7800 that I've had for 2 years. It works very well for the cost ($120.00 at the time). I lack a decent compressor though, mine is about 10 years old - a portable 2hp twin tank Dewalt. Not enough air for serious painting.
Few said:
Doing the inside will create a sandwich panel that will be extremely rigid. Excellent construction!
The pinholes in the epoxy should be easy enough to sand out and fill. You could use automotive spot putty instead of bondo for these, just to get them filled and out of the way.
Looking good.
Have you started the other one yet?
I'll take a look at the paint gun suggestion; thanks. The $75 price at the link you provided isn't too bad. The cost of the compressor is the harder pill to swallow. Maybe I can come up with something that will get the job done but not break the bank.
The sandwich construction resulting from wrapping the MDF in fiberglass was the original motivation for this project---that, and my desire to build something with interesting curves instead of the usual rectilinear boxes. I was very impressed with the results Andy Payor achieved with his Rockport speaker cabinets. I'm not likely to invest the funds he does into his speakers, but there's no arguing with his results. TRULY stiff and dead panels.
Thanks for the spot putty suggestion. I'll have to look into that. I haven't started the second baffle yet, but I'm taking some time off from work next week and hope to make a burst of progress. I also need to try out some of my ideas for the electrostatic panels I'll be building. Looks like a busy week!
Few
The sandwich construction resulting from wrapping the MDF in fiberglass was the original motivation for this project---that, and my desire to build something with interesting curves instead of the usual rectilinear boxes. I was very impressed with the results Andy Payor achieved with his Rockport speaker cabinets. I'm not likely to invest the funds he does into his speakers, but there's no arguing with his results. TRULY stiff and dead panels.
Thanks for the spot putty suggestion. I'll have to look into that. I haven't started the second baffle yet, but I'm taking some time off from work next week and hope to make a burst of progress. I also need to try out some of my ideas for the electrostatic panels I'll be building. Looks like a busy week!
Few
I used a random orbit sander and fairly coarse sandpaper (150 grit) to clean up the layer of epoxy I'd applied to fill the fiberglass weave. I need to get a better dust mask, but other than that the process went pretty smoothly (no sanding pun intended). It didn't take much to remove the pin holes that resulted from air bubbles in the epoxy. There were a few spots where the weave texture wasn't quite filled, and a couple of small low spots, but I haven't yet seen evidence of major glitches in the shape of the surface. So, I decided that there's no need to go nuts with Bondo. Instead, I decided to use a spatula instead of a brush and apply one more thin layer of epoxy. I found it a little harder to achieve a uniform thickness of epoxy, partly because I had to navigate over the curved surface, but the spatula reduced the number of pin holes from air bubbles. I'll leave it to harden up overnight and do some sanding with finer paper tomorrow.
The area where I ran into some trouble getting the fiberglass to follow the intended shape is where it wraps over the sharp edges of the baffle. I was worried about getting it to conform to the compound curves right around the woofer rings, and didn't foresee that the real problem was going to be getting the fiberglass to lay nicely over the sharp 90 degree bend at the baffle's edges. The problem was aggravated by the fact that my fiberglass pieces were just barely wide enough to span the baffle. I was thinking of using some hardwood strips along the two vertical edges of the baffle anyway, so it looks like I'll be going ahead with that plan.
At some point I have to get brave enough to use a router to remove the cotton/fiberglass/epoxy from the woofer holes. I'm going to try to use a bearing guided bit and use the inner diameter of the MDF woofer rings as the guides. It shouldn't be a major problem but I have to admit it makes me a bit nervous anyway. The more progress I make the more I'll have to redo if I do something stupid and irreversible! This second weave-filling coating of epoxy looks pretty good, though, so I think it shouldn't be too painful to sand it down to the point where I can start experimenting with high build primer.
Anybody have advice on a good brand of high build primer in a rattle can? Even if I pull the trigger on a compressor and paint gun I'll probably want to be experimenting with the primer before a gun and compressor could arrive. Also, advice on a brand of polishing compound for the painted surfaces would be much appreciated as well.
Few
The area where I ran into some trouble getting the fiberglass to follow the intended shape is where it wraps over the sharp edges of the baffle. I was worried about getting it to conform to the compound curves right around the woofer rings, and didn't foresee that the real problem was going to be getting the fiberglass to lay nicely over the sharp 90 degree bend at the baffle's edges. The problem was aggravated by the fact that my fiberglass pieces were just barely wide enough to span the baffle. I was thinking of using some hardwood strips along the two vertical edges of the baffle anyway, so it looks like I'll be going ahead with that plan.
At some point I have to get brave enough to use a router to remove the cotton/fiberglass/epoxy from the woofer holes. I'm going to try to use a bearing guided bit and use the inner diameter of the MDF woofer rings as the guides. It shouldn't be a major problem but I have to admit it makes me a bit nervous anyway. The more progress I make the more I'll have to redo if I do something stupid and irreversible! This second weave-filling coating of epoxy looks pretty good, though, so I think it shouldn't be too painful to sand it down to the point where I can start experimenting with high build primer.
Anybody have advice on a good brand of high build primer in a rattle can? Even if I pull the trigger on a compressor and paint gun I'll probably want to be experimenting with the primer before a gun and compressor could arrive. Also, advice on a brand of polishing compound for the painted surfaces would be much appreciated as well.
Few
Apparently I missed the "edit window" before I could stick a couple of "before and after" photos into my last post. I'm not sure they add much anyway, but I'll include them for the visual learners, as we say in the education biz.
The first photo was posted before. It shows the baffle after the first weave-filling epoxy coating, applied with a chip brush. The second photo shows the result after sanding the first coat and applying a second epoxy coat with a spatula. No subsequent sanding (yet). I'm not sure if it comes through in the photos, but the second coating looks significantly smoother when viewed in person.
The ugly flare in the bottom right corner of the second photo is a reflection of a compact fluorescent light bulb hanging from the ceiling. Clearly I'm not setting a very high photographic standard with these snapshots, but I hope they convey the key points. If and when I have a shiny and smooth painted speaker to show off I'll bust out the fancier photographic equipment and be a bit more anal about that part.
Few
The first photo was posted before. It shows the baffle after the first weave-filling epoxy coating, applied with a chip brush. The second photo shows the result after sanding the first coat and applying a second epoxy coat with a spatula. No subsequent sanding (yet). I'm not sure if it comes through in the photos, but the second coating looks significantly smoother when viewed in person.
The ugly flare in the bottom right corner of the second photo is a reflection of a compact fluorescent light bulb hanging from the ceiling. Clearly I'm not setting a very high photographic standard with these snapshots, but I hope they convey the key points. If and when I have a shiny and smooth painted speaker to show off I'll bust out the fancier photographic equipment and be a bit more anal about that part.
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.
Few
Nothing like a day off from work to make a bit of progress... Today I cut out all six woofer rings for the second baffle, a process that spread over several days for the first baffle. The time I invested in creating jigs to speed and simplify the tasks really paid off.
I also bit the bullet and opened up the woofer holes in baffle #1. I used a jigsaw set to cut with no orbital motion to rough out the holes, being careful to cut through the epoxy and fiberglass but avoid the MDF woofer rings. I then used a router bit with a bearing guide on its end to cut the fiberglass flush with the inside diameter of the woofer rings. After a few tweaks to get things set up properly, it worked like a champ. The fiberglass goes through jigsaw blades at an alarming rate, but .this method still beat doing the (w)hole thing with a router. I used one of the new woofer rings as a template to mark the positions of the woofer rings that are hidden by the fiberglass. I then cut within about 1/4 inch of my marks and used the router for the rest. I can finally see what the woofers will look like when mounted in their final positions. I like the fact that there will be no mounting screws visible from the front when all is completed.
I also cleaned up the rear edges of baffle #1. It was a bit dicey at first because I couldn't come up with an elegant way to deal with what started out as such a rough and jagged composite of epoxy, fiberglass, and cotton. I ended up using my jigsaw to cut the fiberglass as close to the MDF edge as I could, and then used very coarse sandpaper in my random orbit sander to take down the remainder until I got the fiberglass flush with the rear surface of the baffles. I turned out better than I thought it would while it was in the throes of hacking away at the rough fiberglass edge with the jigsaw.
I still have to sand the rear surface of the baffle to prepare it for one or two layers of fiberglass. That'll be a task for tomorrow.
Tomorrow I also hope to bend baffle #2 into its ultimate curved shape and fill the kerfs with epoxy. (One of my previous posts---a reply to the question of whether I had started baffle #2 yet---may have been misleading. I cut the kerfs into the second baffle at the same time I kerfed baffle #1 but otherwise baffle #2 has been waiting in the wings.) I'll either repeat the popsicle stick trick described previously, or come up with something that fills the kerfs even more fully so I can reduce the volume of epoxy required.
Few
I also bit the bullet and opened up the woofer holes in baffle #1. I used a jigsaw set to cut with no orbital motion to rough out the holes, being careful to cut through the epoxy and fiberglass but avoid the MDF woofer rings. I then used a router bit with a bearing guide on its end to cut the fiberglass flush with the inside diameter of the woofer rings. After a few tweaks to get things set up properly, it worked like a champ. The fiberglass goes through jigsaw blades at an alarming rate, but .this method still beat doing the (w)hole thing with a router. I used one of the new woofer rings as a template to mark the positions of the woofer rings that are hidden by the fiberglass. I then cut within about 1/4 inch of my marks and used the router for the rest. I can finally see what the woofers will look like when mounted in their final positions. I like the fact that there will be no mounting screws visible from the front when all is completed.
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 also cleaned up the rear edges of baffle #1. It was a bit dicey at first because I couldn't come up with an elegant way to deal with what started out as such a rough and jagged composite of epoxy, fiberglass, and cotton. I ended up using my jigsaw to cut the fiberglass as close to the MDF edge as I could, and then used very coarse sandpaper in my random orbit sander to take down the remainder until I got the fiberglass flush with the rear surface of the baffles. I turned out better than I thought it would while it was in the throes of hacking away at the rough fiberglass edge with the jigsaw.
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 still have to sand the rear surface of the baffle to prepare it for one or two layers of fiberglass. That'll be a task for tomorrow.
Tomorrow I also hope to bend baffle #2 into its ultimate curved shape and fill the kerfs with epoxy. (One of my previous posts---a reply to the question of whether I had started baffle #2 yet---may have been misleading. I cut the kerfs into the second baffle at the same time I kerfed baffle #1 but otherwise baffle #2 has been waiting in the wings.) I'll either repeat the popsicle stick trick described previously, or come up with something that fills the kerfs even more fully so I can reduce the volume of epoxy required.
Few
I've made a bit of progress since my last post. I filled the kerfs of the second baffle with the same epoxy/talc/popsicle stick combination I used on baffle #1. Before doing so I had to cut down the baffle to match the width of the first one, and use hot melt glue to fix the baffle to the supports the define the baffle's curve. As far as I can tell so far, these steps went smoothly.
I also applied fiberglass and epoxy to the rear surface of baffle #1. In order to avoid having dripping epoxy muck up the work I had done so far I had to protect several surfaces with tape. Clear packaging tape has the advantage of not sticking to epoxy, but the tape didn't stick well to the dusty MDF surfaces. I ended up applying masking tape to the MDF surface I wanted to protect (the outside baffle edges and the insides of the woofer holes) and then applying clear packaging tape over the masking tape. I used a razor blade to trim the tape flush with the surface of the MDF. The process was a bit time consuming, and I wondered if it was a waste of time, but I've since seen that it was time well spent.
When I applied epoxy to the rear surface of the baffle there were a couple of spots where the protective tape I applied prevented the fiberglass from lying down nicely on the MDF surface. I had to apply small pieces of polyethylene sheet to the epoxy and then use a clamp to hold things in place. The polythylene absolutely refuses to stick to the epoxy (or vice versa...) so I've used this trick a couple of times. It's been quite handy.
The first photo shows the tape protection process for the woofer holes. The bottom hole has been protected with tape and the tape has been trimmed flush with the MDF. The middle hole has had the tape applied but it hasn't yet been trimmed. The top hole hasn't yet been protected.
The second and third photo show the polyethylene and clamp trick. I used a popsicle stick to distribute the clamping force. Apparently I can't do much without popsicle sticks.
The next two photos show the rear surface after two layers of fiberglass have been applied, two additional epoxy coatings have been applied to fill the weave texture, and I've used my newly purchased Bosch Palm Router to remove the excess fiberglass from the woofer holes. Great tool! Sometimes I think I build speakers so I'll have reasons to buy tools...
While I was out buying tools I bought a better mask to protect myself from the particulates and volatile organic nasties. The thought of inhaling fiberglass fibers as I used the router to trim the fiberglass around the woofer holes started to keep me up at night so I decided to invest in a better mask. I'm surprised how comfortable it is. It's actually more pleasant to wear than the cheap, and essentially useless, white fabric masks that come with a moldable metal band to fit over the bridge over your nose and an elastic band to fit around the back of your head. Routing the fiberglass is still nasty, but I was very glad to have the new mask.
That's it for now. Tomorrow I have to start serving in my new position at work so my flurry of activity is likely to revert to being intermittent fits of progress again. The good news is that each step on baffle #2 is going much more quickly than it did the first time around.
Few
I also applied fiberglass and epoxy to the rear surface of baffle #1. In order to avoid having dripping epoxy muck up the work I had done so far I had to protect several surfaces with tape. Clear packaging tape has the advantage of not sticking to epoxy, but the tape didn't stick well to the dusty MDF surfaces. I ended up applying masking tape to the MDF surface I wanted to protect (the outside baffle edges and the insides of the woofer holes) and then applying clear packaging tape over the masking tape. I used a razor blade to trim the tape flush with the surface of the MDF. The process was a bit time consuming, and I wondered if it was a waste of time, but I've since seen that it was time well spent.
When I applied epoxy to the rear surface of the baffle there were a couple of spots where the protective tape I applied prevented the fiberglass from lying down nicely on the MDF surface. I had to apply small pieces of polyethylene sheet to the epoxy and then use a clamp to hold things in place. The polythylene absolutely refuses to stick to the epoxy (or vice versa...) so I've used this trick a couple of times. It's been quite handy.
The first photo shows the tape protection process for the woofer holes. The bottom hole has been protected with tape and the tape has been trimmed flush with the MDF. The middle hole has had the tape applied but it hasn't yet been trimmed. The top hole hasn't yet been protected.
The second and third photo show the polyethylene and clamp trick. I used a popsicle stick to distribute the clamping force. Apparently I can't do much without popsicle sticks.
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.
The next two photos show the rear surface after two layers of fiberglass have been applied, two additional epoxy coatings have been applied to fill the weave texture, and I've used my newly purchased Bosch Palm Router to remove the excess fiberglass from the woofer holes. Great tool! Sometimes I think I build speakers so I'll have reasons to buy tools...
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.
While I was out buying tools I bought a better mask to protect myself from the particulates and volatile organic nasties. The thought of inhaling fiberglass fibers as I used the router to trim the fiberglass around the woofer holes started to keep me up at night so I decided to invest in a better mask. I'm surprised how comfortable it is. It's actually more pleasant to wear than the cheap, and essentially useless, white fabric masks that come with a moldable metal band to fit over the bridge over your nose and an elastic band to fit around the back of your head. Routing the fiberglass is still nasty, but I was very glad to have the new mask.
That's it for now. Tomorrow I have to start serving in my new position at work so my flurry of activity is likely to revert to being intermittent fits of progress again.
The good news is that each step on baffle #2 is going much more quickly than it did the first time around.Few
Perhaps everyone's getting a little tired of watching me be the sole responder to my own thread, but here are a few updates in case there are interested lurkers.
I'm working primarily on the second baffle, trying to catch up with the work on baffle #1. I decided that I could streamline the process by modifying the order in which I perform a few steps. In particular, I decided to fiberglass the back of baffle #2 before I router (Route? What's the right verb here?) out the woofer holes. The double-layer tape method of protecting the woofer holes from epoxy worked well on baffle #1, but it would be nice to avoid those tedious steps. I figured that I could fiberglass the back of baffle #2 first, and then put in the woofer holes. The rear fiberglass would then be routed flush with the woofer holes at the same time that I created the holes and there'd be no need to painstakingly protect the woofer holes while I slather epoxy onto the back of the baffle. So that's what I did. It worked pretty well, although cutting and routing through the fiberglass sure dulls tools quickly. I'd end up having to do some of that anyway, though, so I definitely am coming out ahead with this approach.
Here are the holes that will accept the woofer rings:
The rear view of baffle #2 showing two layers of fiberglass, one layer of weave-filling epoxy, and the holes punched through for the woofers.
Here's the stack of woofer rings ready to be installed:
The woofer rings in place, but not yet epoxied. I had one of those moments when I thought "I've done pretty well today; I've avoided major screw-ups and everything fits just right without the need for corrective sanding. If I try to do one more step I'm likely to botch it." So I stopped short of doing the relatively quick step of epoxying the rings in place. I'll do that after I've regained my focus. Once they're in, it's back to stretching knit cloth over the rings and baffle and epoxying it so it'll hold its curvaceous shape.
Again, it's been gratifying to have the time I invested into making jigs really pay off. This second baffle is coming out better than the first and it's taking much less time to produce. I won't need to do any gap filling, sanding, or fudging before gluing in the woofer rings and stretching the fabric. Construction of the first baffle went okay, but there was more need for fussy fix-ups before I could proceed with the next step. Moral of the story: Time invested in making repetitive steps idiot-proof is time well spent.
Few
I'm working primarily on the second baffle, trying to catch up with the work on baffle #1. I decided that I could streamline the process by modifying the order in which I perform a few steps. In particular, I decided to fiberglass the back of baffle #2 before I router (Route? What's the right verb here?) out the woofer holes. The double-layer tape method of protecting the woofer holes from epoxy worked well on baffle #1, but it would be nice to avoid those tedious steps. I figured that I could fiberglass the back of baffle #2 first, and then put in the woofer holes. The rear fiberglass would then be routed flush with the woofer holes at the same time that I created the holes and there'd be no need to painstakingly protect the woofer holes while I slather epoxy onto the back of the baffle. So that's what I did. It worked pretty well, although cutting and routing through the fiberglass sure dulls tools quickly. I'd end up having to do some of that anyway, though, so I definitely am coming out ahead with this approach.
Here are the holes that will accept the woofer rings:
An externally hosted image should be here but it was not working when we last tested it.
The rear view of baffle #2 showing two layers of fiberglass, one layer of weave-filling epoxy, and the holes punched through for the woofers.
An externally hosted image should be here but it was not working when we last tested it.
Here's the stack of woofer rings ready to be installed:
An externally hosted image should be here but it was not working when we last tested it.
The woofer rings in place, but not yet epoxied. I had one of those moments when I thought "I've done pretty well today; I've avoided major screw-ups and everything fits just right without the need for corrective sanding. If I try to do one more step I'm likely to botch it." So I stopped short of doing the relatively quick step of epoxying the rings in place. I'll do that after I've regained my focus. Once they're in, it's back to stretching knit cloth over the rings and baffle and epoxying it so it'll hold its curvaceous shape.
An externally hosted image should be here but it was not working when we last tested it.
Again, it's been gratifying to have the time I invested into making jigs really pay off. This second baffle is coming out better than the first and it's taking much less time to produce. I won't need to do any gap filling, sanding, or fudging before gluing in the woofer rings and stretching the fabric. Construction of the first baffle went okay, but there was more need for fussy fix-ups before I could proceed with the next step. Moral of the story: Time invested in making repetitive steps idiot-proof is time well spent.
Few
Few said:
I know this can be frustrating. You are doing very interesting work here and no one seems to be interested. I am, though I've been away for a few days working my rear end off, so I haven't been checking in.
I sometimes wonder if this is a DIY site, as most here don't seem to DIY anything, just sit around and talk.
Don't be discouraged.
Some controversial subject matter, that's what you need.
Looking good.
Thanks, John, for the words of encouragement and the suggestion. Controversial subject matter, eh? (the "eh?" is not meant as an aspersion against Canadians, by the way ). Not my usual style, but what the heck:
1) I just finished reading a few issues of Stereophile and The Absolute Sound (TAS)and I've concluded, for the thousandth time, that many of the folks writing those articles don't know their rear-facing vents from holes in the ground. But then I guess that's not likely to be a very controversial statement around here. I just haven't fully recovered from a statement about some Magico speaker reviewed in TAS (written by Valin?). The idea was that aluminum makes a better baffle material than MDF because it's less resonant. Stiffer for the same weight? Maybe. Less resonant? Gimme a break. When I start seeing bells made out of MDF instead of metal maybe I'll rethink my position.
2) I've not done the blind (or sighted) AB listening tests but I find it very hard to believe picosecond scale jitter in digital clocks has significant audio implications.
3) Electrostatic loudspeakers (ESLs) are not inherently limited in their ability to reproduce very dynamic music. Further, the assertion that ESLs are flawed because they have something in front of (and behind) the diaphragm is a red herring. The spider/basket/magnet assembly behind a cone is more likely to cause audible artifacts than a porous stator that's positioned 1/10 of a wavelength away from an ESL's diaphragm---and that's at the shortest wavelength being reproduced; a wavelength nobody reading this forum can hear. ESLs, like every other speaker technology, certainly have their weaknesses, but it gets tiresome seeing the same misinformation parroted over and over again.
5) Using the word "fast" to describe woofers, even if it's intended as a shorthand for some characteristic other than rise time, is at least misleading and usually just dumb. If it's supposed to mean a short decay time, let's just say "well damped" to avoid confusion. If it's supposed to mean something that could never be measured, even in principle, then chalk me up as one of the skeptics.
I was going to venture into discussions of religion and politics, but I guess that's a sign that it's time to shut up. Anyway, thanks for the invitation to vent my spleen! It'll be interesting to see if shooting my mouth off---all in fun, by the way---triggers more responses than documenting a project.
More seriously though, I'm building these speakers for my own enjoyment; if someone else gets something out of participating in the process, or just reading about it, that's great too. I have to admit I do find it fun to share the ride, though, so I appreciate the comments.
Speaking of the project, I really need to figure out how to mount the woofers by their magnets and also devise an elegant way to support the curved baffles. Some of the methods I've seen used elsewhere just don't seem to do it for me, but I haven't come up with anything I like better. I'm certainly open to suggestions.
Few
). Not my usual style, but what the heck: 1) I just finished reading a few issues of Stereophile and The Absolute Sound (TAS)and I've concluded, for the thousandth time, that many of the folks writing those articles don't know their rear-facing vents from holes in the ground. But then I guess that's not likely to be a very controversial statement around here. I just haven't fully recovered from a statement about some Magico speaker reviewed in TAS (written by Valin?). The idea was that aluminum makes a better baffle material than MDF because it's less resonant. Stiffer for the same weight? Maybe. Less resonant? Gimme a break. When I start seeing bells made out of MDF instead of metal maybe I'll rethink my position.
2) I've not done the blind (or sighted) AB listening tests but I find it very hard to believe picosecond scale jitter in digital clocks has significant audio implications.
3) Electrostatic loudspeakers (ESLs) are not inherently limited in their ability to reproduce very dynamic music. Further, the assertion that ESLs are flawed because they have something in front of (and behind) the diaphragm is a red herring. The spider/basket/magnet assembly behind a cone is more likely to cause audible artifacts than a porous stator that's positioned 1/10 of a wavelength away from an ESL's diaphragm---and that's at the shortest wavelength being reproduced; a wavelength nobody reading this forum can hear. ESLs, like every other speaker technology, certainly have their weaknesses, but it gets tiresome seeing the same misinformation parroted over and over again.
5) Using the word "fast" to describe woofers, even if it's intended as a shorthand for some characteristic other than rise time, is at least misleading and usually just dumb. If it's supposed to mean a short decay time, let's just say "well damped" to avoid confusion. If it's supposed to mean something that could never be measured, even in principle, then chalk me up as one of the skeptics.
I was going to venture into discussions of religion and politics, but I guess that's a sign that it's time to shut up. Anyway, thanks for the invitation to vent my spleen! It'll be interesting to see if shooting my mouth off---all in fun, by the way---triggers more responses than documenting a project.
More seriously though, I'm building these speakers for my own enjoyment; if someone else gets something out of participating in the process, or just reading about it, that's great too. I have to admit I do find it fun to share the ride, though, so I appreciate the comments.
Speaking of the project, I really need to figure out how to mount the woofers by their magnets and also devise an elegant way to support the curved baffles. Some of the methods I've seen used elsewhere just don't seem to do it for me, but I haven't come up with anything I like better. I'm certainly open to suggestions.
Few
MJL21193 said:
was 3x tremclad enough to seal the mdf? I used rustoleum cut 40 to 50% with MS and the mdf ends adsorbed alot of paint. I saw on a auto restoration forum guys using the rustoleum as auto paint, how close do you think this is to tremcald?
so next time im going to im going to try the varathane like you said as a sealer and as a clear. do you have to reduce it to spray it?
that looks great btw jon,
I thought this thread might have fizzled into oblivion. I'm glad to see there are still a few twitches of life left in it.
Thanks, Ted, for the kind words. I'm not sure I'm worthy of them, but I appreciate the sentiment nonetheless. I'm beginning to think I've learned to make up for lack of skill with excesses of stubbornness. I have picked up a few skills as part of this project, though. Since that was part of the motivation for experimenting with a different construction technique, it's been satisfying.
I've been focusing on the construction of the electrostatic panel stators lately, rather than the woofer baffles. I did a bit more surface finishing on the woofer baffles, though, and I now have two baffles at roughly equal levels of completion---or perhaps incompletion. I've painted the front of one of them with auto body primer to get a sense of where I am, and realized I need to do a bit better on the surface uniformity before pressing on with things like finish painting. It's now gotten too cold in Maine, USA to paint outside anyway, so I'm focusing on the ESL panels. Given the size of my woofer baffles I don't know if I can apply the "dip/pour" painting method John (MJL21193) has recently described (see
this thread), but it's an intriguing idea and it would allow me to put off investing in spray equipment and make me less dependent on warm weather. "Fortunately" there's plenty of construction left to play with before I'm ready to worry about putting finish on anything anyway.
Few
Thanks, Ted, for the kind words. I'm not sure I'm worthy of them, but I appreciate the sentiment nonetheless. I'm beginning to think I've learned to make up for lack of skill with excesses of stubbornness. I have picked up a few skills as part of this project, though. Since that was part of the motivation for experimenting with a different construction technique, it's been satisfying.
I've been focusing on the construction of the electrostatic panel stators lately, rather than the woofer baffles. I did a bit more surface finishing on the woofer baffles, though, and I now have two baffles at roughly equal levels of completion---or perhaps incompletion. I've painted the front of one of them with auto body primer to get a sense of where I am, and realized I need to do a bit better on the surface uniformity before pressing on with things like finish painting. It's now gotten too cold in Maine, USA to paint outside anyway, so I'm focusing on the ESL panels. Given the size of my woofer baffles I don't know if I can apply the "dip/pour" painting method John (MJL21193) has recently described (see
this thread), but it's an intriguing idea and it would allow me to put off investing in spray equipment and make me less dependent on warm weather. "Fortunately" there's plenty of construction left to play with before I'm ready to worry about putting finish on anything anyway.
Few
Great work Few
I've been considering fibreglass reinforced woofer enclosures for some time, but my knowledge in this area is serious lacking. Thanks for the informative updates. A lot of folks like to watch your progress but dont have anything to say, so don't take that as a lack of interest.
I've been considering fibreglass reinforced woofer enclosures for some time, but my knowledge in this area is serious lacking. Thanks for the informative updates. A lot of folks like to watch your progress but dont have anything to say, so don't take that as a lack of interest.
tech9_79 said:
Hi tech (pun intended
),Tremco makes rustoleum, so they are probably similar.
Clear urethane is a great sealer for MDF. If you spray it, you will need to reduce it and put on 3-4 good coats for primer letting them tack up between.
Few said:
Hi Few,
Good to see this thread back up.
It's worth trying my pour on method as it will give great results for relatively little money. The biggest expense for this method is to construct a drip pan big enough for your baffles. That could be made from a sheet of cheap - anything - particle board, OSB, whatever.
I'm surprised that there wasn't more interest when I posted that. It's so much easier than spraying. Oh well.
Well I'm certainly interested, and I'm sure I'm not alone. It really struck a chord with me, because I tried a small step in that direction on a project a few years ago. I applied paint onto horizontal surfaces with a foam brush, but tried to load it on to the point where the brush strokes would do a better job of self-leveling. It seemed to have some beneficial results but I didn't pursue it far enough to turn in into a well developed technique. I'm glad you posted your efforts along these lines. I think it just might work for my baffles if I can build the tray and figure out a way to ensure the paint flows where I want it to go.
Thanks, David, for the comments. I'm not sure if I've sounded like I'm offended by a lack of interest. If so, that was poor posting on my part. Documenting a project while you're in the heat of the battle does require a bit of extra effort so it can feel like a waste of time and effort if it's not clear anyone's interested or benefiting. It does raise the interesting question of what the motivations are for those of us who read and post on this forum. No doubt the reasons are as varied as the people. In any case, I appreciate the recent voices of interest and will keep them in mind if I get to the point of thinking I'm posting things into a void. Thanks again.
Few
Thanks, David, for the comments. I'm not sure if I've sounded like I'm offended by a lack of interest. If so, that was poor posting on my part. Documenting a project while you're in the heat of the battle does require a bit of extra effort so it can feel like a waste of time and effort if it's not clear anyone's interested or benefiting. It does raise the interesting question of what the motivations are for those of us who read and post on this forum. No doubt the reasons are as varied as the people. In any case, I appreciate the recent voices of interest and will keep them in mind if I get to the point of thinking I'm posting things into a void. Thanks again.
Few
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