Pricing of perspex sheet is not for the faint hearted (in the UK) but I was wondering if anyone has tried building speaker cabinets from sheet perspex? I was thinking maybe 15mm or 20mm sheets, cut like ply or MDF and bonded.
Thinking of its low resonant frequency and if this would translate to a very rigid non resonant box. specifically BIBs?
Just raising a flag to see who salutes.
Thinking of its low resonant frequency and if this would translate to a very rigid non resonant box. specifically BIBs?
Just raising a flag to see who salutes.
I wonder whether one of the limiitations is the difficulty in bonding it?
I am working from memory but I understood that one of the very few things that can fuse/melt/bond perxpex was chloroform...is that correct?
The other route of screwing sheets to battens is less attractive and also runs into the added complication of drilling it safely. I think you need to modify conventional wood drill bits so as to prevent the stuff shattering everytime you drill a hole.....
But I have always liked the idea......go for it!
I am working from memory but I understood that one of the very few things that can fuse/melt/bond perxpex was chloroform...is that correct?
The other route of screwing sheets to battens is less attractive and also runs into the added complication of drilling it safely. I think you need to modify conventional wood drill bits so as to prevent the stuff shattering everytime you drill a hole.....
But I have always liked the idea......go for it!
Corian (or other solid brand surface such as LG Himacs or Avonite) is a much better material acoustically unless you want it clear. It comes in sheet form in many colours (4mm/6mm/12mm and I think 19mm thicknesses). You can seamlessly bond together and also heat form curves or shapes although with Corian this usually means using a certified fabricator and it gets expensive. You can work it like wood/mdf and then you can then polish between a semi matt or high gloss finish. If you get in touch with fabricators they will sometimes have off cuts going cheap.
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Thanks guys. I was thinking about clear. I like the idea of a single driver and some silver wire all on show. In my BIB build I ended up with very little damping material, so the inside could look wonderfully simple with the driver and supra-baffle appearing to float in air.
I think you can bond it with Acetone but I did use some specific bonding solvent when at college that melted and welded without leaving a stain.
Would be a very expensive trial so I was hoping someone might help offer some thought regarding its suitability (compared to birch ply)
I think you can bond it with Acetone but I did use some specific bonding solvent when at college that melted and welded without leaving a stain.
Would be a very expensive trial so I was hoping someone might help offer some thought regarding its suitability (compared to birch ply)
I've seen subwoofer boxes made from it, but talking to people who have done it, it's not very fun.
I wouldn't do it, unless it was a demo or something where aesthetics were that important.
I wouldn't do it, unless it was a demo or something where aesthetics were that important.
The modulus of acrylic is about 1/3 that of wood, and less then MDF as well, IIRC. 20mm may be workable, depending on enclosure size. It will be heavy, and as you point out, expensive...
I have to deal with acrylic in my day job. The best way to glue the stuff (AKA plexiglass, perspex, lucite, etc) is with modern two part adhesive designed for the purpose. Older type solvent cement will work fine, and may be more practical for the home builder, but the joints won't be as pretty, and are likely to have bubbles. The newer adhesives usually require heat or UV cure.
Acetone won't do anything to most acrylics, but there is a thin wicking solvent type 'cement' that is designed for acrylic. It requires tight fitting joints.
Glass is actually cheaper.
I have to deal with acrylic in my day job. The best way to glue the stuff (AKA plexiglass, perspex, lucite, etc) is with modern two part adhesive designed for the purpose. Older type solvent cement will work fine, and may be more practical for the home builder, but the joints won't be as pretty, and are likely to have bubbles. The newer adhesives usually require heat or UV cure.
Acetone won't do anything to most acrylics, but there is a thin wicking solvent type 'cement' that is designed for acrylic. It requires tight fitting joints.
Glass is actually cheaper.
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Thanks Greg. I needed a reality check from someone who knows the material.
I was thinking about perspex because it is used for its resonant damping properties or at least lower resonant frequency compared to say glass. I can also work it myself (with wood tools and polishing/buffing) whereas glass I would be relying on (and paying for) specialist manufacturing companies to do any shaping etc.
I found Tensol 12 and other 2 part products that I could use to bond, but as you suspect I would require a really clean invisible weld/joint. This might be the thing that shelves the idea or adds prohibitively to the cost.
I was thinking about perspex because it is used for its resonant damping properties or at least lower resonant frequency compared to say glass. I can also work it myself (with wood tools and polishing/buffing) whereas glass I would be relying on (and paying for) specialist manufacturing companies to do any shaping etc.
I found Tensol 12 and other 2 part products that I could use to bond, but as you suspect I would require a really clean invisible weld/joint. This might be the thing that shelves the idea or adds prohibitively to the cost.
What might work is to start with a cylinder... then you just need to fit a top and a bottom, and figure out how to mount the driver.
dave
dave
Mmmm food for thought. I was thinking BIB or something similar. Easy to build and look fantastic. I imagine the internal baffle would be tricky. I wonder if you can buy a 12"dia x 140" pipe from clear perspex?
made a bandpass sub box back in high school but with Lexan aka Polycarbonate sheeting. if you used it say just on the front face it might be ok, but i cant imagine it being very good used on all 6 sides. unless you can find some 2 inch thick stuff.
A cylinder is a good idea. Somebody makes them. There'd be much less flex to deal with inherently. Dividing it with an internal diagonal panel sounds like a nightmare. The shape would be a truncated ellipse, and the geometry isn't impossibly difficult, but I don't see any way of getting a clean joint.
A cone or pyramid shape suspended in the center would do the same thing and be easier IMO, and perhaps look cool.
You may want to start with a smaller box to get a feel for whatever gluing system you choose, before blowing a bunch of money on large panels. Acrylic isn't that different from woodworking, except that it melts if you get it to hot...
Now, what about damping materials? See through polyfill? Wadded up fishing line?
BTW, acrylic is much more rigid than polycarbonate/Lexan.
A cone or pyramid shape suspended in the center would do the same thing and be easier IMO, and perhaps look cool.
You may want to start with a smaller box to get a feel for whatever gluing system you choose, before blowing a bunch of money on large panels. Acrylic isn't that different from woodworking, except that it melts if you get it to hot...
Now, what about damping materials? See through polyfill? Wadded up fishing line?
BTW, acrylic is much more rigid than polycarbonate/Lexan.
You can drill it with wood bits. I've recently done it for another project at 6th Form, but you have to go through every drill bit 0.5mm starting at the smallest you got. Else the perspex won't like you. I was drilling 10mm perspex/ acrylic(I beleive the latter). You do have to be very careful and I found at about 5mm drill bit for no aparent reason other than maybe a old bit it would get a little stuck when i started to drill, but if you have the drill(electric hand drill I was using) spinning before you go in it was alot better. I was joing two peices on top of each with smarter M6 machine Pans. The acrlyic was threaded(Tap and Die) on the lower piece and with a clearence hole on the top with it countersunk it looked ok and was quite strong.
Hope that helps
Hope that helps
a few observations on "Corian", based on over 15yrs in the commercial millwork trade:
"standard" thicknesses may vary by jurisdiction, but the default in North America is 1/2" - sheet sizes 30 or 36"wide by 144" long
pricing not for the faint of heart either - anywhere from $500 per sheet for plain solid colors to well over $1200 for the fancy stuff
cut-outs from sinks, etc would certainly be considered throw-away, but fabricators tend to be careful with the yield, and I'd venture to guess that "off cuts" of sufficient size to fabricate a speaker enclosure of any decent size (all in the same color) might be a bit harder to come by cheap
not all acrylic or polyester based solid surface materials can be successfully thermo-formed - in our experience, most particularly the styles with high quantities of large or metal aggregates
can be laminated to wood substrate by white PVA wood glues, but structural bonding is via proprietary epoxies, requiring special mixing tools, and even though the color-matched adhesives can be very close, absolutely visually seamless bonds are very hard to achieve
don't rely on the screw holding ability of the material itself, whether for wood / machine screws or threaded insert fittings - a minimal layer of wood plate should be used
the material can be worked with sharp carbide tipped wood-work tooling, but is very dense and slow going
it is softer than plastic laminate - the higher the gloss to which it's polished, the more prone to scratches and glazing (of course those can be buffed out)
there's reasons why fabricators are certified
The glass idea is looking so much more attractive! Or maybe 12mm furniture grade birch ply. I can get that for free as I have some bits just the right size currently sitting in my front room, holding my drivers up in the air...
I know this is an old thread, but look what I found at our local auction here in Hobart yesterday! Drivers all shot and foams gone, but quite an oddity. Everything is branded 'Glenwood' - can't find any info at all, and there was just one of them alas.
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