Yeah, a laser vibrometer is like a million dollars. A good anechoic chamber hard to get at too.
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Help me finish my polystyrene cab build
- Thread starter neal sanger
- Start date
Starting to shape up! I admire your tenacity! I wish you success on this one and look forward to hearing it! Soldier on, @neal sanger !
A lot of times you could find that stuff at your local university. You might find young like minded individuals who would "bootleg" you in to the project just for kicks. Scientific guys like to try just about anything! If you try that, DON'T CALL, go in and find a young guy and strike up the conversation, see where it goes. Good luck!
It is expensive.
Lumberyards around boat building places. Cabinet shops that make cabinets for boats. They may have cutoffs at cabinet shops if you ask around.
One more option using a stick frame that you fill in with rigid foam.
Think of how a house is built. They build the stick frame. They sheath it, insulate, the sheath (drywall) the inside. Do the sheathing in reverse.
Build a stick frame using 2x2 (1.5 x 1.5), 1x2 (.75 x 1.5), even 1x1
Line the inside with thin ply.
Lay rigid foam in the frame cavity.
Lay thin ply on the outside.
Stick frame box for loudspeaker using 3/4x1-1/2' and 3/4'x3/4' standard stock | 3D Warehouse
Here you are going to need to glue the ply and foam. The epoxy resins have come down in price. They're often used for table and counter tops these days.
Most definitely, but that wouldn't be the way to fabricate it. I would laminate up flat panels on the bench, then assemble and finish up with fibre tape over the inside joins and all over fibre on the outside.
Yes this is how it is done (carbon fibre tape w/epoxy). Except you ony need to build up the corners inside & out (mostly out). Wrapping the whole deal will be overkill.
That's how I fabricated them commercially. The strength of the polystyrene is of little importance. It's the fiberglass on the outside and inside that give it strength. I'd laminate the panels with 3 layers of fiberglass. I'd then epoxy them together and apply 2 layers of tape on outside corners and one layer inside. Never had a cab come apart.
Would it work to epoxy cardboard boxes as a skin layer? You could get two different sized boxes of the same proportion and epoxy the foam between them like nesting dolls.
No need. It would only weaken the skin effect and potentially buzz like crazy.
Not really. The way the composite materials work is that the strength is provided by fibres, and the fibres are held in position by a matrix. So the glass, carbon or whatever are the fibres, and the epoxy or polyester resin is the matrix. Wood is very much the same, which is why it's a good construction material.
When we get to materials like cardboard the fibres haVe been sliced up and mashed at random, so there's no strength there no matter what you do with a matrix. The resin doesn't really provide strength in itself, it makes it possible for the fibres to work.
When we get to materials like cardboard the fibres haVe been sliced up and mashed at random, so there's no strength there no matter what you do with a matrix. The resin doesn't really provide strength in itself, it makes it possible for the fibres to work.
You can get thin ply
https://smile.amazon.com/dp/B000BQWZFQ/
and it can be cut with a razor knife and straight edge if you're persistent.
When you mix the epoxy you can mix in fibers for example :
https://www.amazon.com/Fibers-concr...73831&sr=8-10&keywords=fiberglass+fibers&th=1
Or a fiberglass mesh, or carbon mesh
"Fiberglass" shell is essentially epoxy + mesh but a lot of things are also made with just fibers.
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I'd be a bit wary about getting too much into composite construction without careful planning. What you're doing now seems like a fun thing that is interesting to try, and hopefully not too expensive although I dread to think what you're spending on glue.
If you take a step into full blown fibre/foam sandwich construction then the materials get expensive very quickly and its awfully easy go badly wrong. That's not to say that the composites are difficult to work with, its just that there are lots of ways of going wrong - and I fear I would list use of chopped strands as being one of them..
Its worth noting, perhaps, that I am very comfortable with foam, epoxy and carbon from home boat building, and yet I have recently built a number of cabinets in wood. The more sophisticated construction just wasn't appropriate. I think there's a lot of potential for the exotics in building superior bass rigs, but I suspect commercial success will require not only the superior physical properties, but also taking advantage of the ability to manufacture shapes that are impractical in timber.
Also, perhaps, epoxy/carbon/foam sandwich is almost purely petrochemical derived, and the wheel is definitely turning away from that.
If you take a step into full blown fibre/foam sandwich construction then the materials get expensive very quickly and its awfully easy go badly wrong. That's not to say that the composites are difficult to work with, its just that there are lots of ways of going wrong - and I fear I would list use of chopped strands as being one of them..
Its worth noting, perhaps, that I am very comfortable with foam, epoxy and carbon from home boat building, and yet I have recently built a number of cabinets in wood. The more sophisticated construction just wasn't appropriate. I think there's a lot of potential for the exotics in building superior bass rigs, but I suspect commercial success will require not only the superior physical properties, but also taking advantage of the ability to manufacture shapes that are impractical in timber.
Also, perhaps, epoxy/carbon/foam sandwich is almost purely petrochemical derived, and the wheel is definitely turning away from that.
@alaskaleftybass I ran out of glue so it's on hold until I get a day off of school to go to home Depot and get some more. The backing panel has cured and I need to finish gluing the top on and fit a jack plate. The last cure should be about 2-3 weeks long.
This material might work:
Link Removed
But, as a number of posters have said, it takes some experience to develop a process. I haven't used syntactic foam before but, a fellow engineer and tech at Hughes were working on a near field radar detection device to detect obstacles and warn the driver. They used it because, at the microwave frequency that they were using, it was nearly transparent and had a low loss.
Link Removed
But, as a number of posters have said, it takes some experience to develop a process. I haven't used syntactic foam before but, a fellow engineer and tech at Hughes were working on a near field radar detection device to detect obstacles and warn the driver. They used it because, at the microwave frequency that they were using, it was nearly transparent and had a low loss.
in addition, the fibre skin only gains stiffness when it has sufficient shearing capacity at the matrix junction and in the matrix itself. Cardboard coated with fibres is a waste.
It's getting there. This is a test fit since I just finished gluing the top. I have heard everyone say I should glue the baffle down, but I thought of a compromise. I'm considering gluing some open cell foam to the front baffle on it's back face so the clamping load between the interior panel and the front baffle has some give and isn't wood onto foam. It will hopefully work like a soft mounted car door speaker. Anyone have thoughts on this?
Does the driver not have a gasket on the reverse face for outer mounting onto a baffle? You could use foam gasket tape and save a metric buttload of messing around by just gluing the ply baffle onto the front panel.
