John's Alu Profile build

[Evengravy]

John,
I haven't tried this but have wondered if polystyrene concrete could be used to damp the gantry without it getting too heavy. I found an article once (don't have it to hand I'm sorry) that described using up to 60% by volume of polystyrene beads (you can buy them for making bean-bag furniture) to make concrete for light-weight structures. It's still quite strong at that percentage and I think the density came out at a little over 1Kg/litre.

Hey. Thanks! That's quite interesting. I was thinking of something similar with perlite and concrete or epoxy. I was told that concrete may react with aluminium though somewhere but I can't recall where exactly. Does a anyone have any insight on that? On this note I was looking at some local companies that sell recycled tyres, chipped up for playgrounds. I was thinking that could make a good aggregate for a damping composite maybe, with either epoxy or liquid platinum cure silicone to bind the chunks together in a similar way to making epoxy/granite.

It sound like some tests might be in order, luckily I'm an acoustics specialist with oscilloscope etc here so could at least test a few solutions on a small scale.

[Kitwn]

It sound like some tests might be in order, luckily I'm an acoustics specialist with oscilloscope etc here so could at least test a few solutions on a small scale.

You're the man then! I like the idea of bendy concrete made with old tyres

[Evengravy]

You're the man then! I like the idea of bendy concrete made with old tyres

Thanks. Sure, I'll do some more in depth reading and maybe some tests soon, the complication at the moment is getting out of the F'ing house to get materials but gives me chance to do some research if nothing else.

I came across a guy on another CNC forum that recommended bitchumen (tar) plus sand, that could potentially be a cheap and available solution, if it isn't too heavy that is. Maybe roofing tar plus rubber chips. Certainly it's common to use roofing bitchumen sheets (old school roofing felt) in acoustic dampening solutions in a studio environment, I see no reason why it wouldn't transfer here, in theory.

Silicone would likely be expensive but should be quite efficient, maybe recycled rubber plus a binder might help. It's always going to be a tradeoff of weight vs dampening factor for a gantry though.

It's simple enough to test smaller pieces in practice though; with a contact mic/measurement mic and some shorter pieces of profile and an oscilloscope, I have some 80x80mm profile I could donate to the cause so I could side by side a few possible solutions as an experiment. Could be useful to see what approaches might work down the line.

At the moment, I'm just awaiting the new ballscrews to arrive so I can get rid of these cheaper ones.

Thanks for chipping in guys, appreciated.