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Balor
recumbent guru

Russia
750 Posts

Posted - 10/08/2019 :  08:59:32  Show Profile  Reply with Quote
Prusa (the printer I've got access too) recommends shore 90-ish filament, so fairly stiff.
Hmm... Bowden or direct extruder? Yours look like direct one, should handle any filament provided you turn off retract (better print in 'vase mode') and keep speeds slow and steady.
Admittedly, I think it is easier to simply buy vibration isolation mounts from amazon, they come with mounting bolts attached, and I think that their rubber has better compression set then printable TPU. On the other hand, you have much more design freedom that way, may print it hollow for instance for 'air suspension' :).
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Balor
recumbent guru

Russia
750 Posts

Posted - 10/31/2019 :  14:36:13  Show Profile  Reply with Quote
Did a test of carbon 'lug'- printed an ABS shell, vacuumed a few layers of carbon around it, than dissolved it in acetone (took awhile, process is rather stinky). Turned out pretty good, except inner diameter somehow ended up smaler than the 'mandrel' - I presume due to print lines. Good thing I've had some leeway! Should have printed it bit larger and polished it first I presume - maybe acetone-polished, by brand of ABS is pretty damn resistant to this stuff.

Next try - HIPS and lemonene (damn expencive though, not exactly mountain dew either, but at least does not stink as bad).

Edited by - Balor on 10/31/2019 14:37:10
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Balor
recumbent guru

Russia
750 Posts

Posted - 11/03/2019 :  10:14:14  Show Profile  Reply with Quote
Btw, experimenting with TPU bladders is more or less a failure: It is extremely hard to make them airtight, and even dunking into dilute glue does not seem to really work in the long run (and is stinky).
I think a better idea is to 'paint' it with a liquid latex, or two-part polyurethane/silicone. Plus, 3d printing TPU is pretty stiff by itself (shore 90Aish) so even a thin wall is rather resistant to being stretched/compressed, will only truly work for larger bladders where forces are much greater I presume.
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alevand
human power expert

USA
3541 Posts

Posted - 11/03/2019 :  11:56:57  Show Profile  Visit alevand's Homepage  Reply with Quote
You can by PVA filament that dissolves in water.


C:
Tony Levand
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Balor
recumbent guru

Russia
750 Posts

Posted - 11/03/2019 :  13:41:02  Show Profile  Reply with Quote
Yea, I know. It is pretty damn expencive though, and not stiff at all (so will need to be prined with a lot of material to avoid distorting during vacuum bagging). But it does seem like the best option if you want to avoid aggressive solvents - I've bought some lemonene, and brand of hips I have refused to be dissolved in it, only becoming kinda 'gooey'. Damn polymer chemistry...
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harv
recumbent enthusiast

425 Posts

Posted - 11/03/2019 :  16:18:29  Show Profile  Reply with Quote
If you can print polycarbonate, acetone will make it craze into tiny easy to break pieces. Even though PC is expensive it has double the modulus of HIPS so you can make the shell thinner. Also has a higher heat distortion temp than HIPS, so if there is heat from the epoxy curing the PC mandrel should distort less than HIPS.
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Balor
recumbent guru

Russia
750 Posts

Posted - 11/03/2019 :  18:45:42  Show Profile  Reply with Quote
quote:
Originally posted by harv

If you can print polycarbonate, acetone will make it craze into tiny easy to break pieces. Even though PC is expensive it has double the modulus of HIPS so you can make the shell thinner. Also has a higher heat distortion temp than HIPS, so if there is heat from the epoxy curing the PC mandrel should distort less than HIPS.



Interesting! But I'll need a full metal nozzle to print PC, something I don't currently have, plus likely a heated bed with temp above 120 - something my printer does not support at all :(.
Plus, I'll have mess with anti-adhesives (otherwise 'crazing' it will not help much, it will remain stuck to the laminate).

It seems that cheapest way is just printing with ABS and dissolving it in acetone. It is not even *that* bad compared to most other solvents, just smells. PVA is also highly hydroscopic (duh!) so some filament enclosure with dessicant will be required...
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