Rubber pads without 3D printing

[mmu_man]

While some people managed to recreate rubber pads with 3D-printed TPU, and it can look quite okay, I thought it could look better, and I wanted to explore other methods. I've had the idea for some time, for another machine, but I had this Color StyleWriter 2200 around with feet turning into goo even faster…

At the fablab we have a large laser cutter, and I already ordered a rubber sheet with double-sided tape, the kind used to make stamps. So I first made a model in OpenSCAD, which could still be used for 3D printing if needed, but for 2D stuff OpenSCAD can only export outlines as SVG, it can't generate gradients for depth… So I redesigned it in Inkscape… but because out machine needs Corel Draw to run (vendor said it could be made to work with Inkscape but can be unstable…), and Corel Draw didn't like importing gradients from Inkscape, I first made a simple cut version:

Which I had to finish cutting with scissors as the default settings was too fast to cut through, but it didn't look too bad. Except it's too thick and I feared it could get knocked off. So after some testing with gradients in Corel I managed to get a decent engraved version:

The grid shape is due to the rasterization of the gradient, maybe it can be made softer, but the result is not too bad. However if I want to make some to sell them cheap enough I'll probably need to do the whole 200 pairs in a sheet to spread the raster time across it.

 

[mmu_man]

I've been modeling (if you can all drawing shapes with grey gradients in Corel Draw modeling) some feet since then, mostly for PowerBook stuff… and VAIO.

Latest prototype, can you guess for which machine? (left is original, right is first version):

 

[Elemenoh]

Last year I did some experimenting with recreating rubber feet. I used an SLA printer to make mold positives. Then cast those into silicone negatives and cast polyurethane parts in those.

The benefit is that you end up with parts that have an original look and feel. But it's a lot of work and tweaking to get everything right. You also need a vacuum chamber to degas the polyurethane or you'll end up with Swiss cheesy parts.

I also tried making SLA negatives and casting silicone positives. The texture and sheen are pretty different from original parts, but it's fewer steps.

The gray parts below are reproductions. The black and white are originals.

This is what happens if you don't degass polyurethane before casting.

This is a cast in silicone. It doesn't look bad, but is more shiny and jelly-like compared to the original material.

 

[mmu_man]

Yeah thought about molding as well but we lack the equipment here… Laser engraving works not too bad, except for the raster effect (although I want to try sanding that), and it takes time so it's not as cheap as I envisioned, but if I use the full width of the machine I can probably make it fast enough to limit the cost (less accelerations/deceleration for the same covered surface). I already tested with a little faster beam, just had to compensate the colors in the gradients.

 

[Elemenoh]

Yeah thought about molding as well but we lack the equipment here… Laser engraving works not too bad, except for the raster effect (although I want to try sanding that), and it takes time so it's not as cheap as I envisioned, but if I use the full width of the machine I can probably make it fast enough to limit the cost (less accelerations/deceleration for the same covered surface). I already tested with a little faster beam, just had to compensate the colors in the gradients.

FWIW, the only special gear needed for casting other than a 3D printer is the vacuum chamber, but you can get those quite cheap. I got this tiny little one for about $40 which was a good size for making a dixie cup of polyurethane for casting. A new pump for that would be about $60 but I'd guess you could find a used one super cheap on craigslist or similar.

Amazon.com

 

[mmu_man]

Updated last prototype, I think it's close enough. Though sanding makes it clearer so not really better looking.

 

[mmu_man]

FWIW, the only special gear needed for casting other than a 3D printer is the vacuum chamber, but you can get those quite cheap. I got this tiny little one for about $40 which was a good size for making a dixie cup of polyurethane for casting. A new pump for that would be about $60 but I'd guess you could find a used one super cheap on craigslist or similar.

Amazon.com

Hmm yeah, I suppose for more complex or visible parts that'd be something to try. But they you'd need to add the adhesive layer, so cut it anyway.

Btw, the round ones if they are what I think they are, you can find them quite cheap already on ali.

 

[Paolo B]

I did some complex shape PU casting some years ago (replacement for NeXT display rollers). There are some pics on this forum, too. It’s been fun, but expensive and utterly time consuming. Degassing the PU before casting is key, but small vacuum chambers are cheap on Amazon.

 

[PL212]

I did some complex shape PU casting some years ago (replacement for NeXT display rollers).

Yes, I think I was the lucky recipient of some of these!

 

[mmu_man]

Nice result!

 

[mmu_man]

Last changes on these, I think we can ship! Wait, I don't have a shop yet

Protos from left to right, original on the right.

 

[Paolo B]

Yes, I think I was the lucky recipient of some of these!

View attachment 17529

Oh, yesss! I am so glad you appreciate them! I literally made them one by one with my hands. It’s been a nice project, I hope your N4000 display is in a good shape, too!