Replacement display screw caps?

Daniel Hansen

Daniel Hansen

Tinkerer
Oct 29, 2021
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I'm wondering if anyone has found or manufactured a decent replacement for the two rubber (?) caps for the display housing screws? I'm missing a couple, and others have turned into playdough.

Possibly something could be made with silicone?
 
Hm... I didn't think of using TPU, I've never printed with it, but this might be a good opportunity!
 
I've been experimenting with reproducing the various rubber bits from PowerBooks lately.

Here's what I've found to work pretty well so far:
  1. Print a positive in resin
  2. Let the resin positive off-gas several days.
  3. Coat the resin positive in clear enamel (spray paint)
  4. Create a silicone (platinum cure) negative
  5. Cast a new positive part with polyurethane rubber with a couple drops of black and white tint to get a PowerBook-ish gray
Below is an example of desktop feet but you can get the idea.
IMG_7619.jpeg
 
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I have one on my PB180 display front bezel but the other one is missing. I was thinking of casting the one I have in a silicone mold and then using a higher shore level silicone to pour into the mold and replicate it. Hard part would be matching the color.
 
I did a quick and dirty model/print just using some grey PLA I had on hand... A softer material would of course be better because it's just a friction fit, but as a temporary solution (and with a little sand / paint) it would be passable.

Original on left, print on right (in both images)

IMG_2345.jpg
IMG_2344.jpg
 
I’d be a bit worried with those that there would be too much flexing there and that it could damage the new parts or worse, cause the bezel to stress crack. I just feel like there’s a reason the originals were rubber.
How do they feel to you?
 
Sideburn said:
Nice. TPU might work. What did you model it in?
Click to expand...
Blender. Super simple little model. I can share the stl, with the caveat that it's probably crap.

3lectr1c said:
I’d be a bit worried with those that there would be too much flexing there and that it could damage the new parts or worse, cause the bezel to stress crack. I just feel like there’s a reason the originals were rubber.
How do they feel to you?
Click to expand...
I'm not sure what you mean about the flexing. It seems to me that whole area is pretty stable, no? Since everything at that site is kept in place by the screw. I'm not an engineer though, so... 🤷‍♂️

But the fit is not so tight that I'm concerned about outward pressure much, if at all (fwiw - again, not an engineer). I did a few test prints at different sizes and ended on a 6mm diameter which feels not so tight that you have to use really any effort to fit, not so loose that it will fall out. I think too - in this case, with the PLA - the ridges from the print interface nicely with the rough texture of the PB's plastic and help keep it in place. i can easily pry it out with a fingernail.

All that said, this is all just for testing at this point and not intended to be a permanent solution. I will still try this with TPU once I get a higher-resolution print - which I probably should by tweaking the print settings. I'm not very experienced with 3D printing, so lots of iterations are in order.
 
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