Home Plastic Injection Molding

[braaaiiins]

Any hackers here have much knowledge on desktop injection molders? I've found this http://www.injectionmolder.net/order_items.htm , which looks promising.

The selection of resins that they have on sale are pretty slim though. Could this type of machine handle other plastic resins, such as PBT?

I want to be able to make my own professional quality key caps =)

[i3oilermaker]

I want that!  The only problem is that you would have to CNC your own molds and that would probably be difficult / expensive.

[sth]

Also there is the problem of it being $1600. Could pay for itself after a little bit but that is a pretty hefty investment even for a group of people.

[MMB]

Yes, making of CNC molds would be the largest cost involved, simply because tooling a CNC machine to build a cherry MX stem requires very high quality bits, that also tend to break a lot.

Alternatively you could make a silicon-based mold that you could probably insert into the metal frame and still inject with the machine.

[The_Beast]

I want that!  The only problem is that you would have to CNC your own molds and that would probably be difficult / expensive.

I don't think you would need to own a CNC mill, but you would need to outsource to someone that does to make the dies/molds

[braaaiiins]

I've got a friend who can help me out with the CNC work. And yes, $1600 is definitely sizable change, but I think still affordable considering I was expecting something around $5k. If this is truly capable of good quality colored key caps then I think its worth it. I never considered the idea of doing this as a group. Interesting idea... but it sounds like it would be complicated. If this thing can handle PBT plastic, I think I just might jump on it.

[braaaiiins]

I'm not sure silicon would hold up to the temperatures and pressures needed to inject PBT plastic. I realize the stem would be the most sensitive area to machine, but someone out there makes these key caps and they're more than likely using cnc machined molds, so there is a way. I'm not at all concerned with making the mold - just what injector to use.

[i3oilermaker]

This machine would not help us produce double shots...just blanks...

[MMB]

This machine would not help us produce double shots...just blanks...

It depends on the mold. You would do it the same way double-shots are made: you mold the first piece, then create a mold that shapes the second piece around the first one.

[braaaiiins]

I think it would be able to handle a double shot, although realistically you'd want to use a second injector to handle the second color. Cleaning plastic from those things does NOT look fun. Any idea how they get that slightly textured finish on top of the key cap?

[TheSoulhunter]

Any idea how they get that slightly textured finish on top of the key cap?

Probably by sandblasting the inside of the mold...

[braaaiiins]

Found something that might be more suitable for PBT injection: http://www.mediummachinery.com/

It's got the higher operating pressure to handle more viscous plastics. Also twice the price =x. I wish there were more products like this to compare.