[sdiy] Molding your own keycaps for tactile switches?

[Brock Russell]

An alternative solution for the cheap DIY kind of person is to buy Vince 
Gingery's book "Plastic Injection Molding Machine" and really do it yourself.

Brock


At 06:50 PM 9/1/2005, you wrote:
>I have some good news and bad news. First, some background:
>
>The best way to mold switch caps is to do injection molding. This is a
>process where hot molten plastic is rammed into a mold under high pressure
>to form your switch cap. Designing basic switch caps only requires a
>modicum of mechanical design skills and a good CAD tool.
>
>Now, the good news:
>
>Injection molded parts are dirt cheap. We're talking pennies in the right
>quantities.
>
>And the bad news cometh:
>
>The major cost of injection molding is the mold itself. Sometimes referred
>to a tool, or a die. It needs to be made out of high quality steel in
>order to withstand the pressure that the injection ram generates when the
>plastic is rammed into the mold. The cost of manufacturing the mold is the
>major expense in injection molding, ranging from a few thousand dollars up
>to over six figures for large, complex molds.
>
>Assuming you can afford to get the mold made, you'd have to buy a minimum
>of several hundred pieces for most manufacturers to take your order.
>
>Now, this is just my experience - I work with a lot of large companies, so
>I don't know of anyone out of their home doing anything like sand casting,
>vacuumforming, or other types of plastic molding. Usually a good rule of
>thumb is the NRE (non-recurring expense) is inversely proportional to the
>piece price. Meaning, the lower the cost of the custom part, the higher
>the cost of the tooling or what has to be done to set up manufacturing of
>the part.
>
>Best Regards,
>
>Joe Grisso
>Detachment 3 Media
>
> > Has anyone tried this? I recently stocked up on a variety of tactiles on
> > ebay, assuming that the caps wouldn't be too hard to find... Much to my
> > surprise these seem quite rare, and certainly lacking in variety. Mostly
> > black circles and squares, ho-hum. I remember reading about how some
> > people
> > were molding plastics to make their own knobs and such (on another forum,
> > I
> > believe) and the designs I want and pretty simple in terms of shaps, no
> > embedded LED's for the most part. Has anyone worked with this kinda thing?
> > What I'd really like is a soft-touch rubber material in several colors...
> > But I'm clueless where to start. Elastomers?
> >