Re: [CAD_CAM_EDM_DRO] RE[1]: Milling Materials

What were you planning to use to cut these pieces? You mentioned dental
drills. I believe that those are diamond bits and that won't work. If
you are planning on these being clear, they would be from
acrylic(plexiglas) or lexan. The others mentioned (delrin ,nylon,etc)
are not clear. The cutter must be that, a cutter. An abrasive, like a
diamond bit will not work on these materials. These plastics come under
the catagory of " thermoplastic" which is heat formable.The speed of the
cutter is critical and a coolant would probably help maybe air would be
best. I have seen plexiglas weld itself back together behind a saw
blade.
There are several other options. 1. You could make one of metal and use
that to make a mold for casting or injection molding. 2. You could do a
reverse impression in metal and make molds for casting or injection
molding.3. you could make reverse metal molds and make the impression in
heated pieces of plexiglas in a press(remember the thermoplastic
thing?) Plexiglas is interesting stuff, it has memory. Heat it up and
it returns to its original shape.If you pressed the impression in heated
plexiglas you could have an added benefit. You could include
instructions-"In case of divorce put in a heated oven for 2 minutes" and
it would return to a flat round piece.
Sign shops are also a source of acrylic. There are special bits for
"routing" plastics. The cutter needs to get the chip out as quickly as
possible so that it doesn't add to the friction and start welding back
together.
I was a shop teacher for 13 years(20 years ago) and plastics was one of
my many areas. I used to get scrap materials from sign companies for the
students to use. You might be able to use materials from scrap bins
also.It doesn't hurt to ask, and they might have cutter bits as well.
I hope that this helps, Carey