engraving plastic

[brian]

I want to engrave and cut a face plate for a guitar amp I'm making
I've done a search on cutting plastic and want to recap on what I gathered from the info.
Cast acrylic engraves better than extruded
0 flute bits in general cut better
remove at least .03 in a pass
x,y .5,.5 IPM 12000 rpm for .25 bit

I have .125 45 deg engraving bits that I want to use for the engraving.
What IPM and rpm should I use for this bit

Brian

[knight_toolworks]

myself the best way is to use a spring loaded drag bit. this give the sharpest and finest detail. but the holder is not cheap that's the downside.

[brian]

I already have the carbide engraving bits.
I've looked at the diamond drag tool and it would be a nice addition but as you said a bit expensive for this.
Brian

[brian]

Forgot to ask,what is the name of the plastic product often use for labeling.
It has a white core with a thin black outside coating.And is it available with different colors

Thanks Brian

[clueless]

Cast versus extruded shouldn't be in the discussion if I'm understanding what you're trying to do. Cast vs. Extruded is a big deal with lasers, but your router won't care which one is it, in my opinion.

The engraving plastic used to go under the name Lamicoid (sp?), and they were phenolic like materials. No need for all that, there are so many other materials on the market. IPI and Rowmark make the material you're speaking of. If you have a trophy shop or anyone with a laser engraving machine in your town, you can probably buy a piece of scrap from them. Some of the places that sell the material don't sell to individuals.

You can also take a piece of white acrylic (or any plastic) and just paint the surface black, then engrave through it. People in the engraving world do that from time to time when they can't find the color a customer wants in the standard colors offered.

You can't run the bit as fast as you need to, so get as close to wide open as you can on the RPM.

Hope that helps some.

[jim_ludi]

I use Rowmark Plastic colored core materials to engrave signs, name tags, etc. - http://www.rowmark.com/rotary/Rotary_Engravable_Materials.asp.

[knight_toolworks]

the difference between cast and extruded is a big one with cutting plastic. cast will not melt and it will cut cleaner. though it does nto always make a difference. but cheap extruded really sucks.

[brian]

I had the time to go to some of the local plastic shops and had no luck finding any cast acrylic.Seems like it isn't used much.
I don't want to buy a sheet so I'll keep searching,may have to get a piece shipped in.

Thanks Brian

[clueless]

Extruded is the normal you'll find in stock most places. Cast is more a specialty item where people need the properties of it for something they are doing that requires it.

I've never seen any difference in machining either one.

It makes a HUGE difference in laser cutting, but I've not seen any difference in cutting with the router. However, Steve says he's seen it cut very differently, so consider that as well.

I also agree with Steve, cheap acrylic can be bad all the way around.

[nailzscott]

I have been cutting 1/2 acrylic for a while with my router set at 16,000 RPMs with a cut speed of 1.3 to 1.5 in/sec. I use a sharp 90 deg carbide vbit and some of the cuts are up to 1/4" deep on the graphic. Some engraving bits have 3 cutting edges and they seem to heat up the acrylic too much. Attached is a sample of one of the cuts.