Engraving and Plastic Panels

I am trying to cut front control panels for electronic equipment out of 1/8" ABS plastic. Actually, cutting out the panels is working great. I would also like to engrave some text and legends into the panels. The material is translucent white, so a nice even, diffused light gets through from behind. What I am trying to do is paint the panel, then engrave the text so that it can be backlit. My problem is that while the upcut bit I use for cutting the plastic works great, it is not meant for engraving. What bit would you suggest for this? I was thinking maybe a 60 degree v-bit, but whatever I get will have to have a 1/4" shank.


Thanks,

BuddyM
Tampa,FL

A 60 degree V bit engraver will work great, just make sure you get a carbide one as the HSS ones dull very quick when engraving plastic.
Onsrud have a nice kit of these v bit engravers https://www.onsrud.com/oc/pdf/NewProducts.pdf or you can buy them loose

Hi Buddy,

I have a HAAS TM-1P 3 Axis CNC

I engraved the attached item with a 2 fute 1/8 ball mill @ 6000rpm. I programmed this utilizing ONECNC XR3 Mill Advantage Software.

I am in Seffner, Florida.

John

1/4" shank shouldn't be a problem. The 60degree bit can be. The point and flutes on these bits are not all created equal. Router bits will normally be ground to center cut all the way to the point. Some metal cutting bits do not in order to get positive rake and a strong point, which may cause it to melt plastic since they cannot center cut. Not insurmountable if you can/must hand grind one to your needs. HSS will be just fine on abs and often cuts cleaner.

Most backlit lettering I have seen is cut with a square end to transmit the light through the plastic with flat bottom letters. A vee cut might absorb more of the light as refracted back into the painted areas requiring a higher wattage source. You might have to trial both and see which is more apealing.along with aspect ratio of letter size to cutter diameter and detail.

Single edge straight flute cutters work great in abs too. I cannot recall what paint we used on abs, but it must be hard enough to cut a crsip edge without chipping or stringing with heat generation in the cut. An air blast from a coolant nozzle worked well to keep the chips out of the way, cool the cut and the painted material.

MSC Page 614

The Single edge carbide engraving bits are nice too. I'm sure they are available cheaper in HSS. The carbide tips are pretty brittle.

MSC Page 619



DC

Thanks for the info guys. I have to look around and get some more bits! My main purpose for the CNC machine (other than it is just plain interesting and cool!) is to cut out parts for a full-size cockpit replica of a jumbo jet (Airbus A320). Many parts will be unfinished and out of site, made from MDF, aluminum, or more often than not, plastic. The instrument panels are what I am trying to cut now. They are available commercially but are relatively expensive, at least to me. So I built a CNC machine to cut my own parts, and have learned some things in the process. Nice, slow simple cuts on wood makes you think at first that this CNC stuff is easy, when in fact the diversity of materials and machining requirements gets very complicated. The limits of one's knowledge and experience, coupled with the limitations of the CNC machine being used make for quite a bit of trial and error!


John in Seffner! We are very close, I buy plastic out in Brandon from Total Plastics all the time!

Buddy

Yea, I would definitly look at getting either a 45 or 60 degree v bit for engraving depending on how fine you want the font. With the 60, you can go deeper without getting wide letters. Also, the end goes to a fine point so you can do many different things with it, the possibilites are endless!