Problelm Engraving Romark Plastics

[kenkelsey]

Hello Team I own a sign shop and the Shopbot is great for making signs. Recently I have gotten orders to create nameplates in plastic (Romark). I am finding very difficult to get letters engraved to the same depth even though I have resurfaced the table. I have searched the forum and find a lot of info on spring loaded diamond drag tools, but I need to engrave with .010 or .020 bits. Anyone know of a spring loaded engraving tool? Or any other ideas how I can achieve a reasonable looking cut into two-ply plastics like Romark? Any tips on feeds and speeds also appreciated.

[bob_dodd]

Ken What type of Shopbot do you have , sounds like your making small engravings , First I would check all axis for backlash ,

as a work around you could try attaching bungee cords to all axis ( X Y Z ) to per load each axis in one direction to reduce the backlash

Do not forget to take them off when done with the tags

Hope this helps

Bob

[chiloquinruss]

Snap a quick pix of a problem piece. The gang here can diagnose most any issue from a pix. Russ

[kenkelsey]

Thanks for the suggestions. The XYZ axes are tight. The issue is the variation in the material thickness (not likely) or the variation in the table top of the router. I am using a 48 X 96 Alpha machine. When I set the zero height in one portion of the 4 X 14 inch tag, some letters may not cut at all. I'm only cutting to a depth of .005 so any variation in the material or table can make the difference of whether the letters cut or not. What I have done as a work around is reset the zero height several times in different areas of the tag and resumed cutting.

[sneakers]

Ken

Which Romark are you using? They make a laser and a rotary engrave type of plastic. Sometimes the bot is not the right tool for the job. You might want to sub out the job to a shop that has a laser.

Gary

[kenkelsey]

I am using the engravable stock and it does engrave just fine, but it starts out cutting just fine, but in another area of the tag, the tool does not reach the material, so nothing cuts or it may cut, but not as deep. I suppose it must be the table is not perfectly flat. True engraving machines uee a spring loaded engraving bit, but I don't know if this is available for a CNC router?

[dmidkiff]

Look on Shopbot price list. They sell a diamond drag engraving bit by widget works.

[jerry_stanek]

After you do your engraving move the z to where you zeroed it andmove it down to zero and see if it is still zeroed. could be loosing steps or bit slipping.

[kenkelsey]

Thanks guys. Finished the project with a few restarts to rezero the Z axis. I believe the biggest problem I was having was that my table top is not surfaced perfectly; and, I found that the z zero was actually above the material about the thickness of an index card. Shopbot advised me how to recalibrate the z zero plate. Have to say that engraving is not so fun on a cnc router.

[chiloquinruss]

"Have to say that engraving is not so fun on a cnc router" You've just got a little growing pains! We have all been der' done dat'!

I use conical engraving tool .25 dia, 2.0 len 45 deg .010 tip general purpose from 2linc.com

I do name badges all the time (prs96) and I have a little jig I throw on the table and cut away. Pardon the pix but my phone is really old! Russ