Backplot "loses" bits on "Run" but stepping is OK?

I have an odd problem trying to engrave lettering. I have LinuxCNC (can't figure out the version) on an old computer (with AMD Sempron 3400+) that came with a turn-key Sherline CNC setup. I have Ubuntu 10.4 on it. I used this setup with success in the past. It's running a Sherline mill, but I don't think that's related to the problem since I see my problem even on the "Backplot" screen with the mill not running

The problem is that portions of my lettering are rounded off and even left out (even in backplot). I thought I had problems in my G code since the errors seem repeatable, but when I single-step through the code in Backplot, everything looks fine. It only gets messed up in "RUN". Also note that not all of my lettering is screwed up, just portions. Though it seems to make the same mistakes on the same letters, like leaving off the lower legs of an "A", or the upper right end of a "W". But again, all the letters are OK when I single-step through the code.

My lettering is a simple stick font made in Cambam, and I have used it without trouble in the past, but now it almost seems like the PC can't keep up in "RUN", though this is a pretty simple job with about 20 short words and some stick graphics. Does anyone have any ideas?

Hi

Are you using G61?
You might need to for engraving, to stop the path blending from 'rounding off' letters

That rather sounds like what might be happening here, it won't occur in a single step, but would in a continous path

Beyond that, need to see the code to test it.

CamBam doesn't enjoy the best of reputations, need to see what it is doing.

regards

If your code is running in G64, mode without any P for setting the path tolerance, it will round corners as you describe. You can run in g61 mode, but it will slow things down a lot because it will stop at every (even the tiniest) corner. Try using G64P0.005 if your using inches. It will limit the amount of rounding.