I've got an Accu Path CNC mill with M400 (V1.27), OS is Linux. I don't do any heavy duty or large stuff....mostly plastic, alum and brass and seldom anything over the size of a small book. I frequently get a couple of glitches when doing dxf import files and depth repeat (notice I said "frequently" since the problems aren't consistent!!!)

The first, and most costly, is that either at the beginning move or, much worse, at the final move, the machine does an arc before retracting. The arc appears to be a half circle. Everything up to that point will be okay. There is no arc indicated at that point in either the .icn file or G-file and of course nothing in the chained profile. It appears to be something happening with Depth Repeat but I can't figure it out. Sometimes I'll import a .dxf file and all the programming goes smoothly with no glitches.

The other is a Z-axis plunge at the beginning of each repeated path. This would be livable except that when it does that the Z-axis goes full bore. Again, this isn't always consistent and sometimes I can play with various Z-axis parameters and get it under control.

Another glitch that doesn't show up much is that sometimes Tool Comp won't turn on until about a quarter of the way through a path.

Can anybody offer any insight into these issues? I'm pulling what little hair I have left out and the end mill and material costs are driving me up the wall.

The arc at the end of the profile sounds like a classic cutter comp error.

Are you sure you remembered to cancel cutter comp (back to OFF, i.e. G40) as soon as you reached the end of the profile, before going off for another pass (depth repeat) or off to a tool change or another feature?

You should have comp ON (LEFT or RIGHT) and an appropriate lead-in move at the beginning of your profile, and comp OFF followed by an appropriate lead-out move at the end. You should include these things in the range of blocks you repeat with the depth repeat.

Regarding the speed Z comes down at: what is the plunge rate you gave in your depth repeat operation? Was the first move you included in the depth repeat a feedrate move, or a Rapid? Is the series of moves you are repeating a closed circuit (ends back where it started)?

I had a very similar issue on a lathe.

There was a parameter, either P98 or P99- that set how far ahead the cutter comp thinks. Techies told me to increase the parameter until it worked...

In my situation however, the cut simulator would show the gouge - if you zoomed in far enough.

My controller crashes some times when importing a DXF file. I have tried importing in Autocad 2000, 2004 and R12. Doesn't seem to make much of a difference. Any suggenstions?

I'm sure you have already checked this, but make sure your cad software is matched to the number of decimal places on the m400 control. I was having tons of problems with dxf import until i realized my dxf drawings were at 3 decimal places and my control was at 4. (drawings were not making complete loops) , cutter comp was turning a circle before retracting etc. All kinds of crazy stuff.

I havn't checked that and I will. Thanks.