LM 2.5, SLB, Vectric. Two cuts: first a 1/4” Upcut Endmill, on the inside of the vector, second a 1/4” rounding bit, on the vector. Most of the arc is fine, but in two areas…see pic. I did a full maintenance on the LM just before the cuts.
Thanks
@Retiree If you return to XY0, does the machine return to the same place it started?
As far as I can tell, same XY. No issues with Z. Best I can see is that the arc of both cuts is not identical, for just parts of the cuts. Most of the cut is on the same vector, but some portions are out - about 1/16” on a 12” diameter circle cut.
@Retiree If you do not have limit switches, and if you have not already done so, run the x gantry all the way to the back stops in Y. It will make a gawdawful sound, but no harm done. Then, run it again.
No limit switches. Gawdawful sound for sure. I assume purpose is to square the Y?, but why would it not be consistent for the two different cuts? My observation is that the drift was in upper L and lower R of the cut, but significantly more so on bottom R quadrant. Regardless, job fixed with some sandpaper. Still curious as to why. Not a pressing issue. Thanks
@Retiree Yes, the purpose is to square up the X gantry.
What feeds and speeds are you running?
When the first toolpath finishes, does the bit return to the same XY0 location as when it started?
1/2” MDF
- Pocket Surfacing, 80/40 to get desired thickness.
- Profile Inside 1/4” Upcut, 60/30
- Profile Outside 1/4” Upcut, 60/30
- Profile 1/4” Roundover, Inside, 40/20
- Profile 1/4” Roundover, Outside, 40/20
All toolpaths returned to XY-0
Thanks
@Retiree Tks. Just to be clear, I understand that gSender showed that all toolpaths returned to XY0. My question, is if the machine returned to the same position vis-a-vis the material. So, if you originally set XY0 to the front left corner, after each toolpath was complete, the bit was in exactly that same position??
Set XY to centre of circles. Z set via AutoZeroTouchplate. XY returned to the point I marked after every cut, as far as I could observe.
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@Retiree I’ve pretty much exhausted my bucket of help. The material is not moving, since it was, XY0 would not return to the same location relative to the material.
Does this happen with all files?
I do not have any other jobs for comparison - yet. At some point I expect that I will use the same tool combo for an edge of a project, and will be watching closely.
Am certainly puzzled that the drift was for only a part of the arc. I estimate approx 40%, and only for the inside arc of the circle. No such issue with the outside arc. Had to cut two pieces, so ran the jobs with same toolpaths, and had exactly the same issue with both. IMO either the toolpaths for the inside circle are not precisely on the same vector, or there is some scewing in the machine structure. Hard to imagine either.
Appreciate the thoughts and comments. Will lay this one on the CNC gremlins…for now.
@Retiree I had another thought. How did you create the vectors that your toolpath is following?
VCarve Pro 12.505. Create Vectors. Create Circle. Used centre as XY datum, then set diameters for 4 circles. Outer two used for pocket path to thickness material (I wanted to go beyond inside and outside diameters of the actual piece). At least one of the cuts in question was clearly not a precise circle, however, I did not measure at the time to see which is which.
@Retiree The reason that I asked was that, depending on how the vectors were created, you can end up with a bijjillion nodes. If these are not cleaned up, strange things can happen when cutting.
Your question makes sense - a reasonable possibility for the many node situation, especially since there are two different tools.
In my situation, using same vector for two cuts, first on the inside of the vector, second on the vector, assuming the calculated toolpaths are accurate, there should not have been any drift. Calculated toolpaths for the different cutters? Intriguing.
@Retiree I admit that I am grasping at straws here. 
I’ll quit now, while I’m behind.
Grant, please do not stop - your questions and advice got me thinking, and more thinking, and… I did a maintenance on the LM before the job in question, but decided to revisit the routines, and…there was a bit of slop on the Z-gantry in the X direction. I had not fully tightened the anti-backlash nut on the X lead screw. Mea Culpa! My thinking is that this explains the “drift” situation I experienced. You are now allowed to quit, LOL. At least this topic.
@Retiree I’m glad that you may have resolved the issue. I’ll leave the topic open until you can confirm that you have, indeed, resolved things. Thanks for the vote of confidence.