Over the past few weeks I’ve experienced a strange situation intermittently on 3 different jobs. I always start with a climb cut then finish with a conventional cut to clean it all up. The run goes fine until the last few inches on the FINAL pass. Sometimes the Bot suddenly takes a turn back towards the X Axis along the Y axis. When this happens. My X zero point is changed by seemingly the distance amount between the original cut and the ‘new’ cut. It seems to be coming a more frequent occurrence. Any ideas on where to look for an issue?
Facts:
1) Older (~2006) PRTAlpha 4x8 Control software 3.6.46 Control board p/n 001003-01 v0.6
2) Windows XP computer - has never been connected to internet, all extraneous stuff shut down. Nothing else is ever run on the box EVER.
3) No comm errors or any other errors or power cliches
4) When jogged home, X home is now changed by the amount of the ‘detour’. Y is fine as is Z.
5) Shut down PC and control box and turned off power at the electric disconnect box, then powered back up normally.
6) Neither the spoil board or plywood is moving. Usually use vacuum hold down but started screwing down to make sure nothing moves.
Details:
2 pics attached.
1) When it occurs, it is ALWAYS in the last few inches of the final conventional pass. (I usually do it in one pass but even changed to 3 passes. Then it ran first 2 fine, opps’ed on last pass, same place.)
2) All 3 jobs have been run several times over months/years with no previous issues
3) Recreated the tool path. Original tool paths were created in VCarve 7.5. Recreated paths Vcarve 9.0. Interestingly file size changed from 205 KB to 72 KB.
4) Changed 0,0 point from actual 0,0 to 0,24. Ran 5 panels and all was fine (almost.) Check image 2. All 5 had a slight deviation as seen withing the green circle though on this job I can live with that.
5) Other day made 3 runs - all fine, next one messed up, next 7 ran fine. Nothing changed.
6) Material - Baltic Birch ply, 18mm with .189 mm DS bit (.189 because I’m creating some .25" bolt holes and don’t want to start a fire again) , 12 mm with .25 DS
7) An interesting observation a couple of weeks ago - was cutting a similar job as this but larger circles. Was cutting 2 pieces - 2x1 matrix. Again this was on final pass. The first one deviated on the X=0 side of the circle by about .45" I didn’t get to the machine instantaneously so the bot had moved over to the second piece for the final pass. It was cutting the final conventional pass there CORRECTLY until it go to the last few inches at the end, then also opps’ed just like the first piece. Very interesting. I would have expected it to cut the final pass on the second one off by .45". Was not so.
Sorry this is so long, but full of details. Any ideas on what is going on and how to fix it?
Image 1.jpg Image 2.jpg