Hi Mike,
Thanks for taking the time to respond. Perhaps I should have explained that this is a scrape piece and what you’re seeing is the cut through to the design on the other side. Material is held against a right angle fence with cam clamps----no way it’s not secure/square.
On a side note…I didn’t save my work before hitting the create G-Code button, is there any way I can get back there through the G-Code?
clamping isn’t the issue and I have used this file many times before and now it has done this twice in a row. it is cutting a 3/4" contour with a 10mm retract height. thoughts?
I had a similar problem when the pulley on the Z axis motor was slipping between the two set screws (the flat part of the shaft). Because it is hiding behind the plates, it took me some time to see it slipping. It was doing this only under load, holding it by hand did not make it slip. I had checked those set screws and they were tight but in fact one of them was not going all the way. Those set screws are way to small. Make a line straight across the end of the pulley and shaft with a marker and move the carriage, it the lines are no longer straight, the pulley slips. If this is the issue, you can get bigger set screws (they are M3 set screws) and drill and tap larger holes. Since I did not have small metric set screws, I used #8 set screws instead. @RichCournoyer used larger cap screws instead of set screws, they have the advantage of being easier to tighten and won’t strip in the hole.
Well, it could be your endmill it’s loose and slipping out. Or, if the endmill is not as sharp it could be grabbing the material, as Will mentioned, and pulling itself in.
You’re losing Z height somewhere, and you might just need to watch closely to see when and where.
Does this happen with other toolpaths?
This is why it took me so long to find the problem. Because they appeared very tight, and could not see movement I was looking for something else. I think that I removed the Z limit sensor plate and carefully looked at the shaft while I moved the Z with manual commands in CM. It was then that I noticed the 1/8 turn slip in the Z gear that was causing me all the grief for over a week.