Z-Axis stair steps up towards the end of the GCode.
About half way through the X-Axis starts running crooked.
I have a Shapeoko 3 xxl I bought about a year ago. I was making a spoil board and ran into the same issue 3 times. About half way through the surfacing the x-axis started to go crooked. On the last 5 passes around the board the z-axis moved up every time creating a stair step all around the edge of the board.
I rechecked the file in carbide create and it seemed to be fine. I exported the GCode again. This time I checked the z-axis belt tension and how made sure the router was tight. With all this checked I ran the file and got the exact same result.
I tried it a third time, but assuming the problem was me I downloaded a spoil board surfacing file from Myer’s Woodshop. I adjusted the size exported this new GCode and ran it again. Same exact result. My z-belt is tight as well as my router. The v wheels are snug as well, but about at some time during the last phase of milling it stair steps up.
This last time I checked my zeros and they were off by 3mm. Interestingly, though, my mill hit the board when it read plus 3mm. This seems counter intuitive to the upward stair stepping.
So in short these are my issues:
Z-Axis stair steps up towards the end of the GCode.
About half way through the X-Axis starts running crooked.
you mention you got your machine about a year ago, did you manage successful cuts before, or is this the first time you run a cut ? (just to rule out some possible causes)
have you checked ALL V-wheels ? (I mean, both the ones inside the Z-plate, and the ones on the X & Y-rails). If you home the machine, grab the tip of the endmill, and try to move it up/down, left/right and front/back, can you feel any slop?
assuming your Z belt is tight, the other likely culprits are the setscrews on the Z motor pulley: check that one of the two is set against the motor shaft’s flat, and that the two are tight. Your Z pulley might be slipping on the shaft, and this could result in the upward stair step that you seen.
Can you also share your feeds and speeds for a quick check (type of endmill, RPM, feedrate, and depth per pass)
I have used it a few time in the last year, but what I try and do seldom works out properly. Therefore, a lack of use, and lack of CNC skills.
I checked the machine and about half the V-wheels were loose. I tightened them and the Y axis belts. I ran a few projects and it worked like a champ. Thank you.
I’m still trying to figure out how to level the outside of the board.
Not sure what you mean by that ? You have to make the spoilboard small enough that its whole surface can be reached by the endmill, given the mechanical travel limits. Maybe post a pic if that’s easier than explaining
Sorry. Due to the z axis jogging up on the outside passes my spoil board is now kind of shaped like a bowl. Since I have already attempted to level it, I don’t have a lot of spoil board left above my t nuts in the center, but have quite a bit around the edges.
If I were you, I’d try to get one good facing operation to complete to eliminate the bowl, then install a supplementary waste board into the “square” created by the machine. Then you can worry about getting the supplementary perfectly flat where you have more material to work with.
EDIT: You can even manually jog your spindle around the perimeter of the bowl until its eliminated.