I am having an issue where my Z axis loses its position and seems to move too far upwards for reasons I cannot decipher. It seems to grow progressively worse as the scallop toolpath passes over the same area.
Occurs about 150k lines into a 35 minute scallop toolpath written in fusion 360, when the tool is supposed to be moving mostly vertically up the wall of a piece, shown here:
Those feeds and speeds look just fine. I know @jjneeb has run into this before and I believe has a fix for it, I believe it depends on what setup you have.
Have seen this on half a dozen machines that are doing these 2.5D carvings.
Try switching your Z axis Step signal active level to the opposite value ( I think it is active high by default, but I don’t have access to my machine right now to verify). This is in the plugin pins configuration area.
Thanks so much @Eric and @jjneeb ! From what I can see this is flipping the output for controlling the z stepper, what effect does this have on the machine and why would it fix the issue?
Correct, it is inverting the polarity of a step pulse. In the end, you get the same number of steps either way. However, I think there is probably a marginal timing or voltage level between the ESS and the stepper driver, but I have never pulled out the oscope to really dig into it. I had this issue several years ago, and AVID recommended trying it. It fixed the problem and had no side affects that I have ever noticed. I have recomended this to a half dozen other people who have had the issue and it has fixed it for them as well.
Whats also strange is that I’ve never had the problem with X or Y steps drifting like that, only Z, and only in the up direction.
That config Eric showed above is the correct one - I just got to the hotel after a roadtrip through a Nebraska/Kansas/Colorado snowstorm and checked it on my offline copy of Mach4.
