I did a cut today with my M4 that was meant to be a 0.5mm - basically a scratch to see the shape that I wanted to cut but it ended up cutting as deep as 2.5mm. It was newly calibrated and I had set the Z home to be on contact with the work-piece.
I needed to cut some dados and a rabbet but couldn’t trust the M4 to do it.
is there any software settings to check it.
I’ll reply below with a photo
outline.nc (4.4 KB)
Using a probe to set the z-axis height is probably the most reliable way to do it. I’ve found that lowering the z axis with the router on I can hear the sound change when the bit gets close to the surface and that’s usually good enough for me.
I just had a very similar issue after calibrating. I reset the Maslow and then it was fine. Sometimes I get an issue where the Z is out of sync on maslow.local and I’ve also had issues where settings aren’t saved until I power cycle the machine, not sure if either of those are the cause. But it messed up this project pretty bad -_-
Hi togheter,
couldn’t find any other topic related to my problem, but this one here seems to be pretty close, so i just want to jump in.
Updated to 0.87 and did a full recalibration, set Z Home with router etc.
but now, when I cut z axis seems to not rise enough, which leads to
any ideas, what can be the cause of that?
(yes Router and bit itself are tight 
)
or encountered the same and has a solution?
any additional information needed?
Thank, cheers and happy new year
Can you post a copy of your G Code file please.
When you just the jog buttons to raise and lower the z-axis does it move the amount that you would expect?
sadly not atm, since I’m on vacation.
but I tried different ones, even those which worked before I’ve build a New frame.
As soon as I’m home I’ll upload one.
yes, manually raising and lowering z-axis just works fine
Calib-test_GRBL.nc (2.0 KB)
just found one wich worked before and Now goes wrong on my Dropbox
Okay,
I might have found one of my problems, which causes the maslow to not raise properly.
It seems that if the machine is lowered until arround 20-25mm near the z-Stop, the “bottom” motor doesn’t move poperly similar to this topic:
just found out while trying to set new z-stop before rerunning calibration today.
Does that motor move properly the rest of the time? Is it only that last 20-25mm that is an issue?
If so I would try loosening up the bolts which hold the stepper motors in place a little and then lowering the z-axis all the way down, then re-tightening the bolts. It sounds to me like the spacing of the motors might be a little bit off which is preventing the z-axis from going all the way to the bottom
I’ve tried unscew and rescrew the bolts with z-axis max, like the spindle completely loose even outside of the guides, and as you mentioned with z-axis lowered untill the maslow is “crying”. still happens sometimes.
I can not tell 100% but from my feeling it as well happens just randomly between min and max, but that is quite hard to see I’d say.
It sounds like you are trying the right things.
Would a little bit of silicone grease on the lead screws help?
tried it with some graphite-powder, to prevent dust to pollute the grease and clog something. did not make big difference 
I don’t think that this is a control board issue, but I’m going to DM you a code for a free one anyway, lets get that in the mail so that we can eliminate that as a cause.
Does it feel like both motors work normally when they aren’t connected to anything? Do you see anything funky or bent or something with either one?
If you can get the machine to reproduce one motor not moving pretty consistently, then try swapping the wires between the top and bottom Z axis motors on the control board and see if the issue follows the motor or the JST connector on the board.
