[Bad Wolf]

Just changed my Z axis from a rack and pinion to a ballscrew and I am having a small problem trying to recalibrate the software. For an initial setting I just doubled the step count on my 10mm per turn X & Y axis to suit my 5mm per turn Z axis.

So I started with 1602.34 steps per unit. I made a mark with a felt tip pen and zeroed off both machine co-ordinates and the offset, so there is nothing affecting the reading. I then entered -150 in the distance to move and started the calibration running. It stoped and I measured right on 150 so I put 150 in the distance measured and hit ok and then it saved and then I used cancel (since there is no exit button).

I then hit apply setting and save setting. Going back to the main page the Z axis was showing -150 (as it should) and then I told it to go home (zero where it started) only problem is it only moved 131mm back and went back to zero o the Z axis DRO, like something cause it to not go the same distance back it came.

An ideas what went wrong? I have done the calibration heaps of times before, and it worked, so not sure why it isn't fully returning now. I repeated the test several times with the same result.

[Bad Wolf]

Bit more testing I tried doing the calibration with -170mm (checked reading 170) and it returned back about to about 20mm away from the mark. So I tried manually taking it manually down to -200 measured 200 and told it to return home and it was about 25mm away from home... So that tells me it the problem isn't in the calibration part of the software. But I am still stumped as to why it isn't going all the way home.

[Bad Wolf]

Using the diagnostics page I took it to -200mm and told it to return home. It went from zero to something like - 316,000 and then back to zero, so it would appear the software thinks it has gone back to where it started from... Hmmm.

[Bad Wolf]

Seems to have something to do with the Safe Zero setting. I tired making it zero in both the software and the profile but it appears as 1 in the profile, so need some way to ignore it. Hopefully I can turn it off somehow.

[Bad Wolf]

Anyone got any ideas? I'm stuck unable to use my CNC until I get this sorted.

[Bad Wolf]

Did a bit more diagnostics but I'm not sure it moves me any closer to an answer. Firstly I disconnected the other axis to see if it was some kind of interference that was causing it. Nope!
Tried it on the X and Y axis and both worked as expected, which means it is strictly a Z axis related problem. Tried it on MACH3 and the Z axis worked as expected so the problem either appears to be in the UCCNC software itself or some unknown setting in UCCNC. I suspect it is some obscure hidden setting I can't find.

Has no one experienced this before?

[OlfCNC]

I did not see this issue yet you described, but I have an idea for you to test to see if the calibration is OK or not:
After the calibration if you move back to that mark manually (jog) and then zero the axis and then move a distance for example 150mm then is that moved distance correct?
If the distance is OK then I suspect it is only a one time error in the UCCNC something when it changes the steps per with the calibration.
And if this is the case then I do not see an issue, because the calibration is correct, so you have nothing to worry about.
I mean if calibration is OK then you can start using your machine again, or am I missing some details?

[Bad Wolf]

The calibration is fine. If I tell it to go 150mm it goes 150mm from the mark, the problem is when I tell it to "Go to Zero", it should go back 150mm to zero where it started from being that the calibrated distance is right, but instead its only move something like 130mm. If I just move it a random amount using the jog and tell it to go back to zero it still does the same thing and stops short. I took the Z axis motor and tried the same experiment on the X and Y controllers using the respective jog buttons, but when I tell it to Go Too Zero on either the X or the Y it does actually go back to zero.

So the problem seems to be unique to the Z axis and it wasn't doing it with the old rack and pinion setup before I went to ball screw. It's like some kind of Safe Z setting is kicking in preventing it from returning to zero. Problem is the distance seems random between about 5mm and 25mm away from the actual mark. The smaller the increment I move away from the mark the closer it gets, so it almost seems like the distance is controlled by a setting that is percentage driven.

[OlfCNC]

So, if you calibrate your axis. And after you move/jog your axis to the mark on the axis (say it is the zero mark) and you zero your DRO with the zero button.
After this if you move a distance, for example 150mm with jogging or MDI move and you press the goto zero then it does not return to the mark?

[OlfCNC]

I also think it is a good idea to home your axis after the calibration.

[Bad Wolf]

So, if you calibrate your axis. And after you move/jog your axis to the mark on the axis (say it is the zero mark) and you zero your DRO with the zero button.
After this if you move a distance, for example 150mm with jogging or MDI move and you press the goto zero then it does not return to the mark?

That's right, but if I jog back to zero it goes back to the mark I started from, so the problem appears to be tied up somehow to the Go To Zero button. It's like as part of the Go To Zero button return code is also is incorporating some kind of safe Z setting, but it only does it on the Z not X and Y.

[OlfCNC]

So, if you home the Z axis it still does not return to 0 with the goto zero button?
By the way the goto zero button calls the M204 macro, it's code is in the macros folder, just found this out a few weeks ago when writting and checking macros.

[Bad Wolf]

If you hit the Go To Zero button the DRO will read like it is counting down to zero and actually show zero on the DRO but will be anywhere from 5mm to 25mm away from the zero mark position.

[OlfCNC]

So, if you zero the axis at a marked point (lets say it is a zero point) with moving to that point and zeroing your axis with the zero button and then you move to for example 150mm then you press the goto zero and it does not return to the mark?

[Bad Wolf]

In the Configuration / General Settings / Safe Z Height units I have tried setting that from 25 to 0 but it still shows up in the Profiles / Default.pro as "SafeZ=25" I have tried manually changing this setting to SafeZ=0 and saving but it seems to make little difference like the setting is either being reset or drawn from somewhere else.

[Bad Wolf]

So, if you zero the axis at a marked point (lets say it is a zero point) with moving to that point and zeroing your axis with the zero button and then you move to for example 150mm then you press the goto zero and it does not return to the mark?

Correct it will show zero on the DRO but be between 5mm and 25mm away from the original mark. BUT If I jog it back to zero it will be on the mark.

[OlfCNC]

Sorry, but I still don't understand.
You said:

1.) You zero with the gotozero button then the DRO returns to zero but the axis not.
2.) You jog back to zero and then it will be on the mark.

How do you jog back to zero when the axis DRO is already on zero according to your first statement?!

[Bad Wolf]

Ok sorry for the confusion. I found a random spot on the Z axis and put a marker mark there, and then pressed zero so there was no offset and it was zeroed to that point. If I jog or calibrate out to that point say 150mm and then press Go To Home it will show zero on the DRO as it counts down but will be physically 5mm to 25mm away from the mark. If I realign the mark up again and I set the DRO to zero and then move it a second time to 150mm and then jog back to zero the marks will line up.

So in summary jogging there and back is ok but if I jog out and use Go To Zero it does return exactly right.

[OlfCNC]

OK I think I got it now.
And what about the case when the second and later times realignment to the mark and moving out with jogging (not with calibration) and then pressing the goto zero button?
Does this returns to the mark correctly?
If it does then I think the calibration makes some kind of issue which normalises after zeroing the axis or homing it etc.
It must be then that the calibration messes up something temporarily.
And if this is the case then I think your problem is solved, because you only need to calibrate the axis once, I mean you will not calibrate the axis every time you use the machine. once it's done on next realignment and movements it will be OK.
But check if this is the case or not.

[Bad Wolf]

I have tried to zero, then move it out and home, then correct and try the same test again, I have tried test in both the positive and the negative number, but each time it keeps on coming up short of the mark, and needs to be reset to the mark every time I try using the Go To Home button.