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Z-Axis tries to go through the roof/top plate of the axis


if i do the z-axis calibration all movements and zero-ing works. When i then auto-continue to the test-cut the z-axis motor tries to lift up the clamp-sled/router beyond the height of the z-axis. (very nasty noises, probably damaged spindle). I tried a couple of different aproaches but i always end up with this problem. The z-axis is probably already damaged.

Which parameter limits z-axis movement? I couldnt find it anywhere. Then, is there a documentation for groundcontrol.ini expcept reading the source-code?!

That sounds good. If you are able to use the up and down buttons to raise and lower the z-axis then I don’t think there are any hardware issues.

This is during the calibration process?


You need to change the pitch of the z-axis. I don’t know what it is for @metalmaslow setup, but its somewhere on the board here.

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thank you for your help: Metal Maslow support did just mail me i need to change the pitch value in groundcontrol settings to -22. As soon as i am back on location i will report back here. I wonder where i did overlook this information. I double checked and its not in the metal maslow assembly instructions. There should also be a list of parameters which need to be changed in groundcontrol which are specific to metal maslow on their website.

Would had been great to know this before possibly damaging something.

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Weird… I found one post that said -8 for @Metalmaslow . Might be a different design you have.

Or you can measure it. Tell it to move 10 mm and see how far it actually goes, then adjust. I found that mine was 24. It has an 8mm shaft with a 3x gear multiplier with the belt pulleys.

Maybe not weird. I did change to -22 and used “lower” in the z-axis menu. The clamp-sled did again hit the upper end of the Z-Axis. So, “-” seems to be very wrong for my motor.

a pitch of 22 is rather large

for the sign, is it moving in the right direction?

for the number, tell it to move a very small amount (say 1mm) and see if the
movement is anything close to what you expect.

David Lang

I changed it to 8 which looks like 1mm movement when i use raise / lower in the z-axis and z-axis calibration menu. Raise/Lower works. Go to zero works.

BUT when i finish the z-axis calibration and start the test-cut the clam-sled hits the top again. Its becoming frustrating…groundcontrol.ini (1.5 KB)

Groundcontrol.ini attached…

Do i need to completely re-calibrate after rewriting the firmware? I get a “chain-length” not found (0.0) please use actions set-chain length. But its still in groundcontrol,ini?!

what is your "safe travel height set to?’ What is your gcode telling the machine to go to when it moves? I use a z travel height of 5 mm, but if you are cutting in inches, then it is going for 5 inches. You may want to verify your gcode and your system units are all in mm or all in inches.

You don’t need to recalibrate, but you do need to reset the chain lengths.

I did reduce z-travel to 4mm. The strange thing is that, if i manually move the z-axis via the calibration or z-axis menu it seems to move correctly. I can set zero, raise and go back to zero. But as soon as i try to make the test-cuts the software runs the router-clamp-sled into the head of the z-axis.

Is there a way to switch off the actual execcution of the code and only display it? I am getting tired of hearing the router-clamp chrrrchrrrchrrr"ing" against the top of the z-axis.


I also had been thinking that there might be a “selective mix up” of inches and mm. I am using a german laptop configured with english language and german keyboard. This sometimes gives problems with delimiters like “.” and “,”. Somtimes software uses “.” as delimiter (like 0.5 cm) sometimes “,” (0,5 cm).

But software should do this consistently. So either “.” or “,”. Guess i have to debug this.

There is the fake servo mode, but I’m not sure it will help you (how would you
know you are hitting the limit)

can you post the g-code you are using?

David Lang

I have one log:

crash.log (6.6 KB)

Is there any documentation for this 1980ties style variables: $1 to $42 ?!

Software Documentation is a bit thin or is it only me not finding it?

And why does “it” say:

$10=4267 (full length of chain, mm)

and at the same time:

Unable to find valid machine position for chain lengths -0.38, -2.72 . Please set the chains to a known length (Actions -> Set Chain Lengths)

Using "Actions->Set Chain Lenghts didnt get rid of the message though.

Then, i did put the firmware back to 1.28. I did accidently downgrade to 1.26 once, after this run i did re-upgrade to 1.28. No difference in bahaviour anyway. Are there any values lost because of an firmware change?!

And why does “it” say:

$10=4267 (full length of chain, mm)

because that is 11’ of chain

and at the same time:

Unable to find valid machine position for chain lengths -0.38, -2.72 . Please set the chains to a known length (Actions -> Set Chain Lengths)

if it thinks your chain lengths are this, no wonder it can’t find a position

Using "Actions->Set Chain Lenghts didnt get rid of the message though.

what shows up when you set the chain lengths?

David Lang