Z axis going deeper and deeper

Anyone have an ides why my z axis go deeper and deeper when i do 3d finish cut ?

You are loosing steps or something is slipping.

my set up per units have been well calibrated and this only happen when i cut in 3d

Are you using Easel to send the gcode? Can you see if the controller is reporting the same Z height you are seeing?
If not,

i am using mach 3 with vectric aspire

Is the Z-depth being reported accurately? After this happens, if you tell the machine to go to Z10, is it 10mm above your stock?
Basically, is the problem that your machine is going deeper than it’s being told (slipping)? Or is the issue on the CAM side of things where your toolpath is not doing what you expect?

its going about.400 inches more than whats its told.it does it gradually

If the work zero (especially Z) is at the same place after the carve, then it is the code.
If work zero is deeper after the cut you are loosing steps or something is slipping.

Loosing steps is easy if:
Stepper motor too weak, or is not given enough juice.
Stepper have too fast rapid/acceleration values causing it to miss steps during retraction
One of the stepper motor wires have poor/intermittent contact
Stepper driver current rating set too high, causing overheat and short burst of drop-out.


ok good but like i said it only happen during 3d cutting

That’s when your Z is most active and more likely to notice the slipping.

Well thanks gentleman i will see what i can do…its probably slipping somewhere

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Is it an X-carve?
If so, check the set screws in the Z-axis pulley.

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yes it is

When the carve is done is the bit at safety height? If it is lower than safety height you are loosing steps when raising or the pulley is slipping on the acme screw.

OK gentleman here it is…i check my z axis and nothing is sliping
Heres some numbers
i have the z axis at zero and the machine coords is -2.2947and i measure the z axis board at 2.4100
now if i do a dry run for 5 minutes here are the numbers
i return the z axis at ZERO and the machine coords is the same at-2.2947 but my z axis board is now LOWER at -2.4720 so lower by -0.0620 inches.
Can anyone help me on this one ?

This confirms that it is a mechanical problem. I’d echo what @BillBlades suggested.

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If it lost steps wouldn’t it still show same position but be actually off by the amount of missed steps? But yes mechanical issue likely the cause of lost steps, a tight spot in the screw mechanism. Have you used the supplied lube for the Z screw?

Yes but most of the discussing has been towards something mechanical loose or slipping. Lost steps is not mechanical but mechanical can cause it when there is binding.
Could also be lack of power to the Z motor if the rate is turned up.
But my guess is binding screw causing lost steps.
He should try to just cycle it up and down in 2.5" cycles with out cutting and see if it holds position.

Hi Mark
when i cycle it up and down it does maintain position

@ConradCaron It might be a current issue? What controller are you using?