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Author Topic: Z axis Tolerance?  (Read 2300 times)

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Z axis Tolerance?
« on: July 17, 2013, 04:58:02 PM »
This is a first for me, my z axis has not reached its programmed zed depth (gcode z level in the minus). I was cutting 0.0625 inch thick material cutting to full depth but Mach would only go to 0.0621 one time then 0.0619 another. Is there tolerances that I am missing somewhere. Like I had mentioned I have never experience this before.

 Thanks MikeB

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Re: Z axis Tolerance?
« Reply #1 on: July 18, 2013, 03:29:07 AM »
Could possibly be you started Z zero slightly higher?
Could it be your axis is loosing steps by being pushed to hard or motor tuning too aggressive or screw/axis binding?
Could it even be your cutter is being pushed up into your collet?

Hood
Re: Z axis Tolerance?
« Reply #2 on: July 18, 2013, 10:45:38 AM »
The DRO was showing a zed depth of 0.0621 and 0.0619 when it should have been 0.0625. I programmed in ArtCam Express to make one pass at 0.0625, simple code. Profiling cutting plexiglas for insert on doors. Z zero is at top of matl, cutting full depth of 0.0625, one pass, profiling. As mentioned the DRO was showing only 0.0621 or 0.0619. Is there a tolerance in Mach that I am missing?
Re: Z axis Tolerance?
« Reply #3 on: July 18, 2013, 10:51:53 AM »
Could be your axis resolution set in motor tuning / steps per unit.     ?

Russ

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Re: Z axis Tolerance?
« Reply #4 on: July 18, 2013, 02:13:50 PM »
Ok thats a different thing then,
 Did the code actually have 0.0625 in it?
As Russ says could be your steps per unit, if they are low then Mach will not be able to resolve small units such as you are attempting.
Hood
Re: Z axis Tolerance?
« Reply #5 on: July 18, 2013, 10:35:03 PM »
Motors are tuned good never had problem there. I'll explain - I am cutting acrylic, set z level to zero at top of matl. Then xy origin to lower left of matl. Start cutting and machine was cutting shallow. (must not set z height to exact matl height) So took z axis to 1.50 inch in MDI mode. Typed in a z level of 1.51 inches to make controller think zed level is higher. After doing this the digital read out would always show max z level depth shallow. The gcode had the correct depth of cut at 0.0625 inches but the DRO would always show actual cut depth at 0.0621 or 0.0619, depending on what part I was cutting out in the material stock. ( Stock: 0.0625 inch thick plexiglas - 36 inches wide X 48 inches long). I never notice this difference in the actual gcode depth to the DRO depth after doing an adjustment to the level. I did the same thing today on different thickness material, readouts were different than the gcode z depth. Thanks for all your help. Have a great day, MikeB

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Re: Z axis Tolerance?
« Reply #6 on: July 19, 2013, 07:08:00 AM »
What we are talking about is the steps per unit you have in motor tuning, what is it?

Hood