Downward drift Z

CNC Machines
1

Stumped on this one. Any suggestions? Using Vcarve Aspire, exporting to correct machine type. Using Carbide Motion to run Shapeoko 5 Pro (2x4).

Simple pocket. Everything starts fine, but later in run, the Z-axis will begin to drift downward, cutting deeper than designed. See fine steps downward near outside edge of pocket.

No loose bolts. Z is zeroed correctly. This happened on several pieces initially, until I quit using Bitsetter. It stopped, now it is occurring again.

Been in CNC for five years and never happened on my old machine (Bob’s CNC).

Any suggestions greatly appreciated.

IMG_3646
IMG_36465712×4284 3.36 MB

2

IMG_3645
IMG_36454284×5712 3.19 MB

3

Which machine do you have? Which Z-axis?

Is there a retract? Could something be interfering mechanically when retracting?

4

Mark where the bit meets the collet, make sure the bit isn’t being pulled down out of the collet.

Could the wood be flexing or warping as you cut it?

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5

Have you lubricated your linear rails/bearings lately? The added friction of dry bearings can cause a lot of weird issues.

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