Going through the material and onto spoilboard

I added a secondary spoilboard and proceeded to make a profile cut/contour and withing 50% of the cut complete the endmill had gone through the material and about .125 into the secondary spoilboard.
I did tram and surface the new spoilboard. I stop the cut.

Was I suppose to make any changes when I added the secondaty spoilboard?
My zero is set at the surface of the material

How accurately did you measure the stock?

How did you set zero relative to it?

What is the safety/retract height? How much space was there above where the origin was set?

Which Z-axis does your machine have? Which did you configure for?

What tool and toolpath were you using? Was it a slotting cut where the tool could pull the machine into the cut?

How did you secure the endmill? Could it have pulled out?

1.The measurement was pretty accurate.
2. I set z left corner (material surface)
3. 25.
4. Zplus
5. #201 .25 endmill
6. With the wrench

How much offset did you use on the contour cut? Is it possible that you didn’t have enough offset and the bit was pulled in the the wood?

#6 - with THE wrench or with BOTH wrenches?

You need to use 2 wrenches, not the button and 1 wrench which is what I did for a long time. I had the bit get slowly pulled into the wood and eventually dig into the surface.


I think that when I added the extra spoilboard I didn’t configure the z axis. So the z axis thinks that it’s still configured to the original spoilboard.

At least that’s what Nick from Carbide let me to beleive so I will try and re program carbide motion again with the zero set with the additional waist board.

If you set Z zero on the top of your material that wouldn’t matter. That is what I thought you described.

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Is your retract height actually set to 25 or 0.25? I assume you are working in inches and it is 0.25 but want to clarify. If you have it set too high and you have a new higher spoil board you may be reaching the top of the Z-axis travel and it is losing steps causing you to drive lower every time it hits the top and loses steps.

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Thats is exactly what Nick from carbide 3d said.

Suggestions on how to fix this?


and yes it is .25 inches

I did a 3d roughing and finish with no problems. It was until I tied to profile cut that I found the problem.

It also does good pockets cut, just not profile through cuts.

Can you share the file you are having trouble with? Generally you need to make sure that the top of your board plus the retract height won’t cause the z-axis to reach the top. With a 0.25 inch retract it is not likely but it depends on your material and how high the second spoil board is. If you share they file it will help confirm a few things just to make sure. Also if you can send a picture of the bit in the spindle positioned above the material. Be sure it also includes the top or the Z-axis in the image so we can see how close to the top it is.

And what is your depth of cut on the profile and as @Brew asked do you have an offset or are you cutting the profile the same width as the diameter of your bit? That puts more stress on the bit which could lead to the bit pulling out if it isn’t tightened with both wrenches.

Depth of cut is.08. And yes it has an offset. I think it has something to do with the added .75 additional spoilboard. That is not accounted for in the software.

I still can’t see how that matters if you are zeroing in the top but I will defer to the more experienced users.

.5 primary spoilboard, .75 additional spoilboard, .25 retract plus.82 material. Plus lenght of tool 2”

If I’m not mistaken Shapeoko Pro z Max is 4”.

.5+.75+.25+.82+2= 4.32 give or take. So that’s where I think is the issue

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When you calculate it out, that may be the issue, “Z” is probably losing steps. You could reduce the retract height to make your clearance within spec, loose the additional spoil board which will give you the clearance you need.

Hope this helps.

If you think your running out of Z height just raise the router / spindle a little higher in it’s mounting clamp. If you using a .750" supplemental spoil board, raise it that much. Also, be sure to check that you have clearance between the lowest part of your Z axis and your work piece.


I am able to do a 3d roughing/finish pass and pocket cuts with no problem. It is only when I do a profile cut and set to cut through the material that I have the issue.

For difficulties with contour toolpath see:


and consider leaving a roughing clearance and taking a finishing pass.