Touch Probe Not Setting Depth Correctly

I purchased a touch probe and have had it for about a month. Every time I set the depth with the touch probe, X,Y andZ and/or just Z the depth is not set properly. Every time I fail to cut through the bottom of the project by 1/16" of an inch. Yesterday I created 12 boxes (3x5) cut out of 1" boards. The boards ranged from 1.040 to 1.032 so rather than plane the boards I just set the thickest board in CC (1.040). In the toolpath I picked use “Stock Bottom” and created the cut outs around each top and bottom of the box. Every single one failed to cut through the bottom and I spend a hour today cleaning up the 1/16" left over. Last week I did a Vcarve on a box top and used the touch probe. The vcarve did not cut deep enough on a horse head in the design. I put another box top in the holding jig and set with the paper method and the vcarve cut just fine with a good depth of cut.

Is there any calibration of the touch probe or setting I can use to get the zero really at zero. With the x,y and Z you put the probe on the corner overhanging the edge and with the Z only you set the whole touch probe on top of the surface so I am not mis setting the touch probe position. I made sure the #201 tool was set in the probing because that was the bit I was using. The X and Y seem to set just fine. It is only the Z that is not setting properly.

Here is the example for the box top. The fully cut was done with paper and the shallow cut was done with the touch probe in Z only mode. On the two examples I did change the text and spacing but did not touch the horse.

Both box tops were sealed with dewaxed shellac and the vcarve was painted with acrylic paint and sanded by 120 grit paper. The one with the touch probe just was not carved deep enough to start with.

Before you start the job and after running the probe cycle have you jogged the machine down to Zero to check it looks correct?


I have not. I will try that tomorrow. I have a bunch of box tops to vcarve. I cut 6 box tops today but I just zero’ed with the paper method and all came out good.

I think thats the next thing to test.

I have been gone to Houston for a few days visiting family and friends. I got back and went to work today. I used my new Carbide 3d touch probe to zero x,y, and z with a #201 bit. After the setup I jogged the router over to the center of the piece of oak I used to set zero and the Z zero was .034" (.8636MM) above the surface of the wood with the Z axis showing “0”. Since this was an x,y and Z probe for zero I had the lip of the touch probe hanging off on two edges. I measured the touch probe and it is exactly 25MM on the tall sides and 22MM on the short sides of the probe. I am running Carbide Motion 4 and the firmware is the latest released 1.1. The machine is an XXL.

Any idea why my touch probe is not setting the Z zero properly. From looking the X and Y are set ok. As stated on a previous post on this subject I had cut 12 boxes and all failed to cut through the bottom but each box was consistent and seemed to be just was the gcode was commanded to cut. I found no variations in the cuts. After zeroing the first board I simply clamped the successive 11 boards in and started the job using the already set up x,y and z zero. If I use the paper method to zero Z the boxes are cut through just like they should.

It is not a big deal to set the z with paper but I bought a $120.00 probe to do that more accurately than manually setting. I dont feel that my Z axis is the problem. The Z axis moves smoothly manually and the belt feels tight and the cuts for depth are consistent. I made sure my bit is tight so I dont think this is an operator error. Anything is possible but if my Z axis was loose or the bit was not fully tightened I would be getting inconsistent results in depth of the pockets.

Wouldn’t be unusual for a piece of wood to vary in thickness or for your wasteboard to be not flat. If you jog to X0Y0Z0, how far off is the Z?

The supplemental 3/4" spoil board is flat. I have verified the flattness. Additionally the board that I had zero’ed on was flat and consistent in thickness.

My point is every time I use the touch probe it is not really setting zero at the top of the material. If I use the paper method the Z zero is set at the top of the board, touch probe setting is off by .034" above the surface of the board consistently. I am using the lower left for zero and I am only moving the router over a few inches to get the bit solidly over the board instead of on the corner with part of the bit hanging off the x and y.

If you jog to Z25 (mm), does the probe slide under?
Try in a few XY locations.

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Usually when there’s a problem with setting the Z for the Probe it’s caused by Probing for Z when the Probe is placed as if it would be probed for X, Y, & Z.

Please describe step-by-step how you are setting your zero in synch with the instructions at:


I have followed your instructions and downloaded the touch probe instructions and updated the steps for X,Y,and Z as well as Z only. The pictures are in the pdf attached. I repeated each step twice and got the same result for both attempts on each procedure.

Uploading: gld_06162019_touch_probe.pdf…


I thought I had uploaded my pdf but apparently it did not upload. I have tried several times. I will upload in the morning. I have an extremely low bandwidth and it is raining so that does not help. Sorry

Uploading: gld_06162019_touch_probe.pdf…

I tried to upload my PDF via WiFi. The message was my attachment was too big. My laptop at home would quit sending and the attachment would disappear. Windows and Firefox never said my attachment was too big.

I will remake PDF and try to get it smaller.

Save your pictures with a lower level of detail i.e: medium instead of high resolution. You can also post each of the pictures directly instead of making pdf so it will be easier to upload.

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I wanted to close the loop on this problem. I was having inconsistent depths when using my touch probe. The problem was corrected not by any adjustment or procedural change but dumb luck. I had removed my fences and clamps and Tram’d my spoil board. When I put the fences back on the 1/4-20 bolts were too long and was causing my spoil board to have ripples in it. When I made my spoil board I used the Myers Woodshop design. That design used 1/4-20 Tee nuts. I sized the bolts to work with the 3/4" MDF spoil board and the 1/2" recess in the cam clamps resulting in a 1.25" bolt length. Because I have Tram’d my spoil board the MDF spoil board is now 1/2" thick requiring a 1" maximum bolt in the clamps and fences. After I bought new bolts and replaced the 1.25" with the 1" bolts the problem with not setting zero properly went away.

Sorry for my confusion but you live and learn. As I Tram my spoil board I will need to have more than one set of 1/4-20 bolts to keep from raising my spoil board as the bolts bottom out when tightening. When I cut out this current spoil board I made 3 all together. My next Tram will require replacement of my spoil board and I can go back to the 1.25" bolts and keep the 1" bolts in reserve for future use.

Strange but true stories in the ongoing adventure called CNC’ing.

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