Z-height issue with bitsetter

I recently installed the bitsetter on my XXL and had an issue today that I was hoping to get some clarification on. I believe the solution is in this older topic link but I wanted to double check. I’m new to the bitsetter and think that’s where I made my mistake.

I was running an Advanced v-carve program in Carbide Create (474) with a total depth of 0.63". I tested the cut on MDF and it looked fine so the next day I went ahead and ran it on my final stock (glued up alder board) and it cut too deep by 3mm. I don’t recall the steps I took in the mdf cut that came out fine but I remember my steps from the messed up cut, which are below.

  1. Turned on the machine and initialized. I believe the machine asks for a tool and then does a bitsetter probing. I had a vbit on so just ran it with that as I wanted to zero to the exact center of my board with the vbit since it is easier to nail down xy coords.
  2. Set my xy coords to the zero mark in the middle of the board. Set my z with the touch probe using the top only with the probe sitting over my zero point in the middle of the board. There is no option in the z-height probe drop down for a vbit so I just went with the 1/16" option as I don’t think it matters.
  3. Opened my .nc file and started it. This program starts with a 1/16" bit followed by a vbit. I followed the prompt to change the tool out to a 1/16" bit which I did. The machine probed the bitsetter and then asked for the spindle to be turned on. Then it started and made the whole cut 3mm too deep. I noticed it shortly after it started but it had already cut the first letter so I just let it run.

At first I though it had something to do with the touch probe not recognizing that the probe was on top of the piece and not on the corner which drops it down by 3mm. I know I had the right option selected though and the touchprobe was in the middle of my board. Then I read the forum topic I posted above and thought it was because I didn’t change the tool to the 1/16" bit with the Change Tool button before I zeroed. I’m not sure why this would matter though. If I initialize without changing the bit on the machine, then zero, then load and start the program, then change to the right bit, why would that mess up my depth? I got a new board and went ahead and pressed the change tool button to change to a 1/16" bit, then zeroed, then ran the program (without changing the tool at the prompt because the correct tool was already on there) and it worked fine. I still want to identify exactly what the problem is so I don’t repeat it. Why would the program need you to change the tool before zeroing only to ask you to change the tool again once the advanced vcarve program starts running? Sorry for the rambling question and thanks for any help.


ok so the bitsetter has the job of correcting the Z “zero point” for the length of the bit in the router.
the way it does this is by, at start of the machine, measure the bit, and then each time the bitsetter probes, it adjusts the zero point of the Z with the difference of the current probe and the previous probe.

now if you put in the new bit, do a normal “zero” operation, and then get the bitsetter to probe, it adjusts the Z for the new bit away from the zero you set.
to get this right, you need the machine to bitsetter probe the new bit before you set the work piece zero, and the easiest way to do that is to use the UI button for changing bits, since that will cause it to nicely come forward for the change, and then it immediately probes.


Thanks for the response. That makes sense, except I seem to remember the machine asks for a bit and uses the bitsetter during initialization after you first turn everything on. Doesn’t that do the same thing as hitting the UI button for changing bits? My machine is running so I can’t turn it off and on to make sure that is right, but I thought it did use the bitsetter during initialization. Do I still need to hit the Change Tool button after initialization then?

I’ve read too many problems regarding this issue that my work flow is now, turn the machine on and initialize, it comes forward and at that point I install my first bit. I hit resume, it probes bit setter, then I zero, then start job. It asks again for a bit, but since I have already loaded my first bit I just hit resume. It probes again and then goes on its merry way. Haven’t had an issue with depth since doing it this way.


the initialization probe counts as the first probe.

only if you change the tool after that do you need to use the button

Thanks for the responses. I’m still confused as to why this happened then if the initialization bitsetter probe counts as the first probe. I know I zeroed after initialization and then changed the tool after starting the job during the bit change request. Maybe I loaded the project file after zeroing? I seem to remember that was an issue in the early days of Carbide Motion. Either way, moving forward I will initialize, load my file, hit Change Tool which will prompt the correct starting tool for that file, zero, start the job, ignore the tool change request, let the machine run the bitsetter, and then turn on the spindle. Hopefully that order will prevent any issues.

I’m with @ctdodge on this.

When you initialize, use your project’s first tool for the BitSetting operation then when you start the job you just let it go about the BitSetting op without actually changing the tool. If you can’t zero with the first tool (X and Y with a Vee bit) or you choose to zero with a different tool (gage pin) then use the “Change Tool” process to change to your project’s first tool after zero’ing [edit 16:27 09092020] but before job start.

Does that make sense?

Isn’t that what he did?

I’m trying to understand as well — I believe he did the following and seemed to have followed what I also though would be correct procedure

  • Initialize machine
  • install bit to zero with (V in this case)
  • machine probes v-bit with BitSetter
  • set origin XYZ with v bit (manual x & y, probe Z)
  • run job
  • load first tool - (1/16” endmill)
  • machine probes 1/16th with BitSetter
  • machine runs job

But instead of running properly, machine begins cutting 3mm too deep. What’s was incorrect?

Not quite. The difference is Stan and I treat that prompt to install your first tool at job start as a dummy prompt. I use the Change Tool button/procedure prior to job start.

To be clear during initialization the BitSetter is setting a zero from the last time the bit was zeroed. So if your last job was 1/4 high and zeroed on top of material then during initialization the BitSetter sets what ever tool is in the router to 1/4 inch above spoilboard where last job was set.

That’s probably the problem — if you Probe for XY and Z, you should do it with a supported endmill, then do a toolchange to a V endmill.

If you Probe for Z you need to reposition the Probe so that it is fully on the surface being probed against.


I’ll note that in the full description, that’s what he indicated he did

Yes Biology Ben, this is exactly what I did to get the 3mm error. I believe the solution when I am zeroing with a bit other than what I will use on the job is to just press Change Tool following initialization. Install my zeroing bit followed by the automatic bitsetting, zero the machine, and then change the tool again for the job. Brian mentioned this method above. What I don’t know is if it matters when in the process I open the nc file. I think it has to be after zeroing since once you open a file and press Change Tool it asks for the job tool, which (sometimes) in my case is not the zeroing bit. But does it matter if, following zeroing with a different tool, I open the file first and then hit Change Tool or instead hit Change Tool and then open the file. I’m guessing either works but don’t want to make a costly mistake if it does matter. Sorry if I am making this more complicated than it is but I already ruined one job and don’t want to mess up another one.

I don’t think it matters when you open the file; it’s more important that you have your first tool installed prior to the job start.

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