Carbide Motion Tool Change Pause

I am using the most current version of Carbide Motion and I have a question about “pausing” between operations. I have two tool paths which use the same tool. The tool being used is a planing bit. If I set my Z = 0, run the first operation and afterwards the program pauses for a tool change, when Bit Setter takes over and looks for tool length to maintain the original zero point I think I’m going to have a problem. I don’t know that the current version of Carbide Motion does this, so I’d like to ask first.

Hi Mark,

If you have two toolpaths in the file that use the same tool, you should not get a tool change routine anyway. Assuming you do, the bitsetter (re)measurement would not be a problem, if would just make no adjustment to Z zero.

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If there is a change request I don’t see how there could not be a problem. Using a planing bit, there is a hollow between the 3 cutters and that hollow is right what would come down atop Bit Setter. The program is then going to think that zero is where the bit and Bit Setter meet. In fact the zero point is not there and is going to be where the cutters meet the wood, nearly 1/4 difference. I am going to presume that you are right about not getting that pause. Thanks, Mark

Sorry, I somehow missed the “planing bit” part of your post.
If your planing bit has a hole in the middle like many do, you could:

  • mount a large enough disc on top the bitsetter button, such that the three cutters push on that disc, rather than the center of the planing bit. If you have it (the disc) installed there from machine initialization, the extra thickness will not matter, the bitsetter will compensate
    EDIT: discussion here about this:
    Bitsetter and large diameter bits issue
    EDIT: another example using a business card
    How to skip bitsetter for waste board surfacing
    EDIT: example, from @Sarge013:

  • or temporarily disable the bitsetter: then you are back to manually zeroing in-between tool changes.


If you have the bitsetter enabled, it should measure the tool before the 1st operation.
If you have the bitsetter disabled, and you have more than one operation, when it sees a toolchange it will still lift up, stop the spindle, and ask you to change the tool.
I shouldn’t ask for a toolchange if the tool has the same tool number as the previous tool.
It is possible, for example to select the #602 McFly, then the #603 McFly, and it would then ask for a toolchange.

How big is your bitsetter? Mine is 1.6" (40mm).
Can you set the bitsetter point off center so that at least one tooth on your planing bit makes contact?


Todd: I’m not at my machine, but I suspect that the size is the same as your machine. With a surfacing bit there is a hollow point between the cutters right at the point where that bit comes down on Bit Setter. Between that point that the cutters is a distance of about 1/4 inch. When Bit Setter measures that it’s going to give you a Z = 0 that is in reality about 1/4 inch off.

You bring up an interesting idea, if I understand you correctly. So, if I put some sort of a disk atop Bit Setter, be it wood, metal, or plastic, secure it there and then re-zero Bit Setter, thereafter I should not have this problem ever again. Correct?

I could move the Bit Setter so that the bit would make contact, but then when I used another bit I’d have to move it back. I’m like electricity, I’m always looking for the shortest path to ground.

Exactly. This bitsetter works by measuring differences in tool length, so it does not matter how thick/high the bitsetter “button” is, as long as it is always the same.

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There shouldnt be a tool change command (M6) between those two ops. if there is, you should delete the M6 in your gcode ( you can edit gcode in notepad ) and the operation should just run as intended.

Thank you. I had to ask because I wasn’t sure if the contact point had to conductive. I thought that it might not make that measurement until an electrical contact was made between the bit and Bit Setter.

that’s how the BitZero works, but the BitSetter is different, is works by triggering an internal proximity switch when the bitsetter button is depressed deep enough

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