# My method to zero Z axis to part.



## S3MIH3MI (Jan 12, 2016)

I have been using this for some time now. I know there is 20 different ways to do this, but this was something simple.
 It's a piece of two sided copper clad circuit board. I cut a slot about 3/4" from one end and soldered a tab to hold a button cell 3 volt battery in place.
Then I placed an LED across the bridge as well as a small jumper to the back side of the board. With it flat on the work piece, when the cutter comes into contact with the board, the LED lights up.
I have the offset programmed in Mach 3 for the thickness of the board.


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## Ken I (Jan 12, 2016)

That gets my vote for the most darstardly simple yet effective idea I've seen in a while.

Thanks - I'm going to make one.

Regards,
            Ken


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## Gordon (Jan 13, 2016)

I just bring it down on a piece of paper and subtract .003. Free and always available.


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## peter2016 (Jan 18, 2016)

I also use a piece of paper. Slide it around as you lower the tool onto it. When it just grips the paper that's it. Generally I don't worry about adjusting for the thickness of the paper unless close toloreance needed.


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## compressor man (Jan 18, 2016)

I always use a .001 shim that I keep by the mill for that purpose.


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## Engineeringtech (Jul 6, 2016)

Clever, but 35 years experience in the electronics industry tells me that circuit board is never very consistent on thickness.    It is, after all, a product made from layers of glass fiber and epoxy.


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## kf2qd (Jul 6, 2016)

Engineeringtech said:


> Clever, but 35 years experience in the electronics industry tells me that circuit board is never very consistent on thickness.    It is, after all, a product made from layers of glass fiber and epoxy.



Yes, but he is not using a bunch of different boards, just that one, and it does not change much from use to use... All he has to do is come up with numbers for his board.


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## XD351 (Jul 6, 2016)

Wow that is simple !
You could measure the thickness of the board where the tool touches and engrave this measurement on the tool i would have expected that over such a small area ( less than 1 inch dia )that the board would be fairly consistent in thickness , surely less than .0005 inch ,could also be used on the lathe .
I usually use a cigarette paper but i found they can  go soggy if the surface is wet with coolant .
A current limiting resistor for that led might be a good idea .


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## bb218 (Jul 6, 2016)

The way I approach setting the Z axis height is using an old .250 gage block, lower the Z axis until the block will not slide under it then raise the Z .001 at a time until the block will slide under the tool, then I know I am very close to being .250 off the part.
  Since I am jogging up instead of down there is less chance of chipping the tool.
    Mike


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## Engineeringtech (Jul 7, 2016)

kf2qd said:


> Yes, but he is not using a bunch of different boards, just that one, and it does not change much from use to use... All he has to do is come up with numbers for his board.



Circuit board is notorious for absorbing moisture and swelling.   May not be significant for most jobs.


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## kvom (Jul 7, 2016)

bb218 said:


> The way I approach setting the Z axis height is using an old .250 gage block, lower the Z axis until the block will not slide under it then raise the Z .001 at a time until the block will slide under the tool, then I know I am very close to being .250 off the part.
> Since I am jogging up instead of down there is less chance of chipping the tool.
> Mike



My method exactly (but 1" gauge block)


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