# Bitzero Probing on Hole in Aluminum

Hey all!

I was curious if the Bitzero Probing procedure had an expectation of a fixed size hole (For instance, the hole that the Bitzero 2 has).

The reason I am curious is I was thinking it could be really nifty if I could probe X/Y to set zero using the “Bitzero 2” probe procedure using a random hole in my Aluminum stock. In theory, because we know how much the head has moved before contacting each side of the hole, one can calculate the exact center regardless of hole size.

Has anyone done this or can anyone confirm that this is a reasonable way to use existing probing procedures?

Thanks,

Nate

The size interaction is determined by whether or no the probing operation times out, so so long as the endmill is large enough for it to traverse the hole before the operation times out — so long as the wiring is set up so that things will complete the connection, it will work.

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Excellent. This is exactly what I was hoping I wanted to use a milled hole as my locating feature, so this will work perfectly.

It would be great to get some input on how this might work.

I’ve never done a BitZero 2 probe, but as an observer, I would have thought the size of the hole must be known by the probing algorithm. That way, it can figure out the size of the endmill since it would be able to subtract travel distance from a predetermined aperture size.

Can it really probe a hole of arbitrary size with an unknown sized endmill and produce an X/Y zero?

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You’d want to use a pin for this, not an end mill.

My use case is doing a job with a flip, so after the flip, I’ll locate on the milled circular hole.

The size of the pin doesn’t matter. It touches one side and then the other, adds the movement distance values and divides by 2 to get the centerline. If it’s 1/8” or 1/4”, it doesn’t matter as the math is identical so long as the probing pin doesn’t change size or shape while it’s probing.

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It’s not necessary to know either the bit or the hole diameter, so long as both are circular.

You probe one axis first, say Y, go +Y until you contact, now go -Y until you contact, halfway between these is the ‘center’
Now go to your Y0 and go -X until contact, +X until contact, halfway is your 0.
Many algorithms will then do a confirm probe of Y again as it may have been well off X center first time round.

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@Gerry
See my CNCjs macro here for the probing logic.

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Do you get enough accuracy from the BitZero V2 for flip operations?

(I’m asking, because I developed a workflow which doesn’t require re-zeroing after the flip, having discovered that I couldn’t get the results that I wanted from the BitZero)

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Yep! I’ve had zero issues with the BitZero v2 for flips. I’m doing all metal, so technically I could just touch off on the metal itself (and may start to do that).

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