# Touch probe and large bits

**URL:** <https://forum.onefinitycnc.com/t/touch-probe-and-large-bits/6523>\
**Category:** Original/PRO Series (Buildbotics) (Gen 1)\
**Created:** [July 4, 2021, 4:59am UTC](https://forum.onefinitycnc.com/t/touch-probe-and-large-bits/6523 "2021-07-04T04:59:33Z")\
**Posts on this page:** 1\
**Showing post:** 7

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**Author:** ![349iq2345](https://avatars.discourse-cdn.com/v4/letter/3/bb73d2/32.png) [@349iq2345](https://forum.onefinitycnc.com/u/349iq2345)\
**Post date:** [February 25, 2023, 5:28pm UTC](https://forum.onefinitycnc.com/t/touch-probe-and-large-bits/6523/7 "2023-02-25T17:28:55Z")

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Hey Wayne,

> [@Mr.Voodeux](#):
>
> I put the size of bit when asked but it is a 1.25" 3 sided surfacing bit and as you rotate the bit the radius is different so it could not get an aceturate reading anyway.

Surfacing bits and V-bits are not suitable for probing X and Y with a touch probe block.

> [@Mr.Voodeux](#):
>
> I guess from reading the post here I have to use a small bit to set the XYZ then change bits and redo the Z? Correct?

Precisely. For probing X and Y, you could also use a bit’s shank. The only thing that matters is that you know its exact diameter (check with sliding caliper) and enter this value into the field that pops up when probing.

#### See also

Support videos:

- [How to Probe a V-Bit on the Onefinity CNC](https://www.youtube.com/watch?v=G2MfNTguvKg&list=PLlCbxVoOUWYVsInAIXHKKvWGEqJqoELFD&index=35)
- [Manually Setting X,Y,Z Zero on the Onefinity CNC](https://www.youtube.com/watch?v=5mhpzL1sAwo&list=PLlCbxVoOUWYVsInAIXHKKvWGEqJqoELFD&index=34)
- [Onefinity Touch Probe Fine Tuning](https://www.youtube.com/watch?v=jsiKYUPfeUM&list=PLlCbxVoOUWYVsInAIXHKKvWGEqJqoELFD&index=7)
- [Installing the Touch Probe](https://www.youtube.com/watch?v=p84CB9iMl6Q&list=PLlCbxVoOUWYVsInAIXHKKvWGEqJqoELFD&index=4)

Accessories

- [Onefinity 3-Axis Touch Probe](https://www.onefinitycnc.com/product-page/onefinity-3-axis-touch-probe)
- [Replacement cable (5 or 8 feet)](https://triquetra-cnc.com/product/magnetic-ground-connector-wire-banana-plug/)

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