# TLS If using spoilboard as z-zer0

**URL:** <https://forum.sienci.com/t/tls-if-using-spoilboard-as-z-zer0/26914>\
**Category:** 📄 General\
**Created:** [August 14, 2026, 10:13pm UTC](https://forum.sienci.com/t/tls-if-using-spoilboard-as-z-zer0/26914 "2026-08-14T22:13:53Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![ChrisAtJohnsons](https://forum.sienci.com/letter_avatar_proxy/v4/letter/c/c0e974/32.png) [@ChrisAtJohnsons](https://forum.sienci.com/u/ChrisAtJohnsons)\
**Post date:** [August 14, 2026, 10:13pm UTC](https://forum.sienci.com/t/tls-if-using-spoilboard-as-z-zer0/26914/1 "2026-08-14T22:13:53Z")

</div>

If I keep G54 z-zero as the spoilboard can I use the TLS to set bit length when I change bits?

---

<div class="post-metadata">

**Author:** ![\_Michael](https://forum.sienci.com/user_avatar/forum.sienci.com/_michael/32/2962_2.png) [@\_Michael](https://forum.sienci.com/u/_Michael)\
**Post date:** [August 16, 2026, 4:21am UTC](https://forum.sienci.com/t/tls-if-using-spoilboard-as-z-zer0/26914/2 "2026-08-16T04:21:21Z")

</div>

Welcome to the group Chris.

I don’t have a TLS but to the best of my knowledge it doesn’t matter where zero is set. GRBL doesn’t know whether you set zero to the material or spoilboard. GRBL just uses the difference from the last tool to the new tool to keep the zero where it was.

I don’t think it matters but it might help if you tell us what CNC and TLS you have. Maybe someone with the same setup knows for sure.

---

<div class="post-metadata">

**Author:** ![ChrisAtJohnsons](https://forum.sienci.com/letter_avatar_proxy/v4/letter/c/c0e974/32.png) [@ChrisAtJohnsons](https://forum.sienci.com/u/ChrisAtJohnsons)\
**Post date:** [August 16, 2026, 1:57pm UTC](https://forum.sienci.com/t/tls-if-using-spoilboard-as-z-zer0/26914/3 "2026-08-16T13:57:47Z")

</div>

I have the Altmill 4x4. Haven’t bought a TLS yet was just wondering if I could use it to replace the touch plate if everything homed off of the spoil board.

---

<div class="post-metadata">

**Author:** ![Jens](https://forum.sienci.com/letter_avatar_proxy/v4/letter/j/d2c977/32.png) [@Jens](https://forum.sienci.com/u/Jens)\
**Post date:** [August 16, 2026, 2:26pm UTC](https://forum.sienci.com/t/tls-if-using-spoilboard-as-z-zer0/26914/4 "2026-08-16T14:26:14Z")

</div>

How would you set the first/initial z zero? I suppose you could do that with the ‘paper’ method. How would you locate the corner of a piece of stock to set x/y zero?  
I suppose it is possible but to me it sounds awkward.

---

<div class="post-metadata">

**Author:** ![\_Michael](https://forum.sienci.com/user_avatar/forum.sienci.com/_michael/32/2962_2.png) [@\_Michael](https://forum.sienci.com/u/_Michael)\
**Post date:** [August 16, 2026, 4:26pm UTC](https://forum.sienci.com/t/tls-if-using-spoilboard-as-z-zer0/26914/5 "2026-08-16T16:26:05Z")

</div>

Speaking for myself, I use the center of the material at the spoilboard surface a lot. If the stock is big enough XY just need to be close enough and Z is set somewhere beside the stock. If I do use my block I need to do two separate probes.

With the center of my mills XY saved in G59 it doesn’t take long for my XY to be set to the center and the grid on the spoilboard makes it easy to place stock centered. A lot of jobs I only need to set Z.

I just had a thought! If you have a TLS, always use it and have accurate homing, do you even need to set Z if it’s kept at the spoilboard surface? If only I had a TLS and a table that didn’t move with humidity changes I could try for a setup where a lot of the time no zeros needed to be set.