# Suddenly losing Z zero **URL:** \ **Category:** Uncategorized\ **Created:** [December 23, 2022, 7:48pm UTC](https://forum.onefinitycnc.com/t/suddenly-losing-z-zero/17598 "2022-12-23T19:48:18Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![dgentner](https://avatars.discourse-cdn.com/v4/letter/d/8e8cbc/32.png) [@dgentner](https://forum.onefinitycnc.com/u/dgentner)\ **Post date:** [December 23, 2022, 7:48pm UTC](https://forum.onefinitycnc.com/t/suddenly-losing-z-zero/17598/1 "2022-12-23T19:48:18Z")
While roughing out the inside arch of an archtop guitar my spindle suddenly lost its Z position and plunged a quarter of an inch too deep. I’m using a Fusion 360 program that I’ve run many times with no problems. I was cutting the arch in two passes removing .125 per pass with a 1/2" endmill. This ruined a very expensive piece of quilted maple that was part of a set. Any ideas what went wrong? ![20221223_133159](https://us1.discourse-cdn.com/flex022/uploads/onefinitycnc/original/3X/a/7/a74297f1e8af0846f9bfccbefb7cbb13d8e36517.jpeg) ---
**Author:** ![Atroz](https://avatars.discourse-cdn.com/v4/letter/a/958977/32.png) [@Atroz](https://forum.onefinitycnc.com/u/Atroz)\ **Post date:** [December 23, 2022, 7:56pm UTC](https://forum.onefinitycnc.com/t/suddenly-losing-z-zero/17598/2 "2022-12-23T19:56:49Z")
Are you sure the router moved down or did the bit slip in the collet? That happens especially if you’ve got a build up of dust in it. ---
**Author:** ![dgentner](https://avatars.discourse-cdn.com/v4/letter/d/8e8cbc/32.png) [@dgentner](https://forum.onefinitycnc.com/u/dgentner)\ **Post date:** [December 23, 2022, 7:59pm UTC](https://forum.onefinitycnc.com/t/suddenly-losing-z-zero/17598/3 "2022-12-23T19:59:17Z")
I don’t think it slipped, but it it’s possible. ---
**Author:** ![349iq2345](https://avatars.discourse-cdn.com/v4/letter/3/bb73d2/32.png) [@349iq2345](https://forum.onefinitycnc.com/u/349iq2345)\ **Post date:** [December 23, 2022, 8:46pm UTC](https://forum.onefinitycnc.com/t/suddenly-losing-z-zero/17598/4 "2022-12-23T20:46:46Z")
Hey Dave, [this](https://forum.onefinitycnc.com/t/machine-ramping-when-not-called-for/17211/2) may help you ---
**Author:** ![dgentner](https://avatars.discourse-cdn.com/v4/letter/d/8e8cbc/32.png) [@dgentner](https://forum.onefinitycnc.com/u/dgentner)\ **Post date:** [December 23, 2022, 10:26pm UTC](https://forum.onefinitycnc.com/t/suddenly-losing-z-zero/17598/5 "2022-12-23T22:26:01Z")
Thanks guys. Looks like it was a dirty collet. I ran the little test program and it did fine. I just finished roughing out the arch in the guitar back (same program as the top) and had no problems.