# Rotary parts under sized **URL:** \ **Category:** General Chat\ **Created:** [May 29, 2026, 8:24pm UTC](https://forum.avidcnc.com/t/rotary-parts-under-sized/6198 "2026-05-29T20:24:10Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Bstanga](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.avidcnc.com/bstanga/32/791_2.png) [@Bstanga](https://forum.avidcnc.com/u/Bstanga)\ **Post date:** [May 29, 2026, 8:24pm UTC](https://forum.avidcnc.com/t/rotary-parts-under-sized/6198/1 "2026-05-29T20:24:10Z")
So I was recalibrating my rotary due to undersize brass parts and I saw that the calibration bar was turning 20 thou out at the chuck. link to the video below. I rechucked it several times, then checked the rod in my big lathe zero runout. Now what? [![](https://canada1.discourse-cdn.com/flex027/uploads/avidcnc/original/2X/d/d4231ffe48c410fdfb682d8aebde84c9366d81c1.jpeg "20260529 145925") ](https://www.youtube.com/watch?v=I9Y1R5zXih0) ---
**Author:** ![djdelorie](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.avidcnc.com/djdelorie/32/515_2.png) [@djdelorie](https://forum.avidcnc.com/u/djdelorie)\ **Post date:** [May 29, 2026, 8:36pm UTC](https://forum.avidcnc.com/t/rotary-parts-under-sized/6198/2 "2026-05-29T20:36:28Z")
What I do on mine (linuxcnc, not Avid, controls) is to rotate the chuck so the probe only ever touches one point on the rod. If you do that, it shouldn’t matter (to the probe-for-center-of-rotation) if the rod is off-center. ---
**Author:** ![Bstanga](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.avidcnc.com/bstanga/32/791_2.png) [@Bstanga](https://forum.avidcnc.com/u/Bstanga)\ **Post date:** [May 30, 2026, 1:39am UTC](https://forum.avidcnc.com/t/rotary-parts-under-sized/6198/3 "2026-05-30T01:39:21Z")
It looks like the jaws were put in the four jaw chuck out of sequence explaining this 20,000 out of round