# PWNCNC Spindle with SLB-EXT Intermittent Issue

**URL:** <https://forum.sienci.com/t/pwncnc-spindle-with-slb-ext-intermittent-issue/26824>\
**Category:** ❓Question\
**Created:** [August 3, 2026, 5:02pm UTC](https://forum.sienci.com/t/pwncnc-spindle-with-slb-ext-intermittent-issue/26824 "2026-08-03T17:02:03Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![randym](https://forum.sienci.com/letter_avatar_proxy/v4/letter/r/c68b51/32.png) [@randym](https://forum.sienci.com/u/randym)\
**Post date:** [August 3, 2026, 5:02pm UTC](https://forum.sienci.com/t/pwncnc-spindle-with-slb-ext-intermittent-issue/26824/1 "2026-08-03T17:02:03Z")

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I have upgraded my Shapeoko 5 Pro to the SLB-Ext with the controller and motor upgrade kit for the Longmill. My PWNCNC spindle is connected via RS485 and responds [properly to both g-sender buttons and embedded g code commands. Some of the time. After some tool changes the spindle does not start spinning and GSender is in pause mode. The onscreen spindle controls are grayed out so I wind up stopping the program, remeasuring the tool and starting from the tool change line.

I’m sure it’s something simple, but I have not been able to find the issue. My only other issue is the tool length probe is painfully slow and changing the firmware settings seems to have no effect. Loving the upgrade so far!

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**Author:** ![bmor02](https://forum.sienci.com/letter_avatar_proxy/v4/letter/b/b38774/32.png) [@bmor02](https://forum.sienci.com/u/bmor02)\
**Post date:** [October 14, 2026, 12:07am UTC](https://forum.sienci.com/t/pwncnc-spindle-with-slb-ext-intermittent-issue/26824/2 "2026-10-14T00:07:21Z")

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Can add some pictures I’m planning to do this setup