# Initial Calibration Failing (fw 1.20, horizontal)

**URL:** <https://forums.maslowcnc.com/t/initial-calibration-failing-fw-1-20-horizontal/25769>\
**Category:** Troubleshooting\
**Tags:** accuracy, calibration\
**Created:** [May 12, 2026, 7:48pm UTC](https://forums.maslowcnc.com/t/initial-calibration-failing-fw-1-20-horizontal/25769 "2026-05-12T19:48:38Z")\
**Posts on this page:** 1\
**Showing post:** 27

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**Author:** ![ian\_ab](https://avatars.discourse-cdn.com/v4/letter/i/a587f6/32.png) [@ian\_ab](https://forums.maslowcnc.com/u/ian_ab)\
**Post date:** [June 23, 2026, 10:56pm UTC](https://forums.maslowcnc.com/t/initial-calibration-failing-fw-1-20-horizontal/25769/27 "2026-06-23T22:56:01Z")

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Some things you can look at

1. Belt end needs to rotate freely on the anchor
2. Anchor block must not move, secure it down tightly
3. You are running two different versions of index.html.gz and firmware.bin. They should match.  
Serial Messages  
Index.html Version: v1.21  
[MSG:INFO: FluidNC v1.20]
4. Floating control board is not a problem, but have a look through the printed parts thread for a couple of solutions which seperate the control board from the router.  
[Maslow 4 3D printed parts thread](https://forums.maslowcnc.com/t/maslow-4-3d-printed-parts-thread/20627)
5. The gap between arms is not generally a problem, putting anything in there may be counterproductive as it may restrict rotation,

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