# Holey Triangular Calibration

**URL:** <https://forums.maslowcnc.com/t/holey-triangular-calibration/6240>\
**Category:** Technical Details\
**Created:** [August 29, 2018, 7:25pm UTC](https://forums.maslowcnc.com/t/holey-triangular-calibration/6240 "2018-08-29T19:25:54Z")\
**Posts on this page:** 1\
**Showing post:** 203

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**Author:** ![c0depr1sm](https://yyz1.discourse-cdn.com/flex031/user_avatar/forums.maslowcnc.com/c0depr1sm/32/9614_2.png) [@c0depr1sm](https://forums.maslowcnc.com/u/c0depr1sm)\
**Post date:** [January 30, 2019, 5:26am UTC](https://forums.maslowcnc.com/t/holey-triangular-calibration/6240/203 "2019-01-30T05:26:17Z")

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I think we are ready to integrate one more Holey Calibration step improvement into the firmware: the **chain tension calculation and chain stretch compensation.**

I propopse to do it so that users get immediate vertical scale improvement of their [center upper workspace](https://forums.maslowcnc.com/t/sled-will-not-go-to-top-of-board-same-parts-are-cut-different-sizes/8646). That would at least improve the standard calibration results.

The proposed implementaiton adds 4 slots into the EEPROM table: sled weight and chain stretch would have default values, plus two reserved slots. Bumping EEPROM table to version 6.

This way, a default value is applied, and macros of the type $4X=YY would allow advanced users to tune manually. Then it would be ready for a later update GC to offer GUI based adjustments.

I prepared a [firmware version for review](https://github.com/c0depr1sm/Firmware) before triggering a pull request. I will test it in the coming days. (Arduino IDE compiles fine)

It is based on the current firmware and integrates these specific items from Joshua’s proposal.  
Please review and comment.

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