# List of sources of error

**URL:** <https://forums.maslowcnc.com/t/list-of-sources-of-error/7523>\
**Category:** Technical Details\
**Created:** [November 1, 2018, 12:19am UTC](https://forums.maslowcnc.com/t/list-of-sources-of-error/7523 "2018-11-01T00:19:03Z")\
**Posts on this page:** 1\
**Showing post:** 36

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**Author:** ![Joshua](https://avatars.discourse-cdn.com/v4/letter/j/48db29/32.png) [@Joshua](https://forums.maslowcnc.com/u/Joshua)\
**Post date:** [February 13, 2019, 6:45pm UTC](https://forums.maslowcnc.com/t/list-of-sources-of-error/7523/36 "2019-02-13T18:45:00Z")

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> [@c0depr1sm](#):
>
> | Error | Description | Simulation Condition | Error Type | Simulation Graph |
> | --- | --- | --- | --- | --- |
> | sprocket “12 o’clock” error | the chain was calibrated starting with a link positioned on the sprocket with one pin not exactly positioned at 12 o’clock. Makes the chain length steadily longer or shorter | Control parameter on the chain position is 1mm underestimated (roughly 1/6 of a tooth distance.) ref: cheatLeftChainLength =1 mm | **Geometry** | See below |

Hey @c0depr1sm, I was thinking about Holey Triangular Calibration, and @Jametek’s test-cuts. I wondered about how the accuracy of the initial 12 O’Clock position of the gears impacted accuracy of the system. I looked at your analysis here. I am trying to understand: what is the error, in deg, relative to the accuracy I thought I was able to achieve with my machine? I see the 1/6th of a tooth. Doing the math with 10 teeth per rotation 1/6th of a tooth is 6 deg. From the hip, I thought I was able to achieve about + or - 3 deg accuracy. That would mean for my machine, I have about half of your modeled inaccuracy as a result of the initial 12 O’Clock position, about 1 mm if you include both. This is not addressed by [Holey Triangular Calibration](https://forums.maslowcnc.com/t/holey-triangular-calibration/6240/227). Not saying it should be.

Nonetheless, this is definitely something that could be improved via a more precise approach on my part.

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