# question about steps per unit

**URL:** <https://forum.lulzbot.com/t/question-about-steps-per-unit/1448>\
**Category:** Software\
**Created:** [March 12, 2015, 9:24pm UTC](https://forum.lulzbot.com/t/question-about-steps-per-unit/1448 "2015-03-12T21:24:36Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Rickta59](https://avatars.discourse-cdn.com/v4/letter/r/ec9cab/32.png) [@Rickta59](https://forum.lulzbot.com/u/Rickta59)\
**Post date:** [March 12, 2015, 9:24pm UTC](https://forum.lulzbot.com/t/question-about-steps-per-unit/1448/1 "2015-03-12T21:24:36Z")

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I’m looking at the marlin firmware on my lulzbot mini and trying to figure out how the x and y axes are using 100.5 steps per unit.

I can understand if it was 100 where I have a 200 steps per revolution, 16 microsteps and a 16 tooth belt.  
However, I don’t see how it ends up being 100.5. Any hints?

Thanks,

-rick

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**Author:** ![Rickta59](https://avatars.discourse-cdn.com/v4/letter/r/ec9cab/32.png) [@Rickta59](https://forum.lulzbot.com/u/Rickta59)\
**Post date:** [March 12, 2015, 9:31pm UTC](https://forum.lulzbot.com/t/question-about-steps-per-unit/1448/2 "2015-03-12T21:31:16Z")

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Actually I just got an answer on #reprap. They add the .5 for shrinkage.

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**Author:** ![Orias](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.lulzbot.com/orias/32/3_2.png) [@Orias](https://forum.lulzbot.com/u/Orias)\
**Post date:** [March 18, 2015, 2:42pm UTC](https://forum.lulzbot.com/t/question-about-steps-per-unit/1448/3 "2015-03-18T14:42:44Z")

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The extra 0.5 steps is there to account for the thermoplastic shrinking. We’ve used that fudge value on all our 3D printers for the X and Y axis. It’s served us well.