# TAZ 6 X and Y steps per mm "fudge factor"?

**URL:** <https://forum.lulzbot.com/t/taz-6-x-and-y-steps-per-mm-fudge-factor/6969>\
**Category:** Hardware\
**Created:** [October 18, 2019, 7:36pm UTC](https://forum.lulzbot.com/t/taz-6-x-and-y-steps-per-mm-fudge-factor/6969 "2019-10-18T19:36:16Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![radensb](https://avatars.discourse-cdn.com/v4/letter/r/ba8739/32.png) [@radensb](https://forum.lulzbot.com/u/radensb)\
**Post date:** [October 18, 2019, 7:36pm UTC](https://forum.lulzbot.com/t/taz-6-x-and-y-steps-per-mm-fudge-factor/6969/1 "2019-10-18T19:36:16Z")

</div>

I noticed in the Marlin code that the steps per mm constant is defined based on the printer configuration being compiled. In the file Conditionals\_Lulzbot.h exists the following:

```nohighlight
#if defined(LULZBOT_USE_Z_SCREW)
    // Older printers had a fudge factor for ABS shrinkage.
    #define LULZBOT_XY_STEPS 100.5
#else
    // In the Mini 2 and TAZ 7 going forward, use true XY steps.
    #define LULZBOT_XY_STEPS 100
#endif

```

Why is this “fudge factor” not needed on the non “LULZBOT\_USE\_Z\_SCREW” printers? What relationship exists between a machine with Z lead screws and XY axis and why do the newer machines use true XY steps?