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gregsaun / prusa_i3_bear_upgrade

Stronger frame for Prusa i3 MK2(s), MK2.5 and MK3
GNU General Public License v3.0
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Custom Z-height: Changed Z_MAX_POS accordingly but Z-Calibration fails #119

Closed Demolux closed 3 years ago

Demolux commented 3 years ago

Hi there,

I recently bought 2 bear upgrades and decided to increase the z height to about 569 mm.

I am using the firmware 3.9.2 release and compiled it via Ubuntu.

I changed Z_MAX_POS to 569but i guess that is not enough:

  1. The printer always goes to the top end leveling the Z axis.
  2. Then it asks for nozzle cleaning.
  3. After confirmation the Z axis goes down
  4. It tops about 10mm above the bed aborting the calibration "Z calibration failed, check axis".

-> Changing Z_MAX_POS to 555 or 565 did not change that behaviour.

I looked around the web to find an explanation what is needed to change in the FW in order to run a successful Z-calibration with modified Z but was not successful.

May you explain what is needed to be changed besides Z_MAX_POS? The only other modification I made was uncomment #define FILAMENTCHANGE_ZADD 2 because otherwise I got compilation errors (Z exceeding 256).

Thank you very much.

Demolux commented 3 years ago

Turns out 5 mm below the max. travel distance in Z as Z_MAX_POSwas the sweet spot where at least calibrate Z worked!