Screwmapping

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This article is really only a placeholder - please re-write it if you have experience of using the screwmapping feature.

Screwmapping allows Mach to correct for non-uniformity of the drive system (typically ballscrews) on the linear axes (X, Y and Z)

It is configured from the menu Config>Screwmapping

You need a way of accurately measuring the actual position of each axis over its whole travel. In practice this will probably be a glass scale. It this is interfaced to Mach via the encoder inputs then the data can be transferred directly to the mapping table but accuracy will be less than that obtainable with an interpolating DRO box interfaced to the scale.

Notes:

  1. If you want to correct for a uniform pitch error of the whole screw then this is best done in Motor Tuning
  2. I believe that the greates cause of error in rolled thread screws is "thread drunkeness". This causes a cyclic error each rev. of the screw. The current screwmapping algorithm is not really suited to correcting for it.