Allow for a list of thickness values OR consider leadscrews

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coredump
Posts: 6
Joined: 12 Oct 2017, 10:07

Allow for a list of thickness values OR consider leadscrews

Post by coredump »

Given that a lot of people use TR8*8 or multiple start lead screws for the Z axis, would be interesting to allow to list specific layer thicknesses on the variable layer control.

For example, using my current leadscrew, a thickness of 0.3 will need a stepper motor half step, that is not optimal. There are a list of layers that are 'optimal' to use, 0.2, 0.28, 0.32 and etc. Currently I can say 0.2 to 0.38, but have no control on the intermediaries.

ALTERNATIVELY, let us input our leadscrew characteristics (lead, pitch, stepper motor steps, etc) and calculate the layer heights that need full revoultions from the screw instead of half/partial/microstep revolutions.

Prusa has a calculator online that does that, for example: https://www.prusaprinters.org/calculator/#optimallayer

And to read more about the issue that this can solve: https://somei3deas.wordpress.com/2017/0 ... ad-screws/

Thanks!
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pjr
Posts: 692
Joined: 05 May 2015, 10:27
Location: Kamnik, Slovenia

Re: Allow for a list of thickness values OR consider leadscr

Post by pjr »

Settings/Printer/Hardware/Z Step [mm]

For the PR Mk2s, set this to 0.0025 (1/16 microstepping with 8mm x 4 lead screw) or 0.04 for full step.

The problem you will have with full steps is that if the Z-Live adjust starts on a microstep (most likely due to bed levelling) you will always be on a microstep. This means that you will only have a 1/16th chance of being on a full step with the Z height at 0.2mm no matter where in XY space the nozzle is at that moment.

Peter
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pjr
Posts: 692
Joined: 05 May 2015, 10:27
Location: Kamnik, Slovenia

Re: Allow for a list of thickness values OR consider leadscr

Post by pjr »

coredump wrote:And to read more about the issue that this can solve: https://somei3deas.wordpress.com/2017/0 ... ad-screws/
That is a very interesting read, but it omits one very important issue - backlash.

The original PR Mk1 had 5mm threaded rods for the Z axis, however this printer was not capable of printing (without modification) with Z-Lift (Z-Hop) due to backlash. The Mk2 uses the lead screws which allows gravity to overcome the backlash and Z-Lift is now working very well with so much more accuracy. And the Z motors use the same power with the lead screws as the Mk1 did with threaded rods.

Peter
coredump
Posts: 6
Joined: 12 Oct 2017, 10:07

Re: Allow for a list of thickness values OR consider leadscr

Post by coredump »

Godammit KISSLicer, you already surprising me with those hidden in plain sight options!

Also that's a reason that I got an anti backlash nut and some single start 2mm pitch screw
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