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calibration OHAI should remove adjustment of backlash
Closed, WontfixPublic


there is no clear way to adjust backlash without using a dial indicator and physically measuring the lash on an axis, so this step should be removed from the OHAI.
if the circle is out of round i would recommend cleaning the nozzles really well and run another auto calibration

if the machine backlash setting is too low, there will be uncompensated backlash left in the system.
if the machine backlash setting is too high, there will be overcompensated backlash added to the system.

Calibrators should only rely on the auto cal for backlash measurements.

Event Timeline

tutley created this task.Aug 9 2019, 3:06 PM
robert added a subscriber: robert.Aug 12 2019, 5:48 AM

@tutley I think if we didn't adjust backlash we'd be red tagging so many machines. The auto cal just gets us so far then the rest is just dialing it in til its in spec.

@robert if you are getting out of round circles then the auto cal isnt getting a good measurement which could be related to T9604 .
If the nozzles are good and clean and can make a good electrical connection with the calibration cube you should not need to touch backlash values.
Also as i mentioned there is no clear way to determine if you need to raise or lower the lash value without using a dial indicator.

@tutley Gotcha. That would be really nice if thats what ends up fixing it cause thats probably the single most thing that causes us time with reprints and tuning.

@robert yea definitely! I think we should try and scrub the black coating off the conical portion of the nozzle prior to running calibration. It comes off pretty easily with the green scotch brite pad. Steel wool may work as well. If we can get them from E3d pre cleaned that would be ideal, but it might be a little while until we get there

We've been cleaning the nozzles with alcohol prior to running auto cal. Do you think this isn't enough?

@paulette i dont think thats enough. if it is stripping the black coating off then it might be fine. The nozzle should look like shiny stainless steel for good conductivity

logan added a subscriber: logan.Sep 13 2019, 11:07 AM
logan triaged this task as Wishlist priority.Thu, Oct 3, 8:37 AM

The instructions at step 19 seem to be yielding good results at calibration. Granted, it doesn't include a process to tell calibrators how much backlash compensation to add or remove, but in the interim until Auto-Cal is improved via hardware changes (T9604) or other software changes, this will have to remain.
Lowering to wishlist priority until removing this is feasible for production.

logan closed this task as Wontfix.Thu, Oct 10, 1:03 PM
logan claimed this task.