Delta calibration

Dugee

Hi, just done a lot of work on a cheap delta, quite a bit still to do, but I'm having a problem with initial calibration. I am running this before setting the machine properly to make sure everything works (which it has so far).

Part way through delta calibration the nozzle hits the bed triggering the bed switches during moves. The settings that were in my configuration were those generated by the delta configuration tool prior ir to disassembly.

I know I need to adjust my endstops as there is about a 5mm difference in heights.

Could the endstop difference be causing the carriage to be out of position and curve into the bed during moves , or should I be looking at r and l figures to try and resolve this initially?

To further complicate troubleshooting for me, I had a reasonable workable calibration at the weekend but had to replace the stepper motor gears, which changed from 14 to 16 tooth.

I took my previous M92 Z, Y and Z steps/mm figures and recalculated these figures by multiplying by 14/16. I wasn't expecting this to be right 1st time, just close enough to start my delta calibration.

T3P3Tony

I would follow this guide:
https://duet3d.dozuki.com/Wiki/Calibrating_a_delta_printer

It sounds like you have a z probe of some sort - in which case the autocalibration will be quicker than trying to adjust the values manually.

Dugee

@T3P3Tony I have 3 switches in series under the points on the bed. Calibration fails due to the z probe (bed switches) triggering when doing a move between trigger points, as if the effector isn't travelling horizontally. I'm going to raise the height that the nozzle stops at before starting the probe back to 30mm. Hadn't thought of that earlier, should give me a better chance of getting the auto calibration to complete. I had amended the dive height due to prior successful calibration.

Danal

Agreed, adjust dive height and do autocalibrations.

Do you have accurate rod lengths? Joint-to-joint? If so, set the M665 L manually, and do the kinds of calibrations that don't change L. That will get things done faster.

Dugee

@Danal

I managed to get the auto-calibration to work by raising the dive height, came in pretty good on the 1st pass, about 0.189. Given that i had just removed the stepper motors and put it back together that was pretty decent.

I now need to work through some more issues. I think it is endstop related, due to the height differences, as once the auto-calibration had completed, the effector couldn't reach it's zero point on my X and Y coordinates.

going to ask a newb question. Rod length is eye centre to eye centre?

ta

Danal

@Dugee said in Delta calibration:

going to ask a newb question. Rod length is eye centre to eye centre?

Correct.

Pivot to pivot. Joint-center to joint-center. Eye-Center to Eye-Center

Dugee

Thanks for the confirmation!