rotary delta + mesh compensation | Strange Z-Lift

dc42 · 16 Feb 2021, 10:30

I've made an attempt at implementing auto calibration for rotary delta machines. The firmware for Duet 2 is at https://www.dropbox.com/sh/q5uqqkjbmhgvlhq/AACYqG0ynLME9ogoLd1zLB2Xa?dl=0.

Calibration factors implemented are:

3 = homing switch position corrections
4 = as 3 + bearing heights (all 3 heights adjusted by the same amount)
5 = as 4 + delta radius
7 = as 5 + tower position corrections

I have no machine to test this one, so it is highly likely that it won't work. It's also possible that it will work but only if you home again immediately after running auto calibration.

Please test it very carefully. Use M669 and M666 without parameters after running auto calibration to see what parameters changed.

Egris · 16 Feb 2021, 17:24

@dc42 thanks alot for your support. Bed probing is working now . I will try the autocalibration function and write a feedback how it works.

Egris · 16 Feb 2021, 18:38

@dc42 did a Autocalibration. Result is as follows:

M669
Kinematics is rotary delta, arms (190.000,190.00,190.000)mm, rods (393.500,393.500,393.500)mm, bearingHeights (422.008,422.01,422.008)mm, arm movement -90.0 to 46.5°, delta radius 45.480, bed radius 212.1, angle corrections (59.839,59.430,60.000)°

M666
Endstop adjustments X-0.82 Y-1.04 Z-1.47°

Start Values:
;M669 K10 U190.0 L393.5 R45 A-90.0:46.50 H418.8 X60, Y60, Z60 B212.132 (59.839,59.430,60.000)
;M666 X0.0 Y0.0 Z-0.28

dc42 · 16 Feb 2021, 21:05

So it's made some small adjustments. Does it print more accurately, or less accurately? If you run auto calibration again, do the M669 and M666 parameters remain stable?

Egris · 17 Feb 2021, 16:56

@dc42 after several calibrations the values will stop at a certain level and are adjusted each cycle a little bit higer / lower. After the calibration i moved the head to a bit above Z0 and moved in X direction. I noticed a bowlshape movment. So i adjusted the rod lenght manually, did another calibration cycles and now i have quiet a steady linear movment above the bed

Then i did a G29 Mesh calibration..
225 points probed, min error -0.188, max error 0.428, mean 0.017, deviation 0.094

When i want to look at the graph it says Invalid Height Map. Im not sure why this will happen. The File is saved to the sd card

heightmap.csv

Egris · 17 Feb 2021, 19:07

This post is deleted!

Egris · 18 Feb 2021, 19:09

@dc42 hello dc42, currently i think the calibration code works! I played again with the radius in which it probes the points and now it looks quiet good . I have one question.
Im using the fw 3.3 and when i do a mesh calibration the header of the hightmapfile is as follows..

axis0,axis1,min0,max0,min1,max1,radius,spacing0,spacing1,num0,num1
X,Y,-140.00,140.00,-140.00,140.00,-1.00,20.00,20.00,15,15
0.115, 0.139, 0.118, 0.101, 0.075, ....

When i want to check the graph on the webinterface it says invalid hightmap..

when i change the header to

xmin,xmax,ymin,ymax,radius,xspacing,yspacing,xnum,ynum
-140.00,140.00,-140.00,140.00,-1.00,20.00,20.00,15,15
0.115, 0.139, 0.118, 0.101, 0.075, ....

It shows me the graph output.

Which format will the firmware need to do the compensation correctly?

dc42 · 18 Feb 2021, 21:26

Either height map should work for bed compensation. We'll need to update DWC to display the new format.

dc42 · 19 Feb 2021, 11:09

There is now a DWC that can display the new format height map at https://www.dropbox.com/sh/q5uqqkjbmhgvlhq/AACYqG0ynLME9ogoLd1zLB2Xa?dl=0.

Egris · 21 Feb 2021, 11:07

Did a first Print after setting up autocalibration, mesh bed compensation and preasure advance..
I´m quiet happy with the result.

Thx again for looking into it

picture of the print