Accelerometer Calibration Tower End Stop Offset Repeatability

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bruceg
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Joined: Sat Nov 15, 2014 9:01 pm

Accelerometer Calibration Tower End Stop Offset Repeatability

Post by bruceg »

Machine: Max v2, Rambo 1.3L, Repetier 0.92.2 (2016 12 27), molded carriages, ballcup arms, 2mm PEI build surface.

Have been using the SeeMeCNC Delta Calibration Wizard to examine the calibration behavior of the SeeMeCNC accelerometer probe mounted on a Prometheus hot end and eventually cottoned on to requirement to get the tower end stop offsets all within a few steps of zero. To that end, i tightened my belts, seated the screws deep into the carriages (they had been protruding 5-6mm and were a little loose) and then adjusted to get offsets even and close to zero (X:5, Y:5, Z:6). Four sets of repeated trials were then performed using G29. No adjustments were performed within each trial set. Minor adjustments to the end stop screws were made between each trial set. Bed and hotend heaters OFF.

Data is shown below. M = Mean, SD = Standard Deviation. Each tower would typically vary by 2-3 steps between each run but occasionally by considerably more.

I was wondering if anyone else has looked at the end stop offset repeatability and if so, what sort of numbers were observed. Also, is there a sense of what level of repeatability is required for successful use of the calibration wizard?

As a note, the calibration process proceeded smoothly with an HE280 in this machine in terms of "good results" from the wizard i.e. repeatable deviations (0.02-0.03) and small (<+/-0.04) and repeatable Probe Offset numbers across the 9 points. More importantly, there was a dramatic improvement in first layer height across the bed compared to manual calibration.

My plan is to compare the HE280 to the Prometheus+accelerometer by looking at calibration metrics and the large diameter first layer ring. If there are suggestions for specific metrics or prints to examine they would be appreciated. My immediate goal is to access the performance of the printed Prometheus mount system with the accelerometer probe (and of course to further expose the depth of my ignorance in all things...)

Code: Select all

Trial Set 1
(steps) X	5.0	2.0	0.0	3.0	2.0	1.0	2.0	1.0	2.0			M X	2.0	SD X	0.89
(steps) Y	5.0	0.0	2.0	0.0	2.0	0.0	2.0	0.0	0.0			M Y	1.2	SD Y	1.36
(steps) Z	6.0	3.0	1.0	2.0	5.0	3.0	6.0	4.0	3.0			M Z	3.7	SD Z	1.41
______________________________________________________________________________________________
    M XYZ	5.3	1.7	1.0	1.7	3.0	1.3	3.3	1.7	1.7	  		M	2.3	M   	1.22
   SD XYZ	0.4	1.1	0.7	1.1	1.3	1.1	1.8	1.6	1.1	 		SD	0.9	SD  	0.22
															
Trial Set 2
(steps) X	0.0	14.	1.0	3.0	6.0	5.0	0.0	5.0	4.0	7.0	M X	4.5	SD X	2.90
(steps) Y	2.0	0.0	0.0	3.0	4.0	5.0	1.0	2.0	4.0	5.0	M Y	2.6	SD Y	1.60
(steps) Z	4.0	14.	3.0	4.0	4.0	8.0	2.0	2.0	6.0	5.0	M Z	5.2	SD Z	2.48
______________________________________________________________________________________________
    M XYZ	2.0	9.3	1.3	3.3	4.7	6.0	1.0	3.0	4.7	5.7	M  	4.1	M   	2.33
   SD XYZ	1.3	6.2	1.1	0.4	0.9	1.3	0.7	1.3	0.9	0.9	SD 	1.0	SD  	0.48
															
Trial Set 3
(steps) X	5.0	2.0	2.0	3.0	4.0	2.0	2.0	3.0	4.0			M X	3.0	SD X	0.89
(steps) Y	3.0	1.0	0.0	3.0	5.0	2.0	1.0	1.0	0.0			M Y	1.8	SD Y	1.31
(steps) Z	0.0	0.0	2.0	0.0	0.0	0.0	0.0	0.0	0.0			M Z	0.2	SD Z	0.40
______________________________________________________________________________________________
    M XYZ	2.7	1.0	1.3	2.0	3.0	1.3	1.0	1.3	1.3	  		M	1.7	M   	0.86
   SD XYZ	1.8	0.7	0.9	1.3	2.0	0.9	0.7	1.1	1.8	 		SD	1.0	SD  	0.31
															
Trial Set 4
(steps) X	0.0	2.0	0.0	4.0	0.0	0.0	1.0	0.0	2.0	3.0	M X	1.2	SD X	1.24
(steps) Y	0.0	2.0	2.0	4.0	2.0	4.0	2.0	4.0	4.0	4.0	M Y	2.8	SD Y	1.20
(steps) Z	2.0	4.0	3.0	4.0	3.0	4.0	0.0	3.0	0.0	0.0	M Z	2.3	SD Z	1.44
______________________________________________________________________________________________
   M  XYZ	0.7	2.7	1.7	4.0	1.7	2.7	1.0	2.3	2.0	2.3	M  	2.1	M   	1.29
   SD XYZ	0.9	0.9	1.1	0.0	1.1	1.8	0.7	1.6	1.3	1.6	SD 	0.6	SD  	0.10
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