Compensating For Bed Irregularities
Hello
Dose any one have advise for compensating for the assumed irregularities on my bed. I have rebuilt my printer a few times and even when I get the result of "No need to compensate, X/Y axis are perpendicular. Congratulations! ", I seem to have issues. I assume due to the results seen based on my mesh bed leveling results posted below, It would appear that I have sagging on the right side of my bed. I have used bed level correction to try and fix this and it helps but dose not completely fix the problem. Any input would be great I am by no means an expert when it comes to this stuff.
Hot
0.11167 0.05926 -0.00296 -0.07500 -0.15685 -0.24852 -0.35000
0.14639 0.10559 0.04793 -0.02657 -0.11793 -0.22614 -0.35120
0.16889 0.13512 0.07978 0.00287 -0.09562 -0.21568 -0.35731
0.17917 0.14787 0.09259 0.01333 -0.08991 -0.21713 -0.36833
0.17722 0.14383 0.08636 0.00481 -0.10080 -0.23049 -0.38426
0.16306 0.12299 0.06108 -0.02269 -0.12830 -0.25577 -0.40509
0.13667 0.08537 0.01676 -0.06917 -0.17241 -0.29296 -0.43083
Hot 1 time change
0.07167 0.08833 0.06611 0.00500 -0.09500 -0.23389 -0.41167
0.19620 0.20390 0.17303 0.10361 -0.00437 -0.15092 -0.33602
0.27315 0.27501 0.23822 0.16278 0.04868 -0.10406 -0.29546
0.30250 0.30167 0.26167 0.18250 0.06417 -0.09333 -0.29000
0.28426 0.28387 0.24337 0.16278 0.04208 -0.11872 -0.31963
0.21843 0.22162 0.18334 0.10361 -0.01758 -0.18024 -0.38435
0.10500 0.11491 0.08157 0.00500 -0.11481 -0.27787 -0.48417
Hot 2 time change
0.09583 0.07704 0.03370 -0.03417 -0.12657 -0.24352 -0.38500
0.18759 0.17340 0.12963 0.05630 -0.04660 -0.17907 -0.34111
0.24370 0.23256 0.18833 0.11102 0.00062 -0.14287 -0.31944
0.26417 0.25454 0.20981 0.13000 0.01509 -0.13491 -0.32000
0.24898 0.23932 0.19407 0.11324 -0.00318 -0.15519 -0.34278
0.19815 0.18691 0.14111 0.06074 -0.05420 -0.20370 -0.38778
0.11167 0.09731 0.05093 -0.02750 -0.13796 -0.28046 -0.45500
Hot 3 time change
0.11083 0.09185 0.04907 -0.01750 -0.10787 -0.22204 -0.36000
0.19519 0.18251 0.14035 0.06870 -0.03243 -0.16305 -0.32315
0.24741 0.23816 0.19563 0.11981 0.01072 -0.13166 -0.30731
0.26750 0.25880 0.21491 0.13583 0.02157 -0.12787 -0.31250
0.25546 0.24442 0.19819 0.11676 0.00013 -0.15169 -0.33870
0.21130 0.19504 0.14547 0.06259 -0.05360 -0.20311 -0.38593
0.13500 0.11065 0.05676 -0.02667 -0.13963 -0.28213 -0.45417
Hot hot 4 time change
0.11500 0.08185 0.03046 -0.03917 -0.12704 -0.23315 -0.35750
0.18472 0.16336 0.11580 0.04204 -0.05793 -0.18410 -0.33648
0.22667 0.21287 0.16753 0.09065 -0.01778 -0.15775 -0.32926
0.24083 0.23037 0.18565 0.10667 -0.00657 -0.15407 -0.33583
0.22722 0.21586 0.17015 0.09009 -0.02432 -0.17309 -0.35620
0.18583 0.16935 0.12105 0.04093 -0.07102 -0.21478 -0.39037
0.11667 0.09083 0.03833 -0.04083 -0.14667 -0.27917 -0.43833
Cold
0.11167 0.05926 -0.00296 -0.07500 -0.15685 -0.24852 -0.35000
0.14639 0.10559 0.04793 -0.02657 -0.11793 -0.22614 -0.35120
0.16889 0.13512 0.07978 0.00287 -0.09562 -0.21568 -0.35731
0.17917 0.14787 0.09259 0.01333 -0.08991 -0.21713 -0.36833
0.17722 0.14383 0.08636 0.00481 -0.10080 -0.23049 -0.38426
0.16306 0.12299 0.06108 -0.02269 -0.12830 -0.25577 -0.40509
0.13667 0.08537 0.01676 -0.06917 -0.17241 -0.29296 -0.43083
RE: Compensating For Bed Irregularities
assumed irregularities on my bed. [...] It would appear that I have sagging on the right side of my bed.
You're using a lot of qualifying language. Have you actually observed issues? Have you enabled 7x7 mesh bed leveling? That will deal with minor bed irregularities. If not, contact support and send a pic of a straight edge laid along the bed lit from behind. If the bed is indeed badly warped, that will show it and support should help.
There's a tendency to "pre-stress" about issues, especially if you're used to cheaper printers or spend time reading up on them. The Prusa is good stuff. If it's not working as it should, you paid for support. Rest easy.
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He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan
RE: Compensating For Bed Irregularities
The X/Y perpendicular and bed levelling are two independent things, I think. X and Y could be perpendicular and levelling (Z) be all over the place, or conversely your bed could all be perfectly level and your X and Y horribly skewed.
One iteration of my printer suffered from a constant battle with bed level. It seemed to always be low (bed low, so nozzle too high) on the right hand side. At some point it sorted itself out, or my habits changed and that sorted it, but I can't say what did it. I can tell you how I investigated it:
I made a calibration job that just prints single-layer 20mm diameter circles across the bed, to help identify what was happening and what helped. I tried attaching that but apparently you can't attach STL files to forum postings.
I was suspicious of the PINDA when it's in close proximity to the print bed as it heats up, so I always park the print head high, so the printer always warms up with the PINDA well above the bed. This might be redundant now teh PINDA allegefdly has a temperature sensor and compensation built in. The easiest way to do that is to put a command in 'End G-code' in the printer settings of the slicer. By default there's a line something like
{if layer_z < max_print_height}G1 z{z_offset+min(layer_z+30,max_print_height)}{endif}
I change that to
{if layer_z < (z_offset+max_print_height-30)}G1 X125 Y205 Z{z_offset+max_print_height-30}{endif}
G1 X125 Y205
The default text raises the print head to 30mm above where it finished, but no higher than the top. Mine raises it to 30mm below the top, back centre as long as it finished more than 30mm below the top (otherwise it just moves it to back centre). The reason I don't go to the top is because of how when you load filament the printhead always rises - if you leave it parked at the top then load new filament it tries to rise, jams and the steppers make a horrible noise.
Also, if you're playing with bed level correction note that at least some revisions of the '3D printing handbook' have the text backwards. It says "Negative values will act as lowering the bed", but negative values put the bed closer to the nozzle, i.e. lower the nozzle / raise the bed. At least, it did on mine at the time - I haven't used bed level correction for some time.