Any guesses as to discrepancy in arm length vs. measured arm length?
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You have some large mechanical errors going on. Either your bed is out of level, one of your towers is tilted, or a good bit of effector tilt. Possibly all of the above.
You need to go through the mechanical aspects of your printer and find what's out of square.
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Neither S6 and S8 would modify your arm length, are you sure your calibration routine is correct?
Do you have other M665 in your config.g or config-override.g? -
no other M665 commands.
I usually move any config override values to the main config file and delete the override.My delta may be out of square somewhere but not massively. All towers are square to the bed when using an 8" precision square.
The end stops are within .3 of each other I believe. I can run though this again.
The effector may have some tilt but not visual to the eye and no room for a level. Haydn carbon arms, all measured to 304mm, delrin ends, magball connections. All 6 pairs of magballs measured in width (of each pair set) to be within 0.1mm or so with calipers.Its not terrible if I use S6, I just find it odd that when I use S8 (or S9) it calculates and changes the L length of the rods to be something so far off.
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One idea on your s8 values:
my guess is that you did s9 calibration, put the values to config and then switched to s8, forgetting to replace the arm length with the correct length of 304.2
As said above, s6 and s8 do not guess the arm length, you have to provide it as input.
Also, run s8 (or s6) several times, it can take a number of runs until everything is dialed in, you will see at some point that the average deviation does not change much anymore. Then do M500 and copy the values over from config.override to config -
@MIR yes you may be correct, I was using S9 at one point.
I have been running 2 or 3 auto calibrations till the deviation amount converges.
Thanks for the tips. -
Sorry to dig up an old thread here, but I am fighting the same issues with my Rostock with all of the trick laser components.
I eliminated the "ridges and valleys" in the bed mesh by upping my stepper current and lubricating the joints of the 300.15mm Trick Laser arms with some 50K diff lube for RC trucks. When I got that result, I was initially very excited, but with the ridges gone I could see the same three point high/low shape described by many other users across this forum.
I have the components to build some new arms to whatever length I choose, but I am having a hard time deciding what length to go with as a compromise between a) getting a good bed leveling result and calibration via FSR by eliminating the effector tilt and b) having the arms become dangerously near vertical when getting near to the edge of the bed near a tower.
Can anyone report further on the performance of their Rostock with longer arms? Have you had any trouble with being too close to vertical on the arms when near a tower?
Thanks ahead of time!
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Having the arms go vertical or even beyond when printing close to a tower isn't a problem. What you need to avoid is arms going below about 20 degrees to the horizontal.
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Perfect, that's exactly what I needed to know. Thanks!
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As an interesting test before making the longer arms, I just reduced the calibration radius to 87.5mm and reduced the probing radius for the bed mesh correspondingly, and the results were pretty astounding. Previously, the best calibration I could get was roughly 0.18 deviation, and with no physical change the the printer, the deviation went down to 0.021!
The bed mesh in the smaller radius was also greatly improved. Linked below are the results of the bed mesh at a 140mm radius followed by the 87.5mm radius.
I will post my results when I change the rod lengths as well.
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I have a trick laser frame and the mini trucks with Duet3d smart effector. I had to modify the pcb truck mounts to fit the trick laser parts. I am using the Hayden 360 arms and consistently calibrate at 0.035 @ 150mm radius. I happily give up the Z travel for being able to print a perfect first layer all the way to 300mm edge. I use the correct arm length and S6 and no G29 mesh.
Add: I think it is something to do with the spacing, 55mm between the arms provides more stability.
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This thread seems to have died down, but have any of you found a definitive answer to the problems posed?
