Marlin 2.0 for delta printer - deploying and stowing allen key probe outside printing area blocked

Hello everyone,

I have a delta printer running Marlin from about 5 years ago. I decided to configure current version of Marlin 2.0 for this printer. The goal is to mitigate inconsitstent ABL where the middle of printbed is great but to the edge it gets much worse.

My problem is that I am using allen key probe so for deploying and stowing I need to go outside the print area and Marlin prevents that. A workaround is to increase the printable radius but that would enable the printhead to crash into one of the towers.

Is there some setting that would allow going out of print area only for deploying and stowing the probe?

The original method was hardcoded to the firmware (in Marlin_main.cpp) I presume to overcome this limitation.

I am attaching the configuration files I am trying to use.

Thank you in advance

Edited 1 time(s). Last edit at 01/05/2021 02:51AM by MStarha.

I can't comment on Marlin, however I think it likely that your ABL issues are caused by the combination of imperfect delta geometry and your use of a Z probe that is offset from the nozzle. Many types of geometric imperfection in deltas cause the effector to tilt slightly with XY movements. This tilt causes the relative height of the nozzle and the Z probe to change, which causes errors when you run delta calibration or probing for bed compensation. So changing firmware versions is unlikely to help.

There's more on this at [duet3d.dozuki.com].

Nozzle-contact Z probes are highly recommended for delta printers.

HTH David

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Thank you for your suggestion.

Although I think the frame is rigid and accurate enough, I cannot say the same about the diagonal push rods. They use magnetic joints with stell balls glued in place on carriages and on efector. These balls have fallen out many times and were glued back in. Also the holes for these balls are worn out makeing them wobble around the balls. I think that is the issue.

I wanted to get more up-to-date firmware because it gives more opportunities to tweak and people are more likely to give advice concerning up-to-date firmware not an obsolete one.

Furthermore with such FW changes the worst case scenario is that I go back to the original FW (and setup EEPROM....).

Still, if anyone knows about the Marlin issue mentioned in the original post, I would be very glad to solve it. Then I can tackle the delta push rods issue.

Thank you.

I have managed to solve the issue of blocked movement outside printing area by adding a default parameter to do_blocking_move_to() function and all underlying functions that allows unreachable movements to happen.

The mentioned bed leveling is not fixed. As suggested the issue is most likely in the geometry (wobbly diagonal arms,...). However, I think the effect of it on bed levelling is lessened. The reason for that is probably a better bed-levelling compensation algorithm that comes with a newer version of Marlin.