Tool changer dual Z probe help

CSLTM · 15 Sept 2020, 10:20

Hi,

We're currently making a large format FDM printer that utilises E3D's toolchanger and Duet3.

We have the limit switch on the bottom of the head wired up and working but I'm a little stumped how to get our next part working.

I would like to use a limit switch positioned next to the bed to report the different z offsets of each tool however I'm a little uncertain how I would define this within the firmware.

We plan on having 3 tools, each with hermeras, two running a volcano and one running a supervolcano.

In theory, the X and Y offsets for each will be the same (but can be tweaked by printing calibration pieces) however Z would be a little trickier.

Ideally, I'd like the printer to grab and probe each tool on this limit switch and then spit out the Z offsets for each tool with relation to 0 so I can imput that into the firmware.

This would be done once a month or if anything has changed hardware wise.

Any help appreciated!

Cheers,

Tom

jay_s_uk · 15 Sept 2020, 10:27

How would you be planning on moving that switch up and down?
Could you provide a bit more information about the switch location etc.

Also, how would you be planning to accurately measure the switch offset?

I would suggest looking at https://github.com/DanalEstes/TAMV for setting the nozzle offsets. Theres also some info in there for tool Z alignment too

CSLTM · 15 Sept 2020, 14:35

@jay_s_uk Thanks for your reply.

The switch won't be moving - its within the limits of the gantry movement but to the left of the print surface. It is just a standard microswitch with a metal actuator.

My plan was to have the machine pick up tool0, have the bed rise to hit the switch three times, make an average of the offset and then put the tool back and pick tool1 up and do the same.

Ideally then each tool would have a -z offset from 0 that I can put into the config.g so that the Z heights are accurate.

Thanks for the link, I'll check that out.

Cheers,