3dp Z axis home up, probe down

this question is for all of those Marlin experts out there. I believe @jeffeb3 has done this before for the LR but I’m working on my 3d printer and want a similar process but not sure what settings to change in marlin config to have this work.

I am installing a BLtouch(clone) and while I have installed them before, normally I simply replace the Z_min switch with the probe. this time I want something different. I would like to have a Z_max switch (using the Z_min plug on my 1.4 turbo) and my BLtouch connected to the “probe” plug. with them both attached I would like my machine to home up to Z max position then probe down to find Z min. I’m 95% sure this is possible, but as I have said, not sure what what to change to make it happen. I feel like I need to change the Z home direction, something to make a Z max limit work and switch the Z min to run off of the “probe” plug on the board. anyone have some insights? and thanks in advance!

I’m not sure what the “probe” pin is. I thought it was usually the zmin.

The dualLR does this, but it has dual endstops on Z, and it doesn’t have mesh leveling enabled.

My guess is that if you have everything working with the bltouch (there are a lot of settings to get right here). Then changing the z home dir will switch to use the zmax plug. There might be a change needed to the zprobe_uses_zmin. Then fixing whatever sanity checks pop up. If you get it compiled, you should see zprobe and zmax in M119 and I would test that with a regular switch (because bltouch is only triggered for a fraction of a second).

By “probe” pin I mean this plug labeled “probe”

Do you belive that having multiple z motors or bed leveling would have an effect? I could put a second end stop on but I wouldn’t want to give up bed leveling.

I think I got it using the probe plug by not enabling the “zprobe_uses-zmin” option but I haven’t tested it yet, waiting on more hx plugs (my current plugs are 2 pin and the 1.4 takes 3 pin) they should get here tomorrow.

I can change the home direction, my only concern is it will set the z max position to 0 rather than, 225mm then try to start printing from the top down XD.

I have a bin that I’m going to try, I will let you know how it goes tomorrow :slight_smile:

If you set Z_HOME_DIR to +1, it will set the coords to the max height you set.

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