Ender 3v2 SKR Mini E3v2 BL Touch and Hemera

Hi everyone. I’m need to call in the cavalry for help.

Am building a Frankenstein printer for making functional project parts, so its got dual z motors, BL Touch, SKR Mini E3V2, TFT 35, and BL Touch all on an Ender 3v2 frame.

I used the firmware build service using and Ender 3 profile and the bin file worked out nicely, except…

  1. My Y axis won’t home, the plate slides back, makes lots of noise and ignores the end stop. The hardware end stop is working properly and I’ve confirmed it using M119. The x end stop and homing works nicely. Z homing just needs fine tuning as it tries to set it right at the very edge of the bed and I haven’t got to the bed levelling session yet.

  2. Anyone recommend the right settings for the voltage rather than the vref on the Hemera extruder motor?


Not sure if I’m the cavalry hahaha - but here goes…

Check to make sure your bed isn’t too far down. The bed can be lowered via the levelling knobs to be lower than the plastic stepper cover on the rear causing the bed to hit the plastic and not make it to the endstop.

The included stepper for the Hemera is rated at 0.94A (940mA) or just under 1.2v Vref. I’d personally go about 680mA to keep it cooler. You can set these on the SKR board using M906 E680

Not sure your the cavalry!! Trust me, you’re way more than that.

The Y carriage is making contact with the limit switch as it should - it’s activated by one of the bed wheels. I’ve confirmed that its working using the M119 to check the state when it should be in its inactivated state, activated manually by just using my finger to close it and also by having the bed / wheel activate it and all is good.

I think that there’s just some setting somewhere that’s screwed up and the firmware thinks the bed Y size is a lot bigger.

I used the defaults when I was using the firmware builder and have rebuilt it a few times to see but no success.

I’ve got the probe offsets for the BL touch but haven’t figured out the offset for the hemera. I’ve it mounted directly onto a nice new metal carriage, not a big printed adapter type thing. Should I be changing so,e of the settings in the firmware build for it?

Any other ideas?
Should I try rebuilding the firmware again and if so, what all settings / options should I use? I was confused too about what advanced features like the ‘classic jerk’ etc….

If only I wasnt on the opposite side of the world and you did house calls!!
Thanks for all the help. Apologies for being a mega noob.

Ahhhhh - I think I might know the issue…

The Hemera X_MIN and Y_MIN_POS reduce the size of the bed - so its no longer 235x235 - as the nozzle being moved limits the movement.

The Y_MIN_POS is -23 in the Hemera documentation - so the bed size likely needs to be reduced by 23mm in the Y direction. Given that the Ender 3 V2 can really only do 225x225 - you might have to reduce it further.

I should have spent more time over the documentation.

Found this on the specific E3D Ender 3v2 setup guide page -

""26. Because Hemera is a different size and shape from the standard Bowden configuration you need to set up a manual home position to ensure the best use of the build area.



change them to:

#define MANUAL_X_HOME_POS -40

#define MANUAL_Y_HOME_POS -10""

I had gotten a nice metal carriage plate to mount my Hemera onto thinking it would be more stable and durable than a printed part, especially given that I’m only working towards working with the good stuff. I thought that the print nozzle wouldn’t have been in all that a different place, especially on the Y axis.

Greed for maximum print size when I’ll probably very rarely needed it got the better of me.

Thanks for the excellent help. The learning curve has been great craic.

Oooo - where did you get the metal plate? I’ve got the Trianglelabs Matrix extruder - and that has a tiny bit of wobble on my 3D printed adapter. In theory, it should have the same mounting as the Hemera…

  1. GGGRRRRRRRRRRRR!!! Firmware rebuild with smaller build plate etc…. All looks ok and now the Y axis is trying to home in the wrong direction !!!

  2. Plate was an Amazon purchase https://www.amazon.co.uk/gp/product/B092QMS8BK/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&psc=1

Ah - Does the axis move inverted or is it just homing that is wrong? If its the entire axis, you can either flip the Invert option in the stepper config, or flip the wires in the motor.

Nice plate - ordered one for myself now :slight_smile:

The Y axis is moving correctly,
It’s just homing in the wrong direction.

The wee plate works very well. I had to fab up a wee bracket out of metal for my BL Touch and modify a few screw lengths for the Hemera (pretty tight tolerances)