nanoDLP

Hi long-time lurker, first-time poster!

Building my first SLA DLP Printer and working with this current build - a Raspberry Pi 3 B+ paired with a RAMPS 1.4 w Mega 2560 - Pololu a4899 as the drivers. The Z Axis is a simple CNC stage using a NEMA 23 as a motor.

For guidance I used the MUVE3d setup guide, running their recommended patched Marlin on my rig and the NanoDLP Muve configuration.

So far so good - after playing with the settings I managed to get a decent print. I noticed how squashed it was - in fact, the print was about 40% shorter than normal (ie 6 mm tall instead of 10)

So I checked how far my stage would move - indeed, inputting 10 mm via the Z Axis control or into the RAMPS terminal would produce around 6 mm instead.

Unbelievably, I had not changed the leadscrew settings - it was 8 mm per turn instead of 5 mm. .... it changed *nothing*.

Most interestingly, I had noticed that sending commands to move the motor from home to something like 10 mm higher it would rocket up to the top of the stage (I have a top down system w home on the bottom). Another example is I would send it up 10 mm three times, and the third time it would go *down*. I had heard that Z Axis control could be wonky - but it might be a symptom of a major issue.

I checked every single element of my design. Wiring was correct, jumpers set to 1/16 (all set pins are tied), the VREF is set to 0.8, etc.  I reuploaded Marlin and that didn't make a difference either. Seems like everything is as correct as can be.

Is there anything I am doing wrong?? I care share my settings to see if I can get some help here - i am SO close to getting my machine going , so I'd appreciate some help!