4th axis closed loop stepper/driver setup query

[marbles]

Hi there,

I made up a new trunnion for holding foam stock. All the unit has to do is hold these 200mm thick foam blocks at 0, 33, 45 and 90 degrees whilst I mill the bulk of it away to leave a plug for casting into. See image of manual trunnion. I've made both a manual version and an automated version but the automated version wasnt strong enough to hold the trunnion and stock whilst milling. To cut a long story short i'm swapping out the Rino wormgear and nema 23 for the motor and deetz below, which i've had to make up at high speed to resolve a group of multisided 3d models which need milled out in 200mm deep foam ASAP.

12Nm Nema 34 and HSC86 closed loop driver , 80v 7.5A PSU.
1:1 ratio 2 x 60t pulleys and HTD belt.

I have a couple of basic questions:

1. What microstepping setting would be best for holding torque, given that all it has to do is move to an exact angle and hold stock in place. I guess I might ocassionally run some true 4th axis toolpaths in which case it will be in continuous motion but the priority is holding only. I've currently got it set to 1000 microsteps.

2. What sort of Mach 3 motor tuning setting might be best for holding torque? The steps per is currently set to 5.555, which does indeed give me 360 based on 2000 microsteps and 1:1 ratio pulleys. Thought maybe it could be a bit smoother when I ran the G0 A360

I'm sure there are other factors such as psu voltage and setting in the driver. I'm all ears :)

Thanks