Duet 3 StealthChop 2 Tuning for Nema23

fractalengineer

@dc42 But the EMF calculator says back EMF is green (17.6V out of the near 30V supplied) and these steppers can still go at least twice faster than the speed they are currently running...

Would plugging capacitors in parallel to VIN help with absorbing some of that back EMF?

evan38109

For posterity --

I was misunderstanding how CoolStep interacted with the other modes. Thank you for clarifying.

I've now gotten in the habit of just effectively disabling CoolStep with M915 X Y Z E T1. I've not been able to find any situations on either of my printers where CoolStep works materially better than SpreadCycle. (That's not to say they don't exist, I just haven't found them!)

SputnikOC3d

I was pointed to this thread from another by DC42 - where it indicated the OP solved an issue by making some changes. I see a lot of hchanges et al ... but it caps out at 42 posts and I dont see the OP indicating a resolution ?

Almost all these StealthChop to Spreadcycle motor banging threads - Have No Resolution defined in the threads ... Troublesome.

Is there a resolution?

ibash

So for folks trying to understand how tpwmthrs is calculated, and especially how to convert it to mm/s...

12,000,000 / (256 * tpwmthrs) = steps / second
You need steps per mm from M92... be careful with units...
Then multiply mm/step * step/second

Using evan38109's config as an example:

M350 X32 Y32 Z32 E32 I1                      ; configure microstepping with interpolation
M92 X{400 / (18 * 2) * 32} Y{400 / (18 * 2) * 32} Z6400.00 E1674.00  ; set steps per mm

They're using 32 microstep units, and M92 gives microsteps per mm.

400 / (18 * 2) * 32 = 355.55 microsteps / mm
355.55 / 32 = 11.11 steps / mm

So for 40 tpwmthrs...

(1 mm / 11.11 steps) * (12,000,000 / (256 * 40)) = 105.5mm/s

The 12,000,000 comes from the clock frequency, tpwmthrs is in units of clock period
Check out the datasheet: https://www.trinamic.com/fileadmin/assets/Products/ICs_Documents/TMC2160A-datasheet_Rev1.06.pdf