Ender 3 V3 KE 0.9deg stepper upgrade choice

[Grexor]

Hi folks. I have a V3 KE here with an annoying amount of VFA (not ringing/ghosting) on x and y axis coming from the motors. I have confirmed it is the motors by reversing the y belt and temporarily running it on the flat side with no change. It is the same VFA as seen on previous Prusa machines which was resolved by changing to 0.9deg motors.

I have found a few options to try and would love some input on the best one to go for. They are longer than the stock motors so will involve some mods to the base and loss of printing height but I’m ok with that. I’m looking at larger motors as I understand 0.9deg motors can have less torque and I don’t want to run any slower than it can currently. The stock motors measure ~3.5ohm coil resistance. The stock wiring concerns me a little, it’s very light gauge, but most likely not an issue.

The Creality board uses TMC2208 drivers with .15 ohm sense resistors, and the machine is running full Klipper now.

I think any of these would work, but I’m a novice at matching drivers to motors and which coil resistance/inductance gives the best results with these drivers. I understand I’ll have to bump the current up a fair bit with new motors. Any help would be much appreciated, cheers!

(I tried to post links to spec sheets, but the new user limitations won’t allow more than 2, my apologies)

Options:
E3D MT-1704HSM168RE

Wantai 42BYGHM810

Stepperonline 17hm19-1684s

Stepperonline 17hm19-2004s

Moon’s MS17HA6P4200

LDO LDO-42STH48-2504MAC(F)

[LifeOfBrian]

What works for one might not work for others.
This is a serious topic.
Does it make any difference when running in StealthChop or SpreadCycle?
Did you check different motor currents?
How tight are your belts tensioned?

[Grexor]

Thanks for replying

I understand it’s a complex thing, hence the questions rather than just buying any random motor. I should say that others aside from Prusa users have done this mod with success for the same VFA problem. One person used the smaller E3D 0.9 deg motor on an older Ender with good results.

I’ve tried various belt tensions with no change. I haven’t tried stealthchop, the only changes I’ve tried as experiments to see if the depth of VFA changed were disabling interpolation and different microsteps - no change VFA, only difference in sound. I didn’t try lowering the current, and assumed raising it would risk overheating the stock motors.

Is stealthchop likely to increase accuracy?

From a novice point of view it seems like choosing a very low resistance coil will put more stress on the driver but give a potentially cooler motor and can affect the torque curve, but I’m not sure what effect resistance and inductance play in how well the driver can control the position.

Cheers!