Maximum motor size for X&Y on core-XY printer

gnydick

I have a Promega (yes, I appreciate the sympathetic crying). The xy motors seem to get rocket hot when trying to print fast. Even at 680mA which is the default current. So, it skips steps.

Am I right in thinking a motor with more windings will be able to run faster? I'm looking at Moons nema 17 that are quite long any rated at .88Nm torque.

I don't know what the stock motors are on this machine, but I wouldn't be surprised if they're junk.

gnydick

@gnydick here's the motor

Moons' NEMA17 Stepper Motor 3D Printer 0.88Nm(125oz-in)1.5A2Phase 1.8 Degree Stepper Motor 62.8mm(2.47in.) 3Stack Smooth Stepper Motor (Stepper Motor Cable00723 Include, Model MS17HDBP4150) https://www.amazon.com/dp/B07G429DL3/ref=cm_sw_r_cp_apa_i_P3r3BbD3CR0QD

dc42

Motors running hot doesn't cause them to skip steps. Things that cause skipped steps include:

Motor current too low (which isn't the case if they are getting hot)
Mechanical issue causing high friction or stickiness
Acceleration set too high in the M201 command, so that the motor can't produce enough torque for the acceleration demanded
Jerk set too high in M566
Using stealthChop driver mode at high speeds (see the V parameter of the M569 command)
Insufficient power supply voltage for the motor inductance and the speed you are trying to run them at. Use the motor EMF calculator at https://reprapfirmware.org/ to check.

If it's the last one, then changing to lower inductance/higher current motors (and then increasing the motor current) will help. For the drivers on the Maestro I suggest you aim for a rated current around 1.3A.

gnydick

Ok. That all makes sense. I'm also hearing a loud "clack" when the motors engage sometimes. This is something new. Any idea what that may be?

I do have a nice motor initialization routine with progressively increasing speed to train the stealthchop system. Sorry the terms in using may be wrong, I just know you want to move slowly at first.

gnydick

I'm trying higher current and it doesn't seem to matter. I just keep hearing a 'clank' while it's printing. I thought before they were rocket hot. NOW they're rocket hot at 900mA. Here are my settings.

M201 X1000 Y1000 Z75 E2000:2000 ; accleration
M203 X24000 Y24000 Z2400 E5000:5000 ; velocity
M566 X1200 Y1200 Z40 E2000:2000 ; jerk

M906 X900 Y900 Z1000 E500:500 I60; Set motor currents (mA) and idle current percentage (dual Z-motors)

I just keep getting clunks while it's printing. Sometimes they're diagonal, but not at 45, sometimes they're horizontal, and sometimes they're vertical.

gnydick

I was just printing a really slow print and "CLANK", skipped step. I don't know what to do.

dc42

The clank could be the stepper drivers switching from stealthChop to spreadCycle mode. When you send M569 P0 what changeover speed does it report?

I suggest you try configuring the drivers to run in spreadCycle mode all the time, to determine whether stealthChop is part of the problem.

deckingman

@gnydick Are you sure the "clank" is coming from the motors? Is it all the motors or just one of them?

gnydick

@deckingman @dc42 Turns out it was loose belts that were slipping one tooth at a time.