[baronpork]

Hello people.

Bought a laser cutting machine, xy gantry, nema17 motors, M415DRV drivers.
Trying to debug very small oscillations happening while travelling at speed.
Gantry and head driven by GT2 belts on your usual pulleys for that sort of thing. Think 3d printers.
Usual speed for cutting paper card is 200-300mm/s, where i see small sinusoidal waving in the
produced cut, always at opposite sides of, say, circle.
Engraving in X at 400mm/s does well (tiny Y steps), but as soon as wide vertical motions are introduced
i get waving in the cut. And sometimes step loss in Y direction.

Checked mechanics, no binding or sticking.

I'm thinking i may need to increase current to the motors to see if waving goes away with more torque.

Cannot identify steppers to see their specs (china, right?).
Markings on motors:
X axis (head motion): Type 17HA705Y-1A, FH171215 Smooth (shorter motor, single shaft)
Y axis (gantry motion): Type 17HA801Y-22P5, FH190104 Smooth (taller motor, dual shaft)
Google-fu fails me on this.

Same with drivers, cannot find M415DRV as such. I did find M415 but those have 6 switches on them, mine got 8.
On my drivers switches 1 and 4 are ON. How do i increase current ? What switches to pull ?

[john-100]

a quick web search did not find your version of the M415DRV stepper driver

can you post a close up of the switches and label ?

with a readable picture of the current table it will be possible to see what the motor current is set to

how hot are the stepper motors ?
usually they can run at 70 or 80 C - too hot to touch !!!!!


the other detail that's needed is the microstepping the driver is set to

with full step to 1/4 you will likely see the motor jitter and have the lead screw resonate

1/8 microstepping is usually a good start - with a 200 step per rev motor it will take 1600 steps for 1 revolution of the motor

John

[baronpork]

Havent run the machine hard enough to see if motors are getting hot.

Label is visible in the photos i attached to my first post. Switches 1 and 4 are in ON position.

#Edit# pics got smallified after uploading. Re-attaching cropped image.

[john-100]

The odd thing about stepper motors is the stepper driver sets the motor current and is constant irrespective of the mechanical load

Depending on the setting of switch 5
your stepper drivers automatically reduce the current to 50% when the motor has been idle for a while

with switch 5 set to full the motor will heat up when it stopped

what is the setting for switches 5 to 8 ?



John

PS
did not see the new photo while posting !!!!

[baronpork]

5 is in OFF position.

[john-100]

OK ,
5 off = 50% current reduction


with switches 6 to 8 set to off , on , on = half step

I would change to 8 microsteps off , on ,off


with switches 1 to 4 set to on , off , off , on = 0.5A RMS
how did you decide to set set the current to 0.5A ?


John

[baronpork]

I didnt, it came from the factory this way.
I suspect motors bouncing on direction changes, which (in my limited understanding) suggests not enough holding torque/current.
And as i cant identify the motors, i dont know their amp range. Driver label seems to suggest max IT can do is 1.6A.

#Edit# Only switches 1 AND 4 are in ON position. 2 and 3 are OFF.

[john-100]

you could try increasing the current setting to 0.57A RMS


switches 1 to 4 = on , off , off, on = 0.5A RMS

the next current setting is off , off , off , on = 0.57 A RMS ( a 14% increase)

Attachment 421610


for your tests set switch 5 to on to switch off the auto current reduction

it will make it easier to check the motor temperature does not go higher than 80 C

example stepper motor data sheet
RS Pro H i g h T o r q u e H y b r i d Stepper Motor.pdf


John

[baronpork]

Running torture test at the moment. Loaded a complex design and let it run with laser off.
About 15 minutes of very small movements, sudden direction changes. Dont know if its losing steps, just want to see if motors get warm/hot on default settings.

#Edit# Results. X motor (head) about 40C, Y motor is 20C, ambient about 18C. Thoughts ?

[john-100]

I would expect the will be too hot to touch unless the motor is being under run or the auto current reduction is keeping the motor cool

see data sheet
RS Pro H i g h T o r q u e H y b r i d Stepper Motor.pdf

John

[baronpork]

Starting to get a hang of this.

Will change to 0.57 and test again.

Here's another question - what does microstepping decrease do to torque ? I'd assume it will increase torque and travel distance (if not corrected in controller software).
Am i correct ?

[john-100]

yes

increasing microstepping is a trade off between a smoother movement and loss of torque

you will need to compensate for an increase microsteps in your control software

John

PS
just thought
the wavey edge could be due to a miss match in pitch between the toothed belt and the toothed pully

[baronpork]

Belts and pulleys look like GT2 on my 3d printers.

[baronpork]

Increased current to 0.57A
Ran the torture test again. Twice in a row.
Results:
X is burning, 65C
Y, stone cold.

While X is a shorter motor, both motors do about the same amount of moving yet X is getting a bit close to 80C, while Y is sitting there just yawning. Never seen stepper to heat up so much on any of my other devices with nema17 motors...

[john-100]

From the photo showing both drivers it looks like they have the same switch settings

with one motor hot and the other cold


first I would check the wiring between Y axis motor and Y axis driver

if the wiring is OK


swap the 2 drivers

so the X axis step & direction signals and X axis motor is connected to the Y axis driver

and the Y axis step & direction signals and Y axis motor is connected to the X axis driver

to see if the problem moves to the motor or stays with the driver

John

[baronpork]

Good idea. Will swap out the drivers and report back tomorrow.
Any idea on origin of the steppers ? Cant find anything on these models.