Facing layer shift after 3-4 hours of print

General Discussion
1

Basic Information:

Printer Model: Sapphire Plus
MCU / Printerboard: BTT SKR Mini E3 v1.2
klippy.log

I have recently configured klipper for my printer, and it was working well. All of sudden i am facing layer shift on all the prints after 3-4 hours of print.

here is my printer.cfg: [include fluidd.cfg][include mainsail.cfg][include macros.cfg][virtual_sdc - Pastebin.com

can anyone help me to fix this?

Regards,
Ben

2

Way more important is the klippy.log

And please: Upload your files here.

And BTW: Pastebin in a pain in the eye: Tiny letters with double line spacing.

3 Likes
3

klippy.log (3.2 MB)
printer.cfg (10.2 KB)

Sorry for that, i am attaching configuration file and log

4

@bentech4u As the original template said, you don’t need to include your printer.cfg . The entire configuration is included automatically in the log, Not literally, but as the scripts have interpreted what you typed which is the important bit.

5

HI

can anyone help me to find/fix my issue?

6

There are some possibilities:

  • Your run_current is unusual low for X and Y
  • Using stealthchop_threshold to switch between stealth chop and spread cycle is not recommended
  • Especially if your TMCs are in an enclosure then active cooling might be needed. Although at your run_current it is unlikely
7

HI

Thanks for the response,

i have added an extra fan recently, not i have 2 fan pointing to board and one fan as exhaust, as it is closed area,

So what is the recommendation, do i need to increase it to .900 ? as this board was fine with marlin(which was .800)

Since i am not an expert in 3d printing and very new in klipper, below term is bit confusing for me. what i should i do with stealthchop_threshold.

" Using stealthchop_threshold to switch between stealth chop and spread cycle is not recommended"

8 
[tmc2209 stepper_x]
...
run_current: 0.580
...

[tmc2209 stepper_y]
...
run_current: 0.580
...

This is from your log.
Something around 0.8 to 0.9 sounds more reasonable, but I do not know the printer, so check if you can find specs for your steppers.

If I counted correctly, this printer has 5 stepper motors. How did you connect them to this board that has only 4 ports? Did you wire it in series or in parallel?

Set stealthchop_threshold: 0 to always use spread cycle. Ref to TMC drivers - Klipper documentation

9

HI

i have increased to .900 and seems print is ok. did some test print and no layer shift so far, will try lengthier prints.

yes this printer has 5 motors, for z axis i connected both parallelly.

10

Be aware that you need to double the current of this axis, compared to one stepper alone.

11

Sure, will do that, is this will the reason for small z banding i am facing now?

when i set stealthchop_threshold: 0 , got big noise from motors ,

thanks for all your suggestions.

12

Is this correct? When I had a bed slinger with two Z axis steppers in parallel, I found that multiplying the current by 1.25 what I had with one motor (not 2x) seemed to be optimal - doubling the current caused a driver overtemp shutdown pretty regularly as well as some apparent mismatches in torque between the two motors (when I added the second one, it wasn’t identical to the first).

If he’s running 0.8-0.9A, I’d recommend starting with something like 1.2A and going from there.

13

Most people run with

stealthchop_threshold: 999999

for quiet operation.

1 Like
14

i will try this,

z-banding can be anything software issue? i have corrected my e-steps

or is this pure mechanical ?

15

Could you try a print with the stealthchop_threshold set to 999999 and then please post a picture of what you’re getting.

16

Well, electrically speaking: When you have two steppers in parallel that have exactly the same electrical characteristics (which you should aim for when having them on the same axis) then it is x2.
Further given that you have calculated your RMS correctly, i.e.

Irms = Imax x 0,707 x 0,85

then the unavoidable (small) differences between “identical” steppers should have no big impact. The x0.85 usually has some headroom between 0.8 and 0.9

Which is generally not recommended if you aim for highest precision and dynamics.
If you care more for noise then of course this is an option.
I’d recommend increasing microstepping to at least 64, which typically brings a big improvement in terms of noise as well

Z-Banding could be caused by too low torque, but typically is a mechanical thing and more dominant with lead-screws compared to belted Z. Higher microstepping usually also helps here a bit.

17

I understand the “electrical” speak - I guess I should have been more specific and said “practical” speak.

Doubling the current also doubles the torque, which is generally not required and is going to push the stepper driver temperature leading to other problems.

Regardless, I’d still recommend 1.2A and, if the gantry is not moving smoothly or is slipping (which should be an indication of another problem) then up the current.

1 Like
18

ok,

i will try to increase microsteps too, will this make any overload or heat on my stepper driver ?

19

Sounds like a plan.

Increasing your microsteps won’t contribute to an overtemp shutdown (“overload” isn’t an issue) - the main contributor is the current setting for the driver.

Again, I’d recommend starting at 1.2A for the two parallel steppers (assuming that your other steppers are running at 0.9A) and see how things work for you.

Good luck!

20

This is only correct for series wiring of the steppers. For a parallel wiring, again given the steppers are electrically identical, each stepper consumes half of the current and is supplied by full VCC.
As per the electrical laws, if you do not double the current, each stepper only has half the current and thus only have half the power.

For series wiring, the situation is the opposite: Each stepper consumes half of VCC and is supplied by the same current. So if you want to keep your stepper’s dynamics, you would need to double VCC.