DOLLY unsolvable X layer shift (I am desperate)

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Row_CZ
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Joined: Wed Sep 27, 2017 7:35 am

DOLLY unsolvable X layer shift (I am desperate)

Post by Row_CZ » Tue Oct 23, 2018 8:09 pm

I built my dolly MK2 prusa clone. It is 24V with MKS gen 1.4 board and TMC2100 drivers, runs Marlin (1.6 but I am not sure now).
Steppers are (Czech made) microcon sx17-1005 (0.52Nm) for all axis and microcon sx17-1003 for extruder (0.3Nm). Vref is set to 1V so it should run on 0.7A and 1A peak. Most steppers are about 65°C during a work and drivers are cooled directly with fans. For print head I used original E3D V6.

It worked for a while and prints was great.
Then occasional layershift on X axis appeared so I lubricated linear bearings with bearing greas. It helped for a while.
Then massive layer shift on X axis appeared so I dissassambled X axis, one of the bearings wasn't exactly smooth so I replaced it with brand new one. It helped for a short time.
Then some squeaky noise appeared with usual layershift. I find out that it can be (and probably was) idler pulley grinding printed idler part on X axis so I placed small washers between pulley and printed part (washers are in contact just with inner bearing ring) that provide smooth run of idler pulley. It helped with squeaky noise but not much with layer shift. I had a bunch of new linear bearings so I replaced all with smoothest I found. It slides like never. Even just tension of inserted filament in a printhead move it from both sides to center until filament is vertical.
I tried everything I found on the internet (even some obscure advices), I messed with motor pulley, change belt tension (up and down) and because I had a slightly deformed Z axis brackets by heat (to much current for a first prints) I replaced them with spare set and reassambled whole Z axis an I did everything I could to make sure that Z axis are parallel. Finally it helped and I was able to print even bigger and longer prints (longest was about 9h) without any issue. It worked for about 30 - 40 hours.

Then I left the printer untouched (literaly) for 2 weeks and now that bloody X axis layershift is back again. :'(
I am not able to print even smaller parts (size of whistle) without issues (usually point of failure appears under 15 minutes)
So I swapped drivers with Y axis to find out if it can be caused by driver (overheating etc.) without succes.
I find out some tiny strings of filament on my smooth rods and linear bearing. So I disassambled it (again), clean rods and replace all bearings with new ones (again). I even changed stepper with one spare. And nothing.

I don't understand it. I tried to stop moving printhead with my hand and it moved with whole printer aside. When I hold the frame with second hand I need and huge amount of force to hold it against stepper and start loosing steps.
Last resort for me is that I checked belt if it is okay, it looks OK but i ordered new one just to be sure. Last thing what i didn't changed is main board. Maybe i can modify firmware to swap X and Y axis ports on board to check if there is some problem in electronics before drivers but if it will not help it doesn't eliminate possibility of faulty board... I also can buy a second board but that also means that I also can build a completaly new printer according to ammount of spare parts I have now. :-/

It is like an Italian sports car, fun to drive it but spends more time on service then on track.
I am literaly desperate. I am "in a war" with this issue for a few months now and I am loosing one battle after another. Luckily I am not a samurai because in this case I should end my miserable life with honor by seppuku. :-/

I am losing my desire and will to solve it so I will be happy for any advice in this case. :?
Thanks

P.S. I forgot to say that TMC2100 are set to spreadCycle mode (I was not able to use solder jumper so I bridged top of the legs directly with wire) and yes I can add a bit more current but according to previous experience I would like to avoid it because I am afraid of to hot stepper and deformation of printed part.

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Moorviper
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Re: DOLLY unsolvable X layer shift (I am desperate)

Post by Moorviper » Tue Oct 23, 2018 11:25 pm

I am using the tmc2100 on my dolly for thw x and y axsis, too.
i have also layershift on longer print.
I am using currently a ramps 1.6 and 12v.
but i have already 2 mks gen 1.4

One printer is 24v both with a mk42 -> one modded for 24v.
i will see if the layer shift go when switching to 24v.

i also use spread cycle mode.

with extra cooling all is fine

maybe this is a solution for you ...

Stefan
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Re: DOLLY unsolvable X layer shift (I am desperate)

Post by Stefan » Wed Oct 24, 2018 8:23 pm

Additional question: Does the layer shift only happen one time, or do you get successive shifts during the print?

-Stefan

Row_CZ
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Joined: Wed Sep 27, 2017 7:35 am

Re: DOLLY unsolvable X layer shift (I am desperate)

Post by Row_CZ » Fri Oct 26, 2018 4:09 pm

Hi,
it is always just one shift at a time... usually in different hight, sometimes it happen few times for a print. For example on the foto... on the left one it is not so visible because i "postprocessed" that print for functional test but there was a shift on start in about forth or fifth layer and then right above that triangle hole. On other prints the shift is pretty obvious. :(
https://photos.app.goo.gl/rYzTmTxT72uzKNSr9

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Moorviper
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Re: DOLLY unsolvable X layer shift (I am desperate)

Post by Moorviper » Fri Oct 26, 2018 6:22 pm

yeah same for me.
it is strange because normally it should skip steps as hell when the drivers are hot.
but only one layer shift happens :D

Row_CZ
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Re: DOLLY unsolvable X layer shift (I am desperate)

Post by Row_CZ » Fri Oct 26, 2018 7:12 pm

Driver temperature should't be a problem. It wasn't a problem even with Vref 1.4V when 1 of Z steppers attacked surface temperatures about 110°C and melt down my printed bracket.
But I measured temperature on heatsink of all drivers just to be sure and it is about 40°C on all of them when it is cooled only passive (and still keep up working). Normaly in my setup I have a fans directly on it.

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Moorviper
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Re: DOLLY unsolvable X layer shift (I am desperate)

Post by Moorviper » Tue Oct 30, 2018 6:00 pm

so yesterday finally magic blue smoke :D

Should be earlier.
Now i replace the ramps 1.6 with the gen 1.4.

maybe i should not heat the nozzle and the bed at the same time :D
but the prusa mk42 uses much less energy than a MK3 so it should be fine ...

Row_CZ
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Re: DOLLY unsolvable X layer shift (I am desperate)

Post by Row_CZ » Tue Oct 30, 2018 6:16 pm

Great... but buddy... I would like to find a solution to my problem and adding irrelevant replies to this topic will not help. Thanks :roll:

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Moorviper
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Re: DOLLY unsolvable X layer shift (I am desperate)

Post by Moorviper » Tue Oct 30, 2018 7:17 pm

now i have the same setup as you

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Moorviper
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Re: DOLLY unsolvable X layer shift (I am desperate)

Post by Moorviper » Tue Nov 06, 2018 10:37 pm

https://youtu.be/j9OuaEgRc34?t=2325

there is maybe a issue @ marlin

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