Layer shift MeCreator2

Hi all,
since some weeks I experience layer shifts in y-direction shift when printing objects higher than approx. 10mm on my MeCreator2. After some googling I found that probably the A4988 overheat and go into thermal shutdown. So I replaced them (x and y) with DRV8825, set Vref to .8V and left the enclosure bottom open to ensure appropriate cooling. Unfortunately, the problem persists. Any helpful suggestions are welcome.

I would say that it is possible the Y-Axis is binding, could be in need of lubrication.
Have heard that some use grease though in my opinion grease is to thick. I use a sewing machine style oil, garage door silicone spray or a good Gun oil like Ballistol works well...

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Computer Programmer / Electronics Technician

It looks like you have some over extrusion issues too.

Thanks for the suggestions. I'll try tomorrow and report

Ok then, I slightly reduced the extrusion multiplier, cleaned and lubricated the x and y rails, and they run much smoother now. But....

after cleaning and lubricating I watched a print of a small cylinder (12mm diameter, 15mm high). At about 11 mm height I noticed an audible "clack", and the y-axis was offset by some 12mm . So I'm still after the reason for that error!!!

Without being able to see your printer all anyone can do is make some best guesses. Is it possible that your nozzel hit the print? If your putting down too much plastic it sticks up and the nozzel hits it.That could account for the noise. Check the z travel to make sure its moving up the correct heighth for every layer. Enabling Z-hop sometimes helps but its not a fix. Sorry if I'm telling things you already know.

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fumo
Ok then, I slightly reduced the extrusion multiplier, cleaned and lubricated the x and y rails, and they run much smoother now. But....

after cleaning and lubricating I watched a print of a small cylinder (12mm diameter, 15mm high). At about 11 mm height I noticed an audible "clack", and the y-axis was offset by some 12mm . So I'm still after the reason for that error!!!

That isn't an error, that is an event!
You know exactly what your problem is, you just don't know what caused it. That clack means that you had a mechanical collision of some sort. On my printers it is usually a fan shroud or nozzle that impacts a piece of plastic that is sticking up. The piece of plastic is usually something that curled up and hardened at an elevation higher than the rest of the print. If that plastic is large then when the nozzle hits it only one of two things can happen: the nozzle melts through it, or the nozzle smacks it and dislodges the print or stalls the end effector or carriage. It sounds like the latter occurred in your case. This makes me think of these things:
Your part fan isn't doing its job and the plastic is not cooling fast enough.
Your Y axis stepper current isn't high enough and your stepper is therefore too weak to handle the collision.
Your Y axis belt has something lodged in it that is stalling the stepper (this is a lower probability).
Your stepper is jamming or the pulley on the stepper has a loose set screw.
The belt pulley on the other end of the gantry jammed and caused a belt skip.

having fun yet?

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Kits: Folgertech Kossel 2020 upgraded E3Dv6, Anet A8 upgraded E3Dv6, Tevo Tarantula enhanced parts and dual-head, TronXY X5SA Pro(E3DHemera).
Scratch: Large bed Cartesian, exchangeable heads, Linear slide Delta, Maker-Beam XL Micro Delta, 220x220CoreXY.

Hi there,
a short update:

The problem is still there. I fully watched a print. Everything went fine until a height of about 22mm, then the slight "clack" and I had my layer shift in y-directon again. It always happens exactly (!) in y-direction, so I ruled out a nozzle collision, because that would happen in variuos directions, depending on the location, height and momentary print direction. I could prove that there is positively no filament that builds up, the nozzle could move freely all the time, no collision with the printed part happened.

So my next task is to check the belt and pulley.

Hermann

Assuming this is a direct extruder.
Might be worth a good look at the extruder mounting. If the hot end throat is close to the gear maybe when the bed moves in Y the nozle catches, tilts the extruder and the throat hits the gear making it jamb and miss.

Hi guys,
I'm afraid I found the reason for my layer shifts

A detailed examination showed that both ends of the x gantry the LM8UU-holders have a crack!

Just tell me if you share my opinion that this might have caused the y-layer-shifts. If anyone knows if (and where) I can get the STL's of these components, that information would be greatly appreciated. I could't find them in the internet yet.

Hermann

Latest (not so good) news:

I fixed (i.e. glued) the cracks in the x-ends, did a complete alignment of rods, belts, etc. and made sure everything is running as desired. The calibration cube came out fine (it finished before a layer shift occured).


Unfortunately, the layer shifts are still there. So I sat beside the printer watching what happens. This is what I found:

At first, printing is going on as usual. After some time (maybe 3 minutes, maybe 10 minutes) the printer seems to hold on for about a second, then resumes printing with shifted y layers. To rule out any network errors, I printed from SD-card (no network, no USB connection). But the issue is still there.

My last idea (for the moment) is to increase the stepper current.

Comments are welcome!

Hermann

Try to eliminate as many factors as you can. Try a dry run to rule out filament catching. Just leave out the filament, or if the slicer supports a dry run, try that.

Lower the maximum velocity, acceleration and jerk settings on the printer by setting it on the display or using gcode.

Monitor the temperature of the stepsticks, monitor the voltage. Look for spikes, dips, ripple etc.

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Kind regards
Imqqmi

NFAN CoreXY printer:
[reprap.org]

Quote
fumo
Latest (not so good) news:

I fixed (i.e. glued) the cracks in the x-ends, did a complete alignment of rods, belts, etc. and made sure everything is running as desired. The calibration cube came out fine (it finished before a layer shift occured).


Unfortunately, the layer shifts are still there. So I sat beside the printer watching what happens. This is what I found:

At first, printing is going on as usual. After some time (maybe 3 minutes, maybe 10 minutes) the printer seems to hold on for about a second, then resumes printing with shifted y layers. To rule out any network errors, I printed from SD-card (no network, no USB connection). But the issue is still there.

My last idea (for the moment) is to increase the stepper current.

Comments are welcome!

Hermann

If the problem always occurs at a particular layer, move your Z to that layer and scan back-and-forth on the Y axis to see if you can get your hit. You do not have an extrusion issue, since the layer shifts over. That is a gantry movement error. This may or may not discover anything.

Having the print pause, and then start up several mm over means that your printer did not get the intervening commands, it stopped getting codes, waited and started getting codes, but the head was now in the wrong place. Because you say that this occurs when connected to USB or when running from the SD card, I am beginning to suspect buffer memory corruption, which would be the main controller. It could also be that your stepper driver wasn't getting instructions, which again means a main controller communications error from the processor to the stepper driver. Because this happens after a certain period of time, that says "thermal" issue to me. Put a fan in the enclosure blowing across the stepper boards/chips. I had freezes on two different printers that were corrected by just putting a 25mm fan near the driver chip "row" blowing over the chips. The freezes went away.

DLC

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Kits: Folgertech Kossel 2020 upgraded E3Dv6, Anet A8 upgraded E3Dv6, Tevo Tarantula enhanced parts and dual-head, TronXY X5SA Pro(E3DHemera).
Scratch: Large bed Cartesian, exchangeable heads, Linear slide Delta, Maker-Beam XL Micro Delta, 220x220CoreXY.

Thanks to all of you who gave good hints. I'll share my latest experiences:

Modifying the stepper current was a good idea, but I got heavy improvement after lowering (!) the stepper current. I set Vref on the x and y-8825 piggyback boards to approx. 0.8V, and the first prints were very promising and made me hope the issue was solved.

It is not! I printed a bigger part, and after two and a half hour or so the printer stopped totally. Examination showed a VERY hot x-stepper and a blown fuse on the GT2560 control board. Since I have no spare fuses (Littlefuse nano, 10A), I ordered some. Now all further action will be delayed until arrival of that fuses ☹.

Probably I have to set a much lower stepper current. Btw, does anyone know the "right" current for the steppers in the MeCreator2?

It could be a short from something else too, maybe you need to replace the board or at least check everything that's connected. Use an amp clamp to measure the current on the input, then add all the sensors and other devices back to the board until you see a big jump in current usage.

Was the fuse also powering the heated bed? If not, it should never have happened as stepper motors really don't draw that much current. My corexy with nema23 steppers draw around 1-2A when running At 12V and lower at 24V. I have no idea what steppers are in your machine. Maybe you can look at the sticker of the stepper motor what type it is? Generally you use a current well below what the stepper motor is specified to handle.
I usually create some gcode that runs the axis at top speed back and forth. If no skipping occurs then I call it good. The noise it makes is also a factor. I also run the motors at very slow speed to see when they run the smoothest. Especially with A4988 steppers it makes a big difference. The TMC2660 not as much, it only produces more noise at higher currents (and heat).

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Kind regards
Imqqmi

NFAN CoreXY printer:
[reprap.org]

I totally agree that the fuse never should have blown. It does not power the heated bed, which has a separate fuse, motors are NEMA17, and the whole system is running at 24V.

Lets find out what happened...

Hi guys,
unfortunately, I could not figure our what was the cause for the blown fuse. I replaced it, and everything seemed to work fine, except that the x-motor is still running hot. So I spent a fan on it and had no further problems until today:

The extruder stepper does not move anymore. Changing the driver board (A4988, lower left position in image GT2560) made no difference, so I guess the motor is gone. Checking the motor coli resistances at the connector yields 2.2 ohms between pins 1 and 4, and the same between pins 3 and 6. The other pins seem to have no connection.
Anybody who knows the correct pin assignment for the stepper motor sold by Geeetech?

Regarding the (still unsolved) problem with the hot x-stepper, I was heavily surprised when I opened the bottom case. The x-stepper still becomes hot, but the y-driver (!) board did not look good (see image Y_Stepper_Driver) , the current sense resistors are coal black, and the capacitor next to them just blew off. Anyway, the y axis worked fine until today.

Any idea what might have happened here?

I think the first step would be to add cooling fins to the stepper drivers. I have never seen a DRV8825 (assuming they are), that was blown like that.

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http://www.marinusdebeer.nl/

Quote
fumo
Hi guys,
unfortunately, I could not figure our what was the cause for the blown fuse. I replaced it, and everything seemed to work fine, except that the x-motor is still running hot. So I spent a fan on it and had no further problems until today:

The extruder stepper does not move anymore. Changing the driver board (A4988, lower left position in image GT2560) made no difference, so I guess the motor is gone. Checking the motor coli resistances at the connector yields 2.2 ohms between pins 1 and 4, and the same between pins 3 and 6. The other pins seem to have no connection.
Anybody who knows the correct pin assignment for the stepper motor sold by Geeetech?

Regarding the (still unsolved) problem with the hot x-stepper, I was heavily surprised when I opened the bottom case. The x-stepper still becomes hot, but the y-driver (!) board did not look good (see image Y_Stepper_Driver) , the current sense resistors are coal black, and the capacitor next to them just blew off. Anyway, the y axis worked fine until today.

Any idea what might have happened here?

My NEMA 17 steppers measure about 2.5 ohms, so that is normal. Pin order seems random between manufacturers, you just have to ohm them out to see what they are.
You obviously were pushing too much current or that sense resistor would not have toasted. With my A4988 boards I've gotten the steppers super hot before toasting the driver board - but maybe I just got lucky and changed it quickly enough. I have a Z-axis stepper on my large-bed Cartesian printer that gets hot and I put a fan on it, its been running for over a year that way and the driver board looks fine. I have a fan that is dedicated to cooling my drivers however.

Since you blew a fuse, toasted a sense resistor and blew a cap off of a driver board I suspect that you have a short on your driver board, your your stepper wiring or stepper. Look for worn spots in your cabling or pieces of stray metal on your driver board. Steppers simply do NOT pull that kind of current. The symptoms that you describe point to a short in the circuitry for that stepper channel. It may have been something that you didn't notice that dropped in there and is now on the floor, but, I'd do some careful visual inspection. Because the sense resistor on the driver was toasted, it is my guess that the short _has_ to be in the stepper wiring, b u t, it could have been the stepper too. Your list of candidates is small - Driver board, wires to the stepper, the stepper itself. Unfortunately, because the fuse is blown, something upstream on the controller board may now be damaged. Look for blown traces or lifted/wrinkled traces between the driver board socket and the fuse. These are usually repairable.

DLC

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Kits: Folgertech Kossel 2020 upgraded E3Dv6, Anet A8 upgraded E3Dv6, Tevo Tarantula enhanced parts and dual-head, TronXY X5SA Pro(E3DHemera).
Scratch: Large bed Cartesian, exchangeable heads, Linear slide Delta, Maker-Beam XL Micro Delta, 220x220CoreXY.