Intermittant diagonal layer shift, how to diagnose? I have a scratch built CoreXY that I recently completed. For a couple of weeks it has worked flawlessly, but now I am getting intermittent diagonal layer shifts toward the "X" stepper (the right one looking from the front). I know this is the direction traveled with the X stepper is running and the Y stepper is not. It seems to happen "mostly" on larger models, more compact models 90% of the time will run. My frame is 300mmx400mm using 37oz.in(26Ncm) 12V 0.4Amp 1.8deg steppers. Controller: Duet 2 Maestro, running the steppers at 800ma Acceleration 700mm/s^2 Jerk 10mm/s Max travel speed 120mm/s (print speed typically under 40mm/s) I do not think that it is mechanical, I am using a pretty typical (unstacked) CoreXY design, and this is a pretty small printer (200mm bed). Nothing seems to be binding, grinding, catching or skipping when I move it manually. But definitely have heard the "bonking" sound of a stepper balking or a belt skip on a pulley. I don't THINK that my belts are either too tight or too loose, they feel the same as another CoreXY machine that I have. My idlers are free moving and there is nothing, that I can see, that is binding. CoreXY printers are new to me, I have only had them for the last two months or so. I am not sure where to go to troubleshoot this problem. I have read enough to know that a 45 degree shift to the "back right" means that the "X" stepper is moving when the "Y" stepper is not moving. So, if both steppers should be moving and the "Y" stepper jams, that would shift everything to the diagonal pointing to the "X" stepper. The steppers get a little warm, nothing to worry about. The "bonking" sound sounds like the motor is either balking, or trying to move too fast and the belt is skipping. Does anyone have a process that they use to troubleshoot this kind of thing? Is my current too low, acceleration too high, steppers too weak, ??? I don't usually start replacing mechanical things when trouble starts, belts, pulleys and motors are really reliable. What are some good steps to take in settings or speeds that can point me to a cause? EDIT I increased the current. No effect. I reduced accel down from 1000mm/s to 200mm/s No effect. I reduced jerk down from 15mm/s to 5mm/s No effect. I have slowed my speeds down by 30% No effect. When I abort the print, I hear the printer "gronk" like a belt skip as it tries, and fails to home X/Y - It never homes X all the way. CORRECTION, it is Y that doesn't home. So, now I AM thinking something is catching in the mechanical system - Time for a tear-down. Hmm. Many thanks, DLC https://reprap.org/forum/read.php?397,873704,873704#msg-873704 Fri, 06 Mar 2026 00:05:29 -0500 Phorum 5.2.23 https://reprap.org/forum/read.php?397,873704,893823#msg-893823 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,893823#msg-893823 the_digital_dentist CoreXY Machines Tue, 21 Nov 2023 18:45:39 -0500 https://reprap.org/forum/read.php?397,873704,893813#msg-893813 Re: Intermittant diagonal layer shift, how to diagnose? SOLVED! https://reprap.org/forum/read.php?397,873704,893813#msg-893813 In short, One belt attached to the end-effector element was not parallel to the travel. The rise from the stepper to the pulley on that "turns the corner" to the other axis travel was 3mm at it's worst location. This caused the belt to climb over the rim of the pulley (which was not very high) and would cause the belt to skip or skew far enough to jam the stepper travel. When one stepper moves and the other stays still, on a CoreXY, you get diagonal travel. This is why that happened.
So, make sure your belts are tensioned enough to avoid a belt skip, and make really sure that your belt is parallel to the axis travel. It doesn't take much to totally jank your hardware.

Wow, that took a while, but I'm stubborn. And I should have known better, but I could have sworn that I carefully measured and adjust for that, but obviously, something changed when I wasn't looking (?).

be well,
DLC]]> dlc60 CoreXY Machines Mon, 20 Nov 2023 22:08:29 -0500 https://reprap.org/forum/read.php?397,873704,877519#msg-877519 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,877519#msg-877519 My issue always occurred during a high speed transition in the X axis, which caused me to focus there. BUT I forgot that in a CoreXY machine, every transition affects every axis, X and Y are linked and must cooperate, so, even though the motion is in X, the hot end carriage is at the center of that motion.
When I dropped the hot end mount 10mm to give me space for a fourth slider, my binding issue got MUCH worse.I had the hot end mounted on a "side" slider instead of the "middle" one of three sliders, using three sliders that could not be helped since the belts attached to each side and other parts attached to the top "middle" one. This 10mm drop made the hot end carrier more unstable and I watched it flex, until it rolled over enough to bind.

Exoslide recommends that you mount the hot end on the middle of a three-sided slider or use four sliders.
I moved sliders around. Instead of three on each motion piece, I made one gantry slider a three, the other a two and made the hot end slider four. This required me to re-orient the "two slider" mount such that I could use the exact same mount as I use on the other end. This symmetry is good for a number of reasons and even though their orientation made the gantry mounts look asymmetric, it simplifies the design.

This three-two-four layout stopped binding (so far) and prints have even less ringing apparent. Everything seems to be much more stable. I will increase my speeds and see what happens, but it looks like this final change may have fixed my CoreXY problem.

More as I learn more,
DLC]]> dlc60 CoreXY Machines Mon, 21 Sep 2020 12:04:57 -0400 https://reprap.org/forum/read.php?397,873704,877430#msg-877430 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,877430#msg-877430
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the_digital_dentist

DLC60, if it's printing square you're done. The X and Y axes are square. The error may be in the frame which doesn't really matter.

Yeah, that is what it looks like. I guess that I can live with just printing slowly if parts are "perfect". Now, if I can just figure out why I get the jams at high speeds then I'd be in printer heaven! :(

DLC]]> dlc60 CoreXY Machines Fri, 18 Sep 2020 00:32:34 -0400 https://reprap.org/forum/read.php?397,873704,877426#msg-877426 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,877426#msg-877426
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dustinoff
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the_digital_dentist
If the frame is square it works fine. if your frame isn't, all bets are off.

Well, isn't the question about how to determine squareness. The only way to do that, other than a lab instrument to measure 90°, is to measure the diagonals. But on printer hardware, measuring two diagonals accurately seems to me to be pretty difficult. The easiest thing one can do is to print a big square/rectangle and measure its diagonals. Then you can relate that back to your hardware. Otherwise, you will just be hand grenade close.

You can always check using a machinist's or carpenter's square. It's usually pretty easy to measure the frame's diagonals, too.

If the ends of the frame pieces are cut square and the pieces are matching lengths, when you bolt them together they will be square because they can't be anything else. OTOH, if you cut the frame members with a hacksaw and built the frame using a bunch of corner plates to hopefully hold everything square, you never know what you'll end up with. You can check squareness of the cuts by standing the frame pieces up on a flat surface next to each other. If they aren't parallel, the ends aren't square. It will be obvious if they aren't matched in length, too.

It's usually pretty easy to line the Y axis guide rails up parallel to the frame members they attach to by using spacer(s). Line one up first, using a small metal spacer to set the distance between the edge of the rail and the edge of the frame member (don't use a series of printed plastic parts- their dimensions are well controlled and they will flex) and bolt it down tightly and it will be the reference. Align the other rail parallel to the reference by bolting a spacer to one of the bearing blocks. Move the spacer bar to one end of the second rail, lightly screw down that end of the rail, then move the spacer to the other end of the rail and screw it down. Finally, screw the first one down tight and run the spacer bar back and forth to check it. Now the frame is square and the Y axis rails are parallel to the frame members and each other.

Building a square frame makes alignment of guide rails easy compared to trying to align them on an unsquare frame...

DLC60, if it's printing square you're done. The X and Y axes are square. The error may be in the frame which doesn't really matter.]]> the_digital_dentist CoreXY Machines Thu, 17 Sep 2020 21:19:29 -0400 https://reprap.org/forum/read.php?397,873704,877395#msg-877395 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,877395#msg-877395
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dustinoff
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dlc60
I printed a 40mm cube, and it was square, and very close to 40mm on each axis.

DLC

measuring each side does not tell you it is square. You must measure the diagonals.
"square, and very close to 40mm on each axis"
means it is square (56.56mm on the diagonal, pretty much dead on) AND 40mm on a side.
Commas matter.

DLC]]> dlc60 CoreXY Machines Wed, 16 Sep 2020 23:57:23 -0400 https://reprap.org/forum/read.php?397,873704,877392#msg-877392 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,877392#msg-877392
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dlc60
I printed a 40mm cube, and it was square, and very close to 40mm on each axis.

DLC

measuring each side does not tell you it is square. You must measure the diagonals.]]> dustinoff CoreXY Machines Wed, 16 Sep 2020 21:48:51 -0400 https://reprap.org/forum/read.php?397,873704,877390#msg-877390 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,877390#msg-877390
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dustinoff
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the_digital_dentist
If the frame is square it works fine. if your frame isn't, all bets are off.

Well, isn't the question about how to determine squareness. The only way to do that, other than a lab instrument to measure 90°, is to measure the diagonals. But on printer hardware, measuring two diagonals accurately seems to me to be pretty difficult. The easiest thing one can do is to print a big square/rectangle and measure its diagonals. Then you can relate that back to your hardware. Otherwise, you will just be hand grenade close.
I printed a 40mm cube, and it was square, and very close to 40mm on each axis.
I moved the carriage close to one end and measured the distance from the slider edge to the end of the printer. There is a 2mm difference. A triangle check tells me that my printer is as square and I can tell from a triangle, in all directions. I spent an hour or so tweaking belts to change that 2mm difference, and was unable to budge it. Moving the carriage back and forth at a variety of speeds gives me no binding. Moving the carriage by pulling on the belts at various speeds didn't bind up either. Grrr. Something is clearly NOT right, but I haven't a clue what. I really don't think it is the controller either, I have a cooling fan running across the electronics and the PCB temperature barely moves during a print. The Duet 2 Maestro is a pretty reliable controller, so I am doubting that I have a driver issue.
I get really good prints from this printer as long as I keep the movement speeds down.
It isn't as fast as I would like, I have plenty of extruder margin in that regard, I guess that I should just be happy that it works well, even if not as fast - I can always send the job to my Delta printer, that will print plenty fast...

DLC]]> dlc60 CoreXY Machines Wed, 16 Sep 2020 18:40:20 -0400 https://reprap.org/forum/read.php?397,873704,877388#msg-877388 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,877388#msg-877388
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the_digital_dentist
If the frame is square it works fine. if your frame isn't, all bets are off.

Well, isn't the question about how to determine squareness. The only way to do that, other than a lab instrument to measure 90°, is to measure the diagonals. But on printer hardware, measuring two diagonals accurately seems to me to be pretty difficult. The easiest thing one can do is to print a big square/rectangle and measure its diagonals. Then you can relate that back to your hardware. Otherwise, you will just be hand grenade close.]]> dustinoff CoreXY Machines Wed, 16 Sep 2020 16:14:07 -0400 https://reprap.org/forum/read.php?397,873704,877385#msg-877385 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,877385#msg-877385 the_digital_dentist CoreXY Machines Wed, 16 Sep 2020 14:55:57 -0400 https://reprap.org/forum/read.php?397,873704,877374#msg-877374 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,877374#msg-877374
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the_digital_dentist
If the frame is square, and the Y axis rails are parallel to the frame rails, all you need is a ruler to check if the axes are square- move the X axis to one end of the Y axis and measure the distance from the end of the X axis to the edge of the frame at both ends of the X axis. if it's square the distances will be the same. Verify by printing a rectangular object and measure diagonals.

Beg to differ with you on that DD. Unless I don't understand what you are saying, high possibility, you are measuring 2 sides of a square. If you tip the square into a parallelogram those two sides will still be = but the diagonals will not and therefore the square is no longer square. Printing a rectangle or square and measuring the diagonals definitely works.]]> dustinoff CoreXY Machines Wed, 16 Sep 2020 11:26:27 -0400 https://reprap.org/forum/read.php?397,873704,877372#msg-877372 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,877372#msg-877372 the_digital_dentist CoreXY Machines Wed, 16 Sep 2020 10:58:40 -0400 https://reprap.org/forum/read.php?397,873704,877371#msg-877371 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,877371#msg-877371
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dlc60

Hmm. Those are good ideas. Figuring out if the entire rig is perfectly square is a challenge. I am a programmer, not an ME. What is a good way of determining this? Can it be done without a fancy tool?

Thanks,
DLC
I am trying to figure out how mine can be anything but square and I can't see it. However, If it is far enough off it could cause binding in the movements. Also if you print a square, it will be a parallelogram but not square. A perfect square will have equal diagonals. So print a square in a few lines/layers at the limits of your bed and measure those.]]> dustinoff CoreXY Machines Wed, 16 Sep 2020 10:04:45 -0400 https://reprap.org/forum/read.php?397,873704,877354#msg-877354 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,877354#msg-877354 RockyAussie CoreXY Machines Wed, 16 Sep 2020 01:15:08 -0400 https://reprap.org/forum/read.php?397,873704,877353#msg-877353 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,877353#msg-877353
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the_digital_dentist
The way you know if the belt tensions are correct relative to one another is that the X axis is square with the Y axis. The absolute tension is another matter- it should be tight but not too tight. In my printer the belt tension is adjusted by sliding the motor mounts back so I get a direct feel for how hard I am pulling on them. If your belt tension adjustment uses a screw it might be harder to get a feel for it. Try plucking a long span of belt - it should ring at a very low frequency. If you suspect the mechanism is binding, try loosening the belts a bit.
Hmm. Those are good ideas. Figuring out if the entire rig is perfectly square is a challenge. I am a programmer, not an ME. What is a good way of determining this? Can it be done without a fancy tool?

Thanks,
DLC]]> dlc60 CoreXY Machines Wed, 16 Sep 2020 00:43:45 -0400 https://reprap.org/forum/read.php?397,873704,877352#msg-877352 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,877352#msg-877352 the_digital_dentist CoreXY Machines Wed, 16 Sep 2020 00:26:14 -0400 https://reprap.org/forum/read.php?397,873704,877350#msg-877350 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,877350#msg-877350
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RockyAussie
To Quote - I am quizzing the Exoslide guy about this, I am using Exoslides for my X and Y axis
I have looked at the design of these on the tube over and over and I have to say I would be quite concerned about having so many rollers continually running along soft and sometimes dirty aluminium. I have seen some applications where running 3 rollers has worked better than 4 let alone 16 as shown in their intro video. That is a LOT of surface area waiting for the rolllers to pick up any little nick or dust particles. Just another observation over time to consider.....many people try and make the top as solid and inflexible as possible and I have noticed way less problems when the hot end is able to move/flex upward just enough to not get knocked out of line when it hits some cold parts of the print. It generally all smooths out fine in the end.

I have watched it happen, the nozzle isn't colliding with the print. "Something" else is happening, and since the belt is skipping, my bet is on a bind because it happens in my X axis, which is the axis that spans the printer rather than the Y which is just one carriage going back and forth. BUT, my belts are parallel to their travel - I keep wondering if I do not have a perfect tension/alignment, I am just not sure how to balance the two belts and KNOW that they are balanced. If you get my meaning. I have another CoreXY that does not do this, but it isn't using Exoslides either, just a"V-belt wheels on bars" sorta linear slide (TronXY x5sa Pro).

DLC]]> dlc60 CoreXY Machines Tue, 15 Sep 2020 23:42:36 -0400 https://reprap.org/forum/read.php?397,873704,877343#msg-877343 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,877343#msg-877343
If the print curls, you need to adjust temperatures, try the print cooling fan (depending on the type of filament), print slower, or print a sacrificial object so the main print has a chance to cool a bit before the hot nozzle comes along and dumps more hot plastic on top of the previous layer.]]> the_digital_dentist CoreXY Machines Tue, 15 Sep 2020 20:09:35 -0400 https://reprap.org/forum/read.php?397,873704,877285#msg-877285 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,877285#msg-877285 I have looked at the design of these on the tube over and over and I have to say I would be quite concerned about having so many rollers continually running along soft and sometimes dirty aluminium. I have seen some applications where running 3 rollers has worked better than 4 let alone 16 as shown in their intro video. That is a LOT of surface area waiting for the rolllers to pick up any little nick or dust particles. Just another observation over time to consider.....many people try and make the top as solid and inflexible as possible and I have noticed way less problems when the hot end is able to move/flex upward just enough to not get knocked out of line when it hits some cold parts of the print. It generally all smooths out fine in the end.]]> RockyAussie CoreXY Machines Mon, 14 Sep 2020 06:21:17 -0400 https://reprap.org/forum/read.php?397,873704,877278#msg-877278 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,877278#msg-877278
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RockyAussie
I noticed that de42 had suggested dropping your z acceleration speed and am wondering if you had tried that and by how much? I had a bit of an issue with the Tronxy x5sa pro when I increased the overall acceleration speed (M8008) from 100 to 700 and the Jerk (M8007) from 20 to 10 and that resulted in a total stop when the head went from front left to rear right and the z started. The fix for this eventually was to bring the maximum speed of the Z (M8013) from 20 down to 5. That worked and the prints are now smoother (Less jerky)and faster and as yet I have not seen any degradation in the prints.
I am not by any means very knowledgeable with this stuff but I reasoned out that the Z does not need all that current draw at the same time as all the others are sucking it up and the board seems to agree with me so far. If you are doing anything on your Tronxy like this you need to do your extruder speeds at the same rate as the others, (8007 I10 and 8007 E10 and 8008 I700 and 8008 E700. I hope this may be of some help. Regards Brian

Dropped accel, dropped jerk, increased stepper current. Only slowing the whole thing down does any good. Even then, occasionally I get the binding and the layer shift. I am totally out of ideas.
I can avoid the layer shift on a long piece if I orient it along the Y axis direction, along the X axis direction, I'll occasionally get the shift. If I have a model that is large in both axis, then I am out of luck until unless I really slow the printer down. Kind of frustrating, the only clue that I have is the potential for a not perfectly parallel belt path along the X axis. It is really darn close, as close as I have on my TronXY x5sa CoreXY, which does not have a layer shift issue.

I am quizzing the Exoslide guy about this, I am using Exoslides for my X and Y axis.

DLC]]> dlc60 CoreXY Machines Sun, 13 Sep 2020 22:50:57 -0400 https://reprap.org/forum/read.php?397,873704,877253#msg-877253 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,877253#msg-877253 I am not by any means very knowledgeable with this stuff but I reasoned out that the Z does not need all that current draw at the same time as all the others are sucking it up and the board seems to agree with me so far. If you are doing anything on your Tronxy like this you need to do your extruder speeds at the same rate as the others, (8007 I10 and 8007 E10 and 8008 I700 and 8008 E700. I hope this may be of some help. Regards Brian]]> RockyAussie CoreXY Machines Sun, 13 Sep 2020 05:21:39 -0400 https://reprap.org/forum/read.php?397,873704,874479#msg-874479 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,874479#msg-874479
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the_digital_dentist
Maybe the range of adjustment for the belt tensioners is too small. It should be impossible for the motors to apply enough force to get the drive pulley to skip on the belt teeth.
Post a picture of the printer showing the XY belts from above, and maybe a few close-ups of the idler pulleys, motor mounts, and belt tensioners.
If you manually move the extruder carriage around, does the belt tension remain constant?

It does now, there were "catches" in it before, but I refactored one of my carriage plates (what are those called anyway?) and found a binding idler, then re-tensioned the whole lot and it is the same in all similar directions (diagonals are obviously easier to move than the straight lines.)

I dropped the speed and the especially the jerk and acceleration and things are reliable, just not as fast as I would like. I also changed how I secure the belts to the end effector. Initially I used the same clamp topology on each end, but that meant zip tying smooth-to-smooth on half of them. I think those slipped, so I created a set that were 3mm "shorter" so that I could run the belts through the other way and zip tie them tooth-to-tooth for a more secure connection. The combination of all those things smoothed out the motion and eliminated what looked like "pushing" a belt on one idler when going a certain direction.

I can probably speed it up now, but I need to get some stuff out, so I'll wait until I refactor the carriage sliders and widen the machine 100mm to change those values.

DLC]]> dlc60 CoreXY Machines Thu, 02 Jul 2020 23:03:09 -0400 https://reprap.org/forum/read.php?397,873704,874110#msg-874110 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,874110#msg-874110 Post a picture of the printer showing the XY belts from above, and maybe a few close-ups of the idler pulleys, motor mounts, and belt tensioners.
If you manually move the extruder carriage around, does the belt tension remain constant?]]> the_digital_dentist CoreXY Machines Mon, 22 Jun 2020 22:14:46 -0400 https://reprap.org/forum/read.php?397,873704,874109#msg-874109 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,874109#msg-874109
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the_digital_dentist
"Tight, but not too tight"- if they can slip on a drive pulley, the belts are definitely too loose. Usually, in a corexy printer, if the belts are so loose they slip on the drive pulleys, there's a problem with the belt positioning relative to the X and Y axis guide rails or linear guides. Be sure the pulleys are positioned so that the belts are parallel to the guide rails. When they are positioned properly the belt tension won't change when you move the extruder carriage around from one place to another.

You don't have to be an ME. Just use what you know- thin things flex, thick things don't- and start from there. Pull on the belts, see what flexes, and fix those things first.

Makes sense. I note on this unit that the belts move differently in one direction than the other on the idlers, looks kind of like they are being pushed rather than pulled. I take it from what you are saying that means that one of the belts is tighter than the other so I need to balance.

As for the "if it bends, make it thicker" mantra. Totally makes sense. :)

BTW, at my slower speeds, all the models are working. I will look into the belts and bending next.

Thanks all,
DLC]]> dlc60 CoreXY Machines Mon, 22 Jun 2020 21:22:42 -0400 https://reprap.org/forum/read.php?397,873704,874103#msg-874103 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,874103#msg-874103
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the_digital_dentist
What does it mean that "overpowers the belt" and it slips? Is the belt slipping on the drive pulley or is the motor slipping - i.e. missing steps?
Neither of those should happen, especially not at such a low speed. Are the motor and pulley mounts solid? Adequate tension on the belts?
Excessive jerk speed or acceleration? High voltage (12V) motors? Low power supply voltage (12V)?

I have 64 oz-in motors (relatively small, low torque motors) in XY and have no problems with layer shifts or anything slipping and can drive the mechanism at over 200 mm/sec even with acceleration set to 10k.

"Overpower" = The motor can drive it but the belt can't move that fast so the motor pulley skips over a few belt cogs.
The belt is about as tight as I can get them
The belts are very parallel. The mounts are pretty solid for the motors and pulleys.
The idlers are simple bearings and I think they are all turning freely, but I can't see a few of them.
I might try lowering the accel and see if it skips then. It is currently set at 9000 max.
PSU voltage is 12V with an overkill of 40A. From when I had a 12V hotbed, which is now 120V.]]> ruggb CoreXY Machines Mon, 22 Jun 2020 16:37:20 -0400 https://reprap.org/forum/read.php?397,873704,874101#msg-874101 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,874101#msg-874101
You don't have to be an ME. Just use what you know- thin things flex, thick things don't- and start from there. Pull on the belts, see what flexes, and fix those things first.]]> the_digital_dentist CoreXY Machines Mon, 22 Jun 2020 15:43:46 -0400 https://reprap.org/forum/read.php?397,873704,874098#msg-874098 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,874098#msg-874098
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the_digital_dentist
What does it mean that "overpowers the belt" and it slips? Is the belt slipping on the drive pulley or is the motor slipping - i.e. missing steps?
Neither of those should happen, especially not at such a low speed. Are the motor and pulley mounts solid? Adequate tension on the belts?
Excessive jerk speed or acceleration? High voltage (12V) motors? Low power supply voltage (12V)?

I have 64 oz-in motors (relatively small, low torque motors) in XY and have no problems with layer shifts or anything slipping and can drive the mechanism at over 200 mm/sec even with acceleration set to 10k.

I feel the same way, I should be able to go faster. In fact, I was running at 60mm/s using PETG initially. However, I am not an ME and I can probably improve my design to make the idler mounts more robust (that is my plan). So it is possible that my current hardware wore out(?) and I need to beef it up for reliability - that is nearly a given I should say...
There are holes in my knowledge though. How tight should the belts be? At what point am I adding friction without adding robustness?

DLC]]> dlc60 CoreXY Machines Mon, 22 Jun 2020 14:07:13 -0400 https://reprap.org/forum/read.php?397,873704,874089#msg-874089 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,874089#msg-874089 Neither of those should happen, especially not at such a low speed. Are the motor and pulley mounts solid? Adequate tension on the belts?
Excessive jerk speed or acceleration? High voltage (12V) motors? Low power supply voltage (12V)?

I have 64 oz-in motors (relatively small, low torque motors) in XY and have no problems with layer shifts or anything slipping and can drive the mechanism at over 200 mm/sec even with acceleration set to 10k.]]> the_digital_dentist CoreXY Machines Mon, 22 Jun 2020 12:14:29 -0400 https://reprap.org/forum/read.php?397,873704,874087#msg-874087 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,874087#msg-874087 Manual X or Y movement feels real tight because I am moving 2 motors and fighting magnetism.
Moving on a diagonal is expectedly about 1/2 that tight feeling since only 1 motor is moving.
Others have indicated being able to print at much higher speeds, but I am puzzled as to why.
However, If I want a great print, 60 is too fast.]]> ruggb CoreXY Machines Mon, 22 Jun 2020 11:54:45 -0400 https://reprap.org/forum/read.php?397,873704,874071#msg-874071 Re: Intermittant diagonal layer shift, how to diagnose? https://reprap.org/forum/read.php?397,873704,874071#msg-874071 Swapped ports for both X and Y - no effect
Swapped X and Y steppers (changed the direction of the shift, and found one stepper that was weak and replaced it - didn't fix the problem)
Raised the current to 1.2 Amp (no effect), dropped it to .4 Amp(too low to run at all)
Changed acceleration, Jerk and even Stealth chop on all steppers - no effect.
Corrected bed plate level, then re-leveled the hot bed - no effect.
Oiled the linear bearings and the lead screws - no effect
Replaced the belts - nada
Replaced toothed idlers with smooth ones - runs quieter, but still shifts.
The X/Y carriage moves very smoothy in all directions and feels the same for all movements. In general I think that I have made the whole printer better, but it still will not print without the layer shift.

So, finally, and perhaps I should have started here, I slowed everything down by half. And I got one of the models that had shifted before to print fully. Not the biggest one, but a middle large model. Dropping my acceleration and jerk down to 1/4 and 1/3 respectively, did nothing, but dropping the speed down seemed to help. Again though, the first two weeks of this printer's life, it worked great at 60mm/s. Then it didn't and it didn't at 80mm/s (base speed), but at 40mm/s and 80mm/s travel speeds it seems to have started to work. Not optimal, but I can work with it. As long as it stays reliable! We will see after I do a few more prints.

DLC]]> dlc60 CoreXY Machines Mon, 22 Jun 2020 00:01:45 -0400