3D Printing Help Needed: Losing Z-axis Steps in Enclosure (Prints fine outside Enclosure)

[BigMacDaddy]

Ok, so I finally have some time to revisit a couple of clone MK3s+ printers that have been giving me issues for a couple of months (since I got them).

I am having the same issue on two printers -- Basically these print fine outside of the enclosure but lose Z-axis steps when I try to print with them in an enclosure. After a few inches of print (seemingly random layer / height) the print head starts grinding into the print since it has not risen sufficiently. I also thought I was having an issue where the printer seemed to lose track of the z-axis calibration (and was grinding into the bed when I started a new print). However, now that I am looking at the printers with fresh eyes I actually think that all the grinding into the print unscrewed the heatbreak from the heatsink a little which dropped the hotend enough to hit the bed. I actually stopped messing with these since they were also suddenly printing with tons of ringing / layer shifts. Turns out that they hotend was totally loose in the heatsink so at least that problem is fixed.

I was assuming that the stepper drivers were overheating but I just swapped boards, since I was replacing bearings on another unit, and the problem persists even with a new main board (the replacement board came from an original Prusa that has been working fine in an enclosure for several months).

So the question is -- if it is not the driver / controller board, what would be overheating to cause z-axis step loss (or is there anything else that could cause this)?

I am assuming that it might be the stepper motors and thought I could try putting heatsinks on them or replace them.

One other option I am kind of considering (although seems less likely to fix this) is to increase amps sent to the z-axis motors << assumes the issue is not overheating but them not having enough power in an enclosure to make the needed steps (not sure why that would happen).

Thank you in advance if anyone has advice.

 

[Bravo52]

It's odd that it only skips in the enclosure. I've never had this issue and the only other time I've heard of it was due to a bad stepper motor. If you have a Mk3 clone, you have two lead screws that are "supposed" to be in sink to raise and lower the z axis. If one of those is out of sync, then it will cause problems.

As you correctly point out, it could be overheating the motor, but that doesn't seem like it should be an issue. You could try replacing the stepper motors (both) and see if that cures the problem. The other option, as you say, is to increase the voltage going to the motor. Have you tried to see what each of the motors are pulling during operation?

You might try realigning the lead screws for the z axis, or if you have a belt drive, tightening the belt. That should be and issue "just in an enclosure" but it's easy to do and cost nothing. I assuming there is no obstruction or obvious binding on the axis so it leads me to believe it's likely a weak stepper motor.

 

[BigMacDaddy]

It's odd that it only skips in the enclosure. I've never had this issue and the only other time I've heard of it was due to a bad stepper motor. If you have a Mk3 clone, you have two lead screws that are "supposed" to be in sink to raise and lower the z axis. If one of those is out of sync, then it will cause problems.

As you correctly point out, it could be overheating the motor, but that doesn't seem like it should be an issue. You could try replacing the stepper motors (both) and see if that cures the problem. The other option, as you say, is to increase the voltage going to the motor. Have you tried to see what each of the motors are pulling during operation?

You might try realigning the lead screws for the z axis, or if you have a belt drive, tightening the belt. That should be and issue "just in an enclosure" but it's easy to do and cost nothing. I assuming there is no obstruction or obvious binding on the axis so it leads me to believe it's likely a weak stepper motor.

Thanks -- yes, it is super strange. I could imagine that the drivers were overheating (they get little heatsinks in these clones and do not in the Prusa so I assume they are heat sensitive -- and this is why I assumed it was an issue with the main board). I suppose it is good news that it is not the main board since those are expensive but the dilemma persists.

Right now I am running them with enclosure doors open to test if they are truly reliable like this (partly to test if the ABS prints peal up -- knock wood, so far so good -- very good adhesion on these textures PEI plates).


The 40mm heatsinks are super cheap so I suppose I will purchase some of them to see if it helps.

 

[Bravo52]

Could it be something as simple as the filament getting bound up? From your it appears the filament is above the cabinet and travels a long way to the extruder. Might be worthwhile checking/adjusting the tension of the gears in the extruder.

 

[BigMacDaddy]

Could it be something as simple as the filament getting bound up? From your it appears the filament is above the cabinet and travels a long way to the extruder. Might be worthwhile checking/adjusting the tension of the gears in the extruder.

It is possible -- and/or possible that the resistance is putting extra strain on stepper motors and this is causing the overheating or something.

The filament does run a good distance through PTFE tube to get to the compartment the printers are in right now. There is not too much resistance but there is some. However, I also had this issue when it was in the top bay right below the filament -- still a short distance through PTFE tube so it could still be an issue. I did consider this earlier and thought about putting a filament spool holder inside the compartment with the printers to see if that fixes things.

I have run a couple of successful prints now with the doors open so kind of still scratching my head.

 

[cwbullet]

If you are still having this problem tomorrow, I will try to help. I just got back from a launch and can't focus on this right now. I have built and set up four Mk3S clones (two for me). What brand did you buy?

 

[BigMacDaddy]

If you are still having this problem tomorrow, I will try to help. I just got back from a launch and can't focus on this right now. I have built and set up four Mk3S clones (two for me). What brand did you buy?

Thanks Chuck. Fysetc.

 

[cwbullet]

Thanks Chuck. Fysetc.

Not bad. Not Triangle labs, but not bad.

 

[BigMacDaddy]

Not bad. Not Triangle labs, but not bad.

I upgraded the hotends to Triangle Labs CHC hotends.

I have been printing with the enclosure doors open with these two printers of the last couple of days. No issues.

I am sure that as soon as I close the enclosure door that the same issue will come back.

Anything else besides stepper motors overheating that you can think of? Should I try increasing the amps to stepper motors (to overcome any resistance) or decreasing amps (to lower temperature)?

Other than replacing the stepper motors or trying heatsinks (or more active cooling), anything I can try to make the Z-axis not lose steps in hot ABS printing enclosure?

Thanks.

 

[cwbullet]

I upgraded the hotends to Triangle Labs CHC hotends.

I have been printing with the enclosure doors open with these two printers of the last couple of days. No issues.

I am sure that as soon as I close the enclosure door that the same issue will come back.

Anything else besides stepper motors overheating that you can think of? Should I try increasing the amps to stepper motors (to overcome any resistance) or decreasing amps (to lower temperature)?

Other than replacing the stepper motors or trying heatsinks (or more active cooling), anything I can try to make the Z-axis not lose steps in hot ABS printing enclosure?

Thanks.

Do you think ti is heat creep? Are the hotends PTFE lined or all metal?

 

[BigMacDaddy]

Do you think ti is heat creep? Are the hotends PTFE lined or all metal?

It is just the Z-axis motors that have issues so I think just ambient temperature is the issue.

I actually went with Titanium dual metal heatbreaks as an upgrade to the CHC hotends. They do have a PTFE tube so not all metal.

 

[Charles_McG]

My CR10S (50mm, dual Z steppers) used to bind until I put a belt across the top to sync the steppers. They'd drift apart (somehow), effectively making the x gantry tilt - it didn't take much until it would bind, too.

It doesn't sound like that's your problem, though.

 

[gsitexas]

Rob,

I received my F-104 kit today and I'm very impressed with the kit and the parts provided, great kit!!!

I did notice the printed parts have ever so slight linear lines or "stripes" on the surface of the parts along the Z-axis print direction. This "vertical striping" is not random, it appears to be very periodic and consistent layer-to-layer.

I only mention it because I thought it might be somehow related to the Z-axis step loss issue you are having when the printers are enclosed and my hope is this info will resonate with someone who has encountered and resolved this issue already.

Perhaps an ambient heating issue is causing slight binding of the filament either inside the PTFE Bowden Tube or perhaps it is causing extruder gear binding due to gear expansion.

Is this problem happening with both your MK3S and the Fysetc clones? If it's only happening with the clones, I would focus efforts on what is different on the clone machines that might be negatively impacted by the high ambient temp used to print ABS.

Maybe try printing PLA with the problematic machine to see if the problem remains when using lower print temps in the enclosure?

Hope this might in some way help you troubleshoot and resolve this perplexing issue quickly!

Best regards,

Keith

 

[BigMacDaddy]

Rob,

I received my F-104 kit today and I'm very impressed with the kit and the parts provided, great kit!!!

I did notice the printed parts have ever so slight linear lines or "stripes" on the surface of the parts along the Z-axis print direction. This "vertical striping" is not random, it appears to be very periodic and consistent layer-to-layer.

I only mention it because I thought it might be somehow related to the Z-axis step loss issue you are having when the printers are enclosed and my hope is this info will resonate with someone who has encountered and resolved this issue already.

Perhaps an ambient heating issue is causing slight binding of the filament either inside the PTFE Bowden Tube or perhaps it is causing extruder gear binding due to gear expansion.

Is this problem happening with both your MK3S and the Fysetc clones? If it's only happening with the clones, I would focus efforts on what is different on the clone machines that might be negatively impacted by the high ambient temp used to print ABS.

Maybe try printing PLA with the problematic machine to see if the problem remains when using lower print temps in the enclosure?

Hope this might in some way help you troubleshoot and resolve this perplexing issue quickly!

Best regards,

Keith

Thanks Keith -- sorry about the banding on some parts. Those parts were printed on different printers than these (I have only just started printing parts on these printers again -- I could not get them to run at all and then they had terrible banding till I retightened the hotends).

These are direct drive printers so there are no Bowden tubes (the PTFE tubes are just to carry filament from storage bins to the printer enclosure boxes). However, the possibility that the extruder gears are impacted by the heat is interesting. I could play with the tightness (or compare it to the other printers). This issue is only happening on 2 clones, not the other 2 or the 2 Prusa's I have.

Good idea to print PLA in the enclosure to see if the problem persists.

Send me a PM with a picture of the parts. There is always a little bit of layering on the z-axis but there should not be much banding. However, I did have a printer that I replaced bearings on since a bearing went bad recently (although I do not think I was printing these parts on that printer). Anyway, send me a picture since I want to be sure that there is not an issue with the parts you got. I will also re-check that the hotends are all tight.

 

[OverTheTop]

Overheating of the stepper driver chips and them going into thermal shutdown was my first thought on this. You could verify by running the motors at higher current and the problem should be exacerbated very quickly. If the problem shows up after a much longer time constant (tens of minutes rather than minutes) then it is possibly related to heat in the motors.

Another problem can be connectors on steppers. I have seen this on a drive we really hammer in one of our spectrometers. The vibration causes fretting of the contacts in the connector. Resistance goes up and connector housing goes charcoal color. We drive them hard (current regulated with 24v on a 1.9v stepper). In the 3D printers with their electronics it would manifest as reduced current and losing steps. Possible cures could be get motors with wires attached rather than connectors.

 

[beeblebrox]

Swap stepper drivers with Z and X, or Z and Y, see if the problem follows the driver chip.

3D print a duct system to bring cool air from outside to the intake of the cpu cooling fan. I have heard of stepper drivers overheating. I was getting layer shifts on my T-Rex. A friend had the same issue with his Rostok. I added three more cooling fans and that problem seemed to go away...

 

[BigMacDaddy]

Overheating of the stepper driver chips and them going into thermal shutdown was my first thought on this. You could verify by running the motors at higher current and the problem should be exacerbated very quickly. If the problem shows up after a much longer time constant (tens of minutes rather than minutes) then it is possibly related to heat in the motors.

Another problem can be connectors on steppers. I have seen this on a drive we really hammer in one of our spectrometers. The vibration causes fretting of the contacts in the connector. Resistance goes up and connector housing goes charcoal color. We drive them hard (current regulated with 24v on a 1.9v stepper). In the 3D printers with their electronics it would manifest as reduced current and losing steps. Possible cures could be get motors with wires attached rather than connectors.

Yeah stepper drivers was my first thought as well but I swapped main boards with a working unit and the problem persisted in the unit despite the new board (and no problem in the other unit that got this board printing in an enclosure).

Bad connections could be a possibility. This only happens with the enclosure door closed so should be related to heat. However, this conversation is making me realize that a number of parts could be affected by heat due to expansion.

 

[BigMacDaddy]

Swap stepper drivers with Z and X, or Z and Y, see if the problem follows the driver chip.

3D print a duct system to bring cool air from outside to the intake of the cpu cooling fan. I have heard of stepper drivers overheating. I was getting layer shifts on my T-Rex. A friend had the same issue with his Rostok. I added three more cooling fans and that problem seemed to go away...

Unfortunately on these models that lead screw and the motor are one part. I could swap with another printer which is a possibility to isolate that as a cause. Thanks.

 

[BigMacDaddy]

Parts are printing quite well on these printers with the doors open -- even the TB-3 cones which were notorious for losing adhesion on inner circles on my previous build plates. Maybe solution is to just leave doors open and stop worrying about it. Heck it is winter so just heats the house a bit

 

[cwbullet]

It is just the Z-axis motors that have issues so I think just ambient temperature is the issue.

I actually went with Titanium dual metal heatbreaks as an upgrade to the CHC hotends. They do have a PTFE tube so not all metal.

Just so you know, it can still be all metal with a piece of PTFE as long as the PFTE does not go into the heatblock or nozzle.