Occasionally, while printing, my y axis will slip and the layer will, from that point forward, be shifted, ruining the print.
What might be the causes of an axis slipping? I have tried cooling the motor which seemed to have been getting warm, and the belts are not too tight.
This does not happen with every print, and seems to be an intermittent problem.
My printer is a MendelMax RepRap, and the y axis is my moving bed.
(source: all3dp.com)
Your printer is skipping steps in the y-direction. This can have several causes. Take a look into Shifted layer guide on RapRap.org which lists 29 possible problems that can cause this issue and how to fix them.
First items of the list:
When I was dealing with this issue on my RepRap I had to increase current to the particular driver.
In my experience, the most common reason for positional offset during printing, is the motor skipping steps due to physical impact.
Your stepper motors do not give positional feedback to your printer. So, if you forcefully move your motor during print, then the printer will not notice, and simply pretend it never happened.
In particular, the motor could skip steps if:
Smaller collisions and nozzle drag at high speed (e.g. during travel) could also cause this problem, since the strength of stepper motors is reduced at high speeds.
The current to your motor driver could be set either too high or too low. If it's set too low then the torque might not be sufficient and the motor will skip steps. If it's set too high then the driver might overheat and occasionally shut down to protect itself.
Another option is that the printing speeds (or jerk/acceleration settings) are too high. I would start by reducing the travel speed (which presumably is higher than your printing speed) and see if that makes a difference.
The motor getting warm is normal and will not cause these issues.
From what I've experienced, there could be three potential reasons.
The latter worked best for me. I tried running MakerBot Desktop on my Dual Replicator 1, but ran into the same exact issue as you. In fact, I encountered this issue around firmware 5.0 on the Replicator as well (7.? is the latest). Finally I switched back to using MakerWare 2.4.? and everything worked fine.
Given the last few questions you have I am going to say that you have too much mass.
F = m * a. If you are trying to move a heavy plate, you will need to reduce the Jerk setting. As well as maximum acceleration.
Post your firmware settings for more advice.
Also just for completion, sometimes the Pololus overheat, that can cause it too. As well as a loose belt.
I fixed this problem on our MakerBot replicator yesterday. The extruder got dislodge on a print some time ago and even after re-attaching it, subsequent prints often shifted sideways on the bed unpredictably. I was skeptical that a firmware update was responsible, so I took a look at the carriage.
The carriage that the extruder attaches to has a belt that moves it from side to side. On that belt is a plastic clip about 2” long that is supposed to be attached to the extruder (actually, not the extruder itself, but the device the extruder attaches to). It had become dislodged and so the sideways motion was entirely relying on friction from the belt which would inevitably slip. Once I got the belt clipped onto the carriage properly, I was back in business.
Make sure your controller board/electronics board etc is as cool as possible - if not the axis may jump - that's what happened with me - after adding additional fans over the Ramps/Adruino - I did not have the problem again (so far)
I had a repeatable problem where my prints were shifting to the side after about 5mm. This was down to a loose z-axis guide rail that would come out of its end support about 5mm into the print, but appeared secure when the bed was set to its initial position. (My print head moves down). There was a grub screw hidden below a panel at the base of my printer.
I'm not familiar with the build of the MendelMax so this may be different for you.
I had the same issue. the only thing that helped me was settings.. uneven surface of layers caused collisions with the nozzle. I adjusted the flow by calibrating my steppers.. also the type of infill pattern you use can cause nozzle collisions.
I have some suggestions that might solve your problem
Try to use belt tensioner which is suitable from your printer.(You'll probably find one on Thingiverse)
The belt has teeth but your bearing which slides your belt does not. So try a bearing cover that has teeth. That will prevent slipping of the belt.
Most importantly lower your acceleration constant. This has a lot to do with missing steps from the motor.
Decreasing the print speed can help as well.
My Y axis runs on a channel and I believe there was some grit or metal flakes in the channel left over from manufacturing. The wheels in the channel got stuck on the debris and caused the belt to slip. It made a horrible grinding noise when this happened.
So I blew out the channel with pressurized air and tested all the wheels.
I'll update if necessary as I test my fix with longer (taller) prints.
Update
Actually, the print had messed up g-code. The gcode file was corrupted.
One possibility is that after some time, your bed's sliding rods become sticky (where printer but not yourself notice). Turn printer's power off, spray windex on rods and bearings, slide the bed forth and back until it becomes slippery, wipe any excess around, turn power back on. reconnect printer and send it to home xyz coordinates since you moved bed, messing up its xyz memory.
