Y-Axis is fine and then offsets several layers and then is fine again.

I can't seem to figure this one out. The belt is snug (not loose and doesn't seem too tight) and bed appears to move smoothly when hot.

Been experiencing this the last couple of days. I let this go for about an 45 minutes last night before I went to sleep. It looked like it was going to succeed after making minor adjustments to the belt and anchoring the bed's wires off to the side in case it was getting caught on the Y stepper.



Any thoughts? I was shocked to see it actually ended up recovering. This is the Ocarina from Thingiverse.

Travel speed was at 100mm/s and print quality was 50mm/s with .15mm layers.

Here is my printer: [www.amazon.com]

EDIT: Was just talking to a colleague and wondered if it could be related to the computer. Last night was the first night I had ever sent the job from the computer (Cura) instead of an SD card. However, this isn't the first time my Y-Axis has offset as it did it the night before. This is just the first time the job actually completed because I wasn't there to witness it.

Edited 1 time(s). Last edit at 11/18/2015 01:35PM by TyCobb.

Check your drivers of stepper motors, there is potentiometer maybe you got it to low,
It's possible that drivers are overheating and it makes offsets.
I had same problem and solved it with those two hints.

Thanks Matys, I thought about the stepper getting too hot because they all seem to get pretty hot. It just seems weird that it actually finished fine which made me think heat wasn't an issue.

Do you happen to know where the pot is? I don't recall seeing anything on the board that looked like a pot, but perhaps it is just smaller than I am imagining. Will look when I get home. Hope that's it and I can determine which direction I need to turn it.

Please tell me which drivers you use and which board.
I used 2 pcs of 40x40 fans on the top of drivers to prevent overheating.

I'll have to look when I get home if it is not listed on that amazon link. I'll be home in like 6 hours.

That type of layer shift is frequently caused by operating at the limit of the acceleration/jerk capability of the machine. It most often affects the Y axis in machines where the bed moves in the Y axis because of the relatively large mass of the bed and undercarriage. Try turning down one or both a little. You can test this by printing something that causes a lot of sudden starts, stops and direction changes. Make an object that has some square posts standing up and try to print it, or something with a corrugated wall so the nozzle has to keep changing direction. If the printer doesn't skip on that it shouldn't skip on anything else.

Edited 1 time(s). Last edit at 11/18/2015 04:42PM by the_digital_dentist.

---

Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Ohhh... I wondered about those settings, but they appeared to be set only on the machine and not through the software so I figured I was better safe not touching them. With that said, I always thought a lot of those movements were too fast. Definitely going to see about adjusting those down because I think that has bit me on some support structures before.

The motor is definitely getting too hot. I tried running it last night and it wasn't too long before I could no longer touch it.

Here's a picture of the board:


The board seems to be a Smoothboard as I had to install the drivers for it, but I think it is a customized version of it as it doesn't seem to really match the images or specs on their website (no ethernet, red instead of black, no sd card for configs). From what I have gathered, it sounds like I need to actually compile the firmware and flash it to change any of the settings since it is missing the dedicated sd card for housing the settings. About to download the firmware from the wiki and pop into Visual Studio and poke around.

Here's a picture of the motor. Product code is the company's own and they removed all markings on the actual motor so I am not sure the specifications, but I slapped on the voltmeter and it is being sent of 12.26V (had to detach the motor and just put the volt meter on the plugs. Unfortunately I could not test the amperage because of the connector.

If it runs smoothieware, there are settings for acceleration and "junction deviation" which is roughly equivalent to "jerk". Try turning down acceleration maybe 20% and set the junction deviation to 0.03 or so (I think the default is 0.05).

---

Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

I don't think it's jerk after last night. They were set pretty optimally when I checked them on the printer and began a small print that does it a lot. It was printing good with a lot of jerk motions. Stuff is just getting too hot. I think the little screws on the board in front of each motor port is the pot. If I remember correctly, normally pots increase resistance turning counter-clockwise and believe I need to start tweaking the Y motor.

Even though it appeared to be a smoothie board, the firmware on the reprap wiki did not have any settings for limiting the voltage through code. I believe they are physical pots.

Edited 1 time(s). Last edit at 11/19/2015 02:53PM by TyCobb.

Motor drivers overheating can cause that sort of shifting, too. They get too hot after a while then shut down, causing the print to shift, then the driver cools enough to turn on again and the cycle repeats.

---

Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

That's quite a nice looking board, I wonder what it is. I'd recommend routing as many of those cables away from the top left part of the board (as orientated in the photo) as you can. That's the area by the power connectors and the mosfets that's most prone to overheating and potentially catching fire. The less you have near there the better.

You need to know the type of stepper drivers and the value of the sense resistors in order to set the motor currents appropriately. Although for a first stab you can assume that if the motor is too hot to touch the current is too high. Measure the voltage to the center of the pot and record it for reference, then turn the pot to reduce the voltage.

Thanks for the suggestion James. Will try to tie them away from it.

Tried to adjust the pot last night. Think I just need one or two more prints to get it narrowed down. My misadventure last had that motor getting up to 111ºC yet it still didn't skip a step which utterly shocked me. The X was only getting to 56ºC and when searching on AliExpress for that motor, it looks like it should be 80ºC max.

I believe that board is modified version of this since I had to install the drivers on my computer: [smoothieware.org]