Print jumps 7mm in Y direction after initial layers

[old man emu]

Have a look at this part way print:

Layer 2.6 labelled.jpg
That's a scan of the object and I didn't get it square on the scanner.


The black lines show the extrusion that was laid down as Layer 7 began to print (Z= 2.6). It was exactly 7mm down the Y-axis from where it should be. X position is correct.

This is the Gcode for the print:

Z-axis LHS plate.gcode

This code printed OK last night, except for a corner lift. The bad print happened twice today. I've just done maintenance on my printer and the belts are tight. Remember that the first 6 layers printed correctly.

Given that the room temperature where I was printing was 36C, could I have an overheat problem in the Y stepper? But the X stepper was operating under the same conditions. Both X and Y steppers were working hard as I was printing linear infill at 45 degrees.

Any ideas as to what gives?

Old Man Emu

[DrLuigi]

Had the same,

Colin told me it could be that my rods arent oiled, that the stepper motors are off as pot meters go,
Uhm and the belts that could be to tight or to losse,

I guess thats it,
Owye i also have a fan now on my makerfarm all the time when its on, a 120mm fan, it didnt do this anymore or not as frequent when i got the fan,

Also perhaps try making the mm/s go slower like 40-45mm/s.

[Roxy]

I never have a jump of 7mm... But I do get a jump of 2 or 3mm if I'm not careful. Do you have your bed mounted on springs? I kind of need that because I need the extra time to react if I load some firmware that goes crazy. The downside is if you push too hard to remove a part, you might leave the bed shifted for the next print. And then part way through the print, it clicks over to where it wants to be and you get that layer jump.

[printbus]

It's interesting that in October you were getting jumps in the X axis and now you're getting them in the Y axis. I'll throw out the same idea I had on the X-axis problem - make sure the belt pulley is tight on motor. It's at least easy to check.

[old man emu]

Everything's tight. I's just come out of the shop from its 10,000 mm extrusion service.

Dr Luigi may have hit on the cause - room temperature too high. Roxy, what is the room temperature you are working at when you get your jumps? I was sitting in 36C without A/C, and 33% humidity.

My steppers were pretty hot, but there were no unusual clicking sounds. That is to say, the steppers were not clicking, which is usual for my printer.

If my belts were loose, or the steppers were missing steps, how do you explain the exact amount of displacement of the Y axis?

Old Man Emu

[Roxy]

Everything's tight. I's just come out of the shop from its 10,000 mm extrusion service.

You should be good for 10,000,000mm of extrusion service. Each 1Kg roll (at 3mm) is about 100 m. So 100 rolls is 10^7 mm.

Dr Luigi may have hit on the cause - room temperature too high. Roxy, what is the room temperature you are working at when you get your jumps? I was sitting in 36C without A/C, and 33% humidity.

My room temperature is usually between 65 F and 75 F. It is more the bed temperature that affects my jumps. The bed gets hot enough to print, but it isn't really up to full temperature until I've been printing for 20 minutes. And then, it is probably a number of things factoring in. The bed and all the mounting hardware is getting warmer. But also, the thing I'm printing is getting higher up off the bed which means any curling up edge presses harder on the nozzle when you go across it. At some point, it is enough of a curl and enough leverage (because it is up above the bed) to click it back to where it wants to normally be. If you don't have a spring mounted bed, this is just an interesting anomaly for you.

[printbus]

When the new motors started being used by MakerFarm, little data was found for them. The manufacturer doesn't do a good job publishing data for every one of their motors.

Any of a number of NEMA17 stepper motors would work fine. I replaced just the extruder motor with a Kysan 1124090 I got from eBay. Kysan appears to be one of the premier brands for stepper motors, a number of people use the 1124090 on repraps, and it met the specs called out in the reprap wiki. When I want to invest more in my April 2014 era printer, I'll order more motors and swap out the rest.

Here, the OP is in troubleshooting mode. Colin continued to empahsize that the motors running hot were not an issue, but some of us haven't been convinced. Most of us have gobs of fans laying around from computers and what not. Experimenting with more airflow on a motor is something that can often be implemented in a few minutes. If testing concludes that the motor temperature is related to the problem, then the decision can be made on formal implementation of the cooling fan as a permanent bandaid or motor replacement.

[gmay3]

I replaced just the extruder motor with a Kysan 1124090 I got from eBay. Kysan appears to be one of the premier brands for stepper motors, a number of people use the 1124090 on repraps, and it met the specs called out in the reprap wiki.

Doing a quick ebay search, do the Kysan steppers you bought from ebay have the Kysan branded sticker on them? There seems to be two, one without this sticker and one with.

[printbus]

Doing a quick ebay search, do the Kysan steppers you bought from ebay have the Kysan branded sticker on them? There seems to be two, one without this sticker and one with.

I bought one from the 3dmakerworld seller. Their picture doesn't show a Kysan sticker, but the motor came with one. Although I do have to chuckle - it looked like a label anyone could have printed and stuck on the motor.

These motors all tend to look the same, but one obvious thing about this one I found impressive is the wire gauge. It's marked #22, compared to the #26 wires on the OEM motors from MakerFarm. Heftier wire should mean less resistance, leading to more power being applied directly to the motor. I'm not sure that difference in the motor specs alone would have justified the increase in wire size for the Kysan.

[old man emu]

I think you blokes have missed something. You are concentrating on the temperature of the Y axis stepper. You forget that at the same time as the Y axis stepper was working flat out, the X axis one was working just as hard, and without error.

The other thing is, if the belt or pulley was loose, then subsequent layers would not be printed accurately on top of the preceding oout of position one.

Old Man Emu