Extruder Stopping, Hot End Not Clogged

[grasshorse]

Hello,

I have just started to have a problem with my Rostock Max. I have been trying to print out an object off the SD card that is 7 inches tall or so. The print quality of the failed prints looks beautiful, but about 3 inches up the printer stops extruding but continues the X, Y, Z movement as if everything is fine. The first thought I had was "oh I got a clogged head" (E3D v5). I reset the printer, reset the computer, changed the filament, extruded 100mm or so, no problem. I ran the print again and the extruder stopped within a 1/4" of the first prints height (X, Y, and Z, movement continued as before). I thought the filament temperature may have been too low which could cause the stepper motor driver to overheat, so I re-sliced the part upping the hot end temperature from 240 to 245. I started the print again without trying to unclog the head, and it has started just fine (it's running now). I know it is not the file, because I have printed it out before, and both parts didn't stop at exactly the same height. There is no ABS dust on the platform, like the machine was trying to extrude but couldn't. Also, there was no divot in the filament like the pinch roller was turning but the filament wasn't moving. So I don't think it is a clogged hot end. I do have a fan blowing on the RAMB0 board trying to keep it cool.

Has anyone heard of the extruder just stopping for some reason at a specific height, or after a length of time? Any ideas are appreciated.

All the best,
Steve

[Tinyhead]

Are you printing in ABS or PLA? Either way, a temp of 140 I'd way too low for either. I'm guessing you've made a typo.

What you're describing is the exact phenomena that happens with the E3D v5. It just plugs and starves of filament, but it's not clogged. Typically this is a PLA-only issue.

To overcome this, I've tried ramping up the speed (almost double) and up the hot end temp a touch. If there are a lot of retractions in the job, it's going to make the problem occur more often.

[grasshorse]

Oops, yes that was a typo. I'll edit the post to change all of the 140s to 240s and 145 to 245.

I have been printing with ABS only. Having not yet mastered ABS, I'm reticent to try different materials. If the print at 245 bombs out I'll up it to 250 and speed it up some.

I have most of the settings around 22mm/sec or 40mm/sec for the less critical movements and 6mm retraction on the hot end. Any of those seem overly cautious?

Thanks!

Steve

[Polygonhell]

FWIW one of my E3D's used to do that, it's not clear to me what the exact mechanism is, but printing hotter usually resolved the issue.
Have you verified the thermistor reading with a thermocouple?
My E3D was reading much higher than actual with the correct thermistor set in the firmware.

[Tinyhead]

Oops, yes that was a typo. I'll edit the post to change all of the 140s to 240s and 145 to 245.

I have been printing with ABS only. Having not yet mastered ABS, I'm reticent to try different materials. If the print at 245 bombs out I'll up it to 250 and speed it up some.

I have most of the settings around 22mm/sec or 40mm/sec for the less critical movements and 6mm retraction on the hot end. Any of those seem overly cautious?

Thanks!

Steve

With the E3D, you could lower the retraction too. You could go from 6 to about 3 or 4mm. Some people go less, but having a long retract length doesn't help on this hot end.

As Polygonhell mentioned about the thermistor, there is actually a setting in the firmware to change the type of thermistor as the E3D uses a different type than the stock hot end. I'm not at home right now, so I can't point out the exact place to set it and I can't remember the two types. You could search the forum if you haven't done it. It might be causing a temperature reading difference for you. Personally I think 245/250 is pretty hot, even for ABS.

[artexmg]

Oops, yes that was a typo. I'll edit the post to change all of the 140s to 240s and 145 to 245.

I have been printing with ABS only. Having not yet mastered ABS, I'm reticent to try different materials. If the print at 245 bombs out I'll up it to 250 and speed it up some.

I have most of the settings around 22mm/sec or 40mm/sec for the less critical movements and 6mm retraction on the hot end. Any of those seem overly cautious?

Thanks!

Steve

With the E3D, you could lower the retraction too. You could go from 6 to about 3 or 4mm. Some people go less, but having a long retract length doesn't help on this hot end.

As Polygonhell mentioned about the thermistor, there is actually a setting in the firmware to change the type of thermistor as the E3D uses a different type than the stock hot end. I'm not at home right now, so I can't point out the exact place to set it and I can't remember the two types. You could search the forum if you haven't done it. It might be causing a temperature reading difference for you. Personally I think 245/250 is pretty hot, even for ABS.

Yeah, I would go first the obvious: temperature and retraction.

Temperature (as poligonhell said), verify that you are having the temperature that your termistor is reading.
Retraction: for me (and I'd seen this recommended by mhackney somewhere), 2mm retraction, at low speed - 15 - 25 mm/s - made the difference. Actually, if I had to guess, I would say that this is the most probably culprit, as per what you mentioned that there is not clogging. See, when you retract too fast, too long distance (6mm or more) a molten polymer, it tends to behave like solid, then it could make prevent the filament to get back to the nozzle. Not sure if this is your case, but I would try lowering retraction to this levels.

Not sure this is necessary as you are working with ABS, but if everything Temperature and retraction does not work, then I would try shortening the borelength (http://forum.seemecnc.com/viewtopic.php ... &start=760). For me, it made my E3D to be very reliable, working with no problems in +12 hours prints (before, I cannot go more than 2 hours!). Of course, it was PLA, not ABS. Also, the process helps to fix any possible imperfection inside the nozzle, making it extrudes better.

I hope it helps, I know how frustrating is having very nice prints that just do not finish!
Cheers.