Strange extruder problem

[ivanhandler]

On my Max (and also just started on my Eris), if I have a long print, say over 2 or 3 hours, the extruder gets jammed and the filament worn down. So when I discover the nozzle is printing with air, I cancer the print, attempt to do a warm pull of the filament out of the hot end, etc. The filament breaks at the point of engagement with the extruder. I pull the tube out of the extruder and pull out the remaining filament with no problem. I will put a new roll on tomorrow and it will start to print right away, (I've been through this several times) so I don't think it is a blockage in the hot end.

The other thing that may be relevant is that I tried printing this octopus from Thingiverse, octo-object-double_sided-low-poly2.stl. I blew it up to maximum size and started printing. This is a really complex print with scads of retractions. In many cases the head jumps from intersections to intersections just printing a single drop. That was the first time this happened and now it feels as if my extruder is cursed.

I'm sure there is a simple way to deal with this, I'm still pretty wet behind the ears.

[Glacian22]

What's your retraction speed set at? If you're too aggressive with it, you can end up grinding away a section of filament during a print with tons of retraction, like the octopus.

[ivanhandler]

I have it at 150. I will take it down to 100 and see what happens. Thanks

[geneb]

Woah, that's insane! Back it off to 45mm/sec at the most. No wonder that poor thing is packing it in after a while.

g.

[ivanhandler]

Thanks much!!

[ivanhandler]

I brought my extruder speed down to 40 mm/s and things appear to be better except that I went to print a large Buddha head and after about 5 hours (when I was asleep), the extruder jammed again. Had to take the bowden out of the extruder and even then the filament wouldn't come out, had to use a pliers to force it out. The filament was ground flat which is why it was so difficult to get it out. Cleaned out the extruder by running a straightened paperclip through to get any material hanging around out. I don't understand how this happened since the retraction speed was low and there were not a lot of retractions happening anyway. There must be other things wrong with my settings though they are pretty standard, speed between 50 and 60 mm/sec, temps: nozzle 210, bed 70, etc. Any ideas or things to check is much appreciated.

It's printing now with no problem, though for how long?

[geneb]

How long are the retracts set to? With the HE280, you want to keep them under 3mm.

g.

[knabo]

I was having a similar problem, i am assuming you are printing with PLA.

It would not be the case with all types or brands, but ultimately I found I was printing at too high a temperature. I did regularly print at 210, now I am printing at 190 and getting better results. Especially at the first layer.

[ivanhandler]

I'm at 5mm. Will take it down, thanks.

[ivanhandler]

I was having a similar problem, i am assuming you are printing with PLA.

It would not be the case with all types or brands, but ultimately I found I was printing at too high a temperature. I did regularly print at 210, now I am printing at 190 and getting better results. Especially at the first layer.

Thanks, I also reduced the temperature, though it varies with the kind of PLA used. I will try to print at the lowest possible temps from now on. I still don't understand how the temperature and retraction settings are responsible for this, but I'm still pretty new to things so I have adjusted my settings accordingly. We'll see how things turn out. I am printing an 8 hour object right now, if it goes to the end, I will feel pretty good about the settings, if not, I will continue to investigate and ask questions.