Heat creep ?

bojan

After 10 years of good service, I encountered the problem with filament clogging the teflon tube near heat-break area. 

Because all worked more/less without problems for a long time, I am puzzled this problem surfaced now.. obviously some setting was too close to wrong value and possibly change of the environmental temperature tipped the scale in wrong direction..

Printer is DIY, with MK-8 print head (one extruder), and I am using ABS (bed 100°C, hot end at 240°C).

Is there some setting in EEPROM that can help mitigating this problem?

Thank you in advance  for any reply/suggestion!

Bojan

Repetier

If filament goes up over heat break it is not working as supposed. Reasons are cooling of heatbreak not sufficient or filament temperature too high. Sometimes it is also granular stuff in filament blocking the nozzle so all goes the other way up instead of through the nozzle.

bojan

Repetier said:

If filament goes up over heat break it is not working as supposed. Reasons are cooling of heatbreak not sufficient or filament temperature too high. Sometimes it is also granular stuff in filament blocking the nozzle so all goes the other way up instead of through the nozzle.

Thank you for the reply.

Yes, I am now suspecting filament, but not 100% sure because I tried two new reels, and both misbehave.
Actually, the most puzzling thing was, after trying this and that, it worked OK for couple of hours, and I thought the problem wassolved, but it was back the next day when I continued (without changing anything in settings !)

When I tried to manually push the filament through, the resistance is not even, so it does look like it could be the granular stuff you are mentioning...

Repetier

Not even can also happen when you push uneven and it takes some time to heat new filament. The throughput is limited by heating power. Granular stuff is especially an issue with small nozzles and special filament with glitter or other additions.

Waht I forgot is it can also be that your tubing has moved a bit in the Extruder. Not sure about the details but when there starts a gap near heatbreak movement gets harder and can require more force. Also check if extruder gear has too much debris preventing best grip so it starts to not have enough force.