My 3D printing has been going great recently, having printed a few very nice items, including this rather fetching phoenix in ‘transparent’ PLA.
Printing this item would take around eight hours but a couple of times, after about a couple of hours, it stopped printing. The head kept moving but no filament was coming out of the nozzle.
Suspecting a blockage, I removed the extruder mechanism, disassembled it and remove a few bits of plastic, clearing the blockage.
I did a bit of googling and discovered a phenomenon called Heat Creep.
On a long print, heat from the Hot End rises into the gears of the extruder, softening the filament, part of which may flake off and jam the mechanism.This is known as Heat Creep.
My printer is enclosed which helps greatly in keeping the noise down but after a few hours of continuous printing can get rather hot.
Anatomy of the Extruder
A. The filament is fed into the top of the unit
B. Meshing gears pull the filament through
C. Heatsink prevents heat from the Hot End (D) softening the filament before the nozzle
D. The Hot End which melts the plastic filament on its way to the nozzle.
To test if I was suffering from the Heat Creep, I removed the top of the enclosure and tried printing the phoenix again – success.
So what was I going to do?
Some filament types require a stable warm environment whereas PLA softens at around 60C. I don’t want to keep removing and replacing the lid so I’ve installed a fan into the upper section of the enclosure to suck out the hot air when printing PLA.
So far this seems to be working.
That was until …
The printing head crashed into the bed. Not sure why but it happened.
I reset everything but the machine wouldn’t print. It went through the motions but no filament was being extruded.
Fearing another blockage, I cleared the extruder (again) but no good.
I bought some new extruder gears from Amazon which arrived the next day. I removed the extruder and fitted the new gears – eventually.
I say eventually as one part had been put together incorrectly so I had to disassemble that bit and put it right before I could fit it into the extruder assembly.
With it all back together, I tried again. The machine went through the motions but the best I could manage was a very poor quality extrusion which was next to useless.
Here’s a photo of the meshing gears that grab hold of the filament and push it though to the heater and nozzle (the Hot End).
There is a screw (not shown) that pushes the lower part towards the larger ring trapping the filament with just the right amount of grip. This adjustment is super critical and it’s taken me much time and hair pulling to get it just right so that the machine will print properly.
I am in ht process of printing a model which will take many hours (with a fair few colour changes) so only time will tell if I’ve got my adjustment correct – so far so good so fingers crossed.
AGHHH !
… and just as I’m finishing writing this, the yellow filament I’m using for the majority of the model is about to run out (I’ve wasted a lot on the failed prints). I’ve ordered a roll for delivery today.
