Friday, December 21, 2007

Extruder Barrel #2

I built a new extruder barrel. This time the nozzle can be removed easily. I did a simple test of heating it up and manually pushing HDPE filament through. Worked fairly well. After I got some plastic pushed through the nozzle, I let it cool down and disassembled it. Here's what I found:
These images show the motor end and nozzle end, respectively. On the motor end, there's a small amount of pooling. I'm guessing the gap is due to the shape of the drill bit. The nozzle end has quite a bit more pooling. The gap there is caused by the shape of the acorn nut.

What I'm wondering is, does this create extra resistance for the filament? If so, is there any way to prevent it? My first thought is to fill in the gaps with JB Weld. Maybe even turn the nozzle cavity into a taper.


Vik Olliver said...


Take one of those dremmel bits that looks like a baby lemon juicer and ream out as much as you can right behind the exit hole in the nozzle. It makes a heck of a difference.

While on the sublect, I've got a barrel that reduces to 2.5mm in the middle. That makes no discernible difference to performance.

Merry Xmas!

Vik :v)

RoundSparrow said...

Using a Fluke IR Thermometer I note that the tip of my barrel is a lot colder (28c) than the Teflon barrel (150c). The thermistor reads something like 130c when on the tip.

Like you, I'm probably going to move my thermistor off the tip as difficult to unscrew with the wires.

Steve DeGroof said...

My current configuration, as of yesterday, is a thermistor wrapped in PTFE tape and attached to the barrel using a piece of copper wire.