Sunday, November 28, 2010

Fixing the Extruder

It looks like it might be possible to salvage my current extruder. I have successfully managed to clean out the brass nozzle by heating it up with a butane torch and pushing the stuck filament through with a drill. It's currently going through a final cleaning by spending the night in a glass full of acetone.


The PTFE insulator was a bit tougher. Due to my earlier problems with the hot-end, it is well glued into the extruder base and it is half-full of PLA that followed the nozzle down as it was pushed out. I managed to get this clear by screwing the nozzle back in as far as it would go then heating it with the torch, then screwing it in some more. This pushed the excess into the nozzle and I could pull it all out with the nozzle.


The nozzle appears to fit still, so I'm not sure why it decided to drop out during the print process, unless the PTFE deformed. I plan to wrap the nozzle in a few layers of PTFE tape and screw it back in, then re-build the whole extruder again. But first, I need a new thermistor, it got destroyed whilst trying to clean the nozzle up. I'll check Fry's tomorrow or place an order with Digikey.


However, I doubt the extruder will last much longer after it is rebuilt so a complete new extruder is on order from Mendel-Parts with the PEEK style nozzle. However, judging by the latest update message from Camiel on his site, I doubt I'll see it before February. Hopefully his assistant is alright, it sounds like they had quite a week!


I also plan on building the brass block style heater instead of the wound wire version. It will give me something to do while I can't print. It's also a great excuse to buy a drill-press. I found that the kapton tape on my current extruder would melt gunk into the objects that I was printing.


I'm wondering if this is an indication the extruder was getting too hot? When I rebuild it I'll put the thermistor slightly further up the nozzle, rather than close to the tip.


Fingers crossed I can at least print something for the next few weeks, otherwise I'll be writing applications or playing with CAD packages.

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