Plastic oozing into threads – is that the end of my insulator?

I don’t know, but I’m about to find out.

I’ve managed to clear out the PTFE insulator pretty well.  I pulled the entire heater out of the extruder, turned up the heat a little, held the barrel lightly in plyers, and unscrewed the PTFE without a problem, and then turned the heat off.  I then used a precision flathead screwdriver to follow the threads, popping/chipping the plastic out as I followed I went.  However, I don’t know to what extent the threads are still intact.  Since the PLA oozed into the threads, I have to think they’re messed up to some extent.

As for the barrel, I used a drill bit with the unsharp end wrapped in a rubber band.  I rotated the bit using the rubber band as a grip to drill out the plastic.  It actually worked really well for clearing out the barrel right to where I can see the barrel entering the nozzle.  The inside is reasonably clean, but I still can’t put a filament into it freely.

I also had to take a precision screwdriver and follow along the threads on the barrel to chip out plastic.  This went reasonably quickly.  Once I was done the nut was able to screw on and off freely.

Now I’m left with a slightly discolored PTFE and a mostly clean barrel.  I’ve got a spare PTFE insulator, but I’m hoping this one is salvageable.  It still has threads and the barrel will screw in nicely.

Rick and Spacexula have suggested I use a torch to heat up the nozzle and let the plastic burn/fall out.  But, this is a trick for another day with proper safety equipment.

Oh, and before I forget, Spacexula suggested keeping a ruined PTFE barrier to slice into insulating washers.  I’m hoping I might be able to re-use the PTFE insulator, but this is certainly my backup plan.

5 Responses to “Plastic oozing into threads – is that the end of my insulator?”

  1. beak90 says:

    I recommend cutting the old PTFE into a very thin wafer to put between the M6 nut and the washer. Its better to use the new PTFE barrel, but you may want to use the old one until you get the temperature right where it won’t ooze up a lot. I highly recommend using a thermocouple to get the right temperature at the top of the barrel.

  2. MakerBlock says:

    :/ I’d happily use a thermocouple – but I’ve read on the Makerbot Operators group they’re pretty inaccurate! At that point, I figured I’d have better luck mounting the thermistor near the top of the barrel.
    But, I tell you what – if I just borked my PTFE, I’m totally chopping it into washers. :)
    Thank you!

  3. beak90 says:

    You don’t have to use a thermocouple for the actual working measurement. Just for testing and calibration. If you buy a nice multimeter (probably 40 bucks) that has a temperature setting and plug for a k-type thermocouple then the thermocouple is extremely accurate. It says ±3% which is about ±3-6 degrees at higher temperatures. Thats accurate enough for this purpose.

    Also, a good way of cleaning out the PTFE is soaking it in acetone overnight which softens it enough to knock it out with a small screwdriver and a hammer. Or you can just drill it out. But if you think it might still have good threads then acetone is the way to go.

  4. MakerBlock says:

    Hmm. The PTFE threads seem good and the barrel seems to go in well. I suppose as long as I have it well compressed with the washer, nut, long bolts, insulator ring it should work reasonably well.

  5. […] Plastic on the threads is not a huge deal, but not trial either – it mostly peeled off in spirals.  Plastic on the nut is not a big deal – I pulled that off with some needle nose pliers.  Plastic inside the barrel can be drilled out using my drill bit and rubber band trick.1 […]