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Illumine 1277747983|%e %b %Y, %H:%M %Z|agohover
We've had problems with our PTFE insulators swelling and allowing ABS to leak out. We are considering using a toaster oven to try and "bake" them back down to their original size.
Will this work at all? More importantly, are we putting ourselves at risk for hazardous fumes? I've read that heating PTFE to 350C or above can cause polymer fume fever.
dataman 1277750254|%e %b %Y, %H:%M %Z|agohover
We just got out plastistruder working from our initial build. Not sure if it's related, but turns out we were suffering from a constipated PTFE. Had to bore it out with a 1/8" drill bit. I've seen that some people are using a pipe clamp around the base near the washer. Perhaps that's to stop the bloat?
clothbot 1277750704|%e %b %Y, %H:%M %Z|agohover
The pipe clamp does double-duty as bloat-preventer and as a heat-sink for the PTFE plastic.
passim 1277751130|%e %b %Y, %H:%M %Z|agohover
dataman -
hose clamp will help stop the bloat and does indeed act as a heat sink like clothbot mentioned.
http://www.flickr.com/photos/botbuilder/4591058367/
copper plumbing part works well too, even without a clamp:
http://www.flickr.com/photos/jabella/4612505571/in/set-72157623829152993/
Illumine 1277752001|%e %b %Y, %H:%M %Z|agohover
Sadly, we don't have any hose clamps, but we're hoping to rectify that soon.
Well, I went ahead and toasted it - 450F for 20 minutes. The results are as follows:
I'll update later on how well it prints, whether it immediately bloats again, etc.
Illumine 1277758760|%e %b %Y, %H:%M %Z|agohover
alas; it leaked again
dataman 1277767657|%e %b %Y, %H:%M %Z|agohover
Oh frack! I'm adding a hose clamp to mine tonight!
Uhm…
M16 Nut BETWEEN the PTFE and the Washer (Nozel, Barrel, Washer, Nut, PTFE)?
or in front of Washer? (Nozel, Barrel, Nut, Washer, PTFE)?
dazeddnc 1277770376|%e %b %Y, %H:%M %Z|agohover
Are you asking how it should be done or are you trying to find out how his is set up? If you're asking how it should be done… I went with a nozzle, barrel, washer, nut, PTFE stackup.
I think the purpose of the nut is to keep the the filament from pushing the barrel out of the PTFE. Once it gets hot, the threads in the PTFE will strip out much easier. The nut is more capable of transferring the filament load down to the washer, which in turn transfers it to the retainer ring.
If you switch the washer and nut, the nut will be trying to pull the barrel out of the PTFE (especially if you make it wrenched-on tight, finger tight might not apply enough force to be noticeable). Once you start extruding, the nut can't transfer filament load to the washer.
passim 1277776313|%e %b %Y, %H:%M %Z|agohover
Yes, the nut should be ABOVE the big washer. Once you nuke a PTFE you can use slices of it as washers between the nut and the big washer, to help insulate it.
Illumine 1277820028|%e %b %Y, %H:%M %Z|agohover
For future reference, when I tried this I didn't know, and thus failed to take into account, that PTFE apparently has no shape memory. Toasting it does make it wonderfully flexible, though.
Going to see about ordering a PEEK insulator or two, maybe even a hybrid, and the PTFE that was used for this exercise will hopefully become washers.
As for the question I had about fumes: the maximum temperature of this toaster oven is 450F. I don't know if that's true of all toaster ovens, but in any case it seems to be a safe temperature for working with PTFE, as my reading indicates that it doesn't start giving off fumes until 500F (260C), and it shouldn't cause Teflon flu until it hits 662F (350C). And I'm still not sick or dead yet, so there's that too.
Overall, though, I don't know how useful doing this would be - if at all.
dataman 1277825066|%e %b %Y, %H:%M %Z|agohover
Sounds like you have potential PTFE Washer Slices now…
Illumine 1277830189|%e %b %Y, %H:%M %Z|agohover
Indeed, indeed. Just need to figure out how to cut it…
passim 1277839520|%e %b %Y, %H:%M %Z|agohover
I used a hacksaw with a very fine blade, and then had to clean them up briefly with an x-acto. One melted PTFE will make you a ton of washers.
Re-use!
