First, if you want a new PTC fitting, you can order one from the SeeMeCNC shop, or get one here from Amazon. (If you have Prime, free two-day is cheaper and faster than getting one from SeeMeCNC.) Once you've got that ordered, you will still find yourself staring at an inoperative printer, but you don't have to. I tried a few things - here's what did and didn't work.
Superglue - this works. The idea is to get a sort of gumdrop shape on the plastic part of the fitting where the tube goes in, which flows slightly over the lip of the plastic. I've found a good way to do this is to put it on in three coats, waiting each time for it to cure.
- Sand the plastic part of the PTC fitting (we'll call it the flange) and the first couple inches of PTFE tube.
- Get a small amount of superglue on the sanded part of the PTFE. Gently push and twist to seat the tube in the PTC fitting, in order to try to get as much Superglue between the PTFE and the fitting as possible. Insert a length of filament through the PTC fitting and into the tube, taking care to hold the tube in place so the filament doesn't push it out. (It WILL NOT stand up to any pressure yet!) Leave the filament there for the remainder of the procedure.
- The Superglue will try to flow with gravity, so you'll need to hold the PTC fitting and PTFE tubing horizontally and rotate them slowly (like they're on a lathe) for a few minutes. This will evenly distribute the superglue.
- Use the filament to "floss" the fitting and tubing a little, to make sure no Superglue got into the inside of the fitting or tube. If any did, you'll want to "floss" it out as best you can. I didn't have that problem, though. If you're careful, you shouldn't.
- Hang up the tube and fitting so that the fitting is vertical, so that if the Superglue has any flow left into it, the flow will go downward to the top of the flange, which is ideal. Wait about 30 minutes for it to cure. You may notice that the Superglue seems to shrink just a little during this time.
- Apply another coating of Superglue to the PTFE and flange. You want to create sort of a gumdrop shape. Not too big or it won't dry properly, but get the edge of the gumdrop to come out close to the edge of the flange. Again, hold it horizontally and rotate for a few minutes so that the glue firms up evenly.
- "Floss" the fitting/tube again with filament, hang it up vertically again, and give it another 30 minutes to cure.
- Put on a final coating. This time, add enough to get the gumdrop to sort of "muffin top" around the lip of the flange. You want a solid mass of Superglue holding onto the tube, and also holding onto the underside of the flange, for maximum holding strength. Rotate horizontally until it's flowed into a nice, even shape.
- Using a heat gun on the low setting, and holding the fitting a few inches away from the heat gun (not too close or you'll melt the filament), "help" the Superglue cure. You may find that a little bit of the stuff seems to boil up out from between the PTFE tubing and the inside of the PTC fitting. It will probably show more shrinkage as well. Your filament should still be in there too. After the heat gun, use the filament to "floss" the fitting and tube a little bit to make sure there's no Superglue that got into where it would cause a problem.
- Hang it up again for 15 minutes.
I also tried thread locker (no luck - this stuff doesn't bond to plastic) and an elaborate system of clamps and a vise grip. The vise grip trick did work for a little while, but would always fail within about 1/2 hour because the teeth would start cutting into the PTFE sooner or later, and it would slip. Tightening it wouldn't work because after awhile it would get so tight that the filament couldn't get by.
