SpudFiles

does anyone have an idea of how to make 3" male/female threaded couplers (I think thats the right name) screw together flush? presently they only screw together about half way

-thanks

well i seem to ave the same problem with just about every type of pvc threaded fitting, it appears to be pretty normal. every once and a while i get a fitting that is perfectly flush (about one out of ten) it seems to do with what manufacture makes them. so if the fittings don't screw in all the way in a dry fit it is unlikely they will at any other time (always test when your at the store buying them, try to find the best one). there is only one thing i can think off... not sure how safe it is, well... if it on a combustion it should be fine. anyway my friend thought of this and has preformed it successfully twice (with lots of help). basically what you want to do is stick the female fitting in boiling water until it becomes soft, then quickly remove it from the water and screw in the male fitting as far as humanly possible. not comes the hard part after the pvc you boiled has hardened you need to unscrew it, which requires a lot of effort (like multiple people and a huge pair of pliers) i personally have not done it becuase i don't think its worth the effort.

Maybe try this and add some type of lubricant to the threads to aid in removing the two fittings.

Teflon tape works well. I severely doubt that having the threads crap out halfway is a problem.

cut half of the male threads off then screw it back on. should go on all the way then

the reason is that pipe threads have a slight taper to them and are wider twords the back than they are at the front.

If you cut the male fitting back, and filed the threads down, would that work? It would require a 60 degree file and a hell of a lot of time though...or access to a lathe set up for cutting threads.

the threads are tapered so its going to be tough to do what you want.

Not so. With a machine lathe, it would just take a little setup. You rotate your piece until the threads start where your tool is, note where the threading dial is, and engage the clutch on the cross feed when it gets there. Then the tool moves along and cuts right in the threads like it's supposed to. I've threaded a couple screws for C-clamps doing that.

As for the taper, you just adjust your headstock. Keep it dead on centered for threading normal stuff, or ofset it to get pipe threads. Of course, you need to use a tool cut to 60 degrees and follow the same procedure as mentioned earlier.

And that is all I ever really learned in high school. Or at least all I can ever see actually using.

They aren't meant to screw together flush, and trying to force them to would be a good way to bust the female adapter. But if you need them to be flush for a design then you would need to modify the threads like the others have suggested.

the problem is the two fittings are dwv, and will be holding sustained pressure... I was pitting on haveing a double wall thickness...

mcmaster is gonna cost me about 30$ for the six new fittings I'll have to buy, fuck!

Hi,

Screw them together well tight (not too much, that will just introduce stresses and make the result weaker), then carefully measure the space between the two. Cut a ring of some pipe to the right length, and epoxy it over the male.
Cut another ring of a smaller pipe (find a way to take to calculate the length) and epoxy that into the female.

Epoxy mess can be removed immediately with alcohol.

Use teflon tape for final assembly.

Regards
Soren

dongfang
I'm going to remember that trick!!
Much cleaner that way.