Threaded Tapers

================= API [American Petroleum Institute] drill stem, collar and bit threads.

Well ... pipe threads are commonly tapered. It provides greater sealing force as you drive the male thread into the female one.

Other than that -- if you have a longer thread (e.g. a screw), you can push it into the hole a ways before the threads engage -- acting as a guide.

There are probably other reasons to have them, but these are the two which come immediately to mind.

Enjoy, DoN.

O.k. That reminds me of another use. The arbors on which buffing wheels are mounted. You need a right-hand thread on one side of the grinder used to drive it, and a left-hand one on the other side. Just push the buffer on, then switch on and it self tightens.

Probably a buffing wheel arbor. Or just a demonstration on how to do it. O.K. Looking at the copy which I have here, it actually states in the description "Tapered screw threads, such as pipe threads ... " Obviously, the one being shown is not a pipe thread, but it could be used as the arbor for a buffing wheel. Or just to train an apprentice on how to do it.

This is in Volume 1 Edition 50 which happens to be within reach.

If I had a matching taper tap, I might use it for studs designed to screw in and wedge really tight.

Enjoy, DoN.

Yes -- but at least a decade out of date. Whoever was maintaining it (at a college) must have retired, and the files are just still there (last I checked), along with archives of many years of postings until that script was shut down. It was not a particularly smart script, so if you are on a Windows system, be warned that it archived a few copies of a virus current at the time. :-)

Here is the URL:

and it is still there.

Enjoy, DoN.

Electric foundry furnace electrode threads.

Steeply threaded tapers are used sometimes to connect things like the drill stem used for drilling oil wells. Once they have loosened just a little bit they unscrew fast. So only a few turns will engage a long length of thread. Look for API threads. Eric

Last time I lathe cut a tapered thread was to replace a lost drain plug for a sail boat - I strongly suspect it was senior son who lost it then asked me to make the replacement. Anyhow, it worked out OK.

When the taper is fairly small, the thread serves to "jam" in the female part, expanding the female, and creating a better seal than would a straight thread. Ordinary pipe threads are tapered for that reason.

LLoyd