Thread type ???

[KenWilliams1966]

Hi All,

I was not sure exactly where to post this, so If I have posted in the wrong area, please let me know where this should be.

We are quoting a threaded component, I hope I have attached the photo properly. The icnluded angle is 20 degrees, and the small end is 1.125 in diameter, and the large end is 2.075 in diameter, and the length of the thread form is 2.85", and it looks like 8 TPI.

Has anyone ever worked with a thread like this, we have already programmed it, that is not the problem, in fact there is not a problem, I just really want to know what this type of thread is called.

 

[crossthread]

A machinist I used to work with made something like that and called it a breach plug. I have no idea if that is correct but I think it refereed to the plug in the back of a rifle barrel. I would just call it a tapered thread.

 

[DDoug]

The material type might give a clue to it's usage and name.

 

[L Vanice]

I have several examples of such a thread, but in smaller diameters. They are commonly used by dental and jewelry polishing lathes to mount buffs and brushes with small center holes in wood, lead or leather. The holes get gradually larger with use, but the tapered screw arbor just keeps working. They are very quick to change from one buff to another, and allow use of accessories with a blind mounting hole.

The picture shows an antique SS White dental polishing lathe that takes standard WW (8 mm) watch lathe collets in the spindle. A WW collet is in the picture, and the tapered arbor has the same back end.

Larry

 

[4GSR]

Looks like a old API Cable Tool thread. OR a rod end used on triplex pumps. Just an WAG. Ken

Correction: The API Cable Tool Threads make up to a external shoulder, which this thread doe not have. Sorry. Ken