Is This Thread Possible ?

That sleeve is known as a coupling sub, and normally is RH thread on both ends. No need to confuse the roughnecks. There are various drill string components that use this thread, up to and including the bit itself.

You're right about component 34. This whole thread is complicated to cut because you are making up at torque on more than a single element, as on a standard RSC. Even those you are making up on a tapered thread and a shoulder at the same time.
 
I don't believe that coupling could not be done with both right and left hand threads. Wouldn't it come apart before the hole was drilled.

"Billy G"
 
Bill Gruby said:
I don't believe that coupling could not be done with both right and left hand threads. Wouldn't it come apart before the hole was drilled.

"Billy G"
Click to expand...
Clockwise torque at the top of the string will tighten all the threads if they are all RH. If one set was RH and one LH, torque one way would loosen one set while torque the other way would loosen the other set.

I don't see the advantage of the design, though. Presumably it solves some application-specific problem.
 
Not that it couldn't, Bill. There's just little point. At times, the drill string must be reversed anyway, negating any advantage to LHT. The idea is for the assembly torque, which can range into the 100k+ pound/feet on the larger sizes to suffice in holding things together.

There is control on the whole assembly while in the hole through the WOB, and the RT applied torque. There actually is a bit of science behind making holes in the ground several miles deep.
 
Yupp has to do with the rotation of the earth and the moon and tides too. Ha ha ha . Lol way to serious I think . But has they say there is a way to do everything .
 
Like said, the oil field thread is a CS Hydril. It is an 8 pitch thread with two diameters. You do have to cut them in the same set up, and the I'd thread in the same set up. To keep the same lead.
 
If you mean something that looks like this 1/2-20 X 1-20, single pointing both threads in the same set up on a manual lathe would work, you would have to do it for both the internal and external threads. The threads do not need to start at the same radial positions (as drawn for simplicity), but the internal and external thread starts must have the same relative radial positions.

An interesting intellectual exercise.
duplexthread_zpsi5a4ok7f.jpg

duplexthread_zpsi5a4ok7f.jpg
 
Yes, if the starts on each of the internal threads and each of the external threads are not in the same position , you will not be able to screw them together. That is the tricky part I mentioned earlier on.

"Billy G"
 
The start position does not need to be in the same 'area'. As long as you run the threads in the same cycle, you will be good. Don't change gears in between running the threads, or they will likely be off. When we ran the Hydil threads in a CNN lathe, we just left the start position in the same place in front of the part for both diameters. Not necessary on the manual as to start position, just best to run the threads in the same process. The hardest part is when the the gage doesn't go on, which one needs tweaked! Unless you have a separate gage for each.
 
A more useful actual product and an excellent challenge would be making a multiple start thread, how is it done?
 
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