Is This Thread Possible ?

B

BillWood

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Couldn't sleep, so started pondering what I can and cannot do on my lathe and somehow started wondering if a skilled machinist could cut the nut and bolt shown in the attached sketch.

I have no need to make this, and cannot think why anybody would want to, but I was wondering if it is possible for an experienced machinist to make such a thing.

I can think of a cheat - cut the nut in two parts then screw them both onto the bolt and glue or pin the two parts together, then unscrew the bolt.

Complicated Screw & Nut.JPG
 
Yes, it's possible. What Rodney said
 
Why not, 20 TPI is 20 TPI regardless of OD or ID. The tricky part would be in making the two diameters in the nut or bolt continuous. You would need to stop the thread and pick it up again for the different diameters. Next time try a sleeping pill, they help to stop the thought process. LOL Good night Mrs. Callabash, where-ever you are. Now I won't sleep. LOL

"Billy G"
 
I just took a good look at your sketch. It calls for a left hand thread. Is that what you are calling for. If so it just got easier because you will be cutting from the chuck end to tail stock. It will take a specially ground tool but I asure you it can be done. Now can I go to sleep or should I cut a set first? LOL

"Billy G"
 
Well ........ thanks - definite agreement here .............the next time I cant sleep I'll go up to the shed and have a go - that was very clever of me to make it an easy to cut left hand thread. Must be some sort of intuitive naturally gifted mechanic somewhere in my family tree.

Why is a LH thread a special tool grind ?

I cut one unintentionally a little while ago using the same tool I'd just used to cut a RH thread .................... thought I was rather clever making things easier by taking the cut towards the tailstock and then wondered why the nut refused to engage with the screw.
 
A LH is not a special grind per say but to get closer to get that close to the shoulder of the bolt you have to grind one side of the tool so you can run the thread right to the shoulder. It's no biggie.

"Billy G"



102_1015 (800 x 531).jpg
 
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There is a premium thread with that feature in the oilfield. It was originally patented and named Hydril-cs. Your shop had to be licensed to cut it. There are still a few such protected threads around, but I believe the patents are expiring on many of them.imgf0001.png

imgf0001.png
 
I've been looking at that monstrosity of a thread, Its an internal thread on a sleeve, for joining two pieces of (probably) pipe together. It doesn't say so, but I'll bet one end is left hand the other right hand. It makes my head hurt thinking about it. No. 34 is a compression device to seal the joint.
 
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