Long skinny threading

[Dan Krager]

RB211, it's not a point of contention as I see it. I just don't have a follower of any sort. I think the lathe threading ion this skinny 3/8 rod 18" long is a good idea...I just am unable to do it at the moment so I'm trying to find another way to do it. And I think I have another way to do it under power now.

By using a different stock I could open the die a couple thousandths and that made all the difference in the world in the forces required to spin the rod through the hand held stock. So, using the setup pictured, the keyed chuck held the rod securely without horsing it down too hard and it took about a minute and half to turn the 9 inches of left hand thread. Lots of oil, chips falling out of the die into a bucket on the floor, and a vice held start before putting it to power works like a charm. The heat build up was significant but not untouchable. I'm impressed with the performance of that ALPs die.

A test fit revealed that the thread is too snug, so I'll repeat the process with the die held to normal size. The hold up to doing that is the old stock that has three set screws to hold the die are all stripped out. The new stock has only one set screw and it's metric, so I'm setting up to drill and tap two more setscrews to match the original set screw. Then it should work to hold the die at finish size.


DanK

[754]

Mic the material , if its .375 could be part of problem. .370 be fine.
follow rest , some if us dont have one.. in 30 years I never got to use one.. do i described a work around..
ANOTHER TRICK.. if precision is not required... only have about 4 or 5 inches out of chuck with tailstock support. Cut thread to fit, then advance out ...pick up existing thread .,continue..

[Dan Krager]

Now, why didn't I think of that.


Don't answer that. LOL!

DanK

[elf]

An even better option when you don't have a follow rest is to hold the stock in tension instead of compression. A tailstock chuck works well for this. It's also a nice project for the lathe😄😄

[754]

Dan the good part... is you only have to learn it Once.. well most of us..
not sure if you are referring to it maybe being off size.. but opening it up, then it worked better but was tight... made me think..
Dies dont deal well with oversize barl,

[Dan Krager]

Zu früh alt, zu spät klug. I finally got smart (thanks to advice from above.... ) and mic'd the rod and it shows up at 0.377", i.e. 0.002" oversize. DOH! For the first pass, the die was pressed open by the stock set screw and that allowed me to thread the first pass easily, which was oversized. Today I finished LH threading the material on hand by measuring the at rest gap in the die. Then I put it in the shiny stock with the set screw pressing 90° to the gap and compressed the slot 0.002" using feeler gauges to measure. The set screw was not in a dimple and I fully expected it to spin in the stock, but it held and a second pass on all the oversized LH threads allowed the rod to spin easily in the mating dowel with no noticeable slop.

So, the shiny new stock will get two more set screws machined in to secure the die in the stock and allow easy adjustments when needed. Less than 1/3 of my dies have adjustment slots, but any replacements will definitely have them.

Next up is the RH threaded end which should go quickly now. Then some brass ferrules turned from hex stock and London Pattern Handles machined and turned.

Thanks again for all your help, gentlemen!

DanK

[754]

Der erste satz war lustig...

[Illinoyance]

Lee Valley sells the hardware kits.

Acme threads on a handscrew? All I have seen were UNC threads.