Threading cutter

Seems like a lot of work to still have to take 4 passes to cut a complete thread in brass. Realistically, you should be able to cut a thread in any material the die is harder than in 1 pass without lead screw engagement and not have to reverse to keep your thread dial in the same spot.

But, even the most rigid lathe will never be as rigid as a die that hasn't been compromised by cutting it in pieces is. And a die can do it in as large a size as you need. I don't know what the largest die made is but I know I have used pipe threading dies in sizes up to 1.5" using a pipe threading machine which is basically a lathe that is meant to grip pipe and spin it roughly in a circular motion and give you a convenient place to rest the die stock handle as it cuts the thread. There is really nothing precision about it besides the die itself.
 
Reminds me of thread milling with a specific insert vs. the single point style cutter. The specific styles do the job quicker, one or two spins around the boss or hole vs. running through the complete thread. Might be applicable if you were making a lot of an oddball like a 1/2"-18 thread, but would sure be a lot of work for just a onesie.

Bruce
 
A lot of work for what is essentially single pint cutting, you still need to use the leadscrew for correct pitch, however the thread form will be more accurate as that is ground into the die.

If I needed to make a thread of such accuracy I would single point it leaving it slightly oversized then run a die or die nut over it.

One advantage is it could be used on a variety of shaft diameters with the same pitch.
 
I can't say that I have single point threaded a ton of times, but I have done a few and only one time that I recall that I would I have been able to use his miracle threader. All other times there wasn't room for such a long relief "groove".

Since I don'ta speaka di Italiano, I'm assuming he cut up an otherwise useless die. Otherwise, he could have just used the original die to cut 100 threads while he was creating his creation. :dunno:

Tom
 
One reason that he could thread with fewer passes is the lead in angle on the throat of the chaser, it cuts a thinner chip than a single point tool depending on the angle of chamfer on that particular chaser. I have seen threading tools made in the same style, from back in the old days and have a few made by Pratt & Whitney. Threading does not have to be slow with fine cuts, I read of a method of cutting coarse threads, and used it for years to cut 1 1/4 - 7tpi threads on tractor disc axles, it could do a finishes thread in 5 or 7 passes, I forget which.
 
well, personally I think the idea has merit ! and it needs to be duplicated and used to find out the capabilities
so what if it only cuts one thread.... you have to have a set of dies to do all threads anyway, but on the lathe with a single point you don't ..so there is a big advantage to single point threading.....
but I am thinking it has possibilities in one area.. fewer passes... to ME that would be a big improvement at .005" per cut it takes a terribly long time to reach thread depth.... obviously if you don't take such a small bite you can get the job done much faster ! .... but I am just learning how to single point thread and I am not good at it...at all ! in fact..... it is giving me hell.... LOL... but I am confident I will eventually get it down pat.
I believe my biggest problem so far has been the thread cutter.... as many of you have so graciously pointed out...it needs to be a good quality and SHARP cutter........
...so that precludes me using my old burnt up dies as thread cutters as they are quite dull...( and untempered too boot )
.....
I love the idea of bringing old technology up to date with the technology we have today.... but the problem is if you know the machine good and it's capabilities, the old technology worked just fine...it doesn't NEED to be improved upon !
..... however there are instances that improvement is necessary...like the bull pin on my Logan 922 it needed modification in a big way ! because everytime I tried to put it in back gears I pulled the bull pin out too far and the entire spindle had to come out to put it back in !
one could contend that it was just operator error.... and I might agree, except that the 2 and 3 time I pulled the pin out too far I Knew what I was doing and the consequences of pulling that pin out too far and I pulled it out too far by mistake anyway..... so it was time to modify ! it was just an ill conceived arrangement, with no provisions at all if you happened to screw up....
.....
I don't have the material to make such a tool ...or I would just to test it out ! .... it could be a real boon to the threading capabilities of the Hobby lathe !.... just like the flip up single point cutter that makes backing out unnecessary !
.....it simply expands your capabilities.....
.....
Bob......
 
Why do so many folks have so much trouble/ time elapsed time threading? they are afraid to take a appropriatly thick chip ---- You should be able to take a chip the better part of 1/2 depth the first cut, given a lathe sufficiently rigid, not mini lathes, but something like a 9" south bend, cutting relatively fine threads, like say, maybe 20 tpi or so; Learning how to do it; push the envelope! If you are just practicing, a messed up thread is not the end of the world.
 
LOL.... well my first attempt at single point threading turned into a disaster ! I took 15 to 20 thow my first cut... the next cut was screwed up because the thread dial went by so fast that I missed the mark and subsequently split the thread I had started.....
so I slowed the machine down to 20 on the VFD...and tried it again..... made about 3 or 4 10 thow cuts and all was looking respectable and then I missed sync again and destroyed what I had !
so I put it in back gears and waited for the thread dial to come around and I still missed the mark !
by now I am more than frustrated with the whole affair, but I finally got a deep enough cut to call it a thread.... but there were balls of metal hanging off the threads and it was the nastiest thread I have ever seen !
so I changed the cutter ! got a real sharp one... that stayed sharp for about 5 passes then the threads started looking like the last one with metal fragments all over the threads....
out of desperation I asked for help here and the first thing was slow the machine down ! use a sharp tool and make your depth of cut only 5 thow
.... so I did that , that turned out a fairly decent thread....( which took over an hour !) but I stopped too soon and didn't get the depth I needed....
.... i've attempted to single point thread about 2 dozen times now....
taking what I have learned from you guys and friends and they are improving but they are far from good threads !
it is so easy to screw up and miss with that tiny thread dial it is un real ....
so yah pushing the limit is one method, but I am trying to learn to do it RIGHT ...then I will play with it and see what I can get away with !
it's not that I am afraid to take a 20 thow cut it's that I have been told "definitely do not do that ".....
and when you only have 1 of the 3 criteria that is right, bad cutter , doing the sequence wrong, and not engaging the half nut at the right time
you definitely are just rolling the dice as to weather you will be able to make a good thread to begin with !
the only thing I have going for me is the machine is set up correctly.....
and then there is the metal I am trying to thread.... it's the softest mild steel I have ever seen ! it likes to ball up and not cut.... even with my carbide cutters. it reminds me alot of copper ! which I find is very strange !yet it is a old rusty steel axle from a hand truck. ( which keeps getting shorter and shorter ! LOL) ( yes it went through the Ranch fire as well so it too is probably annealed ! )
....
Bob.........
 
Bob, you may find some interesting tidbits amongst these.

and although this relates to metric threading its equally at home on an imperial lathe.
 
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