Lesson Learned

[Char-Gar]

You can't cut threads in barrel steel with a cheap Chinese carbon steel die. I turned a piece .500 and tried to thread it 1/2 X 20. Now way Jose!

[leftiye]

Pardon me for being a smart ***. Did you partially cut the threads first with your lathe? It still might not cut if the steel is that hard/die that dull, but it might. I pretty much cut all of my threads on the lathe and finish them with a die for size and form. Also the dies tend to cut all skeywampus (not straight) if they have to move too much metal.

[trevj]

I'd be surprised, actually, if you got decent results with a die at all, if the turned down portion was right at .500"

Digging out the books and checking out the major diameter tolerances of a external 1/2-20 thread shows a class 3 thread (the closest to nominal, and tightest tolerance) has a max of .500", min of .4919". Run your size down nearer the minimum, and taper the leade a little bit, for better results. For best results, start the thread with the lathe, then finish it with the lathe.:D

Dies are OK for some stuff, but I'd stick to cleaning bruised threads on gun stuff, rather than making new ones.

Cheap dies are lousy things, too.

Cheers
Trev

[Buckshot]

...........Years back I bought a set of taps and dies at Pep Boys I think it was, and probably paid something like $12.98, which looking back was about twice what it was actually worth :-) On the taps they couldn't have ground the flutes in, but instead used a dull cutter of some sort as it had both ends of the teeth smeared across. On most the dies the chip clearence holes were not concentric around the central thread cutting hole. In addition the central hole had obviously been drilled and threaded first because when the chip holes were drilled they never even bothered to champher the leading edges of the threads. What trash! But then, what would you expect from a multi piece set for that price? I kept it for some time as a joke, but finally tossed it out.

...............Buckshot

[deltaenterprizes]

Most of those cheap sets are good for chasing threads not cutting them.

[Char-Gar]

Well, they say if it doesn't kill you, it will make you stronger... or maybe a little smarter. I got the project finished and it came out fine, even if I went about it bass akwards. The project was making a new handle for my Pacific Super C loading press out of an old P17 barrel.

I have been putting off learning how set up the gear train on my lathe to cut threads, as every time I looked at it I got quesey in the gut. I am not a natural mechanical sort. I do my best at philosphy and abstract stuff.

So, I gritted my teeth and said, I would have to do it some day and this might as well be the day, so I figured out how the grears worked and which gears to use where to cut 20 tpi and by gosh it worked.

I did cut the threads a hair to shallow so I finished up with the chinee die. I know nothing about minimum and maximum and books with numbers in them. I figured a 1/2 X 20 started with .500 stock that is a half inch right? Life would have been much better hand I known enough to start with .492 or something like that. As it was chasing those oversize threads with a die was possible, but required allot of physical effort.

Things were still a little tight, so I chased the threads in the linkage with the chinee tap and now everything fits like it was made by somebody who knew what he was doing. The days of miricles are not over if you heart is pure :-)

I tell you boys this mechanical stuff is a sore trial for a highly educated egg head with little mechanical education and zero mechanical skills. Every day is a learning experience and at age 67 I don't learn as quick as I once did.

Oh well, enought whining..onward and upward. 'But I do have a nice handle on the press!

[John Taylor]

Good for you. You should be able to learn something new every day. Sometimes the days need to be 72 hours long.

[lathesmith]

Yea, thread-cutting is definitely an art, only learned with patience and practice, research, and a variety and combination of various tools. Cutting good threads gets easy, and cutting fast threads can be real easy, but you know you have mastered the art when you can cut good threads fast!

lathesmith

[big boar]

Chargar, the more mistakes you make, the better you'll be. Don't kid yourself, we all make mistakes. Cut some more threads, every time you do it'll be easier and come out better.

[deltaenterprizes]

The way I was told" If you aren't makin mistakes you ain't doin nothing"!

[Char-Gar]

Well I make a mistake or two everytime I start a project. But thus far, I have not had to pitch anything away and start over. My goofs have always been "fixable". I work very carefully and slow and try to have everything "pre-thunk" before I hit the green button.

Despite my artsie fartsie bent I do tend to be methodical and do things in sequence and by the numbers. I guess I can thank Law School for that. They do teach you how to think and cover your bases.

I can't thank you guys on this board enough. You are a great resource for a mechanical dufas and I have learned so much from you. Thanks again.

[JMtoolman]

Charger, look in the used book dealers listings, and find a "Machinests Handbook". It's a 2 1/2 thick book on everything you might want to know related to machining. If I knew 10% of what is in the book, I would be the smartest guy in the world! Retired machinest, 66 years old. Best regards and good luck machining. The toolman