Thread cutting problem

[wab0372]

This is my first post other than an introduction so please bear with me.

I am attempting to thread both ends of a 5/8" cold rolled steel rod 18 TPI and have been having a problem with the threads skewing off center. I champhered the end approx 45 degrees and started the die. It appeared to track pretty well but after about 1" it was obvious the threads were off center. After the third futile attempt I decided to make a guide for the die. I drilled a 5/8" hole in a 1" thick piece of scrap delrin. Then I slipped the delrin over the rod and aligned it to the die handle which I had previously drilled a hole on each side of the die holder. Two holes were then drilled and tapped for 1/4-20 cap head screw. Assembled it gave me an alignment bushing on the front of the die handle. This worked very well and I had no problem creating true running threads My question is why I was having so much of a problem getting the die to run true. Was this because it was a cheap die? OR was inexperience raising it's ugly head. In any case it has been an interesting experience. Just wondered if anyone else has had this same problem?

[juergenwt]

If you need to cut the tread with a die make a holder from a piece of cold rolled steel. Turn one end down to fit a drill chuck (at least 1/2 inch dia) and drill and bore the front end 3/4 dia somewhat deeper than your 5/8 thread is long. Bore out the front part to the size of your die and add a set screw to hold the die. You can make a holder for different dies like 13/16 dia or 1" or metric sizes. Comes in handy. Juergenwt.

[Geof]

..... OR was inexperience raising it's ugly head. In any case it has been an interesting experience. Just wondered if anyone else has had this same problem?

I wouldn't say inexperience has an ugly head, but failing to learn from experience might.

Many moons ago I had similar problems, and it is also possible to get a similar thing when tapping. I came to the conclusion it was because I was not applying even force to each of the handles on the die; you have to make sure you balance the effort equally so you are 'turning' the die around the rod not levering it sideways.

But the guide you made is really the best solution.

[One of Many]

Also turning the end to the minor diameter of the die to provide a lead-in the length of your die would have sufficed to keep it straight in the start. Then again, I suppose you would have turned the threads single point if you already had access to lathe.

DC

[juergenwt]

Sorry - I did not realize you are cutting free hand and not in a lathe. Free hand requires a lot of experience but for your thread you will need some kind of a guide. Otherwise it's even pressure and keeping your handles at 90 deg.. good luck. Juergenwt.