Thread Chasers

We are using small thread chasing heads (9/16) to thread full length (4'-6') rods. Heads are in good condition, chasers are from a reputable manufacturer. But our results are pretty poor and not very repeatable.

As new the chaser point of contact is about 0.020" above center line. There is a 10 degree clearance below point of contact and the cutting edge is what the supplier calls a "hook" grind.

Our issues are and inconsistent thread included angle, twisting of the rod, and build up of swarf in the head and inserts.

Others must be having better luck with this type threading process. Wht may we be doing wrong?

We need more info.

Which die head you using?

What machine?

Material?

Size and thread ?

Speed?

Coolant / oil set up?

Roscoe,

Go here: Landis Threading Systems - Technical Support
Under the "thread cutting program" download the "chaser management" file. All of the stuff on that section is good to know information.
JR

Die heads are not really designed to thread feet of thread in one hit, due to swarft build up. Adding through coolant may wash it out but might be hard to do as presumably the rod has to pass though for such a long way. why not just buy threaded rod or send it out and get it thread rolled?

Late getting back

We are using "Geometric" die heads on 316 stainless steel. We will thread 0.062 through 0.125" in 2-56, 5-40, 6-32 and similar metric threads.Treading is either less than one inch per part OR a full length rod, threaded in many bites, 1 inch at a time. We have 5/16 and 9/16 die heads on Hardinge second operation lathes. Coolant is flood fed through the die head from the back side. We seem to be doing everything the instructions tell us to do, but with poor results.

on 316 stainless steel.

Click to expand...

Good luck with that!


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Think Snow Eh!
Ox

Yets raise the question again, why are you making threaded rod? Why not buy it in. Threaded rod is not made with a die head, it sure as hell is going to be a very painful process especially in 316!!!!

A industrial rated process to make threaded rod rolls the thread into the bar, its quick, its painless, its even cheep on a per finished bit basis :-) Its just a expensive machine, and a expensive set of rolls. Hence farm it out to some one set-up for it. Normally the material will be centerless ground first as starting diameter is some what important.

purchased rod

Purchased threaded rod does not have the accuracy or consistancy required for tight toleranced customer requirements. Also no available in the multitude of thread pitches we use. Thus we fight with thread chasers. Looking into other brands than Geometric now. Not impressed with the geometry of the inserts we are getting.

A couple of suggestions. Get a "Geometric Standard Screw Threading Manual". In the manual you will find a wealth of information about the use and care of the die head and chasers. The "hook angle" for all stainless steel is 15*. If you bought the chasers from MSC, etc, they will supply the standard 10* hook angle and a 45* champfer. You will have to regrind the chasers for the 15* hook angle and regrind the champfer to a much smaller angle, between 15 and 22*. I would recommend the 15*, as that will give the best long term performance. Instead of having 1 or 2 teeth doing all the cutting, you will have 3-5 doing it. You do not want the cutting edges on center; for the .020" over center you mention, that's good for the sizes I do, but I think it's excessive for the sizes you're doing. The closer to the center line you get, you really start inviting trouble. Learn how to grind your own chasers, the instructions are in the manual. The grind shops I've dealt with in the past ignored my instructions, and as a result they ruined the chasers and had to replace them, a very expensive lesson.
I'm not quite sure of the lathe you're using, considering the sizes, pitches and lengths you're doing. Good luck with your job.
Harry

I never worked with chasers.
I did have part in building the machines and die heads that use chasers.
You guys need to call someone at Ridge Tool Repair Department.
Bruce sent ya.