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Can I have some feedback to geometric die head on 316SS vs thread rolling?

DMSentra

Cast Iron
Joined
Sep 12, 2008
Location
Eugene Oregon
I have a geometric head sized for the coming M8 thread but would need the 1.0 pitch chasers. I'm thinking stringy 316 would probably be a nightmare with a geometric, am I wrong?
Doing research on all the choices brings up a bunch of options. Tangential with and without power closing feature, Some brands I only see in for sale ads with zero mention of them in google searches. Some are comparatively so simplistic to others it's difficult to believe they work, or why the others need to be so expensive.
Going by the videos on how they function a radial head would be my choice as I can run it on the cnc and the little turret lathe, and maybe cost less than other choices.
 
It is going on 50 years since I have used a geometric head on non-free machining stainless and I have forgotten it all. Running cutting oil through the shank is always helpful in flushing out the chips even with free machining brass. It could not hurt with 316.
I would certainly think about think about sending the threading out to someone like Rolled Threads Unlimited. I have had them roll a hundred lengths of 303 bar for me and also semi- finished parts that I sent them.

I have never used a thread rolling die head. I understand they can work well if you have the knowledge and time to set them up properly.
Closing a die head on a CNC or screw machine is fairly easy, On a turret lathe you forget once in a while. Easy enough to not index, close it, and go through the motion again.

Video of a set up on an Omniturn with a die head and an automatic closer.
 
From the initial still frame that video shows before playing, I thought that might be a Nichols, but the arbor support is a bit different from the two styles I'm familiar with.
An excellent illustration of the production value of small turret or gang lathes with a small lever- or pneumatic-operated horizontal mill.
 
When you see new CNCs that are so capable of finishing parts in one chucking it is easy to feel like a dinosaur.

On that mill I was offered one or the other of a pair for some work that I did for another shop. I took the one with the fresher paint. The Label says United States Machine Tool Co. Model No. 1 Cincinnati Ohio

Back to the OP tangential die heads may be preferable in 316 as you would get more sharpenings. I would guess the blades take more skill in setting after sharpening. I have no clue if it would be easier to clear of chips.
 
Seems the slotting cycle operates finger ...or no finger.
Camera placement was bad. I had plenty of clearance and have never touched the blade while running. The collet is pneumatic, the cross slide is lever operated with the left hand. The slotted screw was ejected when the slide was fully pulled back, the collet closed with 1/4 inch of forward motion. It is hard to figure out where to place the camera when taking a video of that operation.
 
Geometric die heads will get full of chips and you need a human standing there with their thumb on the stop button.

I only roll tap 316 and have not external thread rolled it before. I can imagine it can be done fine, with the right tooling.
 
I have a geometric head sized for the coming M8 thread but would need the 1.0 pitch chasers. I'm thinking stringy 316 would probably be a nightmare with a geometric, am I wrong?
Doing research on all the choices brings up a bunch of options. Tangential with and without power closing feature, Some brands I only see in for sale ads with zero mention of them in google searches. Some are comparatively so simplistic to others it's difficult to believe they work, or why the others need to be so expensive.
Going by the videos on how they function a radial head would be my choice as I can run it on the cnc and the little turret lathe, and maybe cost less than other choices.
I used to have stub acme nuts out of 316ss knurled on a thread rolling machine and never had one reject. Threaded them after knurling. 1 1/2 dia. Od.
 

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Buddy was saying there would also be heat and severe dulling problems when running chasers. Is he wrong for 10 parts of 2 sizes? To me this sounds ridiculous, but I'm trying to cover my bases.
 
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He is correct if you run them 2 to 3 times the correct surface speed. The correct speed is fairly slow and depends on how many teeth per inch. My Geometric Standard Screw Threading Manual suggests 15 feet per minute for 3 to 7.5 TPI and 30 feet per minute for 25 TPI and up (several suggested speeds in between).

Curious why you want to do this with a die head with only 10 parts to run? Single pointing on that few pcs would take less time than setting up a die head or purchasing one and running down the chasers for that matter.
 
I have the geo head, but mostly I'm looking ahead at my options. The 10pcs are submission samples for larger quantity orders. I'm also weighing running these in the cnc that's way bigger than it needs to be vs the little old Jet TL42 turret lathe. M8x1.0 and M5x0.5 are the two threads in mind. I do think if I get a large order I'll see about getting a roller to thread them, though.
 
Well, that makes more sense. I think that running the metric threads would be easier on an oversize CNC than special ordering the metric chasers then scrapping a bunch of pieces while you try to dial them in. New chasers sometimes taking some massaging to get them to run good threads and sometimes they do not ever run good threads and you have to exchange them.
The Geometric manual has some tips on fussing with new chasers, occasionally it is a hair pulling ordeal.
 








 
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