O/T Stainless Steel Tapping

[CNCGUY]

1/4-18 NPTF in 316 stainless at 107 RPM with a floating holder.

 

We are using a tapered ream and flooding with coolant.

 

The taps are breaking. Any suggestions as to what we need to change.

 

Thanks

[crazy^millman]

Thread mill the Crap out of it. I use to do these in about 15 sec a hole with a threadmill.

 

Crazy Millman

[Roger Peterson]

Thread mill, oh yeah thread mill...

 

 

Or, get an interupted thread pipe tap. It's the only pipe tap to use if you're not hand tapping.

 

 

HTH

[robk]

Are you using Briggs or Whitworth taps? Each one uses a different tap drill. We run Briggs in here in 420ss @ 200rpm (rigid) without even running the reamer. Never broke one yet because of that. Make sure you use a decent tap also.

[Philcott]

Troy,

 

Thread mill if you can. If not, we use stagger tooth pipe taps and have pretty good life with them. Buy the best tap you can. They are cheap compaired to a part with a broken tap in it.

 

Good luck,

Phil

[jbel]

If you decide to tap it instead of thread mill, be sure to use a premium quality tap. We tap Viscount-44 (Rc 42-46) all the time but we use good quality taps. While its not stainless, its pretty tough stuff. Try www.emuge.com I have had great sucess with them.

[Toolfab]

You know Troy, I have heard of this great company called Tool Fab, that also makes threadmils....lol

 

Our home page might give you some ideas aswell.

 

 

wow was that a shameless plug or what??

 

lmao

[Nominal]

1/4 npt is a decent sized tap to be breaking. How do you know you are reaming deep enough?

[CNCGUY]

My bad, this is a lathe app. no thread milling here.

 

We are using Besly and VT taps.

 

quote:

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we use stagger tooth pipe taps and have pretty good life with them.

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Thats where I was headed next.

 

quote:

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420ss @ 200rpm

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Maybe we should try bumping it up a little higher.

 

edit

quote:

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1/4 npt is a decent sized tap to be breaking. How do you know you are reaming deep enough?

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We have gages to gheck taper depth and threads.

 

[ 12-29-2003, 02:26 PM: Message edited by: CNCGUY ]

[Philcott]

Troy,

 

Lathe eh? I usually bore the hole for a pipe tap when on the lathe. I feel a tapered reamer has the tendancy to work harden the hole in stainless therefore making the tap work much harder getting under the skin.

 

Phil

[CNCGUY]

Right now we have it working, doing peck tap. We are going to get some stagger tooth taps to try.

 

quote:

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I usually bore the hole for a pipe tap when on the lathe.

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That idea was also tossed around a bit.

 

 

Thanks for the help guys, as always good suggestions to try.

[chad fisher]

Is there a reason you have to use a reamer?

The tap drill w/o reamer is 7/16, in the past i have even went up to .453 in stainless to ease stress on tap.

[crazy^millman]

Ok then I would turn the crap out of them threads with a cabide Mini Threading Bar. Should be getting about 100 parts a corner. Internal Tool Makes the Holder and the Inserts will have to call your local dealer to get a number my book doesn't have one. Not sure fi they make a full proifle or not but if not still a breeze.

 

Crazy Millman

 

[ 12-29-2003, 04:19 PM: Message edited by: Millman^Crazy ]

[CNCGUY]

quote:

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Is there a reason you have to use a reamer?

The tap drill w/o reamer is 7/16, in the past i have even went up to .453 in stainless to ease stress on tap.

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These are hydraulic fittings and need to be mfg. per SAE stds. 11mm max drill.

 

 

quote:

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Ok then I would turn the crap out of them threads with a cabide Mini Threading Bar

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Thanks for the tip. I will check into that.

[chris m]

I definitely think Ron's on the right track if this is something you're going to make repetitively. Internal Tool makes a good product but I think I'd look at Circle for somthing like this personally.

 

I'd definitely turn vs. ream and thread vs. tap in this application

 

C

[crazy^millman]

Well if doing SAE fittings then I would most definity turn the bores and create my port areas and chamfers for the O-rings. I dont think Circle makes an internal thread tool they make good boring bars just very proud of them is all Internal is about half price and just as good.

I would also look at Chamdrill to drill out the rough hole will take about 12 sec to pop a hole and get the ones wit hthru the spindle. I hear you compaling right now about the thru not a problem. Get some copper tubing and bend it to your liking it is a little pain to get set-up but once you do can fly like the wind.

 

Crazy Millman teh Crazy Lathe Guy also

 

[ 12-29-2003, 06:37 PM: Message edited by: Millman^Crazy ]

[mike_f]

try p.h.horn for micro boring & threading tools if your going to single point your threads. What type of coolant are you using? For small quantities i'll put in a program stop and use a sulphurized cutting oil or for especially tough apps. i'll mix it with a parafin based cutting fluid called safety draw made by Castrol. increases my tap life tremendously in gummy materials.

[chris m]

quote:

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I dont think Circle makes an internal thread tool

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They do, indeed

 

quote:

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I'll put in a program stop and use a sulphurized cutting oil

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Cutting oils are a coolant killer; I'd stay away from that if at all possible

 

 

Let us know what works out Troy

 

C

 

[ 12-30-2003, 07:13 AM: Message edited by: chris m ]

[Roger Peterson]

Most cutting fluids have some sort of "tapping" "fluid" that can be used without causing too much trouble with the coolant. I used the term "fluid" alone because some of tapping fluids are almost gel like that the different coolant mfg's recommend. Work with your coolant supplier. Chances are having a stronger mixture of coolant will help trmendously and eliminate the need for tapping fluids. Single pointing is a great way to go, but if you are not using interupted thread taps just making the transition to one will more than likely cure your problems. Regardless of mfg most pipe taps are designed as hand taps requiring the back and forth motion to clear chips.

 

 

HTH

[mike_f]

quote:

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Cutting oils are a coolant killer; I'd stay away from that if at all possible

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Chris, you're absolutely right, I should have expanded on that with "if all else fails" they're also messy to work with, especially the parafin based stuff i mentioned. it is very "sticky" and a pain in the a$$ to clean out of holes but I haven't found anything better at extending tap life especially in refractory metals and h.s.s. like M3-2 or CPM-M4. there is definately a trade off though. I haven't used any of the "fluids" that are compatible with coolants though, maybe there is something else that will work as well. I will definately be looking into that.

[Roger Peterson]

Just a little disclaimer. When I said compatible I meant much much better than using moly dee. Seriously though I know hangsterfers(sp) and castrol, or valenite, both have tapping "fluids" that are not nearly as bad for their coolant as an off the shelf tapping fluid.

 

 

HTH

[Kevangel]

For tapping in stainless steel Butterfield tapping fluid is simply,truley amazing.I have seen dull 6-32 taps in bridgeport that won't go....will tap with butterfield. Plastic bottle says Union Butterfield. Asheville,NC. I buy mine from E.M Wick co. Dayton, Ohio 937-293-5330. This stuff is sooo good it blows my mind. Its cheap also.