OMG Taping Woes!!! Help me please!!!

Solar71 · Jan 18, 2011

Hey you guys.
I know i know i only post when i have problems. Sorry.
But i really need some help.

Im taping in 304 (Yuck) a 10-24 hole. Through, about .343 wall thickness.
I am drilling with a #24 drill, (about .152-.154) This is about 70-75% thread engagement.

My tap is brand spanking new, but extremely old... Its a 10-24 GH3 Sossner brand. Its straight, 3 flute.

I spot drill, then Drill through with the #24. Double check that the hole is completely through. Then i add taping fluid, and start.

The tap goes in about .25 (it needs to go through .343) then snap.
Load meter is showing about 10-15% at the snap point.

I really really really wanna drill larger (5/32) or .156 or maybe even bigger.
But my boss does not want that.

Not sure what im doing wrong. I very rarely break taps. Happens only once in a blue moon.
But this 304 and the small dia i think both contribute.

What would you guys suggest ? Make hole bigger ? or am i doing something else wrong...
I can post the program if you like, but i double checked it and then even dry ran it without any problems...

Please help. thanks

bryan_machine · Jan 18, 2011

Is this a bottoming tap? Plug tap? Gun tap?
What is behind the material?

(I ask because I've broken taps mostly when one of three things happens:

a. The tap bottoms on something - usually the point hitting something I didn't expect.

b. Sometimes, I get bottoming taps that break when going through into the open - as though they don't like the sudden loss of material.

c. If you forget the tapping fluid, you will break the tap - but you say you are managing that.)

Also, you do regular tapping with this machine, so you know the tapping cycle works, right?

Finegrain · Jan 18, 2011

You said "straight," that's as in straight flutes? First thing I'd try is spiral point, then a spiral flute. I got away with murder with a brand new OSG HyPro spiral flute this weekend. Without going into details, it worked beautifully in a situation where it probably shouldn't have.

Oh, and Tap Magic ProTap fluid has never let me down.

Regards.

Mike

Dave Cross · Jan 18, 2011

#1-are you sure your hole is straight?
#2-switch to form taps.

jdj · Jan 18, 2011

Solar71 said:
H
I really really really wanna drill larger (5/32) or .156 or maybe even bigger.
But my boss does not want that.

IF...everything else is O.K. (tapping cycle speed/feed, etc...) I guess your boss LIKES broken taps and all the wasted time/money, etc...that goes with it!
If there are not many holes, tap by hand.

Jeff

David Ferguson · Jan 18, 2011

Last time that happened to me, it was because I neglected to select the Rigid Tap Cycle when telling the CAM software to tap a hole. I would verify that your are using the Rigid Tapping cycle, or the proper pitch with a tapping head.

Tonytn36 · Jan 18, 2011

Using a nice new sharp drill, or an old worn out smoker?

keithmech · Jan 18, 2011

try breaking the corner with a countersink after you drill the hole.

jdj · Jan 18, 2011

Tonytn36 said:
Using a nice new sharp drill, or an old worn out smoker?

I should have thought to ask this question! Mind like a steel trap, Tony!

Jeff

rklopp · Jan 18, 2011

Why a 3-flute tap in that small size? Sounds like a hand tap, which doesn't know what to do with the chips. Try a good brand 2-flute spiral point with reduced shank behind the threads. Also, why 10-24? Any chance you could re-design to 10-32? I only design 10-24 into soft materials like aluminum and maybe gray iron.

g-coder05 · Jan 18, 2011

Form tap that puppy and be done with it. Balax has good formers for stainless.

Dave K · Jan 18, 2011

Try a good brand 2-flute spiral point with reduced shank behind the threads.

I never understood why people go for those reduced shanks behind the threads, unless they need it for depth. Otherwise, it's just another weakened point for breaking, if you ask me.

Solar, I would be sure you've got a decent tap that's made to be power tapped through a hole. A hand tap, as mentioned, will not deal with the chips too well under power. (if indeed that is what you're using) 2 flute, spiral point seems to work best for me.

Heinz R. Putz · Jan 18, 2011

Did anyone ask the obvious question?
What is the programmed RPM and what is the programmed feedrate?
Without knowing that, how could we possibly give any advice.
So what is it?
Are you tapping in the excact position where you drilled the hole ?
Are you using a floating tap holder or is this rigid tapping?
A program sample would be nice.
Am I being too picky or is this obvious info we need before giving advice?
Heinz at www.doccnc.com

Dave K · Jan 18, 2011

Heinz R. Putz said:
Did anyone ask the obvious question?
What is the programmed RPM and what is the programmed feedrate?
Without knowing that, how could we possibly give any advice.
So what is it?
Are you tapping in the excact position where you drilled the hole ?
Are you using a floating tap holder or is this rigid tapping?
A program sample would be nice.
Am I being too picky or is this obvious info we need before giving advice?
Heinz at www.doccnc.com

I think you're right on the mark, in general, but since most of us know Solar has been doing this for a while now, we kinda take for granted he knows what he's doing with the basics.

SteveinAZ · Jan 18, 2011

Solar, we had the same problem a couple years back with 10-24's in T316. A couple of things that happened when we started breaking taps on the 2nd or 3rd run of the same job. We switched to a rigid holder from a floater and didn't catch the lack of an M29 prep before the G84 line (on a Fanuc)- with the floating holder we were able to tap fine, with out the float and without the M29, it just wasn't sync'd. We also ended up switching to a "Balax Threadfloer" thread forming / roll tap and a M0 just before the tapping cycle to blow out the coolant (blind holes) and fill them with Castrol Moly Dee. After these minor changes, we are still using the same 2 taps from a couple of years ago with hundreds of holes on them.

Steve

Dave Cross · Jan 18, 2011

SteveinAZ said:
Solar, we had the same problem a couple years back with 10-24's in T316. A couple of things that happened when we started breaking taps on the 2nd or 3rd run of the same job. We switched to a rigid holder from a floater and didn't catch the lack of an M29 prep before the G84 line (on a Fanuc)- with the floating holder we were able to tap fine, with out the float and without the M29, it just wasn't sync'd. We also ended up switching to a "Balax Threadfloer" thread forming / roll tap and a M0 just before the tapping cycle to blow out the coolant (blind holes) and fill them with Castrol Moly Dee. After these minor changes, we are still using the same 2 taps from a couple of years ago with hundreds of holes on them.

Steve

My experience as well, form taps take significant stress out of tapping.

Brian · Jan 18, 2011

Moly Dee on any stainless is like magic too.... messy as hell, and stains everything, but an absolute necessity.

Solar71 · Jan 18, 2011

Wow thanks for all the great tips.
Ok. Rpm is 300. X and Y never move. All
3 tools come up and down in the same place.
The drilled hole has a chamfer. And why would I
Use a spiral tap? This is a through hole.
I thought straight flute taps pushed the chips
Ahead of the tool. Isn't that what I want
With a through hole? Also it's 80 units.
1 hole each. Also we are using rigid taping,
With a non-floating tap holder.

PS : the hole is straight. It's only .34
Of material from the OD to the ID.
Not sure if these manual taps. How can I tell.

Thanks guys.

rklopp · Jan 18, 2011

A spiral flute tap is easy to spot. You don't want one of those in this application. A spiral point tap is not as obvious. It has negative rake in the axial direction, which pushes the chip out ahead. A spiral point tap will give you "Goldilocks" curl chips squirting out the bottom of the hole A hand tap won't have the axial rake, or at least not very much. If you can't go with a form tap, a spiral point tap is the way to go. Most tool catalogs or google can explain it in detail.

KilrB · Jan 18, 2011

Solar71 said:
Wow thanks for all the great tips.
Ok. Rpm is 300. X and Y never move. All
3 tools come up and down in the same place.
The drilled hole has a chamfer. And why would I
Use a spiral tap? This is a through hole.
I thought straight flute taps pushed the chips
Ahead of the tool. Isn't that what I want
With a through hole? Also it's 80 units.
1 hole each. Also we are using rigid taping,
With a non-floating tap holder.

PS : the hole is straight. It's only .34
Of material from the OD to the ID.
Not sure if these manual taps. How can I tell.

Thanks guys.

1. Good sharp drill

2. C'sink

3. Sharp two-flute spiral POINT tap ... not spiral flute

4. Moly-D

Shouldn't be a problem.

If all else fails, do you HAVE to have .343" of thread engagement, or can you c'bore an 1/8" or so out of that?

EDIT:

Check MSC's online catalog Solar ...

http://www1.mscdirect.com/Taps/Cutting-Tools/0000000728.HTML

Look at the pics and you can see the differences between the various types we've talked about.

OMG Taping Woes!!! Help me please!!!

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