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Source for 5-40 taps with no reduced shank

DanASM

Hot Rolled
Joined
Mar 11, 2019
I am running through tons of taps on a stainless job I have done in the past. Its 316L .187" dia.

I have tried 3 different kinds...Gold (TIN), Black (TICN), and HSS Black Ox/Bright finish.

I just put it on another machine and when I set it up I used a plug tap to get it where I wanted it. The tap had no reduced shank but the chips were packed in the part (as it should).

As soon as I went to the Gold tap I snapped 3 in 5 parts. These taps had the smallest shank on it. They all broke on the way in, towards the bottom.

I am having a hard time finding a good source for full thickness shank taps in the smaller sizes (Spiral Flute, Bottom).

I ran 5k of these with 3 taps last time I ran it. I was at first getting 300ish parts per tap. Is that normal? was I just lucky for some reason I made 4k parts on 2 taps?

Thanks in advance.
 
I thought all 5-40 taps have a .141 inch shank. Please explain what you mean by reduced shank.

What tapping fluid are you using?

Larry
 
https://www.mscdirect.com/product/details/65674954

See how the shank that is beyond the thread is reduced. I need the threads to go all the way back without reducing size throughout the tool. The taps I have been using are so thin in that area that they snap way too easy. I need the tap to be as thick as it can be all the way throughout as to be stronger so they dont snap at the weak spot.
 
https://m.grainger.com/mobile/product/WIDIA-GTD-Vanadium-High-Speed-Steel-WP7025931/_/N-18klZ1yza8ws?searchFlag=Browse&breadcrumbCatId=5331&fromPidp=true&picUrl=//static.grainger.com/rp/s/is/image/Grainger/4AHX1_AS01?$smthumb$webparentimage$

Here is something from Grainger, but $8 isn't bad.

R

Posted from my phone, just copy and paste
 
https://m.grainger.com/mobile/product/WIDIA-GTD-Vanadium-High-Speed-Steel-WP7025931/_/N-18klZ1yza8ws?searchFlag=Browse&breadcrumbCatId=5331&fromPidp=true&picUrl=//static.grainger.com/rp/s/is/image/Grainger/4AHX1_AS01?$smthumb$webparentimage$

Here is something from Grainger, but $8 isn't bad.

R

Posted from my phone, just copy and paste

These taps arent bottom taps. I need spiral flute taps where the threads go full length of the shank. Like these.

WESTWARD 5TWR0 Spiral Flute Tap,Bottom,#5-40,S/O,3 Flt 190735876961 | eBay
 
No material removed, no chips in the bottom and in the flutes

My old man says they were always used in softer materials like brass and aluminum. He comes from old school machining techniques and hasnt changed anything since the 70's.

We run Brown and Sharpe screw machines. Still using tooling from 30 years ago. New old stock mostly. Anyone got speeds and feeds for form taps? Should I stick with the same numbers for cut taps?

I am kind of excited to try this now. It makes sense. I know the material is pretty soft. Its not getting work hardened when drilled out. Just had issues with smaller taps not having much "meat" on the shank and snapping.
 
I had to tap a bunch of M2's in 304 a while back. Someone suggested form taps and I thought, no way, this stuff is way too hard. I ran the whole job with one drill and one tap.

That size of tap, 500 rpm would be reasonable. Are you working to a spec? I usually ream the pilot hole. A few tenths on your starting dia can make a huge difference in your resulting minor dia.
 
No spec. I am also making the male part that goes into it so I can check for proper fit. I was tapping at 620rpm I believe. I know I tried a few speeds from 555-750.

I did check for the right drill size and it looks like I have to call Guhring due to MSC not having them in stock (need left handed).

When I ran this job 8 months ago I had way better luck drilling the hole to the major diameter (a little over what the book calls for). I cant seem to replicate this. Even tried it on another machine and couldnt get better results.
 
When I ran this job 8 months ago I had way better luck drilling the hole to the major diameter (a little over what the book calls for). I cant seem to replicate this. Even tried it on another machine and couldnt get better results.

Is it the same batch of steel? I've seen pretty massive differences in 316L bar from different suppliers. Some is pretty nice, some is pretty nightmarish.
 
Just remember a form tap uses a different hole size than a standard tap.

The pitch diameter tolerance on a 5-40 internal thread is min. 0.1088 and max. 0.1121. If a form tap is used then use a drill as close to 0.1121" as possible. A metric drill (2.80 or even 2.85mm) is also an option.

You'll also get a stronger thread with a form tap and, as mentioned, no tap cuttings.
 
I think OP said he is making mating part so not applicable here. But on some things, form tapping is "not allowed" per customer specs so be wary.

I agree it is a stronger thread, and much easier to do with no chips and such. Have no clue why it is forbidden in some areas/specs/applications....
 
I think OP said he is making mating part so not applicable here. But on some things, form tapping is "not allowed" per customer specs so be wary.

I agree it is a stronger thread, and much easier to do with no chips and such. Have no clue why it is forbidden in some areas/specs/applications....

You've got me wondering why form tapping wouldn't be allowed. Can anyone give a logical reason?
 
You've got me wondering why form tapping wouldn't be allowed. Can anyone give a logical reason?

Can't say it is logical, but I have seen it in specs for aero parts. Of course I don't think much of it is logic at all, it is tradition(?), and no one wanting to deal with engineering reveiws /approvals etc...
 








 
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