How would you make 1/4"-80 threads 3/4" deep?

[Finegrain]

This one has me a little stumped. I need to make a bunch of 1/4"-80 holes, 3/4" deep, in 6061, in a VMC. Holes are thru.

1. I have not found a spiral point or spiral flute 1/4"-80 tap, only straight flute. I think that would work, but with a lot of pecks to keep the flutes clear.
2. Harvey 41450 threadmill has enough reach, but with a .115" neck, I'm worried about chatter, and slowing down make an already slow process slower.
3. I haven't found any threadforming taps in 1/4"-80.

Seems to me the best thing would be a spiral point tap, but have so far been unable to find one.

Thanks, and regards.

Mike

 

[Conrad Hoffman]

Sounds like a job for a form tap, if somebody has or will make one.

 

[Bill in PA]

With such a shallow thread depth, would chatter from a thread mill even be an issue?

Bill

 

[gustafson]

Flood coolant?
I think I would try one and see how bad the chip buildup is.
Thinking it will not be that bad.
more like some dust

 

[FamilyTradition]

I would second trying the straight flute and make sure you are blasting as much coolant in there as you can. Depending on how the tap is manufactured, it may have the same flute dimensions as the 1/4-20, but is removing a fraction of volume of material.

 

[DanASM]

Companies do make custom taps. I dont know of any off the top of my head, but Emuge U.S. headquarters is close by and they claim to have a full machine shop in house for regrinds and repairs.

 

[SD&M]

This one has me a little stumped. I need to make a bunch of 1/4"-80 holes, 3/4" deep, in 6061, in a VMC. Holes are thru.

1. I have not found a spiral point or spiral flute 1/4"-80 tap, only straight flute. I think that would work, but with a lot of pecks to keep the flutes clear.
2. Harvey 41450 threadmill has enough reach, but with a .115" neck, I'm worried about chatter, and slowing down make an already slow process slower.
3. I haven't found any threadforming taps in 1/4"-80.

Seems to me the best thing would be a spiral point tap, but have so far been unable to find one.

Thanks, and regards.

Mike

Hi Mike:

I've got some Balax 1/4-80 roll taps I had made special for a job a few years back, and you're welcome to one (just pickup the shipping) for the asking. They've got a steam oxide finish (black). If I recall correctly, you had to get (4) pcs, and hell's gonna freeze over before I ever need these again!

I'll send you a PM.....

Cheers, Brian

 

[Finegrain]

Hi Mike:

I've got some Balax 1/4-80 roll taps I had made special for a job a few years back, and you're welcome to one (just pickup the shipping) for the asking. They've got a steam oxide finish (black). If I recall correctly, you had to get (4) pcs, and hell's gonna freeze over before I ever need these again!

I'll send you a PM.....

Cheers, Brian

Sent you a PM!

 

[Yan Wo]

Where else would you find someone who: A) has a 1/4-80 roll tap; and B) is willing to GIVE it to you? PM is the best!

 

[SD&M]

Right? I never thought these things would ever see any use again....

Mike-sent you an email with shipping options (FedEx)-let me know what works for your schedule requirements.

Cheers, Brian

 

[Ox]

Just in case:

Boy, I personally would think this to be a poor application for a form tap?
You would hav e to have the blank bore SPOT ON, or you will have either poor crests (on an already VERY shallow thread form) or be overflowing (better term?) and breaking.

But - I hope all goes well, apparently it did for the other fella...


But in case - North American Tool lists 1/4-80's (in their Feb '96 catalog) but they don't list it in S/P.
But if I was so inclined, I would ask if they would be willing to point a few?
They very well may.

???


--------------------

Think Snow Eh!
Ox

 

[Finegrain]

You would have to have the blank bore SPOT ON, or you will have either poor crests (on an already VERY shallow thread form) or be overflowing (better term?) and breaking.

Aye, yes!

70% thread >> .2441" hole
65% thread >> .2445" hole
60% thread >> .2449" hole

But, that's what reamers are for.

Regards.

Mike

 

[Ox]

Just so we're on the same page is all...


------------------

Think Snow Eh!
Ox

 

[GregSY]

Why would anyone need a 1/4" 80 TPI hole?

 

[SD&M]

Why would anyone need a 1/4" 80 TPI hole?

This seems to be a rather common choice for adjusting screws....think things like kinematic mounts, etc.

When we had these roll taps made, it was for some custom flexures we made from 6AL4V Ti, but there's all sorts of applications for "weird" threads like this.

Kinematic Mirror Mount

We offer the widest range of off the shelf kinematic mirror mounts from low cost to the highest performing, most stable mirror mounts available anywhere.

www.newport.com

 

[atex57]

Turn your straight flute into a SP with a T&C grinder or use a steady hand. Flutes should be plenty wide enough to grind it in.

Ed.

 

[jwmelvin]

Turn your straight flute into a SP with a T&C grinder or use a steady hand.

do you know the typical angle used for the tip gash?

 

[Ox]

I wouldn't want to just wing it.

Many years ago we had a job of tapping 1/4-20 LH in 1018.
No taps lived all that long in that job, and some were worse than others.
It's like the grinders just didn't doo LH SP well at all?

Meaning that the grind is more than just whatever looks good.
And if the tap MFGer has trouble puting the correct grind on a LH, the odds of us getting it right on our own grinder or by hand would seem tougher yet. (and on such a shallow thread at that)


???


--------------------

Think Snow Eh!
Ox

 

[DavidScott]

For the record, Scientific Cutting Tool makes a large variety of larger diameter for the pitch threadmills.

 

[Finegrain]

Follow up ...

I ended up cut-tapping these. Customer preferred that, and there was a cross-hole going into the 1/4"-80 that I was worried would complicate getting the exact right size and straightness pilot hole.

Thanks a million Brian, even if I didn't end up using the form tap. I did use the Go-NoGo gage though, that will be on its way back to you next week.

BTW, a 1/4"-80 straight-flute cut tap does indeed make stringers:



I'm glad I positioned a strong thru-the-hole coolant blast, to push these stringers down out of the way.

Regards.

Mike