Forming tap
 

I was rummaging through my tap collection and came across a couple of
forming taps. I have no idea how they got there, but there they were.
Now, the question is: where are they better used than cutting taps?
Since they are more particular about the hole size, I won't use them
unless they have some advantage.

Thanks,
Bob

Forming tap
 

"Bob Engelhardt" wrote in
message ...
I was rummaging through my tap collection and came across a
couple of forming taps. I have no idea how they got there,
but there they were. Now, the question is: where are they
better used than cutting taps? Since they are more
particular about the hole size, I won't use them unless
they have some advantage.

Thanks,
Bob

Stronger threads in aluminum...

Forming tap
 

On Sun, 19 Mar 2017 18:38:43 -0400, Bob Engelhardt
wrote:

I was rummaging through my tap collection and came across a couple of
forming taps. I have no idea how they got there, but there they were.
Now, the question is: where are they better used than cutting taps?
Since they are more particular about the hole size, I won't use them
unless they have some advantage.

Thanks,
Bob
Greetings Bob,
Form taps make a stronger thread in materials that are fairly ductile.
So for example, wrought aluminum aloys, mild and stainless steels, and
some copper alloys. It's a little scary but I have form tapped
thousands of 10-32 holes in 304 SS. You need to pay attention to how
many holes have been tapped so that the tap can be changed before the
torque gets too high and the tap breaks. Free machining brass is not a
good material to form tap because it is kind of brittle, but silicon
bronze form taps well. When tapping blind holes form taps are nice
because there are no chips to worry about. They are especially good
when the max length thread is needed in a blind hole. I use form taps
as much as possible in my shop.
Eric

Forming tap
 

On Sunday, March 19, 2017 at 8:05:49 PM UTC-4, wrote:

Greetings Bob,
Form taps make a stronger thread in materials that are fairly ductile......
I use form taps
as much as possible in my shop.
Eric

I have no experience with form taps, but I have the impression that they last longer than cutting taps in some metals. Is that right or am I wrong?

Dan

Forming tap
 

wrote in message
...
On Sun, 19 Mar 2017 18:38:43 -0400, Bob Engelhardt
wrote:

I was rummaging through my tap collection and came across a couple
of
forming taps. I have no idea how they got there, but there they
were.
Now, the question is: where are they better used than cutting taps?
Since they are more particular about the hole size, I won't use them
unless they have some advantage.

Thanks,
Bob
Greetings Bob,
Form taps make a stronger thread in materials that are fairly
ductile.
So for example, wrought aluminum aloys, mild and stainless steels,
and
some copper alloys. It's a little scary but I have form tapped
thousands of 10-32 holes in 304 SS. You need to pay attention to how
many holes have been tapped so that the tap can be changed before
the
torque gets too high and the tap breaks. Free machining brass is not
a
good material to form tap because it is kind of brittle, but silicon
bronze form taps well. When tapping blind holes form taps are nice
because there are no chips to worry about. They are especially good
when the max length thread is needed in a blind hole. I use form
taps
as much as possible in my shop.
Eric

I got a 6061 aluminum part back that the shop had form tapped in holes
that were apparently too large, so the tap left a second false thread
groove between the real ones that a screw could engage. They were
small screws, #3 or #4 IIRC, and the torque difference wasn't all that
noticeable at first.
-jsw

Forming tap
 

wrote in message
...
On Sunday, March 19, 2017 at 8:05:49 PM UTC-4,
wrote:

Greetings Bob,
Form taps make a stronger thread in materials that are fairly
ductile......
I use form taps
as much as possible in my shop.
Eric

I have no experience with form taps, but I have the impression that
they last longer than cutting taps in some metals. Is that right or
am I wrong?

Dan


Dunno, but I've retired several #10-32 spiral point taps after 1000
holes tapped freehand with a Milwaukee reversible drill in 12 Ga CRS.
They were the panel mounting holes in custom welded relay-style racks,
~ 60 panel mounting holes per rail so 8 bays per tap.

-jsw

Forming tap
 

On 2017-03-19, Bob Engelhardt wrote:
I was rummaging through my tap collection and came across a couple of
forming taps. I have no idea how they got there, but there they were.
Now, the question is: where are they better used than cutting taps?

Blind holes is one example, as they don't form chips which need
to be cleared out. Just make sure that the tapping head stops before
they bottom out. :-)

Your workpiece should be a fairly ductile metal, of course.
Forget about tapping hardened tool steel -- but then cutting taps don't
do to well there, either. :-)

I've even used them in Teflon, where the material expands to
grip the screw once it is in place.

Since they are more particular about the hole size, I won't use them
unless they have some advantage.

Be sure that you use the right hole size. You can look it up in
a table in _Machinery's Handbook_, or in certain machinist's
calculators.

Enjoy,
DoN.

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Forming tap
 

"Bob Engelhardt" wrote in message
...
I was rummaging through my tap collection and came across a couple of
forming taps. I have no idea how they got there, but there they were. Now,
the question is: where are they better used than cutting taps? Since they
are more particular about the hole size, I won't use them unless they have
some advantage.

Thanks,
Bob

I wonder how forming taps would work in punched holes to maximize the amount
of thread created.

Forming tap
 

On Monday, March 20, 2017 at 3:44:35 PM UTC-4, Bob La Londe wrote:
"Bob Engelhardt" wrote in message
...
I was rummaging through my tap collection and came across a couple of
forming taps. I have no idea how they got there, but there they were. Now,
the question is: where are they better used than cutting taps? Since they
are more particular about the hole size, I won't use them unless they have
some advantage.

Thanks,
Bob

I wonder how forming taps would work in punched holes to maximize the amount
of thread created.

In interviews with many tap manufacturers, I've always heard them emphasize the importance of hole accuracy for thread-forming taps. It sounds unlikely that punching holes would be a reliable way to do it.

--
Ed Huntress

Forming tap
 

Phil, Eric, & DoN -- thanks. I'm curious enough to get the drill I need
(#16 for 10-32) & try it.

Forming tap
 

On Sun, 19 Mar 2017 17:11:39 -0700, wrote:

On Sun, 19 Mar 2017 18:38:43 -0400, Bob Engelhardt
wrote:

I was rummaging through my tap collection and came across a couple of
forming taps. I have no idea how they got there, but there they were.
Now, the question is: where are they better used than cutting taps?
Since they are more particular about the hole size, I won't use them
unless they have some advantage.

Thanks,
Bob
Greetings Bob,
Form taps make a stronger thread in materials that are fairly ductile.
So for example, wrought aluminum aloys, mild and stainless steels, and
some copper alloys. It's a little scary but I have form tapped
thousands of 10-32 holes in 304 SS. You need to pay attention to how
many holes have been tapped so that the tap can be changed before the
torque gets too high and the tap breaks. Free machining brass is not a
good material to form tap because it is kind of brittle, but silicon
bronze form taps well. When tapping blind holes form taps are nice
because there are no chips to worry about. They are especially good
when the max length thread is needed in a blind hole. I use form taps
as much as possible in my shop.
Eric

Well stated.


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Forming tap
 

On 2017-03-21, Bob Engelhardt wrote:
Phil, Eric, & DoN -- thanks. I'm curious enough to get the drill I need
(#16 for 10-32) & try it.

My lookup shows 4.4mm (usually metric sizes for roll taps for
imperial screws. That works out to 0.1732", while the #16 is 0.1770" so
the thread will be a bit poorly formed.

Good Luck,
DoN.

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Forming tap
 

On 3/21/2017 12:11 AM, DoN. Nichols wrote:
My lookup shows 4.4mm (usually metric sizes for roll taps for
imperial screws. That works out to 0.1732", while the #16 is 0.1770" so
the thread will be a bit poorly formed.

Good Luck,
DoN.


Ummm ... these are Balax taps and this Balax page shows that a .177
drill will give a 70% thread.
http://balax.com/products/thredfloers/12288-000

I'm not used to thinking about threads in percentage terms, but 70%
sounds pretty good to me.

Forming tap
 

On Tue, 21 Mar 2017 00:58:18 -0400, Bob Engelhardt
wrote:

On 3/21/2017 12:11 AM, DoN. Nichols wrote:
My lookup shows 4.4mm (usually metric sizes for roll taps for
imperial screws. That works out to 0.1732", while the #16 is 0.1770" so
the thread will be a bit poorly formed.

Good Luck,
DoN.


Ummm ... these are Balax taps and this Balax page shows that a .177
drill will give a 70% thread.
http://balax.com/products/thredfloers/12288-000

I'm not used to thinking about threads in percentage terms, but 70%
sounds pretty good to me.
70% will be plenty strong enough. If tapping punched holes in fairly
thin material you can get away with a slightly undersized hole because
the metal will just extrude away from the material surfaces. Remember
that a high pressure cutting fluid is good to use because the thread
is being formed.
Eric

Forming tap
 

On 3/19/2017 6:38 PM, Bob Engelhardt wrote:
I was rummaging through my tap collection and came across a couple of
forming taps. I have no idea how they got there, but there they were.
Now, the question is: where are they better used than cutting taps?
Since they are more particular about the hole size, I won't use them
unless they have some advantage.

Thanks,
Bob


I used them for threaded arbors on mini-grinder cup brushes. They take
two to three times the horse power but no chips. They always tell you
when they are too dull....SNAP!

Forming tap
 

Forming tap
 

On Friday, March 24, 2017 at 7:11:56 PM UTC-4, Stephen B. wrote:
wrote:
On Monday, March 20, 2017 at 3:44:35 PM UTC-4, Bob La Londe wrote:
"Bob Engelhardt" wrote in message
...
I was rummaging through my tap collection and came across a couple of
forming taps. I have no idea how they got there, but there they were. Now,
the question is: where are they better used than cutting taps? Since they
are more particular about the hole size, I won't use them unless they have
some advantage.

Thanks,
Bob

I wonder how forming taps would work in punched holes to maximize the amount
of thread created.

In interviews with many tap manufacturers, I've always heard them emphasize the importance of hole accuracy for thread-forming taps. It sounds unlikely that punching holes would be a reliable way to do it.


We have progressive dies at work that use them. The main advantage there
are no chips to deal with.
The punches are sized per tap requirements. This means we get less
engagement at the bottom (in the punch blowout). The bolts are not under
high stress so we are not worried about striping out.


--
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I'm sure that if you have properly-sized punches, you can do it. It sounds like a production thing, though, that would take a few trials to get it right.

--
Ed Huntress

Forming tap
 

On 25/03/2017 10:26 AM, wrote:

I'm sure that if you have properly-sized punches, you can do it. It
sounds like a production thing, though, that would take a few trials
to get it right.

Shouldn't be a big deal. Holes come out pretty much to the punch size,
so likely just need a custom decimal size punch, I'd think.
Pretty sure I watched a YouTube video of a punch press that could
produce a bit of an extrusion, offering more material for threading.

Jon

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