I'm building a 4140 3" rivet squeezer yoke out of 4140. Here's a
couple of pictures as examples:

Yoke itself -
http://www.averytools.com/images/variant/icon/1124.jpg
Mounted on squeezer -
http://www.clearairtools.web.aplus.n...%20New%20S.jpg

I think of machining the profile from 1/2" bar stock, drilling the
holes, and then having it heat treated to Rc 42-46.
However, this is my first go at heat treating and I'm concerned that
growth and warpage are going to be a problem.

Will this process work or should I heat treat first and then machine/
drill? Is it feasible to drill 7/16" holes through 1/2" of Rc 46
steel?

Thanks for the help,
-DC

DC wrote:

I think of machining the profile from 1/2" bar stock, drilling the
holes, and then having it heat treated to Rc 42-46.
However, this is my first go at heat treating and I'm concerned that
growth and warpage are going to be a problem.

Will this process work or should I heat treat first and then machine/
drill? Is it feasible to drill 7/16" holes through 1/2" of Rc 46
steel?

With carbide, no problem. Probably with HSS at Rc 46.

Now, I'm going to sit back and hopefully learn from someone that knows this stuff what
kind of factors are used to make a part in soft condition that is right when hardened.
That would be the right way.

I have had the joy of dealing with a test cell spindle that was tapped with a H2 or H3 tap
then hardened. Guaranteed siezed fastener. My boss (now fired) didn't reject it because
he was late on the project. Jerk.

Wes

--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller

On Sep 10, 3:41*pm, DC wrote:
I'm building a 4140 3" rivet squeezer yoke out of 4140. *Here's a
couple of pictures as examples:

Yoke itself -http://www.averytools.com/images/variant/icon/1124.jpg
Mounted on squeezer -http://www.clearairtools.web.aplus.net/mm5/graphics/00000001/Pneumati...

I think of machining the profile from 1/2" bar stock,

It's difficult to tell, but the original could have been forged into
shape and them machined all over. Mucho stronger that way...


Will this process work or should I heat treat first and then machine/
drill? *Is it feasible to drill 7/16" holes through 1/2" of Rc 46
steel?

Your hole diameter will change perhaps .003 or .005" It looks like
these holes are clearance for some bolts(?), so who cares if the grow
or shirk a wee bit? Drill clearance holes with clearance! Make your
life easy.

Overall, you're probably not going to have a lot of warpage/growth.
It's important to recognise where the important surfaces/relationships
are. Clearance holes - not important. The parallelism of your punches
- very important.

If the hole at the end of the hook is important, I'd drill undersized
(1/64" or 1/32") while soft, and then drill the hole correctly with a
carbide endmill once hardened. You'll get pretty good size, and
excellent location (assuming your setup is correct to begin with). You
can also drill even further undersized while soft, then endmill to
1/64" undersized after hardening, and then use a carbide-tipped reamer
(faster) or a barrel lap (slow as ****) to size the hole correctly (to
perhaps .0005" or less on the diameter).

Make sure to put a correctly sized block inside the hook as it *will*
flex and it *may* flex enough to make your hole in the wrong location,
over-sized, or even jam your cutting tools (dulling/breaking them).

As far as flats, you're likely going to have to process the flat at
the end of the hook (inside) after hardening. You can get it pretty
good with a carbide endmill, or really good with a surface grinder (if
you have access to one).

Now, this advice is worth what you paid. There are quite a few places
where there could be some "gotcha!"'s but I don't personally
understand the function of the unit enough to make that determination.

Good luck. Let us know how it goes.

Regards,

Robin

Robin,

Thanks for your advice.

Your hole diameter will change perhaps .003 or .005" It looks like
these holes are clearance for some bolts(?), so who cares if the grow
or shirk a wee bit? Drill clearance holes with clearance! Make your
life easy.

You're right, those are holes for bolts that hold the yoke onto the
squeezer body. Take a look at this better shot of how the squeezer
works:
http://www.rv7factory.com/images/tools/squeezer.jpg

A shaft extends through a hole drilled on the bottom of the yoke and
supports the moving riveting die. The hole at the top of the yoke
holds the fixed die. When a rivet or other part is part is placed
between the dies, the shaft extends the moving die toward the top die
until they meet. This particular squeezer is rated to produce a force
of 3000 lbs.

In my mind the first important part is that the fixed die hole (3/16")
and the moving ram hole (larger) be aligned and parallel. The second
part is that the yoke face where the fixed die rests be perpendicular
to the ram travel. It sounds like its best to rough these features
while soft and then finish cut them after hardening.

I'll be building the prototype in the next few weeks and I'll report
back on how it goes.

Thanks again,
-DC

So why did you choose 4140?
A machine shop teacher once told me that hardening something does not
change its elasticity, just changes how far it will bend before either
breaking or exceeding its modulus of elasticity. I hope I got that
right. If not someone please chime in and correct me!
I got into a discussion on making boring bars that won't "give" a
couple of years ago on this ng. I don't think 4140 was very high on
the list.
I like 4140 a lot and use it for trip hammer dies, hammer heads and
jsut general use where I want something stronger than mild steel. But
for this application, there must be something better????


Pete Stanaitis
-----------------------------

DC wrote:
I'm building a 4140 3" rivet squeezer yoke out of 4140. Here's a
couple of pictures as examples:

Yoke itself -
http://www.averytools.com/images/variant/icon/1124.jpg
Mounted on squeezer -
http://www.clearairtools.web.aplus.n...%20New%20S.jpg

I think of machining the profile from 1/2" bar stock, drilling the
holes, and then having it heat treated to Rc 42-46.
However, this is my first go at heat treating and I'm concerned that
growth and warpage are going to be a problem.

Will this process work or should I heat treat first and then machine/
drill? Is it feasible to drill 7/16" holes through 1/2" of Rc 46
steel?

Thanks for the help,
-DC

"spaco" wrote in message
.. .
So why did you choose 4140?
A machine shop teacher once told me that hardening something does not
change its elasticity, just changes how far it will bend before either
breaking or exceeding its modulus of elasticity. I hope I got that right.
If not someone please chime in and correct me!

You got the first part right. So did your shop teacher. This is a widely
misunderstood fact.

But it doesn't exceed its *modulus* of elasticity when you bend it. What it
exceeds is its elastic limit. I'd explain, but these terms are better
explained in many discussions about them on the web. I'll bet that Wikipedia
has a clearer explanation than I could muster on short notice.

The very short take is that the modulus of elasticity is its stiffness, or
springiness, before it takes a permanent bend. The elastic limit is
essentially the material's yield strength: the amount of force it requires
to give it a permanent bend.

I got into a discussion on making boring bars that won't "give" a
couple of years ago on this ng. I don't think 4140 was very high on the
list.

It's the same as any other steel, including mild steel. Stainess is 5% or
10% less stiff. To get a stiffer bar, you have to use a material stiffer
than steel: usually tungsten alloy or cemented tungsten carbide.

I didn't look at the links below so I'm not commenting on the application
here, only on the point you made above.

--
Ed Huntress

I like 4140 a lot and use it for trip hammer dies, hammer heads and jsut
general use where I want something stronger than mild steel. But for this
application, there must be something better????


Pete Stanaitis
-----------------------------

DC wrote:
I'm building a 4140 3" rivet squeezer yoke out of 4140. Here's a
couple of pictures as examples:

Yoke itself -
http://www.averytools.com/images/variant/icon/1124.jpg
Mounted on squeezer -
http://www.clearairtools.web.aplus.n...%20New%20S.jpg

I think of machining the profile from 1/2" bar stock, drilling the
holes, and then having it heat treated to Rc 42-46.
However, this is my first go at heat treating and I'm concerned that
growth and warpage are going to be a problem.

Will this process work or should I heat treat first and then machine/
drill? Is it feasible to drill 7/16" holes through 1/2" of Rc 46
steel?

Thanks for the help,
-DC