[TheForge] LG dies, was cast iron - Little Giant pulley

Tue Aug 13 09:46:00 2002

        Hi Dave,  I have used 4140 drops from a machine shop on my air
hammer also.  The thing I just found out about this is it was 4140
HT...........not 4140 annealed.  There are about five different grades of
4140 and 4340 when they come from the tool steel place(I've found out with
some calling to Burgon tool steel).
        I was wondering why the hell I had used this 4140 in my air hammer
for three years and it had never dented with low profile tooling on the top
die.  Well I started making dies a few weeks ago with milled dovetails and
found out about the different milling qualities of the tool steels as
supplied in their different states/forms.
        The 4140 HT does cut with carbide cutters.  The 4140 annealed cuts
five times easier.  I found this out by being able to square up blocks with
.005 passes with a face mill.  On the 4140 that I got from Bob Bergman in
Wisconsin it was annealed and I could take .025 in one pass with the face
mill.    The 4140HT comes thru somewhat hard......about 40-45 rockwell.
This does still cut with a carbide face mill, but passes were cut down 5
fold as compared to the annealed.
        Long story short is obviously I had welded on some 4140 HT to the
air hammer for dies and this is why it held up so well for three years.  I
tried some of the annealed material Bob gave me for a power hammer tool, and
it dulled very quickly.
        Often we get material that is marked on the alloy, but the finer
details are not given.  I found that all these 15 blocks of 4140 were indeed
4140, but it was the HT not annealed as I could tell instantly by taking a
.025 cut with a carbide mill head and if it chattered......it was HT, and it
it was annealed, it was fine to cut at that rate.
        Just maybe the 4340 was an HT condition and not annealed as the 4340
from what I'm told will take a real hardness of 55-60 rockwell if oil
hardened.   The 4140 is only about 45-50, but the beauty of both alloys is
the "toughness" of them.  They are both abrasion resistent, and impact
steels for die alloys.
        Just my findings from "found" 4140 at the scrap yard from cleaned
out machine shops.  Interesting as to what a cutter pass can tell you.  I
dug thru all the scraps and finally found one that had the HT designation on
one of the pieces.......this I further took to mean as this is what they
bought to do the jobs they had for the materials.  Knowing what you have can
save time, money, and headaches.
        If you just weld on the dies to a fastening plate........you'll
never know if you had HT or annealed.  Both will weld and work......the HT
will hold up for years, the annealed will dent from tooling impact.
        Did you buy the 4340? or was it scrap from a machine shop? or tool
and die maker?
        One word of caution is when machining these alloys, some have lead
in them, wear a respirator when milling unknown alloys.
        I have built three of the air hammers so far, and had two of four
die bolts come loose, but re-tightened and never a problem again.  I was
cold texturing and the extra shock must have loosened them.  Hitting hot
stock has never loosened the die mounting bolts.


Ralph


----- Original Message -----
From: "lama" <[email protected]>
To: <[email protected]>
Sent: Monday, August 12, 2002 12:22 AM
Subject: Re: [TheForge] LG dies, was cast iron - Little Giant pulley


> Ralph, the dies on my 75# Kinyon air hammer, my former 50# LG,
> and my heavy treadle hammer are all made of 4340 not heat treated
> in any way and in daily use for years & years and are still in great
> condition. I am using 4"x4"x10-1/2" 4340 for the dies on my big air
> hammer. By the way, my bolt-on dies have never come loose of their
> own accord.
> dave m
>
> ----- Original Message -----
> From: "Ralph Sproul" <[email protected]>
> To: <[email protected]>
> Sent: Sunday, August 11, 2002 8:05 PM
> Subject: Re: [TheForge] LG dies, was cast iron - Little Giant pulley
>
>
> >         Cameron, I find no reason at all not to use 4140 for hammer
dies.
> >         You may find many a damaged cutter if you try to mill a forged
> piece
> > of 4140.  It is a chrome alloy and will get hard in the air to a certain
> > degree.   Welding to 4140 will yield hard spots that will dull inserts,
> and
> > take the rake of your band saw blades.  I think it is wishful thinking
to
> > figure your going to make an accurate set of dovetails on a press.
> >     If you have a milling machine, buy the stock the right size, and
mill
> it
> > the first time.....your short cut will cost you in the long run.
> >         My two cents.
> >
> > Ralph Sproul - Bear Hill Blacksmith
> > Webster, NH
> >
> >
> >
> >
> >
>
>
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