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

Tue Aug 13 17:16:00 2002

        Dave,  You learned the lesson the hard way as I did on the cutting
of the material after torching or welding has been done.  Forget it.  It
will air harden after the heat of torching or welding and makes sawing or
machining a bad idea as we both found out.
        Nice score on the bar of 4340.  I've never worked with it, but hear
it hardens much better than 4140.  Both are "tough", abrasion resistant die
stock.
        I found the 4140 HT will cut with a saw but yellow and an occasional
light blue chip will come off the blade with no water being used(that's how
my saw has been set up). The annealed will cut just like A36 as far as I can
see.  It wiped out the blade that I tried to cut the welded parts
..........after air arcing the welds out.  I use them as hard billets now,
and they will remain in that classification - as I'm done wasting $32
blades.

Ralph


----- Original Message -----
From: "lama" <[email protected]>
To: <[email protected]>
Sent: Tuesday, August 13, 2002 2:03 PM
Subject: Re: [TheForge] LG dies, was cast iron - Little Giant pulley


>
> Ralph, this is something that I found in the scrap yard years ago.
> They had several 4" x 4" x 20' long pieces of this 4340 that had been
> lying around for years. One day Japh Howard & I stopped by to browse.
> I showed him the stuff just because I was impressed with the size. He
found
> and translated the mil specs that were stenciled on this 4 x 4 stock in
> yellow
> paint about every 5 feet. he told me to buy a piece of it which I did and
> got
> for scrap price of the day ( 1987 ?) I still have about 4 or 5 feet of it
> left
> for making the dies for my big hammer. As I recall, Japh told me that this
> stuff was annealed. I know that I can cut it with the band saw but can't
> cut it within an inch of where the scrap yard had cut it in half with a
big
> oxy/propane  torch. I will try to find the specs. I know that I wrote them
> down somewhere around here in 1987.................
> dave m
>
> >         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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