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Posted by Curt Welch on July 12, 2009, 10:29 pm
Please log in for more thread options > I can't.
> I am usually working with round or square less than 1" x 30".
> All I end up doing is bending the piece where I am attempting to offset
> it. I beat the piece on its end, on top of the anvil. I even made a jig
> so I could beat it sideways into the anvil. No help. It just bends. I
> use a propane forge and I have not tried cooling most of the stock before
> hammering. I don't like the idea of putting my single anvil on the
> ground and using long stock and a stepladder.
> Sure could use some suggestions. I went back to my teacher last week and
> forgot to ask him how to do it. He's out of state for 3 weeks now.
> charlie in MT.
What is offsetting? I'm new the blacksmithing. Are you just trying to
form a jag in the piece such as two 90 deg turns close together so that the
long ends still remain parallel?
Here's a reference on the web I found that should give you some ideas if
that's what you are trying to do:
http://www.scribd.com/doc/944936/Making-an-OFFSET-BEND-by-Alexander-Weygers
Your talk of a the anvil on the ground and a stepladder however doesn't
seem to make any sense.
Are you actually asking how you can _upset_ the material (make it thicker
by hammering on the end)?
If that's what you are trying to do there are are few things I could
suggest (though I'm certainly no expert here).
First, yes, it will always try to bend on your. You can't heat up a
large section of the rod and try to upset it. It will just bend. You have
to work on small sections at a time. As you said, if your gas forge is
heating up too much metal, cool down the stock except in the small section
you want to work on. you just have to keep repeating like that for the
entire area you want to upset. Even then it will bend on you, and you
simply have to stop and straighten it out from time to time (which also
undoes some of your upsetting work).
Upsetting is a slow and hard work. Don't expect it to go fast - it takes
time. However, the hotter you can get the metal, the better - as far as
speed. Push it all the way just short of burning if you are trying to do a
lot of upsetting.
The little upsetting work I've done, was achieved by laying the bar flat
across the anvil, holding it tight with my left hand against my leg to
create a little more mass to hit against - and then just lending over the
anvil and hitting the far end back towards me. The longer and heaver the
piece, the better that technique works because the mass of the piece itself
creates the back force to do the work for you.
If the piece is short enough, you can stand it up on end on the anvil and
hit down with the hot end up. If your anvil has an upsetting block (a
block that comes out the bottom typical on the back side) you can use that
to deal with longer pieces. You can also put the hot end down, though it
will cool faster if the end is hot and in contact with the anvil.
For longer heaver pieces, you can use the mass of the work to act as the
hammer. That is, instead of using a hammer, just hold the work with the
hot end down and bang it down against the anvil letting the mass of the
piece do the work for you.
I've never tried it (or seen it done) but for long pieces I guess you could
try to use the side of the anvil and hammer against that. But you don't
even need to use the anvil. For a long piece (many feet) the piece itself
has enough mass that you can just hit the hot end and let the mass of the
piece act as it's own anvil. Anything you can rest the piece against could
be used. If you have a hard concrete floor I would think simply placing a
think plate on the floor and then using that to hit down one would work
nicely (but don't blame me if you develop cracks in your floor!).
Watch out for the hot end mushrooming out into a sharp edge. Don't let
that happen. If it goes too far, you won't be able to hammer it back
without folding it over. You have to keep hammering it back, and you can
even bevel the end so that mushroom effect causes it to return back to a
straight (but wider) side.
That's about the limit of what I currently know about upsetting (if that
was what you were asking about).
--
Curt Welch http://CurtWelch.Com/
curt@kcwc.com http://NewsReader.Com/
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