[TheForge] Upsetting the middle of a bar

[Peter Fels And Phoebe Palmer]

Hello Bruce and Stephen;
This technique is called "jumping" and  is worth setting up if you have 
a bunch of them to do.
Frosty's hydraulic jack proposal sounds good too.
In the past I've just used a piece of pipe a bit shorter than the bar 
and a heavy baseplate with a welded ring that the pipe fits into. The 
pipe is a little bigger ID than the upset.
 Spot heat the area to be upset and drop it down the pipe to the 
baseplate and honk on it with a sledge. You'll probably have to drive 
the bar out with a drift and take another heat to straighten it out. Way 
quicker than the multiple heats otherwise necessary.
Pete F

Bruce Freeman wrote:

>The following is either "book larnin'" or else something I picked up
>from a demonstration or a video - I just don't remember.  But I haven't
>tried it myself.
>
>First, the physics:  If you tie a steel cable tightly between a heavy,
>movable object and an immovable object, then push sideways on the middle
>of the cable, the heavy object can be moved with ease.  The reason is
>that the relatively small force exerted sideways on the cable is
>translated into a large tension on the cable that can move the heavy
>object.  It's rather like leverage, but different.  If you've never
>played with this, try it with small objects and you'll be convinced...
>
>This upsetting technique is sort of the inverse of the above technique
>- a sideways force is put on a slightly bent bar to exert high
>compression force along the length of the bar.  Drop a couple of drift
>pins in your acorn table, separated by a little more than the length of
>the ballaster bar.  Against one of the pins, put a (sideways) "stack" of
>"shims" to reduce the distance between the pins to something a little
>less than the length of the ballaster bar.  
>
>Heat the ballaster bar to yellow in the center (preferably with a
>torch, but heating on a forge and selectively cooling should work too).
>Bend the bar slightly at the hot spot, place it between the two
>pins/shims with the bend up, and press (or hammer) the bar down.  Repeat
>this step, adding shims, until the desired upset is obtained.
>
>Bruce
>NJ
>
>  
>
>>>>irony at epowerc.net 10/27/2004 10:40:29 PM >>>
>>>>        
>>>>
>Y'all:
>I have a stair and a parapet railing to make with about 60 balusters,
>each having a long leaf forge welded near the middle of each bar.  My
>stock is 5/8 square.  I am looking for a simple way to upset each bar
>for the weld and am not having much luck.  I have used my coal forge
>with a fairly narrow fire on some and on others, a rosebud to make the
>heated area shorter.  I have been using a 2-1/2" depression in a swage
>block as a base and either a 4# hand hammer or a special tool for my
>air
>chisel that is a cup about 3" deep.  Either way the process seems far
>too slow.  If I use the air chisel and keep the rosebud on the stock
>constantly at almost a welding heat it barely upsets the metal even
>after 5 heat/upset/straighten distortion cycles.  Using the hand
>hammer
>seems to be the fastest way, but even that way it still takes 5 heats
>or
>so.  Is there something basic I'm not seeing here?
>
> Stephen McGehee
> Publisher of
> Irony, the sketchbook of an apprentice blacksmith
> P. O. Box 9822  Pine Bluff, AR 71611
> irony at epowerc.net 
> (870) 540-0142
> (479) 643-3299 (farm)
> You can see a sample of IRONY magazine here:
>
>  http://lametalsmiths.org/news/page4.htm  )
>
>
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