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I Forge Iron

Mitchell power hammer UK.

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I'm not familiar with the Mitchell, but in my experience with mechanical hammers you want the link arms (between the ram and the bigger arms) to be about horizontal. This would be achieved by tightening the springs on top. The variable stroke comes from the flexing of the triangular assembly holding up the ram, if it's not at it's widest point the ram will have several inches of uncontrolled movement at the top and bottom of the stroke.

The four parts of the action (the two arms and the two links) should actually form a triangle while at rest with the two links forming a straight line. (If the pins on the links are offset then all of the pins joining them should form a straight line.) This puts the action in it's widest possible configuration and the ram cannot move in either direction without compressing the springs.

If the ram is below that point it's momentum at the top of the stroke will carry it through that center point, widening the assembly and loosening the springs. It will pass through that point again on the way down. This causes some unpleasant noise, extra wear and loss of energy that you want for forging. I just finished a rebuild on my Little Giant, which has a similar action, and there are no clunks or rattles anywhere in the stroke. That's what you're looking for; the only rhythmic noise should be the BLAM of the dies coming together.

It looks like there are some provisions for adjusting the ways that the ram rides in. You want these to be as close as possible without binding. I usually oil things up and turn all of those adjusting screws in by hand until I feel the ways touch the ram. (Try everything even while doing this, one could tighten one corner too far and not be able to bring the opposite corner in as a result. Then I turn the hammer by hand while I make adjustments by tightening one screw at a time until the ram sticks and then backing that screw off an eighth of a turn at a time until the ram frees up. If it's your first time you might have to go around a couple times until your get the feel for things.

Hope that helps, real experts will be along soon.

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