... If you put soft materials under the tree stump to absorb the
vibrations do you still have the full force of your blow acting on
what ever it is that you are hammering?
In a word, no. The more solid the base under the stump the more of
your hammering force goes into the metal. Solidity (more or less)
equals hammering "efficiency" but of course it's a trade off between
that and shock absorption.
This is where the concrete slab on some soft thing comes into it's
own. The force of your hammer isn't enough to move the concrete much
so you get high hammering efficiency. But the concrete sits on spongy
stuff so any force that it does absorb is not transmitted
effectively. It looks like a lot of hassle to set up but it works
like a dream.
That said the old stump on blankets thing works quite well unless
you're into substantial forging. In my experience it's perfectly
satisfactory for jewellery level forging and chasing but I wouldn't
want to use it for hot forging knife blades or the like. When you're
doing jewellery stuff the stump is proportionally heavy enough that
your little hammer taps aren't enough to get it moving much hence you
have the perception of (sufficient) solidity.
As ever your mileage may vary.
in The City of Light