[TheForge] Re: chinese airhammer anvil ratios

[Thomas A. Troszak]

> Subject: Re: [TheForge] Re: chinese airhammer anvil ratios
> From: Ries Niemi <rniemi@fidalgo.net>
 
> Tom- I have a little chinese hammer. It is not a fabricated self
> contained, but a cast iron self contained. It weighs 1130 kg, or 2486
> lbs, and the anvil is 480 kg about 1056 lbs. It is rated as a 40kg
> hammer, for a ram/anvil ratio of 1 to 12.
> I have it mounted on a sheet of steel, probably not heavy enough- I
> think it is about 4 x5 feet and 3/4" thick. I
> 
> Judging from what you have  said, I am guessing if I had an even
> bigger, heavier slab of steel, less vibration would emanate out from
> the hammer?


Dear Reis,

From my experience, yes absolutely.  I have solved several thumping issues
by supplying thick (3" or thicker, more is better) plate for under the
anvil.  The big flat sheet like you have currently won't work as well
because the hammer is just pounding out near the front end, and because the
plate is too light and flexible anyway.

Part of your problem is the slab.  Even with the rubber mat, your floor is
actually a huge "sounding board" which vibrates like the top of a guitar,
and it shakes every time the hammer smacks it.  The slab then shakes the
building and the rest of the world.

One idea is to cut a "window" hole in the floor, and set the hammer (and the
plate) directly on the soil.  This will cut down on the vibration and noise
in the building dramatically, but not in the soil.

You can also rent an abrasive saw and slice a rectangular perimeter slot
(all around the hammer) clear through the slab, so that your hammer is now
floating on (but still bolted to) its own section of what used to be the
floor.  Essentially now the hammer has its own personal 4" thick foundation,
which can move independently of the rest of the floor. You then stuff some
rope or wooden wedges between the "island" with the hammer on it and the
hole in the rest of the slab, to keep the "island" from jiggling back into
contact with the hole.  This will "uncouple" the vibrations of the hammer
and its "island" from the main slab, and the building will shake much less
indeed. This is an easy way to cut down the jiggling and noise in the
building itself, but still won't reduce the thumping in the ground. Please
write back if I'm not explaining this adequately.

Still, to minimize the thumping in the earth, some additional mass under the
anvil is needed. if enough additional mass is added, no excavation is
necessary.  

If you were to mount the hammer on a much thicker plate, then float the
plate on a layer of soft PORON (TM) foam between the plate and the existing
slab floor, I predict your thumping will decrease dramatically.  This has
been the case for many customers of mine, so I see no reason that it
shouldn't work well for you also.

I hope this is helpful.

Please excuse the long delay in answering. My tom@tomtroszak e-mail account
is currently hosted by a friend of mine (www.flakyserver.com), and his
hardware is sketchy at best.  I have lost my e-mail for up to a week at a
time... phoo.