[TheForge] air hammer

[sos at frii.com]

Hi Bob,

I'll give you a quick once over, then you can get the details as people
add to and correct me.

There are several different hammer mechanisms:
Mechanical hammers most people have encountered. A weighted head is driven
against the work by a linkage which has a spring in it to act like a shock
absorber. The hammer hits at a rate determined by the motor drive.

External compressor driven air hammers use air pressure in a drive
cylinder to force the head against the work and pull it back up for the
next cycle. I don't know much about these hammers; I'd guess that the
frequency of blows varies (no direct motor drive involved).

Self contained air hammers are different. The motor drives an air cylinder
back and forth via a crankshaft. When you push on the treadle, you are
adjusting airflow from the driven cylinder to the air cylinder that moves
the hammer head. The head moves at a fixed frequency (driven by the
motor), but in a different fashion. As you push down on the treadle, a
given percentage of the air from the drive cylinder is applied to the head
cylinder. This makes it move in a partial stroke, the same stroke length
each cycle. Push the treadle part way down, the head will cycle to
mid-stroke, reverse in mid air and repeat.

Mechanicals--lots out there, Little Giant's being common. People make them
(junk yard hammers), apparently with good success.

Compressor driven air hammers--these are probably the hammer to go for if
you want to make it. There are a variety of them manufactured, like Big
Blu.

Self contained air hammers--people have made them, but not very many.
Kuhn, Nazel, Striker, Say Mak are all examples of self contained hammers.

If you're thinking about a hammer, definitely try them out.
Speaking as an amateur, ANY kind of hammer is a major improvement over no
hammer. I own a Turkish self contained (predecessor to the Say Mak that
Tom Clark imports) and like it a lot. A Nazel is a major investment in
time, facilities and money.

Steve

> Over the years, I have seen many shop photo's/videos in which the smith
> has
> a nazel  air hammer. I assume these hammers are at the top of the food
> chain. I have never seen a nazel in a shop and few advertised for sale by
> private party. Does anyone on the list own one and how does it compare to
> a
> mechanical hammer they have used. How comparable are the other air hammers
> such as Kuhn, striker , Big Blu etc. What is the base price one should
> expect to pay for say a 150 llb to 250lb. decent shape air hammer?
> Just dreaming.
> Thanks,
> Bob