[TheForge] Re: self contained air hammer

[Mike Spencer]

> A while back I noted that there was a good bit of talk about the
> making of an self contained air hammer.  Is any one out there
> persueing this still?

I just finished putting the A&O (self-contained) hammer together
today.  Just have to plumb the oiler and it's all back together.

Before I installed the valve and sleeve, I made some diagrams and
notes.  I think I pretty well understand how the valving works now
although I'm missing a couple of fine points.  I'll post some notes
and diagrams when I've had a chance to study my notes and the mfgr's
info a little more.

So far as I can see, the blows are mostly gravity, assisted by the air
pump a bit.  (The tup and die do, in fact, weigh just a bit over 300#
and the tup is *hollow*.)  In "heavy blows" mode, the piston is
connected directly to the tup via boring staright through the valve
body.  In 'hold up" mode, the piston sucks on the tup but a reed valve
prevents air going the other way.  In "hold down" mode, the reverse is
the case via another reed valve.  Rotating the cylindrical valve body
to shift gradually from hold-up to heavy-blows is alleged to permit
varying force of blows.  A quick blip of the valve is supposed to
deliver single heavy blows.  There's an exhaust reed valve on the
piston bore that I don't quite get yet.  It appears that the big
piston is more a sucker than a compressor because that weird reed
valve appears to release compression over all but maybe 25% of the
up-stroke and is adjustable over a range of about 3".

My son got one of the junker Chevs running pretty well this week and
we're going to try to jigger up an ad hoc friction drive.  Gee, I
might see this thing *actually run* in the next few days.

- Mike

-- 
Michael Spencer                  Nova Scotia, Canada       .~. 
                                 						   /V\ 
mspencer@tallships.ca            						  /( )\
http://home.tallships.ca/mspencer/						  ^^-^^

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