[TheForge] Re: Krause/Nazel type air hammer

[Mike Spencer]

> The difference is that the rectangle opening has a linear change and
> the round hole has a progressive change for the same amount of
> movement of the handle.

That makes sense.  But then one should be able to hook the treadle to
eccentric gears or the equivalent that compensate by offsetting the
non-linearity of the valve opening shape.  I've never seen such gears
that I recall (unless it was in the Boston Science Museum) but I've
seen pictures of them in old books on engineering mechanisms -- late
19th century stuff.  Anybody know where you could salvage such gears?
I think you could even make them just by re-boring ordianry gears.

FWIW, the valve on my as yet inoperative A&O self-contained hammer is
a cylinder some 6" in diameter and over a foot long, cast iron, with
rectangular openings and thin, metal flap valves over the openings.
Notably, the flap from one opening is missing so I now wonder if the
last owner to actually use it had full functionality.  I have some
figgering to do.  The blueprints kindly supplied by A&O's successor
company just show "valve" but no details.

Unclear?  Pix?  I hope some picture of the valve will be available
on line some time this winter.  Maybe as soon as next week if the friend
with the digital camera makes the promised visit and doesn't get
snowbound in Cape Breton.

- Mike

-- 
Michael Spencer                  Nova Scotia, Canada 
                                 
mspencer@tallships.ca            
http://home.tallships.ca/mspencer/