[TheForge] Re: long stroke cylinder (was Cylinder Size)

[Thomas A. Troszak]

> Message: 3
> Pete,  Yes, if you were to use it full stroke.  If you keep it to 5" out of
> the 10" open die space it should remain the same as my other one (208 bpm).
> 
> Ralph
> Subject: Re: [TheForge] Cylinder Size
> 
> 
>> Ralph;
>> Will the extra air volume of the long cylinder cause  a  slowed rate of
>> BPM?...........PF


I couldn't resist the temptation to comment on this.  My experience would
indicate that using only  part of the travel of a long stroke cylinder would
waste a tremendous amount of air because the entire volume of the each end
of the cylinder would fill with air and empty to an extent for each stroke
regardless of how far the piston moves, unlike a hydraulic cylinder.

I am aware that at high cycle rates, a certain amount of air remains in each
end of any cylinder as back pressure due to the ports being so small, but
this is only true at high speeds, according to my measurements with an
indicator. I have only taken cards on my own hammers, so it would be
fascinating to take a card on a "Ron Kinyon style" hammer and measure back
pressure,  horsepower, etc.  In any event, I don't think that even this
phenomenon would save you much in the case of a 20 in. cylinder with a 5-10
in. stroke.

A couple of years ago, I had the opportunity to examine a Trip-Air hammer
which, I think (please correct me if I'm wrong here) operates on much the
same principle as the Ron Kinyon design. One of my concerns was that the
hose leading to the exhaust valve appeared to be connected to one end of the
cylinder all of the time, and would have to be filled with air every stroke,
which is not only wasteful, but diminishes the control and "authority" of
the ram, making it kind of "rubbery" stopping on the down stroke.  It would
also slow the cycle rate down because of the time it takes to fill the hose
every stroke. 

If I remember correctly, this hammer also had a spring return pilot, which
is also slower than the double air pilot.

The Trip-Air was the first of the "Kinyon-style" hammers that I had ever
seen, but by the time I saw it, I had already come up with my own idea for
cylinder and the valving anyway, which uses similar components, but is based
on a completely different "theory" of operation.

Please don't take any of this a a criticism of Ron or his design! Ron is a
great guy, and his hammer design is Fab, and many smiths are making tons of
great work with his hammers.

Tom Troszak