[TheForge] treadle hammer design (was: treadle hammeranvils)

[Bruce Freeman]

Pete,

Garage door springs kill people when they're abused and nobody stops the =
abuse in time AND there's no safety cable inside.  Mostly the abuse is due =
to long streching of the spring.  These things start at 26" long but reach =
their rated force (e.g., 160 lbs) at 42" STRETCH.  That's 68" total =
stretched length, over 250% of their original length!

Now have a look at the Grasshopper in action:

http://www.monmouth.com/~freeman/bmf/GHanimNW.htm

You can see that the springs strech nowhere near this much.  It IS true =
that they are under tension in the rest state, but (1) there are safety =
cables designed in, and (2) there are shields designed in (mostly to keep =
fingers out) http://www.monmouth.com/~freeman/bmf/GHNWguard.jpg

Shifting the weight out on the see-saw hammer would not provide RAPID =
lifting of the hammer.

Bruce
NJ

>>> Artgawk@thegrid.net 01/24/03 04:27AM >>>
At 12:27 PM 1/23/03, you wrote:


I was wrong when i said that a split weight ( counterbalancing ) would =
be=20
slower..misread, sorry.
But if the hammer head only had 1/2 the weight  it would be less =
efficient=20
because the mechanism would absorb some of the blow. Think of how much=20
difference there is  just working on the heel VS the middle of the =
anvil=20
face.  When the hammer isn't directly above the work and/or the anvil =
mass=20
isn't directly below the work, considerable loss is the result. To get =
the=20
same forging effect, the counterbalanced assembly would have to be=20
considerably heavier than a conventional sprung TH. It would, however, =
have=20
some compensating virtues. If nothing else, those tensioned springs =
spook=20
me. Garage door springs kill people.
Larry, why bother with a light spring? just shift the counterweight out =
a=20
little.....Pete