[TheForge] Re: Little Giant / pulley / rpm / ???

[Mike Spencer]

> I believe this number to be correct,  It is slow for a 25 # Little
> Giant -- most were set up to run between 350 to 400, 375 being a good
> number.  

Mine runs from a line shaft at 388 as calculated from the wheel sizes.

I've always assumed that there was a native or resonant frequency at
which a mechanical hammer was optimal and that the builders figured
that out, either by calculation and engineering or by the seat of
their pants.  For a given hammer head weight, that would depend on:

   + RPM of the shaft

   + Spring constant of the spring

   + Spring pre-load

   + The setting of the open-die adjustment.

Other contributing factors, such as varying size of work pieces and
the elasticity of the blow -- nearly perfectly elastic on a cold piece
but much less on a yellow-hot piece -- would cause things to depart
from any ideal setup. 

> Remember these hammer were built mostly for drawing out and for
> drawing out plow points as their bread and butter job.

I supposed that the makers would have tried to figure out some optimal
speed for just this sort of work. "How fast do you want to hammer?"
proposes that any optimal rate that might exist isn't important.

I have a computer model of the LG that I made some progress on several
years ago.  Ran out of Round Tuits.  It remains, for the moment, at a
rather elementary level.  But it *does* show [1] that speeds outside a
certain range lead to chaotic behavior of the tup.  I thought I might
get back to it this winter but it's been a hard, cold winter.  Here
it is nearly Spring and there's nearly 4' of snow on the field.  A
foot fell night before last.  We don't expect the climate of Moscow
here in coastal Nova Scotia.


- Mike

[1] Based on various informed but possibly wrong assumptions about
    springs, elasticity, momentum etc.

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