Virtual Capstan

[Richard Brekne]

Bill Ballard wrote:

> Keep in mind that when you move a regular capstan towards the balance
> rail, what's being changed is the leverage of the key. Actually the
> formula should be, work done at the front of the key should equal the
> work done at the capstan (less amount of energy lost to friction),
> for any particular set-up. Because of the leverage change in moving
> the cap closer to the fulcrum, the capstan's motion is now decreased
> in relationship to the key front.
>
> Force at the front of the key needed to overcome the top action
> weight (BW-FW) is reduced, but the other consequence is that the
> front of the key has to move further. In this situation as well, work
> done at the front will equal work done at the capstan.
>
> What balances out is that you've bought the ability to move a heavier
> weight, at the expense of how far you can move it.

Which is exactly what a double capstan scheme overcomes... especially if
one of them is...compressable to some appropriate degree.

>
> >With your idea, however, the wippen and hammer move the SAME
> >distance with or without magnets (same amount of work at back of
> >key) but with different amounts of work at the front of the key.
> >This is actually a huge advantage because you do not have to
> >re-regulate dip/blow etc.
>
> The only reason to re-regulate dip/blow would be if you'd hanged the
> mechanical leverage ratio. Because the capstan is still in place to
> govern the rotation of parts, and because it hasn't moved, the
> leverage ratio is unchanged.

Ah... but it HAS changed... and thats the point.  Its been effectivly
split into two seperate issues. The weight aspect of the ratio has gained
in mechanical advantage, but not at the expence of distance.


> In this respect, springs and magnets
> offer the same thing. Let's hope that Antares isn't being too hasty
> in pulling out the springs out of his own action.
>

I dont think Andre does much of anything to hastily. Tho he and his
pawdner are certainly interested in pursuing this further. Gotta try it
out in the end to see if its good enough eh ? Paperwork and formulas will
only take you so far.


> Bill Ballard RPT
> NH Chapter, P.T.G.
>

Cheers
RicB

--
Richard Brekne
RPT, N.P.T.F.
UiB, Bergen, Norway
mailto:rbrekne@broadpark.no
http://home.broadpark.no/~rbrekne/ricmain.html
http://www.hf.uib.no/grieg/personer/cv_RB.html