Hi,
The procedure that Ted describes (Thanks, Ted!) is very like what I
used to use (and probably would again...but, only in some kind of
purgatory) for working with leather plectra.
My process differed, I think, only in using leather outsoles (much
more available a couple of decades ago...and, in much better quality,
too, than anything any of the supply houses had, even then. Part of
the problem is that they simply had sheets or rolls of
leather...which might or might not be either thick or stiff
enough. With an outsole, you already had a differing density and
flexibility of the leather as you worked through the thickness from
one side to the other. Harry Ohlund, of Long Beach, CA, whom some of
you may remember from a very long time ago is the one who put me on
to this...and, while still more labor intensive that I would prefer,
the system works very well.
Here's a link to a page with some tools like I have used for the
process. I think being able to see pictures of what I'm describing
will make more sense:
http://www.mainethread.com/cutting_tools.html
Obviously, some preliminaries are knowing how wide and thick the
eventual plectra need to be. Once that is determined, I used a Draw
Gauge (like the Osborne #51 - 1/2) to cut strips of the
outsole...cutting so that the most clean part of the cut was where
the "hardest" leather would be (the part that would otherwise
actually have hit the pavement).
Once that is done, I found the "Skife", what I think is an Osborne
original design, very useful for cleaning up the rougher side of the
strips without too much waste or danger of cutting too deeply. This
tool is also very useful for voicing.
The Sloyd style knives or actual Skiving knives are useful for making
precision cuts and/or index marks when you need them.
I've personally found tools like incising knives and swivel cutters
to be almost too "quick" for this kind of work...but, I'm a Luddite.
As Fred and Ted note, getting the correct 45 (or so) degree angle is
imporant, and that's another place that I found the Skife to be helpful.
Fred's point about "massaging" the leather is really important. I've
seen and followed some otherwise good to excellent jobs and pretty
consistent seen that whatever voicing was done was accomplished with
a knife while the leather was still new and relatively inflexible.
Ah, rereading Fred's' comment below one other thing occurs to me
about voicing leather plectra is that this is another reason why I
think the outsole leather is vastly superior to just about anything
non-delrin for this use. That said, though...part of the joy of
working on period instruments is knowing that they're going to be
uneven in so very many ways....
Kind regards.
Horace
At 02:37 PM 8/11/2011, you wrote:
>Thanks for sharing those details, Ted! That is an excellent
>procedure for preparing plectra, especially if you have taken care
>to find leather just the right thickness, a wee bit thicker than the
>mortise is tall so it will hold securely. My experience is in using
>the stuff the makers and suppliers offer, which is provided in
>strips that are both too tall and too wide. So the first challenge
>is to trim those to fit the mortise. It is one thing to cut leather
>2.5 mm wide (or the like), another to try to trim 3.5 or 3.0 mm leather to 2.5.
>
> In any case, once you have got the right dimension material, with
> the right amount of stiffness (a lot), it is not a very precise
> operation to voice, as delrin can be. You can shave miniscule bits
> of delrin and trim to length very precisely. Leather is far coarser
> deal with. Essentially you just figure out a taper, cut that taper
> by eye before inserting it in the mortise, and after that it is
> just trimming length. It is essentially impossible to correct the
> taper once it has been made. You need 45 degrees or so at the tip
> so it will escape past the string, and usually any finesse is done
> with a tongue adjusting screw or just massaging the leather. As
> long as you aren't too particular it is OK, but being used to
> working with delrin, I find it maddening in the lack of finesse to
> touch and tone.
>
> But I'd be very interested to hear more details about procedures
> people use, what works, what doesn't. I try to keep an open mind,
> and would be happy to get a different perspective.
>
> Sambell "I replaced all the leather plectra on a four rank Challis
> many years ago."
> -------------------------------------------
> Fred Sturm
> University of New Mexico
>
fssturm@unm.edu
> "The true sign of intelligence is not knowledge, but imagination."
> - Einstein
> -------------------------------------------
>
>
>
>
>
>
>