Phillip Allen wrote:

> How do I determine what size hole to drill for these [3.45 mm] tuning pins?

Trial and error: do some test holes in a piece of wood of the same 
species as the wrestplank. I'd try a 3.4 mm drill first. But drills do 
not always drill *exactly* the nominal hole size in wood, and such 
things as the roughness of the pin affect force needed to turn it in the 
wrestplank, so as always trial and error is your friend.

> How tight should the pin be in the hole?

Common sense should tell you the answer. Tight enough for it to stay put 
when the tension is on the pin, but free enough for it to turn quite 
smoothly with the leverage of your tuning key. Tensions on a clavichord 
are not likely to be in excess of about 9 kgf so the usual fault is to 
make the pins too tight rather than too loose. I would not go so far as 
to say (like Ed Kottick) that if you can't turn it with your bare hands, 
then it is tight enough, but he is on the right lines.

> How far down the hole should one be able to insert the pin before it
> requires hammering?

You will not be able to push it in very far with your bare fingers - 
just the tapered part and 2 or 3 mm more (basically the thickness of the 
soundboard covering the wrestplank). But DON'T hammer the pin into the 
hole. Push down with the tuning key, turning this way and that. If you 
can't do this, the hole is too tight. [I know some members of this list 
will disagree with this.]

In practice about 20-25 mm finishing up buried in the wood is sufficient 
for most clavichord pins, but it does depend a bit on the length of the 
pins and the depth of the case rim, and the amount of downbearing etc. 
etc. Drill the holes deeper than this so the pins are in no danger of 
bottoming out.

Peter.


-- 
Peter Bavington
Clavichord Maker
291 Sprowston Mews
LONDON
E7 9AE
www.peter-bavington.co.uk

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