Hi, MMD:  I read the new group "rec.crafts.metalworking" a good deal,
and while those guys can build just about anything (e.g., model loco-
motives driven by steam) it occurred to me that you piano people might
know how to make or obtain counterfeit wood screws.  I've included his
entire letter, including his address.  It would probably be more useful
if any replies went to him instead of me -- my principal use for wood
screws is for splitting large pieces of wood into smaller pieces of
wood.

Mark Kinsler -- giving that screw head one more mighty twist...


 -- forwarded message, please reply to sender and MMD --

From: tknostf@foxvalley.net (Richard Anderson)(fwd)
Article: 114415 of rec.crafts.metalworking
Date: Sat, 22 May 1999 10:47:32 -0500

I need to make very large wood screws to replace broken or missing
ones on 75- to 150-year-old pianos.  Please note I'm talking about
making screws out of metal for wood, not making screws out of wood.
The threads look like pointy acme threads.  Does anyone know what
kind of tooling is used to cut wood screw threads?  I haven't had
much luck grinding my own.

I have an inventory of every available wood screw currently made.
The screws I need to reproduce are often size 30 or greater (no they
are not lag bolts), and have a head shape or thread pitch that is
unique to an individual manufacturer.  Most piano makers made their
own hardware back then.  For example, in my shop we have a saying,
"there's standard and then there's Steinway."  Steinway made fasteners
that are almost a modern 1/2" lag screw, but they have the thread
pitch of a 3/8" lag.

Although I can plug, re-drill, and use any other fastener I want,
I got my lathe specifically for making these odd screws.

The difficulty with making wood screws is that they are tapered
(I've got a taper attachment) and they don't have standard 60 degree
threads.  The included angle of the lands is about 60 degrees, but
there is a width of thread root between the lands that varies with
the size of the screw.  The root diameter also changes within each
root width.  It's a sort of saw tooth or stair step taper.

I'm wondering if I can use milling inserts (DGMs perhaps) in some
sort of AXA holder.  Has anyone made any wood screws?  Are the threads
cut toward the chuck in front, or away from the chuck in the back?
I've tried both with mixed success.

Richard Anderson