In article ,
GTO69RA4 wrote:
I've been going through some buckets of tooling I've accumulated, and here are
a couple things I haven't been able to ID:

http://members.aol.com/gto69ra4/Photos/whatsit1.jpg
http://members.aol.com/gto69ra4/Photos/whatsit2.jpg

First one is about 3" long, steel, has rosewood inserts on either side. Two
edges are beveled but not sharp, the other two are flat with a small groove
milled down the middles.

Hmm ... this one I'm not sure about, but as a guess, it might be
intended for checking the angle of a dovetail when scraping it. Depends
on what the included angle of the beveled edges is, of course.

Second is also steel, about 5" long. Some of the holes are threaded, some
aren't. The two tube sections on either end are held on with headless screws
from the other side.

However, this one is quite obvious. It *used* to be a sine bar,
but with that rust, especially on the rollers, and probably on the top
surface (not visible in the photo) as well, it is no longer capable of
the accuracy for which it was made.

The rolls should be *precisely* 5.000" apart, and *precisely*
the same diameter. The roll on the lower tight hand end (as
photographed) rests on a surface plate, and the one on the upper left
end rests on a stack of gauge blocks built up with the help of a sine
table and the knowledge that the centers are 5" apart. (Multiply the
sine of the desired angle by 5, and build a stack of gauge blocks
precisely that high to generate the desired angle. The threaded holes
are for attaching extra fixtures to the bar, for holding the workpiece,
perhaps for use in a surface grinder or something similar.

Now to see what others have said.

Enjoy,
DoN.
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