Door hinge turns

For doing delicate, precise work, between-centers turning on a lathe is preferable.  Generally, in the past this was done using a set called "the turns", a manual lathe of sorts.  I saw a pivot polisher setup by Charles Davis made from a door hinge, so this is my rendition of that idea.

Start by knocking the pin out from the hinge, and cut out the middle loop:

Then, I clamped the hinge on my lathe face plate and drilled holes for the locking screws:

While still secure in the lathe, I swapped out the tailstock drill chuck for a tap and threaded the hole:

The threads were checked with the thumbscrew:

Repeating on both slides and deburring results in a mostly complete turns frame.

Now for some centers... I made two from the hinge rods, since these seemed sturdy.  I started by center drilling the ends

and the tapering them.

I also filed flats on the side of each center, to ensure a stable grip for the thumbscrew.  Here two female centers are mounted in the frame:

The frame is intended to be used under magnification, and needs to be lifted to the microscope stage.  In order to mount the hinge to the top block, rather large screws are needed to not slip through the holes.  But I did not have any screws short enough to remain flush with the bottom of the block.  So I simply cut off the screw threads and made them into pegs that are hammered into the block.

Here is the completed setup under the microscope, ready for use.

Now for the bad news...  The Charles Davis setup is supposed to be powered by a squeegie blade, and is intended for clocks.  I'm intending for this to be used on watch arbors, and also didn't have a squeegie handy.  So I tried several other options, none of which worked...  For future reference, I tried:

• kite cord on a bow
• thread on a bow
• 30 gauge kynar wire on a bow
• 15 lb monofilament line on a bow
• various things with rubber bands.

In each case, I tried to drive a small balance staff directly, like the Charles Davis setup.  Most of the literature suggests using a carrier of some sort for watch arbors, which I don't have.