I made these a few years ago I don't believe I ever shared 'em.

back story  I was  jonesing to try hand cutting DTs but was off put with the cost of a decent saw.

So I got some sheet rock mudding tools and scrounged up some hardware  I had a couple of real nice drawer slides from the 1960s made for the computer industry and military and some bronze bushings and all-thead and  I had a gear reduced Dayton motor  and the base from an old lamp and  a stub axle from an old car and set about to convert an unused plywood stand I'd built for something else but no longer used.

The result  was a reciprocating machine a lot like an old school die filer.  It held a little itty bitty file and went up and down on steel rods in guide bearings   It was served by the drawer slides mounted to more steel rods and guide bearings and all thread creating a little X-Y table for the sheet rock mudding tool blades.  I uses 1/4-20 all thread for the Cross feed so I could turn very a very precise 0.020" per revolution ERGO  20 TPI saw toothing,.  I built it so I could change out all thread and get different pitches. 

And Hot Dawg if it didn't work a trice.

 

All that and I got two rather nice saws that I use an awful lot

I learnes a few things about how to mount a handle to a blade.  Get it wrong and the blade Jams to a dead stop and won't budge for love or money.  Feels like it's nailed in place. It's just the angle of the pressure of the hand pushing.

Two little beauties, right there.