Less Is More, or Supercharging A Mill File For More Precise Metalworking

Not too long ago I discovered something that perhaps many of you knew already (and if so, why didn’t you tell me?), and my response to the problem and solution imparted great satisfaction.

Being both a metalworker and a tightwad I  am pretty fussy about my files, and in fact have a substantial number of them.  One I could never talk myself into getting was a die-maker’s mill file with one shoulder devoid of cutting function.  All the ones I had seen while shopping were simply more money than I wanted to spend.  Since this is a utility I need on a fairly frequent basis I generally just put a strip of tape along one edge of the file so I could work into one side of an inside corner without boogering up the adjacent shoulder.  Perhaps I had some bad tape but recently I was continually frustrated as it peeled off while I was working the inside corners of the Roubo squares.

I decided to deal with the problem once and for all.

I took my new-ish mill file to the disc grinder and very gently just ground away the teeth/grooves on one edge.  I say “gently” on purpose because I did not want to heat up the tool and have it lose its temper.  So gently it was.

After that I took it to the vise and dressed the sanded edge to a fairly nice polish (1200 grit diamond stone).  In almost no time  (less than ten minutes) and for no money(!) I had a die-maker’s mill file that allowed me to work both more aggressively and more precisely on inside corners.  And if I need to do any edge filing, I simply rotate the file 180 degrees and use the opposite edge.

I hope I don’t hurt my shoulder patting myself on the back…