Making Wrist / Hand Strap Inserts

[RWL]

Although inserts are available inexpensively ($2.50 apiece) from Concertina Connection, I decided to make the four that I needed. I measured the inserts in three different concertinas that I have (two Lachenals and a Wheatstone) and got three different diameters - 0.300", 0.320", and 0.330". When I install these, I'll need a flat bottomed hole. Since end mills produce flat bottomed holes and a 5/16" end mill is 0.312" diameter, I turned a 3/8" piece of brass rod to that diameter and drilled two holes in the end. I beveled one of the holes for a #1 wood screw, threaded the other with a 3-48 tap, and then cut off a 1/8" segment of the rod - presto, one insert. I beveled the hole in the end of the rod and cut another segment off, etc to get the four inserts I need. Photos below. The last photo of a single insert is copied from the Concertina Connection and illustrates a commercial insert. I'll start another post to get opinions on how to install the inserts.