Fly Cutter

I came into possession of a Downham Mini Borer which can be used for light milling operations. I lacked tooling so I soon set to making a fly cutter with a 3/4" shank and indexable 1/4" and 3/8" HSS cutting bits.

Fly cutter

Unfortunately I didn't take any photos during the making. I began with a lump of steel that was largely the right shape; a little turning in the lathe removed the surface imperfections and reduced the shank to the correct diameter. Two 1/4" holes were drilled on the diameter close to the edge to allow the toolbit to be inserted and to provide a reference that allowed grubscrew threads to be made tangential to the cylindrical surface. Insets were milled and holes drilled and tapped for the grubscrews to hold the toolbits in place. One of the holes was then drilled out to 3/8" for it to accept a larger toolbit.

This fly cutter is by far the most frequently-used tool on the mill. I've used it to square-up a perspex block for a turner's cube and lots of little machining jobs like this camshaft setting tool.