Nearing the end of the Must-Do list prior to starting the Jan Ridders engine.
Several years ago I bought a lovely 30mm boring head from Chronos in the UK. I had adapted it to the Unimat and kept it after that lathe was sold. For the engine I need to counter bore various holes to seat bearings, a perfect job for the boring head.
Lee Valley supplied the blank arbor, I bought 3 this time and milled the tightening flats on all 3 to save that setup when I need to make a custom tool.
A bit of turning, tapping with the die holder, polish up with emery cloth and oil to end up with a shiny new arbor. The thread is M10x1.5 .
The overhang is as short as I can make it. The 6mm boring bars will need to be razor sharp and small feeds to avoid flexing them. A test cut prior to making the arbor worked quite well. More practice aligning the cutting edge should result in excellent bores.