Decided to do a bit more to the crank webs tonight..
First thing was to drill and tap the holes for the clamping screws. I used a center and the mill to find the center between the two rods. The center finder is 5mm and the mill showed me a 1/2mm gap. Exactly as it should be
So let the center finder kiss one rod and back away 1/4mm. Perfect.
Using the stop each piece was center drilled, note the use of a Stanley knife blade to lift the 4mm rod.
(the rods are 4 & 5mm dia, so from the center line the 4mm rod is 1/2mm shorter than the 5mm, the blade is exactly 1/2mm)
Drilling the 2.1mm hole right through. Note the liberal use of WD40, I find Stainless a bear to drill as it work hardens in a flash, grabs the drill bit and snaps it off. Or it just rounds the end of the drill bit.
So what I did here was use cobalt drill bits, plenty of fluid and peck drill leaving plenty of time to let things cool. It worked a treat.
Then I drilled 2.5mm to half the depth for thread clearance. Finally the remaining half of the hole was tapped 2.5mm.
Not a very clear picture, the parts where marked with a sharpie that Ralph left behind the other day
and two center lines scribed with digital calipers from both sides. This leave two marks with a tiny gap in between. This shows the true center and any error clearly.
My slitting saw didn't like SS
So I attacked it with a junior hacksaw.....
A bit more cleaning up and they are done
Unless you are really sad like me, forget SS here, you might find brass to be much easier to work with