Pulley grub screw location

[booski]

That's all fairly reasonable. Not seen a 1/8 adjustable reamer yet but tempted with the 10mm.

What would be preferred though, interference fit or snug fit with grub screws?

And any more info on balancing with a scope?

My alu tube turns up soon so I can start building the spindle and once its done, ill get some pulleys.

I assume when turning shop bought pulleys its better to chuck up by the boss and not flanges?

[Jonathan]

And any more info on balancing with a scope?

Something like this:
Balancing Tool
Or you could use accelerometers...

I assume when turning shop bought pulleys its better to chuck up by the boss and not flanges?

Never hold them by the flanges - they're only pressed on and not very strong. Hold the pulley by the boss and it's sensible to check with an indicator that it's on center.