Hello, the discussino is long time ago but i want to finish it!

I drilled my 3bill vario with 7,5mm. there are no vibrations!
It workes very good, because if you drill with example 7,5 then the hole is with 7,5mm and if is not exactly in the middle it doesn't matter because the weight is correct! It is only min.out of the center so you do not realize it. I drilled in 0,5mm steps.

I have the athena 70ccm kit and the perfect drill would be 8-8,5mm.