Many thanks everybody for kind, encouraging words and all the likes.Very good idea to mill the 9mm hole ! I think your both are right with sanding on the milling machine.
But I think the forces are too high to sanding on the sweet little MF 70.
The Scheppach Spindelsander costs 130 Euros here in Europe. Its better to invest than kill the MF.
Finaly you will buy both. A new MF and a Spindelsander. If you have a little fine exact tool, don´t use it for rough works !
...only my opinion.
But one thing. I dont want to kill your entusiasm because entusiasm is force, but the notches on one side of the beam are different.
For now, not a problem, but keep it in you eyes for future projects.
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You are absolutely right, Oliver. Notches on the fore part of the beams are not cut right through. Since I don't have small enough chisels (my smallest one is 16" - 1.6mm), I decided to cut yet another corner. I simply inserted a strip of wood of the same thickness as the depth of the notch, cut it off and sanded flush. Far from correct, but it will do. Mast partner will definitely have to be redone. What one sees in these closeups is phenomenal. Many thanks for your interest and advice.