The easiest way is to modify an existing arbour but threaded chucks normally fit on power drills, they are not precision and any run out at high speed will be bad.
Placing a chuck on a router spinning at high speed would not be my first choice. I would contact this company, I believe I have seen there link on the forum here.
So you are saying I would be better off with a new chuck and a custum arbor?
I am on bit of a budget for now, so I would like the cheapest possible solution. And I mostly need to drill softer materials like Delrin/POM, Plywood and very occsionally some G10. So I dont have a great need for speed....
That particular chuck came from another (chinese) milling spindle, and I have used it with succes as a drill in the same mill. So I am pretty sure it can suit my needs until I can afford to buy a really nice chuck and custum arbor!
Bottom line: Can you point me towards a suitable combination of chuck/arbor? I dont have access to a lathe...
Been looking some more, and I think I can make this one fit my need with the chuck I already got:
The Kress can run 5000 RPM, which should be quite safe for drilling delrin and other plastics, I think! The other one could only go as low as 10.000 rpm and taht worked just fine....so I am pretty sure it wont be a problem!
But of course - in a perfect world you would not use a Milling spindle as a drill