Using a metal cutting burr with a router...?

[Edward]

In my case, a Sieg2.7 probably about the same size as yours I think, I machined the top of the ballnut flange a little , about 2.5mm, so I could still use the two top side holes of the flange, and this allowed the ballnut to fit under the table, so the table didn't need any machining at all. Then I had to machine the end side of the saddle (that's where the ballnut housing goes in my machine, I think yours may be in a different place) I just ground a little crescent concavity for the bottom of the ballnut to sit on.

After doing that, the ballscrew had a clearance of about 2mm from the saddle, but unfortunatelly at the other end of the saddle, the clearance gradually diminished as the casting was irregular, not level. So I just had to groove that end a little to allow the ballscrew to clear by about 1 mm.

When fitting the end plates, I found that the existing threads at both ends of the table were not tapped perpendicular, they were clearly askew, you do find surprises here and there, but you somehow work around them:)

Although I feel your excitement, I think there is no point in planning anything too seriously until you actually get the mill, then you will be confronted by the real problems.

For cutting the top end of the ballnut flange I used a little dremel cutting disc, ( took 5 minutes) but I think if I had had a proper grinder, it would've been done in no time.

I too worried about the metal stress, but hopefully I didn't grind too much metal to cause any trouble.

Edward