Another start-point picking problem

I am still wrestling with the problem of finding start points. In this Exercise (6.119 from Giesecke F.E., Mitchell A., Spencer H.C., Hill I.L., Dygdon J.T., & Novak J.E. (2014). Technical Drawing. Upper Saddle River (NJ) USA: Prentice Hall p.214) I laid out the underside of the item first.

Aside from Extension 18 which is a repair, I think this is okay but I will appreciate constructive criticism.

BTW: can someone tell me why this

edge refuses to fillet?

Thanks

6-119 Boom Swing Bearing for a Power Crane.pdf

6-119 Boom Swing Bearing for a Power Crane.ipt

Try filleting the inside corners first, then apply the rounds on the outside edges.

Try filleting the inside corners first, then apply the rounds on the outside edges.

I tried all sorts of combinations, but in the end it appears that even Inventor gives up and I had to make one of the fillets at half the radius.

Inventor says the calculations are too complex, and I can believe them. Patternmakers have some putty-like stuff for situations like that!

Thanks for the advice.