Welded construction for surface grinder arbor?

[Flynth]

It turns out there is welding /brazing used in this project after all...

I had to braze extra weight to the weight I previously ground down. Also I opened up the groove they ride in by half mm (on diameter) and they fit very nicely.

This is the bottom side so it will be invisible ant it was ground down to just add 2g to the weight.

Interestingly, with a grub screw each weight came to almost exactly 50 grams. I suspect that's how they designed it

This wheel hub and weights must be the most complex part in the entire machine. Having spent so much time making an extra I'm not surprised so much by high prices they want.

 

[Flynth]

I "found out" what those grooves are for. I feel pretty stupid not noticing it immediately, but they are actually a square profile thread. I think they are some sort of a manufacturing fixture holding system.

I noticed it myself that regardless how tight the 3 jaw chuck is and how nicely turned the gripping area is the part will move during drilling of the large hole in the front. I resolved it by loosening my 3 jaw after roughing and indicating the part, pushing it by giving it taps with a lead weight, then re-tightening. This way I can have about a thou of runout at the furthest from the chuck. Using a strong square thread to hold it makes complete sense.