I've been meaning to make a couple of Oland tools.
http://www.aroundthewoods.com/oland.shtml

Previously I've just welded a piece of 3/4" bar to a similar length of
3/4" thickwall tube (for balance) and then wrapped the handle in
neoprene foam strip (Armorflex pipe lagging - it's like foamy gaffer
tape!).

My question is how best to mount the HSS square bar lathe tooling. This
bar is square, yet most descriptions talk about drilling a hole and
clamping it with a grubscrew. A square hole ?

How do I make the nose to take the insert? Is this a drilling process
or (as I've done so far) welding it up and grinding the outside round
(works fine, but it's 5 pieces!).

Is there any real advantage to using a grubscrew, rather than just
brazing the insert into place?