Bill Schwab wrote in message
link.net...
Hello all,

The added strength, no worries about slipping, and some extra work for
tool changes that go with R8 are obvious. $28+/- will get me either
three round shaft cutters or one R8.

Since I envision using a flycutter mostly for squaring raw stock, I'm
leaning toward R8, but would be easily persuaded the other direction.
Any preferences?

Bill

If you only want to do Mickey Mouse flycutting (3" to 4" diameter) then
something that mounts into an R8 or other mill tool holder will just about
suffice. For serious flycutting (8" to 12" diameter) you want something very
sturdy that clamps round the protruding nose of the quill and becomes an
integral part of it. A picture would be worth a thousand words but I'll try
and describe the one I made for my Bridgeport.

Part 1 is the clamp ring. Some mild steel scrap bar about 2" larger in
diameter than the quill nose and 1" tall. Bore through to the quill
diameter, machine or just hacksaw a slot through the side of the resulting
tube and drill and tap for a 3/8" UNC cap head screw to close the slot up.

Part 2 is the flycutter bar. Mine is 2" wide x 1" deep x 10" long. With
hindsight something even more rigid wouldn't hurt for roughing out. This
attaches to the underside of the clamp ring with two more 3/8" UNC cap head
screws. I slotted my bar so I can alter the cutting diameter. I also
countersunk the slot so the screw heads sit under the surface. This lets me
gets the tallest possible work piece on the mill table.

The cutting tool can be either a brazed tip carbide tool held in the
flycutting bar with a grubscrew or like me you can make a holder for a
carbide turning insert. Mine is a DNMG insert held in place with a 4mm screw
through the centre hole. You want a very sharp edged insert to get a clean
cut so uncoated non ferrous types for aluminium or cast iron are best even
if you're flycutting steel.

With a setup this rigid you can flycut engine blocks and cylinder heads and
put a mirror finish on aluminium with a slow feed and high speed. I can just
about take a 1mm deep cut on cast iron when I'm roughing out but the machine
and everything near it shakes and the noise is fairly intimidating. The
final 2 or 3 thou finish cut on a slow feed puts a finish on cast iron that
almost looks surface ground though.

The only thing I might do in the future is go to a PCD (polycrystalline
diamond) tool which lets you cut very hard materials as cleanly as a carbide
tool cuts aluminium.
--
Dave Baker