Model Forum / General / Models / April 2009

With a multi tooth cutter clearly you can remove stock faster but you also
have to align the tips very accurately or you still get grooves in the work.
My single point flycutter for engine heads and blocks was made very easily
for free out of bits of scrap and can generate a finish you can see your
face in. The key is rigidity and mounting anything like this on an R8
fitting is not the best recipe for that.

I made my system to clamp round the nose of the quill so it becomes an
integral part of the milling machine rather than something dangling loosely
out of the end of it.

The cutter bar is a big chunk of 10" x 2" x 1". This screws to a clamp ring
made from 4" diameter stock about an inch thick which was bored to just slip
onto the quill, slotted and then drilled and tapped for a clamp bolt across
the split line. Two 3/8" threads were tapped into the face of this and the
cutter bar screws up into those. The bar is actually also slotted so I can
adjust its operating diameter from about 8" up to 11" at a pinch.

The cutting tool is a standard carbide lathe insert mounted on a bit of 3/8"
bar which goes into a hole at one end of the cutter bar and is held with a
grub screw. You could just as easily use an off the shelf brazed tip tool on
a 3/8" shank or similar.

It takes about 20 to 30 minutes to run a finishing pass across an 18" long
cast iron cylinder head or block and about half that at higher speed and
feed for aluminium ones. At a slower roughing feed I can take 1mm cuts in
iron or 2mm ones in aluminium although I rarely work it that hard. 50% of
that in either material gives the tip an easier life. Time is not really an
issue with the flycutting because I can get on with other things while it's
working although the tendency is still to stand and watch it with a fag in
one hand and a cup of coffee in the other :)

It's very relaxing watching a good piece of equipment do its thing.