In article ,
says...
On Fri, 15 Jul 2005 12:52:32 -0400, Ned Simmons wrote:

In article ,
says...
On Thu, 14 Jul 2005 18:50:40 +0000, Tom Gardner wrote:


The part I need thoughts on are how to pre-load the carbides in such a way
that it is easy to unload to change the carbides...(notice I get 8 cutting
edges on each insert!)

Tom, this might be a crazy idea, but I wonder if it'd be too complicated
to incorporate a mechanism to rotate the cutter 90 degrees on each return
stroke, thereby presenting a "new" cutting edge to the work on each cutting
stroke. This would make the cutter last 4 times as long between changes,
requiring the cutter only to be flipped over when dulled. I'm imagining some
sort of a ratchet/indexing mechanism.



With the right details it's possible to do this passively.
The rotating tools need to have a circular form and the
force that drives the rotation is usually a result of
placing the cut point somewhat off center. I've built
cutters for tungsten wire (tungsten is horribly abrasive)
that operate up to 1800 pieces per minute with auto-
rotating tools.

Yes, that's much better for a number of reasons. When I was writing up
my description I was thinking what a waste it was to not be able to
use up all of the cutting edge on each face of the square cutter. With a
passively rotating circular cutter, much more of the total cutting surface
can be exploited. I would think that another advantage to an offset
circular cutter would be in its cutting action; more of a slicing
action than a chopping action (think of the angle on a guillotine
blade), potentially reducing burrs and reducing the power needed
to make the cut (and that saved power can be translated
into increased speed).


Exactly, but you have to be careful how far off center you
go or you can have problems with the wire slipping out of
the desired nip point as the shearing angle between the
blades gets too large.

Ned Simmons