On Mon, 16 Jul 2007 21:05:18 -0700, Andrew VK3BFA
wrote:

On Jul 17, 6:54 am, Wes wrote:

I gotta ask why are you fooling with a fly cutter when an insertable carbide
em is inexpensive if you shop around?

HTH,

Wes

Because I want to do it meself. Could go and buy a face mill, but
wanna do it meself.
Wanna learn how to make things rather than buy them...
Sick of being a consumer...

Andrew VK3BFA.
==================
Commercially available face mills and carbide insert fly cutters
[like the B-58] are reasonably enough optimized for commercial
high volume use in rigid high power machines, where the cost of
tooling is included in the job bid price, and stocking a variety
of inserts in the tool crib is accepted practice. Many of these
tools are designed with negative/negative rake.

In many [but not all] home/hobby shops, the mills are low power
and lightly built. From a power point, positive rake tools are
desirable, as are smaller size tools with 5/8 or 1/2-inch shanks
[e.g. 1/2 inch is the max size #2 MT collet available, 5/8 inch
is the max ER25 collet]

The "standard" fly cutter is designed for a single tool bit set
with 0/0 radial/axial rake. Of course you can grind in rake/hook,
but as you sharpen the tool you are also cutting it in two.

In general, home/hobby shop equipment does not have the
power/speed and more importantly the rigidity to effectively use
carbide tooling.

Creation of a fly cutter with built in axial/radial rake
[possibly 2, one for aluminum (c. +15 degrees) and one for steel
(c +7 degrees)] using inexpensive M2 late tool bits that most any
home/hobby shop machinist can easily shape/sharpen on a belt/disk
sander or inexpensive grinder makes perfect sense.

Fabrication of such a fly cutter is well within the capabilities
of all but the newest machinists, and requires only a minimum of
tooling, and inexpensive materials [1/2 or 5/8 inch stripper bolt
for the shank and a 2 X 2 X 1_1/2 block of steel], while
providing very useful practice in precision layout, shop math,
set up and milling. If 4 tool bits are used it is easy to set
the cutter up so that you have rougher and finisher tools, and
can employ different grinds/geometries. Try to buy one of
those!!! Negative radial [chips to outside] positive axial fly
cutters are also easily created.

FWIW - the commercial insert face mills use negative radial
[chips to the outside] positive axial rake because the volume of
chips produced and the number of inserts tends to trap the chips
"inside" the face mill. With only 2 or 4 tool bits and much
lower chip generation because of limited power, a multi tool fly
cutter on home shop equipment does not have this problem.

How many people would like plans for such a fly cutter?








Unka' George [George McDuffee]
============
Merchants have no country.
The mere spot they stand on
does not constitute so strong an attachment
as that from which they draw their gains.

Thomas Jefferson (1743-1826),
U.S. president. Letter, 17 March 1814.