Ken Sterling wrote:



Interesting, John. Did you use an arbor press, vise, or what to press
the cutter through? Were there any specs (that you remember of)
concerning the "height" of the cutter/and the bar stock the cutter is
milled into? (or the depth of the slot into the bushing?) Thanks.
Ken.

I believe that I used an arbor press. That isn't critical, though, as
the force needed to drive the single point cutter isn't very great.
The pulley that I keyed was aluminum, but I don't think steel would
have been that much more of a problem. My arbor press is an old
Greenerd #1 which is rated at 1/4 ton. While I suspect I often
overload it, it didn't require a huge amount of pressure to cut the
keyway. A multi-toothed broach would have required much more pressure.

Made and used this cutter maybe 15 years ago, so I can't remember the
specs. But I still have it, so I measured.

Pulley bore .875", bushing turned to a close sliding fit. Keyway and
cutter tooth width .1875". The cutter is actually a piece of .500"
square stock, milled to that .1875" width, centered, for the top .25"
or so. Profile is like that of a nut for a T slot.

There is no good reason to make the cutter that T profile rather than
simply to the width of the keyway. All I had for a mill at that time
was a milling column on a Sherline, which was not the greatest at heavy
cuts in steel. And it gave me a better finish on the bottom of the
slot than the sides. So I opted to use a wider bottom rather than the
sides of the slot to keep the cutter from rocking.

The single tooth is no wider than the body of the cutter is at the top,
so there is no side clearange or side rake. The cutting edge is proud
of the top surface of the cutter by .014", both in front of and behind
the tooth. The top surface of the tooth has 2 degree clearance. The
front of the tooth is at 72 degrees - 18 degrees of rake. The front
and top of the tooth were lightly stoned after hardening.

The overall length of the cutter is about 4", but only the first 2"
have the leg of the T sticking up. The tooth is about centered in the
2" T section, with the long tail behind it allowing it to be pressed
completely through the workpiece.

With my cutter having such a wide base, the slot is obviously milled
deep into the bushing. Deeper than it has to be, as I used a lot of
shims. If you use a cutter the width of the keyway, a deep slot will
better prevent any twisting of the cutter. As above, mine relied more
in the wide bottom for that.

Hope this helps,

John Martin