"Karl Townsend" wrote in message
...
snip-

I hate to hihack iggy's thread. Well,not really.

Knurling is one lathe operation I still F$%^ up and don't know what
was wrong. I did go to a scissor type tool so the machine doesn't
provide the force and its balanced on forces. But sometime it still
comes out double tracked and I don't know why.

Care to look up or repeat your advice?

Kar

Karl,
It's all in how you start the knurl. There's generally two scenarios---one
whereby you knurl from the end of a piece to some predetermined width, and
the other is starting a knurl anywhere but the end of a part. The technique
is similar in that depth is critical.

For starting a knurl on the end of a piece of stock, try this. Follow the
instructions exactly as I present them---it almost never fails, and when it
does you can try a second time. Be advised that this method has the
potential to go too deep, so it's not a bad idea to have a little extra
stock on the part that can be faced off, or you can chamfer the piece to
eliminate the undersized area. It's always nice to chamfer the end of a
knurl, anyway, to avoid getting cut.

I read your comment about the scissor type of tool I'm almost embarrassed
to say, I started in the shop back in '57, and I've never used one.
They're good. In fact, damned good, but I have no experience with them, so
I can't address how it would work for these instructions. I expect not too
good.

Ok, lets get started. I'm going to assume you'd use the conventional
knurling tool, one that mounts in the tool post, and is not a scissor type.

Align the tool so it is parallel to the part, and on center. Start the
spindle, and move the knurling tool to the very end of the part, so only
about 1/16" of the knurls will contact the rotating piece. Oil the tool
and work piece, then rapidly plunge the knurling tool in to the rotating
part (which should be rotating at a modest speed). Try for full depth of
the knurl immediately. This generally doesn't permit the knurl to split.
If it does, chamfer the knurl so it can't guide the next attempt, then
rotate one of the wheels slightly and move over another 1/16". Repeat. If
the knurl starts successfully, back off slightly (don't try for full depth
with one pass) and run the knurl to length, using a coarse feed (.010" or
greater). If the tool is square with the part, you can knurl in either
direction with equal success. When you hit the length desired, reverse the
machine if you have that capability. Otherwise reverse the feed. Take as
many passes as are required to achieve the depth that pleases you. I'm a
full depth kind of guy, like to see the knurl pointed. YMMV. My
experience with this method, and I've pressed hundreds of knurls, is
virtually 100% successful.

If you must start a knurl away from the edge of the part, make a couple
pencils marks on the rotating material that define the boundaries of the
knurl. With the spindle running at a modest speed, locate the wheels
between the two lines, but favor one side or the other, for you're going to
move the carriage as you engage the wheels. I like to move the carriage
towards the headstock, so I generally pick near the left hand line to start
the knurl. Oil the tool and part, then rapidly crank the cross slide in
as you move the carriage to the side. Insure that you've cranked deep
enough that the knurl is well defined. If you don't, it can split. Take
note if the knurl is proper as it comes around. If it has split, pull out
and move over and repeat, after nudging one of the wheels. When the knurl
is acceptable, you can track right over the other one, which it will
correct, assuming you have the proper knurl to an acceptable depth.
Using the same method as above, feed side to side and deepen the knurl to
your satisfaction.

The above applies to a diamond knurl only. A straight knurl won't respond
in kind, although if you have poor spacing, you can generally knurl again
and again until the metal has cold flowed to yield a proper knurl. It does
that by shedding metal until it's the proper diameter. Much easier to start
with the right diameter.

Hope this helps.

Trust me---it works! ;-)

Harold