Can somebody explain to me the basics of knurling? My machine shop
teacher showed me how, but screwed it up and explained nothing as he did
it. /:
Also, the knurls I wound up with I kind of flattened. I found I had
to drill the piece out a little more after I'd already knurled it. It
hung on the drill and spun in the chuck. Oops. The chuck flattened all
of the knurls nearly out of existence. Can I repair this by knurling
again, or do I need to take a light cut (it's just a handle, so
dimensions don't matter much) before knurling so I'm starting with a
smooth surface? The piece is steel. I don't care about how it looks, I
just don't want to damage the knurling tool.

--
B.B. --I am not a goat! thegoat4 at airmail dot net
http://web2.airmail.net/thegoat4/

In article ,
B.B. u wrote:
Can somebody explain to me the basics of knurling? My machine shop
teacher showed me how, but screwed it up and explained nothing as he did
it. /:

It is simple enough -- the knurling rollers displace metal,
pressing it down in one area to form the grooves, and allowing it to
rise in between, to form the peaks.

You do need to make a fairly strong knurling pass, so the knurls
will self center when they come around again -- otherwise you will wind
up with double-pitch knurls or other problems.

You want to flow a lot of oil through the interface between the
knurls and the workpiece, and to be running a very slow spindle speed.

The best standard knurling tools are the scissors style, which
applies one knurling roller to the top of the workpiece and the other to
the bottom, putting all of the force into the hinges on the scissors
knurling tool, instead of requiring the cross-slide and the compound to
provide all of the force. (But I'll bet that the school only has bump
knurlers -- but that the machine is strong enough to handle it.)

Also, the knurls I wound up with I kind of flattened. I found I had
to drill the piece out a little more after I'd already knurled it. It
hung on the drill and spun in the chuck. Oops. The chuck flattened all
of the knurls nearly out of existence. Can I repair this by knurling
again, or do I need to take a light cut (it's just a handle, so
dimensions don't matter much) before knurling so I'm starting with a
smooth surface?

Not necessary -- it will give a starting place for guiding the
knurls to pick up their step.

The piece is steel. I don't care about how it looks, I
just don't want to damage the knurling tool.

Unless the steel is thoroughly hardened, you probably *can't*
damage the tool, except by running it dry -- remember *lots* of oil, and
slow speeds.

Next time you need to work on something already knurled, take
some soft aluminum or copper stock (say 16 ga (0.625") or so and put it
between each chuck jaw and the workpiece, giving you a better grip and
avoiding damaging the knurled finish.

Good Luck,
DoN.

* Notice that above I said "standard" knurling tool. There is another
style which cuts the knurls, instead of deforming the workpiece.
It results in crisper knurl finishes, but they are typically
*very* expensive, and won't be found in a school shop. They can
be identified by the fact that they present a sharp edge to the
workpiece instead of the middle of the roller.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

Also, a piece of round alum/brass would be even easier to knurl.
Looks nice.
----------------------------
Mr. P.V.'d
formerly Droll Troll
"DoN. Nichols" wrote in message
...
In article
,
B.B. u wrote:
Can somebody explain to me the basics of knurling? My machine shop
teacher showed me how, but screwed it up and explained nothing as he did
it. /:

It is simple enough -- the knurling rollers displace metal,
pressing it down in one area to form the grooves, and allowing it to
rise in between, to form the peaks.

You do need to make a fairly strong knurling pass, so the knurls
will self center when they come around again -- otherwise you will wind
up with double-pitch knurls or other problems.

You want to flow a lot of oil through the interface between the
knurls and the workpiece, and to be running a very slow spindle speed.

The best standard knurling tools are the scissors style, which
applies one knurling roller to the top of the workpiece and the other to
the bottom, putting all of the force into the hinges on the scissors
knurling tool, instead of requiring the cross-slide and the compound to
provide all of the force. (But I'll bet that the school only has bump
knurlers -- but that the machine is strong enough to handle it.)

Also, the knurls I wound up with I kind of flattened. I found I had
to drill the piece out a little more after I'd already knurled it. It
hung on the drill and spun in the chuck. Oops. The chuck flattened all
of the knurls nearly out of existence. Can I repair this by knurling
again, or do I need to take a light cut (it's just a handle, so
dimensions don't matter much) before knurling so I'm starting with a
smooth surface?

Not necessary -- it will give a starting place for guiding the
knurls to pick up their step.

The piece is steel. I don't care about how it looks, I
just don't want to damage the knurling tool.

Unless the steel is thoroughly hardened, you probably *can't*
damage the tool, except by running it dry -- remember *lots* of oil, and
slow speeds.

Next time you need to work on something already knurled, take
some soft aluminum or copper stock (say 16 ga (0.625") or so and put it
between each chuck jaw and the workpiece, giving you a better grip and
avoiding damaging the knurled finish.

Good Luck,
DoN.

* Notice that above I said "standard" knurling tool. There is another
style which cuts the knurls, instead of deforming the workpiece.
It results in crisper knurl finishes, but they are typically
*very* expensive, and won't be found in a school shop. They can
be identified by the fact that they present a sharp edge to the
workpiece instead of the middle of the roller.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

B.B. wrote:
Can somebody explain to me the basics of knurling? My machine shop
teacher showed me how, but screwed it up and explained nothing as he
did
it. /:
Also, the knurls I wound up with I kind of flattened. I found I
had
to drill the piece out a little more after I'd already knurled it.
It
hung on the drill and spun in the chuck. Oops. The chuck flattened
all
of the knurls nearly out of existence. Can I repair this by knurling

again, or do I need to take a light cut (it's just a handle, so
dimensions don't matter much) before knurling so I'm starting with a
smooth surface? The piece is steel. I don't care about how it
looks, I
just don't want to damage the knurling tool.

--
B.B. --I am not a goat! thegoat4 at airmail dot net

http://web2.airmail.net/thegoat4/

If you go back in the RCM archives on groups.google.com, you'll find
any number of opinions on how to knurl. I've got a copy of a small
book on the subject that I found in the library, basically it says your
work circumference has to come out even with the diametrical pitch of
the teeth on your knurl. Kind of like cutting a gear blank, if you
don't have the right diameter on your workpiece, you'll end up with
fractional teeth and it won't be right.

It's hard to damage a knurling tool unless you're trying to knurl
hardened steel or something.

The best way I've found is to leave a band proud on the surface that's
the correct diameter, then knurl that. If you look at a Starrett mike
sleeve, you'll see what I mean. You can size the band so you get a
good knurl the first time around. A scissors-style of knurling tool
helps, too. You probably won't find one in a school shop, though.
Enco used to have cheap import ones if you want to go on their website
and see what one looks like. Might be a good school project to make
one.

Others will say just to ram the tool in there with as much force as you
can, sizing doesn't matter. If you've got sufficiently ductile
material and a heavy enough cross-slide with enough lube, it'll
probably deform the material enough to get acceptable results. You
might also deform other areas that you may not want bent, too.

It's not that hard to calculate what your desired diameter would be on
the workpiece surface once you know the diametrical pitch of the knurl.
It's basic machine shop math.

Stan

"B.B." u wrote in
news
Can somebody explain to me the basics of knurling? My machine shop
teacher showed me how, but screwed it up and explained nothing as he did
it. /:

Here is a link to good knurling info:
http://www.accu-trak.com/technicalinfo.html
http://www.formrolldie.com/page2.html

Also, the knurls I wound up with I kind of flattened. I found I had
to drill the piece out a little more after I'd already knurled it. It
hung on the drill and spun in the chuck. Oops. The chuck flattened all
of the knurls nearly out of existence. Can I repair this by knurling
again, or do I need to take a light cut (it's just a handle, so
dimensions don't matter much) before knurling so I'm starting with a
smooth surface? The piece is steel. I don't care about how it looks, I
just don't want to damage the knurling tool.

Over rolling, that is to say dwelling too long, blank size too big, or
taking two passes, will cause the knurl to flake. I would turn the handle
down if that's acceptable and start over. Other wise your knurl is likely
to be full of needle sharp flakes. A trick I've used on engine lathes is to
engage the knurl into the work with the spindle stopped, then start the
spindle and knurl. If you are traversing to put a knurl on the work that is
longer than your knurl is wide, remember to break the leading edge of the
knurling tool with a 45 degree chamfer. The best thing to use, if they are
available to you, is a convex knurl.



--

Dan

The method I was shown in high school machine shop, was to advance the
toolpost-held style knurl gently to the workpiece (kinda like taking a
scratch cut to check thread pitch).
With the knurls in light contact with the workpiece, rotate the chuck by
hand to see if the pattern is correct (nice shaped diamonds), and that the
knurls contact the work flat/full width of the knurls.

When the knurls are set correctly for the nice diamond pattern around the
diameter, the knurls can be advanced more tightly into the workpiece, and
power applied.

Cutting oil required, and slow rotational speed, then knurls can be advanced
more and hand or power fed along the workpiece.

WB
...............


"B.B." u wrote in message
news
Can somebody explain to me the basics of knurling? My machine shop
teacher showed me how, but screwed it up and explained nothing as he did
it. /:
Also, the knurls I wound up with I kind of flattened. I found I had
to drill the piece out a little more after I'd already knurled it. It
hung on the drill and spun in the chuck. Oops. The chuck flattened all
of the knurls nearly out of existence. Can I repair this by knurling
again, or do I need to take a light cut (it's just a handle, so
dimensions don't matter much) before knurling so I'm starting with a
smooth surface? The piece is steel. I don't care about how it looks, I
just don't want to damage the knurling tool.

--
B.B. --I am not a goat! thegoat4 at airmail dot net
http://web2.airmail.net/thegoat4/




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wrote in message
ups.com...
snip---
, basically it says your
work circumference has to come out even with the diametrical pitch of
the teeth on your knurl. Kind of like cutting a gear blank, if you
don't have the right diameter on your workpiece, you'll end up with
fractional teeth and it won't be right.

It may say that, but it's *wrong*. Only when knurling a straight knurl
would that be true. Diamond knurls compensate for less than perfect pitch
by wandering side to side. You can achieve a perfect knurl on *any*
diameter.


Others will say just to ram the tool in there with as much force as you
can, sizing doesn't matter. If you've got sufficiently ductile
material and a heavy enough cross-slide with enough lube, it'll
probably deform the material enough to get acceptable results. You
might also deform other areas that you may not want bent, too.

Smart people don't knurl finished parts for that reason. Knurling is one
of the heaviest of operations we perform on lathes. It should be done
before finish cuts are taken.

It's not that hard to calculate what your desired diameter would be on
the workpiece surface once you know the diametrical pitch of the knurl.
It's basic machine shop math.

Stan

It's also a waste of time. It's much easier to learn to knurl properly,
then the size won't matter. When you have enough experience, you can start
a knurl 100% of the time without splitting, diameter be damned. Just make
sure your knurling tool has a bit of side clearance on the rollers so they
can hunt to maintain perfect alignment with the established knurl.

Harold

In article ,
Harold and Susan Vordos wrote:

wrote in message
oups.com...
snip---
, basically it says your
work circumference has to come out even with the diametrical pitch of
the teeth on your knurl. Kind of like cutting a gear blank, if you
don't have the right diameter on your workpiece, you'll end up with
fractional teeth and it won't be right.

It may say that, but it's *wrong*. Only when knurling a straight knurl
would that be true. Diamond knurls compensate for less than perfect pitch
by wandering side to side. You can achieve a perfect knurl on *any*
diameter.

Exactly! I didn't bother mentioning diameter in my reply,
because I have found it to not matter.

And even if you calculate the proper pitch for a diameter --
which diameter do you use? The first pass pitch diameter? The average?
The one at maximum depth? If it matters, what is right for one will not
be right for another.

I think that it might make a difference with a very shallow
knurl pass, which is not what I ever use. With deep starts the knurls
are self-correcting, as you suggest.

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On Fri, 15 Apr 2005 12:25:27 -0700, "Harold and Susan Vordos"
wrote:


It's not that hard to calculate what your desired diameter would be on
the workpiece surface once you know the diametrical pitch of the knurl.
It's basic machine shop math.

Stan

It's also a waste of time. It's much easier to learn to knurl properly,
then the size won't matter. When you have enough experience, you can start
a knurl 100% of the time without splitting, diameter be damned. Just make
sure your knurling tool has a bit of side clearance on the rollers so they
can hunt to maintain perfect alignment with the established knurl.

Harold

Ayup. Ive never calculated knurls/diameter etc. I didnt know you were
"supposed to". My old homemade pinch knurler doesnt know that either.

Still makes nice knurls just the same.

Gunner

"At the core of liberalism is the spoiled child -
miserable, as all spoiled children are, unsatisfied,
demanding, ill-disciplined, despotic and useless.
Liberalism is a philosphy of sniveling brats." -- P.J. O'Rourke