OK, What's the secret to Knurling?

[KiddZimaHater]

GGRRRR...
I need to make a knurl on some aluminum parts, but haven't been too successful.
So what's the big secret to knurling?
I first tried one of those "Fixed" knurlers, but the pattern seemed to double-track.
So I switched to a "Floating Head" type knurler. The first attempt came out beautifully. Then on the following parts, Double-Tracking nonsense again.
UUUGGGHHH !!!!
What gives?
The knurler is on center. I have low RPM's. I'm feeding it at .015 per rev.
Plunging in about .01-.015.
Please educate me.

[Ted Coffey]

Start by reading this:

http://www.proshoppublishing.com/articles_knurling.html

[goose]

So what's the big secret to knurling?

3 bills

Gary

[Black_Moons]

0.5 bills, ebay.
+ reading about the correct diamiters.. some go by the correct diamiter school.. others just mash it in really deep and it usally works out.
the ones that put stress on your compound/cross slide etc are not very good unless you have a GIANT lathe, though they do have unlimited diamiter, and can be used ok for soft materials..

[Doozer]

"Quick" brand knurling tools are also very good.
They have straight knurl wheels mounted at a 45* angle,
that produce the diamond pattern. It actually cuts the
knurl, not just upsets the metal.

--Doozer

[polepenhollow]

Come up to the part w/ the knurl. appx 200 RPM. Feed knurl in w/ r/h as you turn the saddle wheel w/ the LH. Feed towards chuck. Let Knurl wheels come half way off part and then feed to the right until the knurl wheels come off part. Feed left and feed in more w/ the crosslide. Only feed when full knurl is on part..
If you get cross knurl or double knurl, increase the feed speed (LH) on the saddle wheel.
Get rid of the cross or double knurl on the first or second pass, otherwise it may be impossible to remove.
KL

[Dr Stan]

The floating head is superior to the fixed.

1) Increase your feed rate to about .025"/rev

2) Make sure your knurling tool is good and square with your work

3) Have a good quality knurling tool. If you are using Chinese knurling tools you will probably never get a good knurl.

4) Use some cutting fluid such as Tap Magic or flood coolant to keep the tool and the part flushed. This will keep the "chips" from embedding themselves in the tool and/or the part.

5) Do not disengage the knurling tool from the work until you are done. Feed one direction, stop the lathe, reverse your feed and go back over it. Repeat as necessary increasing pressure on the part until you have a good knurl.

[lazlo]

Start by reading this:
http://www.proshoppublishing.com/articles_knurling.html

That quote from Machine Shop Trade secrets will pick a fight here. He's a diametral pitch knurler

"Following the formula stated previously, 0.060 divided by 3.14159 is 0.019. Therefore, any multiple of 0.019 should provide a diameter for a perfect knurl. "

[Ken_Shea]

That quote from Machine Shop Trade secrets will pick a fight here. He's a diametral pitch knurler

"Following the formula stated previously, 0.060 divided by 3.14159 is 0.019. Therefore, any multiple of 0.019 should provide a diameter for a perfect knurl. "

What/where does the .060 come from?

[lazlo]

What/where does the .060 come from?

The distance between two teeth on the knurling wheel.

[TGTool]

"Following the formula stated previously, 0.060 divided by 3.14159 is 0.019. Therefore, any multiple of 0.019 should provide a diameter for a perfect knurl. "

Well no wonder. I'm doing everything wrong! I never measure or calculate a diameter or know what my knurl wheel pitch is. I just mount a straddle knurling tool, the cheap Enco one, get it about centered, tighten the crap out of the nut, run 5 seconds or so to see if it's raising the knurl right and crank some more if necessary. If it's looking good I keep feeding it oil and traverse down the stock for as long as I need a knurl and quit.

So it's my defective methods that are producing such defective knurls. Verrrry interrresting.

[Doozer]

I have always had better luck if the knurling tool was NOT square to the work. I point the knurling tool just 1 or 2 degrees towards the direction of travel. This gives the wheels a gradual lead in to the cutting action. A similar concept that allows use of setting the tool square to the work, is to use crowned knurling wheels. Same idea of giving the cutting part of the wheel some approach. Crowned knurling wheels are a but expensive and less common, so I just angle my tool. If you want, I believe J&L has them.

--Doozer

[Carld]

There is truth to what lazlo is saying. I cut knurls from time to time on different diameters and have found the if I have a hard time getting the wheels to make a diamond if I reduce the diameter some the knurl starts easier. Sometimes it don't take a lot because once the diamond starts it's easy to work it into a good diamond.

I experimented once by taking a few thousandths off and knurling and the diameter changes did make a difference. Most the time I can force a good diamond and when I do I think what is happening is I am eating the metal off reducing the diameter until the diamond starts and then forms up real nice.

Sometimes I start a knurl and get such a fine pattern I get a little disgusted and force the knurling tool in real hard and shortly the diamond starts coming up. Other times it just jumps right out of the surface with little forcing. All this happens on different diameters.

There have been a lot of threads on knurling and several posters profess the correct diameter for the pitch of the knurl wheel and I have began to believe it has merit. It's the only thing that can explain taking a few thousandths off the work and getting a good knurl when it didn't with the original diameter.

I guess this will be argued until the end of time much like the use of SFM charts.

[MuellerNick]

These are my self-made knurling-heads:


And this is one of the results:


Admittedly, the left part is not perfect.
I never calculate the diameter, because you always get it working. Do not use oil, you will end up with some kind of metal mill. Use flood coolant to wash away all the fine chips.
Simply start with about half the wheel's width in contact and feed in until the pattern "catches up" (no doubles) then move left/right and feed in until the pyramid's tips are closed.


Nick

[John Stevenson]

Steel, 30mm diameter 15" long, 500 rpm.






No calculation, just go for it.

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