Knurling help

mwill135 · Aug 31, 2020

Recently got a scissor style knurling tool. Came with medium grade wheels (diamond). Was looking at getting coarse and/or fine wheels. Web site notes right or left? I know I'm a newbie, are you only suppose to knurl in one direction?

L Vanice · Aug 31, 2020

If you look at the wheels you have, you will see that one spiral is right hand and the other is left hand. Catalog pictures usually show that detail.

https://www.amazon.com/Grizzly-H757...rling+tools&qid=1598915826&sr=8-9&tag=mh0b-20

Larry

upm2019 · Aug 31, 2020

You need Both a right and a left hand knurl to make a diamond other wise you get a spiral . You have to size your blank diameter to the pitch of the knurled or you will likely have trouble getting them to track properly

mwill135 · Aug 31, 2020

awesome thank you

dgfoster · Aug 31, 2020

upm2019 said:
You have to size your blank diameter to the pitch of the knurled or you will likely have trouble getting them to track properly

That is an old wives tale. There have been numerous threads in the past explaining why trying to figger the circumference divided by the pitch = integer or some theoretical variation (there are lots) is waste of time. In PRACTICE starting with the wheels about half on the part with a decent bite will result in a single-track clean diamond knurl using a common forming (not cutting) knurl. I tried all the mathy stuff—-useless. Start half on half off the work piece, tighten the scissor so that the wheels are taking a decent bite, apply lube oil (not cutting) turn fairly slowly and advance fairly fast. Don’t over roll the knurl and make it turn to powder. Tighten the scissor a bit more and repeat about 2 times. Voila! Done.

Just get out some scrap 12L14, 4140 PH, 6061 AL and spend an hour practicing. It works, is not rocket science, and allows for some handy grips—-both coin and diamond knurls. Then there’s decorative knurling, cut knurls etc. But just stick with diamond and coin knurls—-that will serve 99% of most folks needs most of the time.

Denis

James H Clark · Aug 31, 2020

I disagree with you on that. The theory about making the pitch of the knurling tool relate to the diameter of the work is similar to cutting gear teeth. Nobody likes for the last tooth to be thin.

JH

camscan · Sep 1, 2020

dgfoster said:
. I tried all the mathy stuff—-useless. apply lube oil (not cutting) turn fairly slowly and advance fairly fast. Don’t over roll the knurl and make it turn to powder. Tighten the scissor a bit more and repeat about 2 times. Voila! Done.

Just get out some scrap 12L14, 4140 PH, 6061 AL and spend an hour practicing. It works, is not rocket science, and allows for some handy grips—-both coin and diamond knurls. Then there’s decorative knurling, cut knurls etc. But just stick with diamond and coin knurls—-that will serve 99% of most folks needs most of the time.

Denis

The maths does work,how else would you get a good knurl on a required diameter?
Do not use cutting oil and run fairly slowly??? Have you ever watched a screw machine forming a knurl? They definitely use cutting oil and run at a surface speed that the main operation requires.

cudafamily · Sep 1, 2020

Just my thoughts but don't think that you will ever be able to turn out decent looking knurls with any Chinese on Indian knockoffs. Pay the extra money for decent American precision machined devise. And every type of material will need need it its own set of pressure feed parameters to get the same results. You will have to plays around with it first to determine exactly what those are. I like to start off with about a 1/3 crank down on the on the screw (90 RPM @ 15 secs.) I then use a low power loupe to examine the knurl and go from there. When you see that the "PEAK" is getting close to closing, do not add any more pressure. Just continue to add more lube and revs and observations. Many will say to stop before you top the peak out, but if you are diligent and careful you can can produce a full knurl that really has a full "bite" when you grab it.
If you do go too far you will immediately notice that your wheels will start loadings with smalls fines as they are chewing off the tips of the peaks.

lazz · Sep 1, 2020

Here is a knurling calculator app.

After spending a lot of time getting everything just perfect....
I changed to something very similar to dgfoster's method and it works just fine.
I will mention like Denis did.... practice until you develop a technique.

crossthread · Sep 1, 2020

I guess everyone has their own opinion and experiences with knurling. I agree with dgfoster on this one. I have formed many knurls over the years and have never worried about the diameter of the part. The key is to get a good starting knurl and the subsequent knurls will follow. You have to be extra careful when knurling soft materials like AL. Hard material will force the knurl to "slide" into the starting knurl but AL will sometimes try to double strike because it is not hard enough to push the knurling wheel into alignment. This requires plenty of lube and as deep a starting knurl as you can get. Easy enough with AL however.

dgfoster · Sep 1, 2020

James H Clark said:
I disagree with you on that. The theory about making the pitch of the knurling tool relate to the diameter of the work is similar to cutting gear teeth. Nobody likes for the last tooth to be thin.

JH

Disagree all you want, the method I described works and works reliably. In actual practice the knurl finds the impressions made in the round and smooths out and averages the result. I’d love to see a pic of such a narrow tooth due to a “mismatch of pitch and diameter. I’ve seen double tracking where a false knurl forms roughly twice the expected pitch. But that problem is solved by taking a better bite. I have done hundreds of knurls, but I’ve never seen an odd thin tooth. Have you actually seen such? Pics?

BTW, Which diameter would someone use to make the circumferential calculation into which you would divide by the pitch?? The untouched round OD? The OD defined by the valleys of the knurl on the first pass, the second pass, or the third? It keeps changing as the knurl deepens but the knurl remains clean and sharp and the diamonds raised do not change in number or location. Or would you use numerical calculation that is, say, arbitrarily 70% valley and 30% untouched OD that actually after the first pass is increased over the untouched diameter?

That’s why diameter/pitch calculations just do not work for formed knurls. Good knurls can be made with cheap crappy wheels but good quality ones with both a convex shape and/or a bevel makes the job easier.

Note the disclaimer in the paragraph on diameter vs pitch—-“usually involves experimentation.”

Denis

dgfoster · Sep 1, 2020

One way to make a straight unbeveled and not-convex wheel track more easily is to just take the wheel to the bench grinder and letting the wheel spin freely, on a loose fitting axle, touch the wheel at an angle to the grinding wheel to cause the knurl to turn at a moderate speed while chamfering the outer sharp edge of the wheel for a distance of a little less than an eight of an inch and removing nearly all the ridges at the shoulder of the wheel tapering back to the full height an eighth from the corner.or so.

Denis

upm2019 · Sep 1, 2020

While you don't aleays have to drive yourself mad with calculations with short runs and one off's It pays to do it for production runs . You will have better results and a more consistant knurl part to part

James H Clark · Sep 1, 2020

upm2019 said:
While you don't aleays have to drive yourself mad with calculations with short runs and one off's It pays to do it for production runs . You will have better results and a more consistant knurl part to part

Amen: Sounds like the voice of experience.

JH

Dan from Oakland · Sep 1, 2020

Dorian Tool has a very nice knurling app that works well. Call them up and they will e-mail it to you. Also, the Form-Roll website has a lot of knurling info that you might find useful.

jim rozen · Sep 1, 2020

Step one: apply sulfurized cutting oil with a chip brush.

Step two: chip brush gets sucked in between knurling tool and part.

Step three: curse like a drunken sailor.

Step four: remember to run the machine in reverse so this doesn't happen. Again.

FredC · Sep 1, 2020

In a turret lathe I have used the B&S equivalent of this tool:
https://r.search.yahoo.com/cbclk2/d...DMgRydAMw?IG=0ac4d7d783b948ac8400000000931bd2
s
Much stronger than any of the scissor types I have seen. As for tracking I did find one or both knurls would double track if the blanks were not the right size. I never calculated the size but did a trial and error till I got good tracking and the desired size. I then wrote the size of the blank down and the diameter that I set the knurls too and it would repeat fairly well when the job came up again. The Brown & Sharpe or Somma tool use straight knurls set an angle which makes everything easier for diamond knurls. For straight knurling you would use angled knurls.
Long since sold the tool to a friend and use cut knurls on my gang tool machines and have never had a mistrack. just easier all around. Make the blank about a thousanth larger than your intended size and go for it. Always used flood cutting oil with either style. No clue how to do it with coolant.

jim rozen · Sep 1, 2020

The actual B&S tool like this allows the user to adjust the angle of the individual knurls. Once set up those things are dynamite.

I think the folks who say the starting diameter does not really matter are seeing the effect that the tool tends to reduce the part diameter
until it *is* a good size, and then it finally picks up and tracks well.

I finally figured out how to do straight knurling on a conical surface - it has to be single tool, and the tool has to be right on center, and the
compound angle has to be *just* right, although just right somehow does not seem to be the same angle used to generate the cone surface
in the first place.

The fact that you can get tracking straight knurling on a conical surface sorta gives a lie to the theory that the diameter has to be exactly correct.

DanASM · Sep 1, 2020

camscan said:
The maths does work,how else would you get a good knurl on a required diameter?
Do not use cutting oil and run fairly slowly??? Have you ever watched a screw machine forming a knurl? They definitely use cutting oil and run at a surface speed that the main operation requires.

Amen to that

Ox · Sep 1, 2020

Years ago I was dooing that math thing ...
Need a blank size correct eh? No difer'nt than rolling threads ....

'Till the voice at Accu-Trax said .."Yyyyyyyyyyyyyy .... not really..."

However - I am a strong proponent of Accu-Trax convex knurls if you are planning on dooing anything longer than your knurl is wide.

And per the voice (especially with scissors) just run it in there, don't baby it.

I get very few double knurls with this method and these knurls.

------------------

Think Snow Eh!
Ox

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