# Finally- perfect knurls! Let's talk knurls...



## wildo (Apr 24, 2017)

Having been frustrated with double-tracking on my knurls, I finally did some research and found that you can't just guess on the work diameter. Turns out there's formulas and such for knurling; who knew!? I found the youtube video series and accompanying spreadsheet by "ghostses" and that made all the difference! 

Check out my knurls on this spinning top stem that I'm working on. I used 33 Pitch wheels and turned the work to .2026. Well, my goal was .2026 but I landed on .2025, which seemed to work just fine.












Size comparison:





Purposefully over exposed so you can really see the knurl form:





There are two things that I'm still curious about that I haven't found answers to.

What does the "pitch diameter" actually mean? What does 16P mean vs 33P other than the former is more course than the latter?
I used the BR/BL knurl tools as seen below. They obviously create a 30 degree diamond pattern. But I noticed that Knurlcraft also has diamond wheels- the GE/GV ones seen below. What are the diamond patterned wheels used for? I see that one's male and the other is female, so it would seem to me that these also produce the same diamond pattern as the BR/BL tools. What's the story with these?


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## wildo (Apr 24, 2017)

Also- I have this Knurlmaster tool. In the box I have six different sets of knurl wheels. For each set of knurl wheels I have two marked "L" and one marked "R". I have been putting the two left wheels on the fixed jaw, and the right wheel on the movable jaw. For both sides I've been putting the wheels in such that the "label" side of the wheels are all on the same side. There was no instructions shipped with the tool. I've been wondering if the wheel orientation in the tool actually matters. Can anyone comment on this?


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## rgray (Apr 24, 2017)

wildo said:


> For each set of knurl wheels I have two marked "L" and one marked "R". I have been putting the two left wheels on the fixed jaw, and the right wheel on the movable jaw. For both sides I've been putting the wheels in such that the "label" side of the wheels are all on the same side



Lefts and rights are that no matter which side is up. So you have it correct with the left rights. You can forget about worrying about what side goes up.
I was thinking the diamond pattern wheel was for making that pattern with a single wheel pressed into the work. But the male female part of it tells me there must be more to that story.


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## westsailpat (Apr 24, 2017)

.0001 +- ?  I have been reading about the knurling formula here on HM and now your post , I find it interesting . I had never heard of such a thing . I like that Knurlmaster tool . Back in the day I had a recurring job that required a knurl  a straight knurl , the OD of the part had a larger OD about a 1/4 wide in the middle of it the job was always about 200 pcs. . Finally I got this tool to do the knurl , it was a cage frame that held two knurls opposite of each other and had a arbor in the back  I mounted it in a turret lathe turret . I was able to produce a decent knurl quickly and because I pushed it on and all the way over the raised part and then pulled it off , the edges of the knurled area rolled over so I didn't have to chamfer or deburr .   Sorry I can't find a picture of the tool and I forgot the name of it .


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## wildo (Apr 24, 2017)

westsailpat said:


> .0001 +- ?



Yep. That's pretty exact, but I recently bought a Starrett No. 221 and _love_ it! It makes measuring ten thousandths simple as pie. And it's just an absolutely beautiful tool!!


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## mikey (Apr 24, 2017)

wildo said:


> There are two things that I'm still curious about that I haven't found answers to.
> 
> What does the "pitch diameter" actually mean? What does 16P mean vs 33P other than the former is more course than the latter?
> I used the BR/BL knurl tools as seen below. They obviously create a 30 degree diamond pattern. But I noticed that Knurlcraft also has diamond wheels- the GE/GV ones seen below. What are the diamond patterned wheels used for? I see that one's male and the other is female, so it would seem to me that these also produce the same diamond pattern as the BR/BL tools. What's the story with these?




There are two general classes of knurls - diametral pitch and circular pitch. The former are intended to knurl work that is sized on the 32nd or 64th of an inch; they work pretty good and there is no calculating beyond the nominal sizing. I had some but they wore out and I never replaced them. The number of teeth on a DP knurl is fixed - 64 or 128 tpi for work on the 64th inch and 96 or 160 tpi for work on the 32nd inch.

Circular pitch knurls are more popular. Calculations for these can be more complicated and even when you turn the work to the calculated OD, you can still have mistracking. It that happens the you can angle your knurler by a few degrees and that helps. So does increasing the pressure on the knurls. 

I forget exactly how you read tpi on the CP knurls but I think you have to count them on the diagonal. Anyway, fewer tpi produce coarser knurls and more teeth produce finer knurls. 

Hand knurlers are good for stationary knurls but if you must make a long knurl then you really need a straddle knurler or bump knurler, preferably the former. Maybe make or buy one?

As for the diamond knurls, dunno', never used them.


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## darkzero (Apr 25, 2017)

As you know in a 2 wheel knurler you use a LH & a RH wheel to achieve a diamond knurl. The diamond knurls are for use in single wheel bump knurlers to achieve a diamond knurl. 

But what's cool about the single wheel diamond knurls is you can knurl the typical diamond pattern where the pyramids are raised (male) with a Female wheel or you can use the Male wheel to knurl a reversed diamond pattern (female) where pyramids are recessed. Well so I've heard, I've never done it myself but I have seen knurling like that on parts. I don't think you can knurl the reversed diamond pattern (female) using a 2 wheel knurler with LH & RH wheels but I'm not sure.

If I'm not mistaken, I believe you can not knurl axialy with diamond pattern wheels.


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## benmychree (Apr 29, 2017)

mikey said:


> There are two general classes of knurls - diametral pitch and circular pitch. The former are intended to knurl work that is sized on the 32nd or 64th of an inch; they work pretty good and there is no calculating beyond the nominal sizing. I had some but they wore out and I never replaced them. The number of teeth on a DP knurl is fixed - 64 or 128 tpi for work on the 64th inch and 96 or 160 tpi for work on the 32nd inch.
> 
> Circular pitch knurls are more popular. Calculations for these can be more complicated and even when you turn the work to the calculated OD, you can still have mistracking. It that happens the you can angle your knurler by a few degrees and that helps. So does increasing the pressure on the knurls.
> 
> ...


I'd like to add, that to start a knurl and avoid double tracking, on knurls that are axially fed, I like to start the knurl on the edge of the part using only a portion of its width, say, 1/3 or 1/2, and bear down hard on it until nearly the full form is impressed into the part, then start the axial feed.  I much prefer the scissors type knurl tool holder for engine lathe use.


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## Rootpass (Jun 26, 2017)

Online calculator for knurl diameters 

https://littlemachineshop.com/reference/knurler.php


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