Radius Knurling.

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armscor 1
Posts: 311
Joined: Sun Jun 12, 2016 3:12 am
Location: Philippines

Radius Knurling.

Post by armscor 1 »

Hi Guys,
Been scratching my head how to radius knurl, they look good and have a more tactile feel like on the old pocket watch winders.
Hobbed various knurls on the mill, 4, 5 and 6 mm dia using drill rod, hardened and tempered.
Pleasing result and happy with some knurls I completed.
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TimTheGrim
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Location: El Paso, TX

Re: Radius Knurling.

Post by TimTheGrim »

Nice.
Illigitimi non Carborundum
'96 Birmingham mill, Enco 13x40 GH and Craftsman 6x18 lathes, Reid 2C surface grinder. Duro Bandsaw and lots of tooling from 30+ years in the machining trades and 15+ years in refinery units. Now retired
Russ Hanscom
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Joined: Wed Mar 15, 2006 11:10 pm
Location: Farmington, NM

Re: Radius Knurling.

Post by Russ Hanscom »

Nice,

I am lucky, have a few that belonged to my grandfather, used for making electrical parts.
whateg0
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Joined: Sat Mar 28, 2009 3:54 pm
Location: Wichita, KS

Re: Radius Knurling.

Post by whateg0 »

Have you watched the Clickspring video where he makes several rope knurling tools?

https://youtu.be/i9pD5vIHJ8M

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Harold_V
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Location: Onalaska, WA USA

Re: Radius Knurling.

Post by Harold_V »

He'd have enjoyed much better success with his cutting tool had he relieved it properly. Otherwise it's quite informative and should provide guidance for folks who would like to produce custom knurls.

His trick with soft wire to hold boric acid while heat treating is exceptional.

Thanks for posting.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
armscor 1
Posts: 311
Joined: Sun Jun 12, 2016 3:12 am
Location: Philippines

Re: Radius Knurling.

Post by armscor 1 »

Hi guys, yes watched Clicksring, in my view making the cutter and angling the knurl to achieve the 60 degree angle on the knurl and laborious indexing is too intense.
Simply Hobbing with various diameter taps is quick and easy and creates knurls similar to telescopic sight clamping nuts.
whateg0
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Location: Wichita, KS

Re: Radius Knurling.

Post by whateg0 »

Using a tap, you are limited to a very shallow helix though.
whateg0
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Joined: Sat Mar 28, 2009 3:54 pm
Location: Wichita, KS

Re: Radius Knurling.

Post by whateg0 »

Harold_V wrote: Sat May 09, 2020 1:46 am He'd have enjoyed much better success with his cutting tool had he relieved it properly. Otherwise it's quite informative and should provide guidance for folks who would like to produce custom knurls.

His trick with soft wire to hold boric acid while heat treating is exceptional.

Thanks for posting.

H
I've always wanted to try building one of those attachments for turning relieved cutters on the lathe.
John Hasler
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Location: Elmwood, Wisconsin

Re: Radius Knurling.

Post by John Hasler »

Harold_V wrote: Sat May 09, 2020 1:46 am He'd have enjoyed much better success with his cutting tool had he relieved it properly.

H
I assume you refer to the lack of front relief?
whateg0
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Re: Radius Knurling.

Post by whateg0 »

No, he relieved the back side of each cutter tooth simply by filling the outer corner/edge down behind the cutting edge. But the flanks retained their shape.
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Harold_V
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Location: Onalaska, WA USA

Re: Radius Knurling.

Post by Harold_V »

What whatego said, and you can see the results of that in the less than good finish in the milling cuts. A circular cutter should be fully relieved in order for the tool to cut properly (think of how a countersink works).

The only cutting tools I can think of that violate that rule would be drills and chucking reamers, where they rely on thin margins, which act as a pilot, and are not intended to be cutting surfaces. In both of those cases, the diameter of the cutting tool is largest at the point of cut, so there is a minimized amount of contact of the surface with the generated cut. (You do know that twist drills and chucking reamers are not straight, don't you?)

You most likely understand that, unless a twist drill has a split point, the web of the drill doesn't cut, as it is hugely negative rake. What it does is displace metal, which is then removed by the lip of the drill. That's why cutting pressure is so great with twist drills, and why a pilot hole makes so much difference.

It should be noted that circular ground surfaces will cut, but under protest, and that's the reason he had such a lousy finish on his cutting tool (and also why such a large burr was raised in the cut).

I don't mean to diminish the value of his production. It is very good. I just don't agree with his lack of relief of the cutting tool and feel others will benefit by paying attention to the need for such. It makes a huge difference in how the tool performs, and the finish one can achieve. I also understand that it's a bit tricky generating the relief, but it can be done, even by hand.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
armscor 1
Posts: 311
Joined: Sun Jun 12, 2016 3:12 am
Location: Philippines

Re: Radius Knurling.

Post by armscor 1 »

Lathe change gear door thumb wheel knurled.
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