Cut knurling

[FulmenParticipant @fulmen]

I’m sure I’m not the only one who fell in love with knurling when starting out in the lathe. It’s a cool feature that somehow makes anything look “professional”  🙂

But in time I’ve come to detest it for it’s brute force approach and the high strain it puts on a flimsy hobby machine. But it’s still a nice feature at times, so I’m considering upgrading to cut knurls.

Here’s a recent build on youtube: https://www.youtube.com/watch?v=vrbYJhL4EgI

His approach is fixed indexing and swapping the rollers for different patterns. It’s not bad but I’m wondering if a fully adjustable one will be more versatile. Any opinions?

Here’s the simplest version of that: https://www.youtube.com/watch?v=Uit30Ih809E

I’m favoring a more elaborate version with a scale for increased accuracy. I doubt it’s that important for a regular helical pattern but a straight knurl will quickly reveal any misalignment.

I’m also considering making my own cutter wheels. I have some O1 tool steel to spare and it could be a fun side project.  I’ll make sure to copy a readily available size so I have a way out if it doesn’t work.

[Nigel Graham 2Participant @nigelgraham2]

I take it you mean by “brute force” using the tool that tries to bend the bar – and yes, I agree that is very unfair to any small lathe.

An alternative, and the one I use, is the clamp-type knurling-tool which has two opposed rollers closed by a screw onto the work-piece from each side. This removes the radial load the plain knurling tool imposes.

An equally professional touch is scalloping rather than knurling: shallow indentations milled into the rim, using a suitable dividing arrangement for spacing. This is normally for larger handwheels and the like, but I have seen it on small items.

[FulmenParticipant @fulmen]

It’s everything it does and how it does it. It cold works the part, not all materials responds well to this. And once you start working on anything harder than mild steel both the lathe itself will start giving.

I do have a clamp style tool and while it helps it’s not magic. Cutting them seems like the better approach…

[Neil LickfoldParticipant @neillickfold44316]

I used a twin knurl unit when I was in the USA . It was really impressive. So I though I would buy one until i saw the price. It was going to cost more than my S7 is worth used.

I may get inspired one day and make one.

The real advantage of them when  the wheels are sharp and cutting properly, is that they are not stressing the material nor growing the material to create the knurl. This is important if you have a part that is relying on the inner bore dimension to be very stable over a long period of time.

You got me to thinking of the clamp style tool, and if the rollers are kicked over, can you then have a pair of effective cutting knurls happening. Will need to give it some more thought.

Neil

[bernard towersParticipant @bernardtowers37738]

If you are going to use standard knurls for a cut knurled project they will need their leading edge grinding until you have the full profile visible as this is the cutting edge. A rope knurling project is quite satisfying and they look quite classy when done

[noel shelleyParticipant @noelshelley55608]

I bought a collection of Coventry die heads and in the collection was a strange device – looked like a 3 jaw chuck with knurling wheels, It’s a Miller/Quick cut knurling attachment which I think was at some point on a capstan, along with a die head. If the perceived quality is anything to go by then it cost, as Neil said a small fortune. Not used it yet but from the video Fulmen listed I would use it with flood coolant to clear the chips. Numerous wheels are available. Noel.

PS a look on the Auction site shows one at £1300

[Andrew CrowParticipant @andrewcrow91475]

There was an article in the June issue of ME&W about making a knurling tool for conventional and cut knurling.

Andy.

[Michael GilliganParticipant @michaelgilligan61133]

One of several advertising videos:

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MichaelG.

[Graham MeekParticipant @grahammeek88282]

Trying to do conventional knurling on an Emco Compact 5 was never going to end well. Talking it over with John Slater I later received a link to an article by Jacques Maurel, entitled “Shiny knurls”.

Since making this knurling tool I have never looked back.

There are two positions for diamond knurling, obviously the tool is shown in a more convenient position for the photo shoot. The index plate gives the normal 30 degree diamond pattern and the less common 45 degree pattern.

While the recommended path for straight knurling with this tool is by using a Helical instead of the Straight knurl used for Diamond knurling. I have found the Straight knurl used for Diamond knurling will also cut a straight knurl if it is used in the vertical.

Initially the tool needs a little patience when setting up, but I have found it stays set for good. Even when changing the pitch of the knurls. It cuts Delrin just as well and examples can be seen on the digital readouts added to my Proxxon Mill modifications.

Regards

Gray,

[John HaineParticipant @johnhaine32865]

CNC Knurling

[VicParticipant @vic]

I don’t use diamond knurling very often but I’m normally happy with the results. I prefer straight knurling though and would like a better result. Seeing this thread is prompting me to consider making a cut knurling tool. Anyone know a source for the wheels at a reasonable price?

I bought these many years ago that might do to experiment with, but they’re quite fine.

Thanks for the links Fulmen, and all the other comments and pictures, very interesting. 😉

[FulmenParticipant @fulmen]

@Gray: Very nice work. Have you ever felt that the indexing plate was too limited? I was thinking of a fully adjustable one with a graduated scale, but yours looks a lot simpler both to make and in use.

[Graham MeekParticipant @grahammeek88282]

Hi Fulmen,

I had never considered the use of a degree scale. Given the index plate is only 22 mm diameter by 2 mm wide. There would be little chance to have a useful scale around the O/D. At this diameter a scale graduated every 5 degrees would give less than 1 mm between each graduation.

The index plate gives a positive lock to the device with no chance of the head rotating and this makes it very quick to use. Plus there is an adjustment in the location pin, (up & down), in order to get the knurl cutting correctly.

Regards

Gray,

[FulmenParticipant @fulmen]

You’re probably right. And If I really want some obscure angle I can always make another indexing plate.

[Neil LickfoldParticipant @neillickfold44316]

I really do like the indexing plate idea.

[Fulmen]

On Fulmen Said:

You’re probably right. And If I really want some obscure angle I can always make another indexing plate.

If you know the exact angles required I can see the advantage. Would you really stop what you’re doing and make a new plate if a particular angle wasn’t giving the required result? I can’t help thinking your first idea would be better, simply a plate marked say every 5° or 10°? Looking at those on YouTube, once the angle is set they seem to stay locked at the required angle so a detent doesn’t seem needed.

[JasonBModerator @jasonb]

Given the position of the indexing wheel it would not get in the way if you made it a lot larger diameter, could even be a ring that can be removed or stick it at the other end where it won’t be near the cutting action. If worried about teh tool rotating add some form of clamping to the main housing that grips the spindle rather than rely on the knurled knob to hold it if there were no pin.

For straight cut knurls I have just indexed the work and dragged a V shaped tool along the length of the work, Could be done with an ELS too.

[Graham MeekParticipant @grahammeek88282]

As I said earlier I did not give the requirement to have a degree scale a second thought. The design is Jacques and I have merely adapted it so suit the C5. By using the wheels which were in my cache.

I for one cannot see the necessity for additional angles in between. Especially if you are using a standard Helical wheel to do the straight knurling. Trying to use this type of knurl at an odd angle would probably lead to interference and a ruined knurl. A straight wheel would probably be OK, but it seems an awful lot of trouble to go to me. Maybe I am missing something?

Regards

Gray,

 

[FulmenParticipant @fulmen]

If I understand the mechanics of these right, the wheel will always mesh with the corresponding knurl pattern. But you also need to present the wheel with a positive rake angle which limit the useful range.

It might be possible to get the best of both worlds here, I will try to cook up a design that allows for both precise indexing plates and graduated scales.

[Michael GilliganParticipant @michaelgilligan61133]

Awake in the middle of the night [don’t ask] … I stumbled across these:

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MichaelG.

[John MCParticipant @johnmc39344]

I made this cut knurling tool many years ago when I only had a relatively flimsy lathe.  Haven’t used it for sometime, decent industrial machinery is more than capable of cold forming knurls.

What was meant to be a quick job turned out to be a lengthy one ultimately worth the effort.

The three square headed bolts  are for rotating the knurling wheel supports, (in opposite directions),  to raise and lower the head when mounted in the tool post and lock the knurl shafts.

When I first tried to use it I the results were disappointing, for diamond knurling, it would always bias the cut one way.  A bit of practice with it showed that the adjustments were critical.  All was well when I got my head around that!.

When deciding on the knurl to use, straight vs diamond, I use diamond for things that need to be picked up and held, centre punch or scriber for instance.   For axially assisted, a thumbscrew running along a screw thread, straight knurl.

[FulmenParticipant @fulmen]

I agree, straight knurls are usually better for dials and thumbscrews. And yes, this is mainly a problem on smaller machines but it will also be an issue on thin walled parts. I used to make silencers in aluminum where weight is an issue, and one of the features I always missed were some light knurling for better grip.

I really like your design, but honestly the geometry is giving me a headache just thinking about it.

[Wade BeattyParticipant @wadebeatty78296]

I saw this thread yesterday on a knurling tool that looked handy

https://forum.zerspanungsbude.net/viewtopic.php?f=9&t=55975

Wade

[Wade BeattyParticipant @wadebeatty78296]

There is even a video of the build

[Author]

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