Another cut knurler....

[Arbutus]

I was quite shocked at the cost of a cut knurl tool from a commercial supplier - $400 - $700 and even more for a fancy one. So I took a day and made this lovely little thing. It does the job perfectly!

The knurls are the same ones I use with the Hemmingway sensitive knurler, they are 3/4"x1/4 wide with a 1/4" bore. I have a pair of 30 degree and a pair of straight wheels. To cut a straight knurl using a cut knurl, we use a spiral knurl wheel set over at the helix angle. To cut a spiral knurl, we use a straight knurl, set over at the helix angle. That sounds backward, but check out the photos and it may be clearer!


The idea is that the leading edge of the cut knurl wheel shears the material, whereas scissor knurling deforms the material. A knurl produced this way is the same diameter as the workpiece. To get this to work, the height of the knurl wheel must match the centreline of the work, which is handled by the toolholder adjustment, and the tool is set to a -2 degree rake, such that the leading edge of the knurl wheel cuts, while the trailing edge is in very light contact with the work. If the tool is square to the lathe centerline, the cutting action is slower and produces a rough surface.

It started as a 4" long bar of 1" CRS. It was cut on the bandsaw to remove the unnecessary stuff, leaving an offset head and a 1/2" shank to fit the toolholder. The swivelling head is 3/4" bronze. It is indexed and locked firmly in place with the M5 screws. The head can be indexed to +/-45, +/-30 and vertical to suit the knurl wheel.

 

[Jswain]

That looks awesome!

 

[kstrauss]

I'd like to try it. What was the source of your knurls?

 

[140mower]

Very nice...... Would have taken me a week and it would be half as nice. Well done!

 

[Arbutus]

I'd like to try it. What was the source of your knurls?

KBC Tools - they stock a good selection: KBC Knurl wheels

 

[Susquatch]

I was quite shocked at the cost of a cut knurl tool from a commercial supplier - $400 - $700 and even more for a fancy one. So I took a day and made this lovely little thing. It does the job perfectly!

Me too. It's the only reason I don't have one yet.

What you have done looks amazing and not too difficult either. I will study your photos to see if I can understand how yours works.

 

[PeterT]

That's a good looking tool. I always thought regular wheels had to be surface ground a bit to make a sharp edge in order for them to cut, or at least remove some of the chamfer of a typical pressure type wheel. Yours look quite sharp as-is. Did you spec them from different catalog, or they just came that way from KBC?

 

[Arbutus]

That's a good looking tool. I always thought regular wheels had to be surface ground a bit to make a sharp edge in order for them to cut, or at least remove some of the chamfer of a typical pressure type wheel. Yours look quite sharp as-is. Did you spec them from different catalog, or they just came that way from KBC?

The knurl wheels are made by Form-Rol, the ones in the photos are 40TPI which is a very fine pitch. No sharpening required!

Thanks for the nice comments folks!

 

[Ironman]

Thank you for the photos and inscription. I'm just going to have to steal the whole thing and make my own

 

[Susquatch]

KBC Tools - they stock a good selection: KBC Knurl wheels

Did you get the Dorians, the Form-Rol, or the KBC?

 

[Arbutus]

Did you get the Dorians, the Form-Rol, or the KBC?

Form-Rol - around $30 each

 

[jorogi]

Very nice indeed Sir !
As you now have both a cut knurler and a Hemingway scissor style would you be so kind as to compare the two.
If you were only able to have one, which one would you choose and why.

Thanks.

 

[Janger]

Very nice indeed Sir !
As you now have both a cut knurler and a Hemingway scissor style would you be so kind as to compare the two.
If you were only able to have one, which one would you choose and why.

Thanks.

Please show your spiral knurling results too. Will you do two passes with your tool?

 

[Arbutus]

Very nice indeed Sir !
As you now have both a cut knurler and a Hemingway scissor style would you be so kind as to compare the two.
If you were only able to have one, which one would you choose and why.

Thanks.

Good question!

There is an order of magnitude difference in the complexity for one thing. The cut knurler took about 6 hours to make but the scissors type took about three days. It is pretty though.

With a cut knurler and a +/- 30 degree adjustable head, you only need one straight wheel to cut diamond knurls, and if the setover angle can be adjusted to say 15 degrees a tighter pattern will be produced. So theres the versatility factor. The scissors type requires two spiral wheels (left & right) to cut a diamond knurl, so there's the cost factor too.

The cut knurl tool I designed, can work very close to a shoulder, compared with the scissors tool.

The cut knurl can work on a bevelled surface or a tapered shaft with both the straight and helical knurl wheels, and it produces a lovely decorative spiral on bevelled surfaces. This is not possible with a scissors tool, but is possible with a simple single wheel bump-knurler.

The scissors knurl doesn't do well on most plastics, since the material tends to spring back. The cut knurl removes material.

Oh and the cut-knurl can work with any diameter of work while the scissors tool is limited to about 2-1/2".

I prefer the finish produced by the cut knurl and its versatility, over the scissors type.

 

[Arbutus]

Please show your spiral knurling results too. Will you do two passes with your tool?

Ok, this is O1, cut with a straight 40TPI wheel at -30 and then +30. One cut pass per angle.

Spindle speed 315, feed .005/rev Cut depth is about 0.3mm. Lots of lube.

The screw is M6x0.5

 

[jorogi]

Great answer and comparison. I was about to start a Hemingway inspired knurler but now I think I wait till you felease the drawings
Course I probably could get off my mental ass and figure it out from your very interesting post.
Thanks

 

[DPittman]

Great answer and comparison. I was about to start a Hemingway inspired knurler but now I think I wait till you felease the drawings
Course I probably could get off my mental ass and figure it out from your very interesting post.
Thanks

Yes! A Hemmingway knurler was on my want to do projects but now that has been replaced by your design.

 

[Susquatch]

Yes! A Hemmingway knurler was on my want to do projects but now that has been replaced by your design.

I stopped any thought of Hemingway knurlers when I saw @gerritv 's cut knurler. But the cost stopped me.

So I'm thrilled to see this lower cost version.

 

[Arbutus]

I stopped any thought of Hemingway knurlers when I saw @gerritv 's cut knurler. But the cost stopped me.

So I'm thrilled to see this lower cost version.

Yeah, it's pretty straightforward. Just two parts plus a ball tipped screw.
The trick is....

Well, you'll figure it out !

 

[Perry]

I stopped any thought of Hemingway knurlers when I saw @gerritv 's cut knurler. But the cost stopped me.

So I'm thrilled to see this lower cost version.

@gerritv 's cut knurler thread has a great video in it.

@Arbutus and @gerritv great work gents. Thank you for the posts.