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View Full Version : Metal Lathes A couple of Rope Knurls



Leigh Betsch
07-06-2011, 8:23 PM
George Wilson posted how to make these in the Neanderthal forum a while back. I finally had an application for some brass knobs so I made a knurl holder, a few knurls and some knobs based on his description. The attached pics demonstrate the process.
Not pictured here, but I first made some plunge tools for the lathe so I could get the radius of the knurls and the brass knobs to match the 10x32 tap diameter. I used a 3/16 end mill to cut the right radius into a O1 blank, heat treated it and then used that as a tool bit to back cut a male form into another O1 blank, which I also heat treated. I then had matched tool bits (male and female) that I used on the lathe to cut the knurl and the brass knobs to matched 3/32" radii.
I then made the knurl holder for the lathe and the O1 knurls. I hobbed the knurls with a 10x32 tap in the lathe. This worked great! A nice accurate way to get a fine pitch knurl. I then heat treated and tempered the knurls with my A/O torch.
I set my lathe tooling up in a square turret (made this 30 years ago). I got a little production run going and could knock out a knob every 13 minutes.
A fun little project.

Leigh Betsch
07-06-2011, 8:30 PM
A few more pics. I didn't have room in my square turret for a cut off blade so it was a hack saw job. Next (not pictured) I mounted them on a mandrel, faced and shaped the tops.
I made a few with a 10x32 tapped holes and 10x32 threaded rods for thumb screws and a few with 3/8x16 tapped holes to be used as knurled nuts.

Bruce Page
07-06-2011, 9:37 PM
Way cool Leigh! I would love to make a knurl like that. I wish I had the heat treating equipment/knowledge!

Bruce Boone
07-06-2011, 11:37 PM
Very knice knurls.

Mel Miller
07-13-2011, 2:14 PM
Very nice! Thanks for posting pics of the process. I have managed to collect a dozen or so of the old rope knurls, but haven't felt confident enough in my machining skills to attempt making one.

Mel

george wilson
07-13-2011, 9:58 PM
I have said it before,Leigh: One user of the technique I posted made it worthwhile. Also helps keep the knowledge from dying out. I saw a post where a guy laboriously indexed a knurl to cut each "thread" in the knurl. A needlessly long,involved process,requiring equipment some may not have: a mill and an indexing outfit. With this method,all you need is a lathe. You could saw and file out the slot for the knurl holder without a mill.