Kant-twist Knurling Tool

MrWhoopee

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I've grown tired of fighting bump knurling, so it's time for a scissor type knurling tool. After shopping a little I decided to make my own. I started with one of these imitation Kant-twist clamps.

At less than $7 ea., I figured I could afford to sacrifice one. It needed to be wider inside to accommodate the 3/8 wide knurling rolls, so I took it completely apart and fabbed replacements for all of the pivots, nuts and spacers. While I was at it, I increased the thread to 5/16-18.

Here it is just mocked up, I still have some things to do before it gets riveted back together.

20211128_173717.jpg

Despite working all the details on the fly, I only made one mistake and it took less than a minute to recover.
It was a good day.
 
There is a lot of side load when moving the knurl from left to right.
just saying.
 
I've grown tired of fighting bump knurling, so it's time for a scissor type knurling tool. After shopping a little I decided to make my own. I started with one of these imitation Kant-twist clamps.

At less than $7 ea., I figured I could afford to sacrifice one. It needed to be wider inside to accommodate the 3/8 wide knurling rolls, so I took it completely apart and fabbed replacements for all of the pivots, nuts and spacers. While I was at it, I increased the thread to 5/16-18.

Here it is just mocked up, I still have some things to do before it gets riveted back together.

View attachment 386768

Despite working all the details on the fly, I only made one mistake and it took less than a minute to recover.
It was a good day.
interesting idea.
 
There is a lot of side load when moving the knurl from left to right.
just saying.
Do you think that could be mitigated some with larger diameter material at all pinned areas? Maybe through bolts clamping a larger diameter spacer?
 
I finished it up this morning, swaging all the rivets down with a punch.
Much to my delight and amazement, the damn thing works.

20211129_124237.jpg

on aluminum
20211129_125605.jpg

and steel
20211129_130551.jpg

There is some looseness on the center pivot which allows it to tilt slightly under load. I could see some axial (left to right) motion of the upper roller mount while knurling the steel. As a result, the ends of the knurls are not always fully formed. The shank should also be longer, the adjusting screw has some clearance issues with the tool holder. Shortening the screw to minimum length will help.

For a wild hair, first attempt I'm pretty happy.
 
I’d say that works pretty good for a first try. I have one of those Chinese made ones with the two pivoting legs that hold the rollers. It didn’t work worth a darn until I removed all the pivot pins and replaced them with bolts that are tight enough to almost lock up the entire thing. I’ve had an idea for one bouncing around in my head for a few years now. If I didn’t have so many half done projects already I’d probably start on making it. Not much about knurling is cheap except some of the folks trying to do it. The design of knurl holder in my head is a scissor type I believe it was inspired by an accu-trac tool.


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nice. you never know till you try.
And when someone (like me says nay) just keep plodding along.
That's how our continent was discovered..
 
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