Knurling tool build

[rwm]

I have a poor quality pinch type knurling tool that so far has not done well. I believe the machine that cut the arms was out of tram and the arms are crooked. After looking at prices I decided to make my own.
I am thinking about something like this:



To get started I bought these:





My plan is to make this tool kind of like a Kant Twist clamp. I will have a 3/8" thick piece on the inside and 1/4" arms on each side of that.
So I have an issue I need guidance with. My original plan to hold the knurling wheel was to braze or weld flat pieces on the sides of the 3/8" arm and then cross drill these. (The knurls are 3/8" wide.) Welding is not a great option due to inevitable warp and the fact that the inside of the slot is inaccessible. I tried a test piece with silver solder but I could easily make the joint fail with a wrench. Would brazing be stronger? If so, what rod and flux for mild steel? I have bronze rod and nickel silver. How can I get the braze material to flow into a joint between flats? Should I "tin" each piece first and then joint them?

Robert


EDIT for completion:
I will add the prints to this first post to make them easy to find. These may get revised over time. The prints for the 1/4" CRS parts are 1:1 so you should be able to print these on paper to duplicate the cuts.
(Rev 3/26/20)

Robert

 

[brino]

Sorry I have no answers/advise, but....... oh boy, oh boy oh boy.......I am looking forward to this build!



Thanks for sharing it!

 

[mmcmdl]

I made a very nice scissor type knurler years back . I still have it and sold the Eagle Rocks . This one was made from solid Almar and heat treated . A very keen eye spotted it on one of my threads recently . I like the Kant Twist clamp style also , lot easier to make .

 

[rwm]

The one I posted above is Accutrak. I think it is machined out of solid stock. After I saw the pic my brain clicked on and said "Kant twist".
Robert

 

[rwm]

Rough rendering of upper arm for clarification. So how do I attach the two side wings that hold the knurling wheel?

Robert

 

[4ssss]

View attachment 316001

Rough rendering of upper arm for clarification. So how do I attach the two side wings that hold the knurling wheel?

Robert

Make it all 1 piece

 

[C-Bag]

Nice render. I would think pinning and bolting the wings would do it. Or get a piece of 1 1/2" thick steel plate and mill it

 

[rwm]

My toy mill is not going to be able to cut that slot. Hence plan B. Plus that is a lot of steel to subtract.
I just made a test joint using nickel silver. It flows at a much lower temp and made a very solid joint. That may be the way to go. My brazing rod is coated with blue flux. Is there a specific flux I could/should put inside the joint in addition?
Robert

 

[C-Bag]

I'm not an expert welder but I've done a lot of different kinds of welding, brazing and soldering. But not a lot of silver soldering. I just got a stick of silver solder that has blue flux too and it did not flow like my buddy described. But he also told me the usual braze flux would work and it didn't flow either but I got patches to at least stick. So I looked online and everybody seemed to like Harris STA-Silv black flux so I ordered me a tub. Not tried it yet so dunno. But I'd rather braze something like that. I'm not sure if it was tig welded it would warp that much.

 

[rwm]

I have the Harris black flux and the white. So far better luck with the white. I don't think the 56% silver solder will be strong enough. The nickel silver rod is tough stuff.

I have another design problem. If I attach the wings I will have no way to put in the pivot for the screw. (It would go in the upper holes above.) I could make those holes .375 and just slide a cylinder in there but that would limit the size of the screw I could use. I was planning on a .375 screw but I may have to use .250? That would be kind of wimpy for this. I may have to redesign. Thoughts?
Robert