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Need barrel plating action to shift a slidebar so all of assembled part gets plated

I am an engineer for a company that makes hand tools. I have an assembly consisting of a screw and tommy bar (sliding bar), like you would find on a c-clamp, or bench vise. The bar slides back and forth through a hole in the screw. What I would like to do is cold form one ball end on the bar, pass the bar through the hole in the screw and then cold form the other ball on the bar. After assembly, I would then like to zinc/clear chromate plate the assembly. My concern is getting an even finish on the area of the bar that is covered by the hole in the screw. Does anyone have an opinion about using barrel plating to do this? Would the tumbling action cause the bar to slide back and forth through the hole in the screw and give me an even finish?

Any advice will be greatly appreciated!

Rob Smith
Hand tools - Huntersville, North Carolina, US
2003

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An authoritative answer would require experiments with a given barrel size, load size, and rotational speed, followed by statistical analysis. But my gut feel, no, it won't work, you'll have too high a percentage of rejects, unless this is a really cheap item.

I think you would need to rack plate the parts and flip something one or more times mid-cycle. Even then you'll get no plating inside the screw, which may mean early rusting.

You know much more about hand tools than I do, but I think you may need to plate before assembly and use some kind of drive pin to complete the assembly.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003