Somebody oughta' make these...

[Mike Kolb]

Sure, everyone loves and uses radius cauls all the time.... indispensable, really.  But every so often, there's a need that arises for one that's convex instead of concave. A "reverse caul", if you will.  

Maybe for the underside of a curved nut, or....?  

Anyway, I had use for a 12" "reverse caul" so sanded one up by hand (on the left, obviously). It was a lot of work and isn't 100% accurate, but there ya' go.

Then it occurred to me that some outfit could churn-out a matched set and make some profit.

Any StewMac or LMI employees want to chime-in? 

[Richard Bales]

Hesh, you work on instruments with input jacks???  Perhaps I'm missing some business.

Sorry - couldn't resist.

[Paul Verticchio]

I'm convinced that some instrument owners have a biological component in their physical makeup that causes jack (and control) nuts to loosen. Myself included.

Not a foolproof fix but they help: Belleville Washers. I've employed them for years with great results. Every 'little bit' helps.

http://www.mcmaster.com/#belleville-disc-springs/=w53f6v

http://www.mcmaster.com/#belleville-disc-springs/=w53fx7

[Ned Knepp]

Paul said; I'm convinced that some instrument owners have a biological component in their physical makeup that causes jack (and control) nuts to loosen. Myself included.

I've been doing some research into USB charging station. I came across a post in which the poster explained why no one can plug in a USB cable on the first try. He said that USB jacks and cables were not made in this universe and that we can all save ourselves a lot of frustration by using the "Law of Three". It went on for a while but boiled down to the  idea that USB cables must, by design, be turned over 3 times before they will properly insert into the jack. 

Maybe the jacks and knobs on guitars follow the "Law of Three" too. Perhaps you need to install it, remove it, install, remove and, finally, install it. Either that or you can just use any number of products made by Permatex but you "Electric" guys seem to have this compulsion to make everything so it can be removed for serviced.