John,
3.5mm hex wrenches show up on eBay from time to time and sell for up to $10 USD. That's a lot of money for a $.25 tool. I can get them but have to buy a box of 100 so I've never bothered because I already have a 3.5mm hex wrench.
I've been told that a 9/64" hex wrench will work in the brake cable screw on Campy Delta brakes. It's only .003" larger than 3.5mm.
3.5mm = .1378" 9/64" = .1406"
I have several bikes with Deltas so I'll have to check it out.
Chas. Colerich Oakland, CA
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