Using a stainless steel screw.

[Sugar Bear]

I am thinking of using a stainless steel bolt and nut on a copper cap at the bottom of a copper pipe siphon. I plan to buy it from the hardware store.

Is there any risk of sap/syrup contamination from a small stainless steel nut and bolt from the hardware store?

[Sugarmaker]

Sounds good to me! Stainless grades may vary. But I think your going in the right direction!
Good luck with your season!
Regards,
Chris

[maple flats]

It should be OK with the SS. If you was it well before using. However, in time you may get corrosion, not from the SS but from the copper.