3/16 diameter sounds like way too big for solder to use on a clevis. It sounds like your solder is a rod used for large work. There is a wide variety of silver solder available but the most common for our use is mostly tin with 2-4%silver. It requires a fairly active flux usually containing ammonium and zinc chlorides. I normally use 60/40 electrical solder which I find tins and flows better, but it is getting harder to obtain since lead has been declared bad stuff by the EPA.