I am using windshield wipers stainless steel and welding wire stainless steel to make an egg beater for practice. I worry that using this steel for food or mouth is hazardous. I have a hard time finding small dimensions food grade stainless steal. Is this safe? If not, where can I find them?
Any non-corroding stainless would probably qualify as food grade. Types
304 & 316 are readily available and should work fine. The "food grade" requirement, in a commercial setting, is usually described like:
"Examples of acceptable equipment materials include some types of stainless steel, various plastics and laminates. Some types of stainless steel can corrode. Stainless steel that can corrode is not acceptable for food processing facilities. It is very important that equipment and utensils be constructed of food grade materials so as not to create a health hazard to consumers."
For personal use those requirements don't necessary apply and you could even use mild steel as long as you took precautions to see that it didn't get a chance to rust.
The biggest issue I know of, from a guy who used to make food processing equipment, is that the welds must be flawless. If there any pits or imperfections in the welds bacteria can't be washed off during cleaning and therefore contaminate the food. Welds must be ground/machined flush & smooth.