Warren, that sounds pretty easy, tempering in the kitchen oven I can handel. I've included a picture. The drawing on top has two small bits (ment to spring) shaped like tong jaws, about 1" to 1 1/2" out from plate. The 3-d drawing is a spring steel ring about 5" across on a mild steel plate ( my preferred design cuz its simple).

Rich, These are quick release ties for polo ponys. My 1st sample was a mild steel ring not welded so that it would just stretch out and release a spooked ( and expensive) horse. The stable manager thought the horse might wind up falling while stretching it out. Hence the spring steel which sould be quick acting. The mechinism needs to let go at the same pressure that would break thick hay string ( havn't tested it yet but guessing 100-150lbs. ) so we are not talking heavy material. The spring ring ( in drawing) would need to deflect the thickness of the rope ~ 3/4" , the other thingy would need to open 3/8" . There will be 50 of the ties ( which wouldn't fit in my forge at the time for normalizing )so that whatever I wind up doing I'm gonna want it to be as repeatable as possable for consistancys sake.

Thanks for the info guys, Artmetal is a wonderfull resource and I don't take it for granted.

Kevin