2 years ago a former machine shop student of mine made a mainspring vise for me. He needed a project and I needed a vise. Another student took it and drew up plans after it was finished. You need to remember these are plans made by a high school student. He did a decent job for doing it as his first "job" besides a class assignment. So I guess the question is anyone want a copy? I try to post it if there is any interest.
Al Nielsen
Charles City High School
Charles City Iowa
I have added the link for the plans to the shop tools section. Enjoy