A few times I have purchased hole saw kits, there is one center piece and bunch of different sized saws every time I have tried to use one them by the second or third hole they are coming apart... It gets very frustrating. Now I just buy one that is together and the size I need.
It seems like having one center bit and several interchangeable hole sizes would be a great idea. But I never get it to work in practice. Is there a secret to how to make them stay together, when you swap out pieces?