This is a razor saw I bought in the early sixties that has a removable blade attached with 2 or 3 screws and nuts. I'm sure I got it at the local hobby shop at the time. It has 'ECLIPSE' 'Sheffield, ENG.' and 'NO. 45' stamped onto it. So, replaceable blades saw were made at one time. I don't know where you'd find one now but hope this helps somewhat.