i have a 20+ year old Sears Craftman 1-1 1/4 hp router that only has a
collet for 1/4" router bits. i have been told that there is an "adaptor" on
the market that will allow me to put a 1/2" shank router bit into the 1/4"
collet. do you know if and where i might find one?
P.S. i don't plan on doing heavy work with it. however, the up spiral bit
i need to use only comes with a 1/2" shank .
While you can safely use a reducing collet to put a ¼" shank bit in a ½" router, going the other way is not recommended. First you'll have depth of cut and clearence issues, 2nd the router is not of sufficient power to spin a ½" shank router. This would be an unstable and possibly dangerous configuration and I, for one, wouldn't do it.
Get the *right* tool for the job. Either find the bit in a ¼" shank or borrow a ½" router.