Hi Keith, While it is possible, it will take some ingenuity. What you really want is a stable pivot point in the middle of your present hole assuming it is located where you want it and a means to trammel the router around that point on a 2 inch radius from the pivot point to the outside edge of a straight edge router bit.
In this case I think I would remove the base plate from the router, form another from hard board or quarter inch plywood with a pin through it at the 2 inch radius and do the deed that way. What I do have and may be of interest to you is a double mandrill hole saw which permits two saws to be mounted on a single mandrill. The smaller saw is mounted on the inner part of the mandrill, in this case your 2 and a half inch hole saw, and the bigger 4 inch saw on the outer mandrill. The smaller saw projects below the larger one and can therefore be fitted into the original hole to guide the larger saw which will then cut out the 4 inch hole. This can be purchased from Lee Valley and probably many other places. Way cool! ----- Original Message ----- From: Keith Christian To: Blind Handyman Sent: Monday, March 16, 2009 10:05 PM Subject: [BlindHandyMan] Cutting with a router Hi, I cut a hole In a box with a large hole saw. It is not big enough and I want to make it bigger. The wood is half inch plywood. The hole is a 2.5 inch hole and I need to make it 4. I have used the router to take edges off of projects but never to cut like this. Is it possible? I don't have a jig saw. Thanks, Keith [Non-text portions of this message have been removed]
