I’m charged with the task of building a 5 ft diameter (circular) table top. The base is not part of the project. The top will be 1 and 1/2 thick very seasoned pine. Each board will be 6 to 8 inches wide, jointed and glued. What is the easiest and best method to cut the circle after the top is assembled? While I have routers and a 14 inch bandsaw, I have nothing that can immediately cut a 30 inch radius.
Thanks in advance for your reply.
Replies
A circle cutting router jig: https://www.thisoldhouse.com/house-one/21221690/diy-circle-jig-for-a-router
You can purchase one but making one is easy; there are plans for shop made ones with adjustable length arms and all that, but for one circle it's probably better time spent to make a single use one as quickly as you can like the one shown in the link above.
You can cut the circle in successive passes. For stock that thick, I typically route using the jig about 1/8" to mark the circle, cut near the line with a jigsaw, and clean up with the router.
Drill a hole in the center of the bottom of the table top to fit a dowel. Put a large piece of plywood on your band saw table, big enough to have a hole to receive the dowel slightly more than half the 5’ (so, 2 1/2’ +) from the band saw blade. Spin the top to cut a perfect 5’ round top. You can then either use the jig in Drew’s link above, or you can clamp a belt sander on edge and spin your new circle.
Mount your router on a long arm of thin plywood or masonite, drive a screw into the bottom of the table at cernter. Drag the router bit to make a scratch to check for size, then screw the arm to the top. Light passes with an upcut spiral bit until you are through. Best results with a plunge router because it will not change center when increasing depth of cut. Elevate the whole thing on stickers to save whatever surface you are working on.
The above options are great. You can also draw a circle, cut with a jigsaw, and finish the edge. It's more work, but if it looks round, it is round.
But if I had a good router, I'd use it.
That is what I have done albeit with smaller diameter A & C table tops. Made circle jig, peg in the bottom, multiple passes.
Also add to John's comment, if it looks round - and has no bumps - it is round.
Not disagreeing with any of the good comments, but just to add, since you already have a bandsaw it will be a lot less strain to only use the router at the end, after roughing to size with the band saw, to clean up the edge, not to plow through 1 1/2” thick wood. Let us know how it went.
You can cut a perfect circle on your bandsaw by mounting an auxiliary table with pin on top of the saw's table(outboard). The pin needs to align with the leading edge of the blade, and the distance of the radius from it.
Same concept as the router jig but the jig is fixed and the workpiece spins.
Just another method.
Agree with trimming down close to a circle with the bandsaw (or even a jigsaw). And you can find router bits with long cutting surfaces (2") if you look hard enough, so you could trim the edge in one pass.
Just the bandsaw jig is a pretty big build for a 60" table.
Um, piece of plywood with a 2x4 holding it up is a big build? Maybe it’s the dowel that makes it a big build? :-). I guarantee anyone could be cutting the circle of their table within 5 minutes of starting to build the very basic, simple jig. What part seems like a lot?
I'd use a jigsaw to get it close to the pencil line and then a router jig to get to the pencil line. The less stock to remove with router bit, the better.
The tablesaw jig would be my second choice with a helper to assist.
I'm most appreciative for the swift and thoughtful suggestions. Given the setup in my shop I will probably do a first cut on the bandsaw and the finish, trim cut with the router.
Thanks everyone.
One thing I would recommend if it is in the budget is a 2” long straight compression router bit. I’ve gotten great results using this when needing to go from with the grain to against grain.
Absolutely agree. I picked up a couple of 1/2" bits on eBay that had been resharpened, and were about 0.015 undersize. Best part is that I paid $16 each.
Keep a watch for things like this !
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