Routing A Radius On An Outside Corner

[Ken Krawford]

I've build numerous table tops and always struggled trying to achieve a nice looking radius on the outside corners. I finally broke down and purchased a jig thinking this would solve my problems.
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I used the supplied screws and fastened the jig to the underside of the workpiece. All 4 corners ended up with less than perfect radii and required sanding to make the corner - edge transition smooth.

Has anyone used one of these jigs before. It seemed like the perfect solution but left a bit to be desired. What am I doing wrong?

[Dave Richards]

You say you "ended up with less than perfect radii." What exactly was wrong with them? Are you trying to hog off all the waste with the router? What kind of bit are you using?

[Robert Parent]

Years ago I made some templates similar to the ones in your photo except larger and without the tabs for screws. I just clamp them, and route but never had an issue with non-perfect corners. As Dave mentioned, maybe it's your bit selection or the hogging of material??

I typically used flush trim bits with bearing either on top or bottom depending on the project.

Robert

[Curt Harms]

Years ago I made some templates similar to the ones in your photo except larger and without the tabs for screws. I just clamp them, and route but never had an issue with non-perfect corners. As Dave mentioned, maybe it's your bit selection or the hogging of material??

I typically used flush trim bits with bearing either on top or bottom depending on the project.

Robert


Ditto. I use 1/2" ply or MDF with a 1/2" X 1/2" pattern bit. I use a larger piece so I can clamp the pattern in place thus no screw holes.

[Lee Schierer]

When routing around the four corners of a piece of wood, two of the four corners will tear out if you don't climb cut. Conventional cutting will lift the grain or the cutting edge will hit the grain end on and the grain will shatter instead of cutting. When climb cutting you need to take light cuts and have a good grip on the router or work piece to prevent self feeding. The result of climb cutting will be a much smoother finish on the cut.

[Bradley Gray]

+1 I use a foot square piece of 3/4 birch ply, clamped, and a top bearing pattern bit.

[Joe O'Connor]

I got a flush trim bit with top and bottom bearings so that I could cut from either side of the table top to prevent tear out.

[Jim Dwight]

I just use the sander.

[Mike Henderson]

I just use the sander.

Me, too. Sander and my eye. If it looks good, I'm good with it.

Mike

[Ken Krawford]

I'm using a 1/2" flush trim bit. The problem I ran into on all 4 corners was that the bit was cutting into the edge of the top past where the radius ended. It wasn't a lot but required getting a sander out and feathering in the depression.

[Brian Holcombe]

A good fine rasp.

[Kent A Bathurst]

When routing around the four corners of a piece of wood, two of the four corners will tear out if you don't climb cut. Conventional cutting will lift the grain or the cutting edge will hit the grain end on and the grain will shatter instead of cutting. When climb cutting you need to take light cuts and have a good grip on the router or work piece to prevent self feeding. The result of climb cutting will be a much smoother finish on the cut.


A good fine rasp.


Both of these are my suggestion. Depends on the situation.

Most often, though, I'm with Brian after whacking the corner with a handsaw. Then the rasp, and then sandpaper and cork block.


Lee did a very good job of describing this situation and routers and climb cutting. FWIW - you need to know this when you are using a router and a circle jig for a round table top [say, a tabouret] - you have to do it in quarters, climb cutting your way through the grain pattern.

[Peter Quinn]

+1 I use a foot square piece of 3/4 birch ply, clamped, and a top bearing pattern bit.

This is what Ive always done. Make one good template, make it so you have plenty of reference edge to lead into and out of the corner, no problem.

[Jamie Buxton]

I'm a big router guy; I use them for many tasks. But for this, I generally just draw the radius on the wood, roughly remove some of the waste with a handsaw, and then get out the belt sander. This is good use for a belt sander. You can cut nicely to the line, and fair the curve smoothly to the straight edges. And if you're a sixteenth off, but the curve fairs smoothly, nobody will ever notice.

[Greg Hines, MD]

I would suggest that for your templates, you should screw on short cleats to the side you intend to use, so that it sits atop your work piece, hooking over the edge, and then running your pattern bit across the corner. Woodpeckers came out with a very nice machined aluminum set of these a while back, way too expensive for me, but if you did a lot of them, they might be worth it.

Doc

[john bateman]

I'm using a 1/2" flush trim bit. The problem I ran into on all 4 corners was that the bit was cutting into the edge of the top past where the radius ended. It wasn't a lot but required getting a sander out and feathering in the depression.

That sounds as if your flush trim bit and bearing are mismatched. Like the bearing is a little smaller diameter than the cutter. Or your router bit is not at a perfect 90 degrees to the template.

[Ken Krawford]

That sounds as if your flush trim bit and bearing are mismatched. Like the bearing is a little smaller diameter than the cutter. Or your router bit is not at a perfect 90 degrees to the template.

The bit was a brand new, never been used Freud bit. I guess it's possible that the router was tipped but unlikely that I did it to all 4 corners.

[Mark Rakestraw]

I still think John is correct Ken. If the bearing is on the template and the cutter is going deeper it must be a slightly larger diameter. (assuming the router isn't tipped, etc.). I guess the other possibilty is that the pins do not hold the template perfectly even with the edge. Since its easier to smooth something that is a tiny bit proud rather than take out a depression I would shim something. You could shim the pins, or the template or the bearing with a piece of electrical tape -- any of those would effectively move the cutter out. Of course if it is caused by a difference in the bearing and bit diameters the shims might well need to come off when you change to a different bit.

[glenn bradley]

I'm using a 1/2" flush trim bit. The problem I ran into on all 4 corners was that the bit was cutting into the edge of the top past where the radius ended. It wasn't a lot but required getting a sander out and feathering in the depression.

This sounds like a couple of possibilities;
- The corner of the material and the template do not match causing the bit's cutter to contact the material where it should not.
- The flush bit is not truly flush (I've had this more often on bargain bits, never on a name brand).
- The "top" surface and the "edge" are not truly perpendicular; the router and bit have no way to compensate for this.