Roundovers on edges greater than or less than 90 degrees.

[Chad Schmitz]

I'm working on a project that uses two boards that are joined at a 45 degree angle and would like the corner created to be rounded. (I'm interested to know how to do this for any angle other than 90 degrees) Other than using sandpaper, is there a precise way to use any type of router bit for this. I have over 100 router bits and none of them will achieve this for me. Most bearing guided bits are geared for a 90 degree edge prior to routing. The graphic below shows the before (left) and after (right) of what I'm trying to solve. I've been woodworking for over 10 years and have made countless items, but haven't been stumped like this before.

Any help?

[dadiOH]

Assuming you have enough of them to do to make the fussing around worthwhile...

1. Use a *big* finger nail bit

1. Make an angled platform for your router table so that the work will be at the proper angle to the bit

2. Use just the a portion of the bit center to do the cutting.

The problem is going to be getting the bit out far enough to reach the joint...that depends on how wide the pieces are and how close the router is to the table edge. It might work better to make an angled shoe for the router base rather than use it in a table.

I'd just whack it off with a plane...

[pat]

[Name]

Chad Schmitz skrev:

An old molding plane (hollow) might be a good option:

to find on eBay...

[henry]

Would a modified spokeshave work?

[Chad Schmitz]

Pertaining to #3....

On acute angles, I agree with you, but for obtuse angles (like in the graphic I included) the bit has 90 degrees of sweep, which on a 45 degree joint would create a beaded look on one side of the edge.

dadiOH wrote:

[Pat Barber]

[dadiOH]

That's why you need a big bit - a *really* big bit...so the joint area being cut can reach into the bit without the outer portions of the bit cutting. That's also why the angled platform is needed...so the plane of the joint can be perpendicular to the bit.

dadiOH _____________

Chad Schmitz wrote:

[CW]

You can have any profile you want ground.

[Tom Watson]

depends on craftsmanship in its execution on replication that is usually beyond those who ask of it."

Joe Bob Donovan

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Tom Watson

tjwatson1ATcomcastDOTnet (real email)

[jackmcclurg]

Pat has it right as far as he goes. The trick is postioning the fence right on a router table with a round over. Do the math this way: A roundover bit is a quarter of a circle, so four roundovers will collectively complete a circle, which is what you see when you have rounded over all four corners of a square. If you were to route each

1/2 of the joint of a square before putting it together, then the two halves would each use 1/2 of a roundover as measured along the cutting surface of the roundover. Since you are making an octogon, each 1/2 of the joint would use 1/4 of the length of the roundover as measured along the cutting surface.

This is really a problem in trigonometry [sin(22.5 degrees)] which gives a numerical result of 0.3826... Which means that you position the fence so that 38.26% of the linear measure of the roundover will be used for the cut. This will work with any size roundover. I cannot position my fence that precisely, but you get the idea.

Jack

[e-mail] wrote:

[jackmcclurg]

I forgot to say that you will need to make multiple passes. The miter holds the wood away from the fence. Two passes may not be enough, so experiment with some scrap.

Jack