router bit...router bit....

[Patrick Melchior]

which shall I use.... to round over a 3/4" board? I want to round over both sides so I have a 'round' profile. I don't have a router table....
is there a formula or just bit depth setting?

[Jim Becker]

It's hard to do this with a hand-held router and no fence as a complete roundover (bullnose) doesn't leave anything to support a bearing, at least on the second pass. You might want to rig up a quick and dirty inverted "table" with a fence to do this or hook up with another woodworker who does have a router table.

[J. Z. Guest]

There are a couple ways.

1) Use a 3/8" round-over bit. Practice on 3/4" scrap until you get it right. It will take a few tries.

2) Get a bullnose bit of the right size, and clamp a straightedge to your workpiece the appropriate distance from the edge so that your router base rides along it. You'll probably want to do this in several passes until you get the right amount of roundover without trying to take too much material in one pass.

[Patrick Melchior]

thanks jim and jeremy....I was thinking along those same lines...sometimes a second opinion is reassuring.

[Prashun Patel]

I used a 3/8" roundover to do a full bullnose.
I found that if you set the depth just shy of the full 3/8" then the bearing will still have enough material to ride on.

Any kind of flatness on the center (assuming you find it at all objectionable; I didn't) will be quickly removed when you prep-sand the edge for yr finish.

[Peter Quinn]

Amana makes roundover bits with two beaings for this application. Run the first pass with the standard bearing. You run the second pass with the same router setup but change to a slightly larger back beveled nylon bearing that accomodates the profile you have already run. Don't know if they have a 3/8"R, but a 1/2" might work for you.

http://www.amanatool.com/bits-fv/57190.html