how do I make this type of hole?

[Christof Grohs]

I would like to take a piece of 1" thick stock and cut a 1" diameter hole 1/2" way through the stock...no biggie. But then I want to put a 3/8"" round over on the outer edge of the hole. I cant use a router bit with a bearing because the bearing hits the bottom of the hole....how do I do it?

http://www.audiocircle.com/gallery/albums/userpics/12241/tvc_birdseye_with_cherry_top.jpg

thanks
c.

[Christof Grohs]

Forgot to add that the 1" stock I'm trying to do this to is quilted maple.

[Jason Beam]

Drill your 1/2" deep hole in your finished stock.

Drill a larger hole in some scrap stock that will be thick enough to accomodate much of your router bit as well as act as a pattern for a guide collar attached to your baseplate. It'd probably take a 2" diameter hole or more and maybe 3/4" thick at least.

Put a collar in your base plate that is just larger than your router bit. This is where you may have to make some tests to find the right collar to fit the guide hole that gives you your 1" diameter pattern.

Take the bearing off and route away!

Lots LOTS and oh yeah ... LOTS of test cuts before this will work right.

Alternately, if the bit won't work at that depth (it could have a post on it that gets in the way, for example. You may try all of the above with a bit like this:

http://www.amanatool.com/bits-fv/56190.html

in which case, it already has the bearing so you won't have to do all that extra math to get things right. It'd still take a larger hole in the scrap, but you only have one variable (the bearing diameter vs the cutting arc) rather than two (bit diameter to collar diameter).

[Travis Gauger]

Guide Collar and template?

[Chris Padilla]

If you only have 1 to do, sounds like some sandpaper and elbow grease might be the fastest unless you really want a precise 3/8" roundover.

Even if that hole went completely through, I'm not sure a 3/8" roundover bit would even fit in the hole.

Tell us more about what you are wanting to accomplish...maybe the bigger picture will help.

[Christof Grohs]

I attached a pic in the original post. I would like to flare the hole out, if possible, to use a thumbnail bit for the round over, giving a more gradual slope to the flair. There will eventually be a solid 1" dia. aluminum volume control knob in the hole.

After making my original post I realized, just as the second poster mentioned, my only option is probably a template and guide bushing.

[Lee Schierer]

Here's what I would do. I would make a template that would fit my router and guide collars enabling me to make the diameter hole desired. Attach the template where I want the hole. Put a straight bit in my router and remove the majority of the material to the desired depth. Then replace the straight bit with a round over bit without a bearing and use the same template to round over the edge of the hole. To do this the center of the round over bit would need to be the same diameter as the diameter of the straight bit used to make the hole. You should end up with a flat bottom hole with rounded top edges and a smooth transition to vertical near the bottom.

[Christof Grohs]

Good idea, thanks!

[glenn bradley]

I attached a pic in the original post. I would like to flare the hole out, if possible, to use a thumbnail bit for the round over, giving a more gradual slope to the flair. There will eventually be a solid 1" dia. aluminum volume control knob in the hole.

After making my original post I realized, just as the second poster mentioned, my only option is probably a template and guide bushing.

I would drill the hole all the way through, round it over with a bearing guided bit and mount my volume control to a seperate piece recessed in from the back.