Router Technique
Roundover a Circle

by The Multitude
July 2004

stoppy

I'm using 1/4" roundover bit on 2 3/4" diameter half circles for 2 new grandsons' play blocks.   I'm having a tough time on the curved surface getting an even roundover.   Is there a jig or technique to doing this to keep all my digits 'cause I can't seem to get it right?

Augi

Are you sure that the stock is flat.   If table routing, the stock lifting would create an uneven cut.   If freehand routing, the baseplate tilt could be an issue.  

2 1/2" semicircles are pretty small in either case.   I would have jig set up to keep my fingers away from the bit.
Steve K

There are two things that come to mind that should help.   First, since you're doing half circles, don't part the circle area from longer stock until after the edges are rounded.   That will give you a little more margin for safety.   Secondly, it's very difficult to hold a tight diameter against a bearing when routing.   It's easy to fashion a fence to help maintain even pressure.   A fence for what you're attemping may need trimmed a little differently than this one but it should give you an idea of how to make one.

Drill a hole slightly larger than the bearing in a piece of wood and then cut a 45 "V" notch to the center of it.   Clamp the fence so your half round pieces contact either side of the fence and the bearing all at the same time.   The contact area doesn't have to be large so you should be able to make the fence small enough to work for you.   That will give you much more control.

Steve
Barry

If you're freehand routing, make a hole in a piece of stock the same thickness as and about 1-1/2" larger than the circles, and screw/clamp to a base.   Use a piece of carpet tape to stick the circle in the hole.   That will help you keep the router from tilting.
stoppy

Thanks Steve...   I am table routing these and I knew there had to be a better way of doing it.

My brain just wouldn't engage.

The half circles come out of blocks that make arches so I have to cut them out before I can rout them.   Your jig idea will work perfectly.

Jim
daddo

"Atta boy Steve".


I made one of those too and it worked great, but not after ruining a few cuts.


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