roundover router bit difficulty

[vernonls]

I have a woodworking problem.  I frequently make cabinet frames using rails and stiles with 1/4 dados down the middle on the inside edges to accept 1/4 plywood.  I would like to round over the insides of the rails and stiles with a 1/4 round over bit before I insert the plywood, but the bearing keeps just slipping into the dado slot and frequently ruins the nice round over. The bearing is a typical 3/16 thick or so bearing and it is so placed on the router bit that it easily slips into the dado slot and when it does, it messes up that nice roundover.
Surely I cannot be the only woodworker that would builds cabinet frames this way. How do other woodworkers get a nice roundover on the inside edge of a frame.  A thicker bearing would do it, but I don't see such a thing offered by the router bit manufacturers. A 5/8 thick bearing would do it perfectly.

How do others solve this problem. 

vern

[brianwelch]

I have a woodworking problem.  I frequently make cabinet frames using rails and stiles with 1/4 dados down the middle on the inside edges to accept 1/4 plywood.  I would like to round over the insides of the rails and stiles with a 1/4 round over bit before I insert the plywood, but the bearing keeps just slipping into the dado slot and frequently ruins the nice round over. The bearing is a typical 3/16 thick or so bearing and it is so placed on the router bit that it easily slips into the dado slot and when it does, it messes up that nice roundover.
Surely I cannot be the only woodworker that would builds cabinet frames this way. How do other woodworkers get a nice roundover on the inside edge of a frame.  A thicker bearing would do it, but I don't see such a thing offered by the router bit manufacturers. A 5/8 thick bearing would do it perfectly.

How do others solve this problem. 

vern

Unless I am missing something...Stile and rail cutters?
As an example:
http://www.rockler.com/traditional-stile...1AQAvD_BwE

[rlnguy]

I cut a spline of wood, to fit the groove, slip it in, make the roundover, then take it out.
Even a loose fit will support the bearing
Depending on the door, sometimes I make the round over before I cut the groove.

[JGrout]

I have a woodworking problem.  I frequently make cabinet frames using rails and stiles with 1/4 dados down the middle on the inside edges to accept 1/4 plywood.  I would like to round over the insides of the rails and stiles with a 1/4 round over bit before I insert the plywood, but the bearing keeps just slipping into the dado slot and frequently ruins the nice round over. The bearing is a typical 3/16 thick or so bearing and it is so placed on the router bit that it easily slips into the dado slot and when it does, it messes up that nice roundover.
Surely I cannot be the only woodworker that would builds cabinet frames this way. How do other woodworkers get a nice roundover on the inside edge of a frame.  A thicker bearing would do it, but I don't see such a thing offered by the router bit manufacturers. A 5/8 thick bearing would do it perfectly.

How do others solve this problem. 

vern

you pretty much are actually.

the solution is two bearings and a longer screw you have to make sure the bearings are in the same plane and both can spin . 

Or use rail and stile matched cutters. 

Joe

[vernonls]

Unless I am missing something...Stile and rail cutters?
As an example:
http://www.rockler.com/traditional-stile...1AQAvD_BwE

So, if you use the stile & rail cutters, how do you adjust for plywood that is always less than 1/4 ?

vern

[DFJarvie]

Use your router table. The bit will be set back enough so you won't need to worry about the groove.

[Bøb]

Lose the bearing and use either a straight guide or a router table with a fence.

[Big Dave]

Router table & fence gets my vote.

[JGrout]

Router table & fence gets my vote.

with a long fence and additional stops to prevent  over cuts  on the stiles..... The rails do not matter

[vernonls]

with a long fence and additional stops to prevent  over cuts  on the stiles..... The rails do not matter

Well, I tried the extra bearing, but then the end of the bit wanted to scrape the bench top.  Not so good.  I tried the narrow strip inserted in the dado slot and that works much better.  Having already partially assembled the frame which looks like an H (with the middle divider installed) and being rather ungainly as assembled, the router table was not a good option.

If I had it to do over again, I think I would take the mitered corner approach, but then cutting perfect 45 angles is not always easy either.  The other approach which I have done before is to do the rails on the router table (no problem) and then carefully do the stiles using a positive stop to make nice inside corners. 

The rail/stile cutter approach is nice if you are making lots of the same parts, but for one cabinet, you spend all of your time sneaking up on the perfect fit.  Even using a pre-made guide just gets you close.  And in all cases, I would do the round over before I cut the dado. 

However, having partially assembled the frames I am stuck with a work around using the narrow strip. 

Oh, well, this gives me something to do better next time. 

thanks for all the advice.

vern