Do I need an expensive router bit or lower expectations?

[Scott Winners]

I am in the home stretch on a current project. I have built a case out of 1/2 inch USA birch veneer ply. It has shelves in it. The face is now covered with 1/4 actual BB plywood.

I did shelf lips (opposite of drop edges) as a structural component, and then wee slivers of more BB between the lips to make it uniform.

There is a pic of the scale model in this thread, post 7 I think: https://sawmillcreek.org/showthread.php?298532-cellar-shelves-for-canned-goods&p=3207113#post3207113

For the outer edges of the casework I used a 45 degree chamfer bit with a guide bearing on it and I am satisfied. I could do the same up and down the front on the outer edges.

The problem is I was hoping to put a 45 degree chamfer on all the shelf openings all the way around, one eighth by one eighth. By the time I park one eighth inch of my guide bearing on the 1/4 actual BB face pieces, I won't be making a visible cut with the chamfer bit I have. If I set my existing bit for 1/8 depth of cut the bearing will be riding on air.

My best guess at this point is to use a sanding block to make a chamfer maybe 1/16 x 1/16 in all ten openings... I have only got two coats of shellac on the visible side and the opposite side is bare factory, so I do have time to order up a special bit. I should mention my one router has a quarter inch chuck and I am not especially excited in buying a trim router, the router I have is my least favorite tool.

Couple current pics.

Thanks in advance.

484157484156

[glenn bradley]

Clamping a straight cut piece of scrap to use as a guide for the bearing to ride against is not unusual. Doing the same to provide a larger surface for the router to ride on is common as well. Sanding could get you there but will be a bit irregular and on inside openings, tedious.

[Lee Schierer]

Clamping a straight cut piece of scrap to use as a guide for the bearing to ride against is not unusual. Doing the same to provide a larger surface for the router to ride on is common as well. Sanding could get you there but will be a bit irregular and on inside openings, tedious.

Yes, this is what I would do! There is a space between the bearing and the cutting edge on all bearing type router bits. If the bearing doesn't have enough surface to guide on you get a poor quality cut. Give your bearing a larger guide surface.

[Derek Cohen]

Use a block plane.

Regards from Perth

Derek

[Jim Becker]

To do a machined chamfer like you describe, it's likely best to do it prior to assembly so you can take advantage of a fence. At this point, I'd do the abrasives route...make a jig that holds the abrasive and also acts like a stop for depth so you have a consistent chamfer across the surfaces. You'll only need to touch up the corners manually.

[Jim OConnor]

I second the block plane. This should be easy for a sharp good quality block plane. Make sure you draw pencil lines on the top and side edges then plane to the lines.

[Scott Winners]

Appreciate the inputs. Given the side cheeks(?) and the bottom edge of each shelf lip have a bearing surface to ride on I did consider trimming up the inside edges with a flush trim bit and then only having to put a fence on for the upper edge of each shelf lip for the guided chamfer bit.

But I was stopped by the horizontals I had put on the side panels (top, middle and bottom) to use as guides when gluing up the outer case. In the attached pic there is especially good contrast at the top shelf. I can kinda see the middle one. I did go round and round the mountain in the design phase but opted for ultimate strength rather than shape the end of those horizontals.

I had thought about chamfering before assembly. Honestly I did think about it; instead I made my pieces as best I could knowing they were going to move around a little bit at glue up.

The vertical cheek pieces are nominal 6.5 inches tall each, so a block plane would leave a lot of area to clean up.

Ultimately I chose to just use a sanding sponge, or a soft sanding block, more than five years old and labeled 320 grit. With that I was able to break all the edges of each of the openings equally so it looks good enough. I still don't have a signature or well loved corner treatment for my work. The 3/16 chamfer on the outside of this case is plenty serviceable, the sanding block leaves the inside edge of each shelf opening looking crisp but not sharp enough to cut skin.

I need to get this thing done and out of the garage to make room for both my wife's car and the snow thrower. I have already had the wood stove lit once this autumn and I am running out of time to get this out the door.

Again, thanks for your thoughts.