Cutting miters for recipe box

[banderson]

Anybody ever cut (successfully) mitered corners for small boxes. I am planning on making a few recipe boxes out of 1/4 inch plywood but I am wondering if the shopbot can cut the miters or is it better to do it on a router table.

[steve_g]

Bret

I make what are essentially "fold up" boxes using a 90° V-bit. The grain can be made to flow around the box or up and over the box. I glue them up and tape the corners with masking tape... no clamps! I cut the boxes open after the glue has dried. I have never done this with 1/4" material but think it should still work well.

SG

[Brady Watson]

Bret,
Make sure your spoilboard is nice & flat. Run the Tabletop Surfacer under the Tools menu in SB3. If your spoilboard is not flat, then the miter depths will vary, which is not good for this application. This is ideally done with vacuum hold down - with carpet tape being a close 2nd.

Amana makes some nice precise v-bits for miter folding: http://www.amanatool.com/cncroutingdetails/rc-1028.html

Keep in mind that this technique can be used with a variety of materials. However, each material will be different in terms of where the 'sweet spot' is for the ideal depth. For instance, DiBond (http://www.graphicdisplayusa.com/prod_dibond) should be cut to a depth where it's max depth is about .005 to .01" above the bottom aluminum layer for best results - you should NOT be able to see the bottom layer of AL from the cutting kerf. Plywood however, should go deeper than this, leaving only .008-.012" of skin on the back side of the miter cut. This works quite well with plywood, although Luan/floor underlayment is 'splintery' no matter what you do with it.

-B

[banderson]

Wow. Do you guys mean that the thin skin left over would actually bend around the corner without breaking? I have never heard of this...no surprise as I am not a professional woodworker. I am blown away at the possibilities of this though. Do the corners still look sharp?

[Brady Watson]

This is what is called miter folding...a new technique for you to try :)

The corners are not sharp, but 'eased'...meaning that whatever skin is left at the corner is wrapped around the corner. For most things it is 'sharp enough' - if not, just sand or shave the miter on each leg to get a sharp corner back again after you glue it up...but who wants a corner that sharp anyway on a gift box etc?

-B

[blackhawk]

Brady,

Have you ever tried the miter fold technique with solid wood like cherry or walnut? Just wondering how well that would do.

[Brady Watson]

Brad,
No I haven't - but keep in mind you can always apply a little 'English' to the joint with a steam iron and a towel. Flip the miter over with the skin side up, lay the towel over it and crank your steam iron all the way up. Then steam that joint. It will soften up the fibers and prevent them from snapping @ the bend.

The same trick works to iron out dents in wood if you accidentally gouge it...

-B