Making a Miter-Fold Joint

Here's a detailed description of how to make a miter-fold corner with laminate material. July 3, 2008

I've seen clean mitred Formica corners that don't show the grey phenolic laminate substrate on casegoods for retail display. How is this achieved? I can imagine on a cube that you cut your mitres after the laminate has been applied and then the panels are glued to a frame. But I imagine it's much more difficult to do on a 6'x3' piece. Your thoughts?

Forum Responses
(Laminate and Solid Surface Forum)
From contributor S:
These super clean miters on production casegoods are usually done with a V groover. Tape is applied to the outside and a V is cut on the other side right through to the tape. Squirt in some glue and fold it up. Can also be done very successfully by taping mitered pieces together and folding the same way.

From contributor J:
There is another way. It's called a miter fold technique. Take your table saw and tip the blade to 45 degrees. If it tilts left, move the fence to the left side of the blade. Lower the blade below the table.

Clamp a sub fence to the table saw fence, but keep this sub fence off the table. Raise it about the thickness of the stock you are using for your cabinet, minus 1/16". This space is for safety and will allow the cutoff to fall away from the blade, preventing kickback.

Lay your stock flat (pre-lam - you know, with the laminate already on) on the table saw top and slide it up against the sub fence. Now take a very sharp pencil and draw a line on the sub fence where the stock meets it. Remove the stock, raise the blade, and move the fence to the blade. You now need to turn on the saw and just get that blade running into the sub fence, just under that pencil line. This takes some practice the first few times, so be patient.

Now when you place the stock up against the fence and run it into the blade, you should cut a perfect bevel on the edge of the board without going all the way through the last one hundredth of an inch of the laminate.

If the fence is too close, the edge of the board will have a flat spot; if too far away, the saw will cut away too much, leaving a jagged ugly gap visible when looking down at the cut. It will also chip the hell out of the plastic laminate.

We call this miter fold because you do this with two pieces, place the knife edges together (careful, the miter edge will literally be as sharp as a razor blade), then place some packing tape across and down the joint (I like to wash where the tape will be with alcohol to make it stick really well). Now flip the pieces over, spread some glue in the valley, and fold it up. Makes a seamless joint. You may also want to burnish the outside corner to ease it a little.

From contributor O:
There is also a router bit with bearing to do this. This way you can do very large pieces. We used this method and several others in the architectural and fixture shops I worked in. Any good tooling maker should know of them. I think I still have one. You are able to do radiuses as well with it.

From contributor O:
My first post was for laminate thickness only. Another way, for laid up material, is to make an attachment for 2 or 3 hp router base to tilt router on angle and slightly downward so bit cuts down on material. Use a 1/2 x 2 1/2 down cut spiral and run against a straight edge. This will do radius work as well. You need a center line across the base attachment to indicate where the bit cuts. Measure across the base to edge of fence the part that will run against the straight edge. This measurement is subtracted from the radius you want. Make a template with that radius. Say base measure is 4", you want 6" radius, the template will have 2" radius on it. Precut outside finish line 1/8" or closer. Go around radius holding centerline against the template exactly.

There is or was a router attachment made by a guy in Santa Barbara California. This rig used a 21/2 hp pc router and cut from the bottom with a bit that was like a flycutter for end mill. It cut a concave on the miter and worked like the one mentioned above. Miter was sharp as a razor. Very spooky to run this thing. This was some time ago - probably outdated by now. Then on very large jobs, with miter on both sides, we used the double end tenoner. But that's another story