Kitchen Cabinet Door Question

[Johnnyy Johnson]

I have made many raised panel doors, but never any with 45 degree corners. Several years ago I bought a PC 557 biscuit cutter. Never used it that often. After reading many post on biscuit strength, I am wondering how they would work on the mitered corners. I know the tung and grove is the preferred method. Since the joint is end grain to end grain (I guess), will biscuits make a sound, strong joint on a 13/16" thick door?

Thanks
Johnny

[Lee Schierer]

In test data that I've seen, biscuits add little strength to edge grain joints. I don't recall any data on 45 degree joints. One trick to use on mitered corners is to dilute the glue with some water, and apply a thin layer to each side of the joint. Let is set up, then apply glue to both sides when you are ready to final assemble the joint. The thinned glue keeps the final glue from getting sucked into the wood an creating a starved joint. Joints I have done this way are nearly impossible to break as long as the fit is nearly perfect. Cut your pieces a bit long and then dry assemble to insure you are cutting true 45 degree miters. If you have gaps the joints will fail sooner than later.

[Cary Falk]

I use biscuits all the time for mitered picture frame corners. You could also do a spline with a contrasting wood to accent it.
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[Jim Matthews]

+1 on the cross splines for strength.

I would skip the biscuits, altogether.
A well fit miter with a crossgrain spline is wicked strong.

(The grain of the spline must run perpendicular to the miter edge for maximum strength.)

[Pat Barry]

Personally not a big fan of biscuits although your application seems like it would be a perfect application for them. The thickness is too thin to double them up so you should use the biggest biscuit that you can fit. I think its still a light duty solution, marginally improved by the spline method. If you don't want to see the splines they you have few options. For a picture frame I can see the biscuits being a perfect solution since those frames don't really get manipulated.. For a cabinet door, that might take some abuse, I wonder if there are any documented tests regarding the use of biscuits.

[J.R. Rutter]

Biscuits work. Pre-coating with glue definitely helps. We smear a light coat onto all of the mitered ends of a door, then go back and start assembling with fresh glue. The first application wicks up and starts to dry almost immediately. Sizing with diluted glue works as well, just takes an extra step. The joints need to be good. Err towards having them be slightly open in the inside if it proves difficult to dial in a perfect 45. Splines are great, just extra work to cut, glue, trim, and sand them.

[Jim Andrew]

I have had good results with biscuits on miters, use as big a biscuit as possible, think MLCS uses a round biscuit for their mitered doors.

[Johnnyy Johnson]

I'm wondering if I could not cut a small amount of biscuits out of a hardwood. Kind of like a internal spline and a little like a domino. Use a number 20 cut adjusted for a little more depth. Going to do a test today and glue up a couple miter joints.