Reinforcing Miter Joints

[Greg Esres]

I made a foolish design decision in building some window Z-frames for shutters. I cut the pieces in order to miter them, thinking that the joint would be easy with the biscuit cutter. Turns out the 0 biscuit slot is too wide for the 1x3 stock. The end grain would never have been visible, so I should have used rabbet joints.

What's the best way to reinforce the miters for someone low in experience? I'm considering finish nails or a biscuit into the outside corner after gluing. More ambitious is to trying to drill accurate holes to allow a dowel to run perpendicular to joint orientation. Once installed, these units won't receive a lot of stress, so I don't want to overengineer them.

Thanks for any thoughts.

[B A R R Y]

Doweling is actually relatively easy with a $50 jig.

On the cheap, you could carpet tape a hardboard spacer to the front of your biscuit joiner to eat up some of the plunge depth and cut the biscuits down to fit.

You could cut slots with a 3 wing slot cutter in a router table and use cut-down biscuits or shop-made splines. If you use the biscuits, a 5/32" cutter will do the trick.

Pocket holes would work with the holes plugged, but you'd need to see if the visible plugs might be too visible. If you're painting, these might be my first choice.

[<marierdj]

First have a look at these corner joiners:

do not have a mental picture of your design so I may be shooting at point blank here.

Next make test pieces with metal spines, corrugated fasteners or chevrons. The later are not too strong but if your frame is going to be anchored on a wall, it may do. Check with some photo framing stores.

At this stage you may not be able to do a lock miter joint. However, If you think you can get enough confidence in yourself, you can first practice on pieces of scrap wood. Apply glue on the miter joint I and hold it together with the proper clamp/belt. Then drill a proper size hole (drill and countersink # 10) in the middle of the thickness and spaced as you need. Then drive a Robertson wooden screw in. After you will be left with the countersunk hole. Once all the screw are in and the glue is dry you have to drive a taper wooden plug with glue to fill the holes. Once the glue has dried you cut the excess plugs sticking out and sand to a smooth finish to match. The plugs can be made with a taper wooden plug cutter.

[Greg Esres]

You mean like this one?

that's a thought!

[Greg Esres]

The idea of a metal fastener is a good option, assuming that I can put these on the outside; they will not be visible there. This thought never occurred to me. I'm glad I asked!

So you're suggesting using the screws instead of the nails that I considered? The wooden plugs wouldn't be necessary....the outside of the joint will not be visible.

Thanks for your suggestions. Very helpful.

[Old guy]

I suspect screws are the easiest answer--

But did you think of cutting a spline across the joint on the outside (saw blade wide) and then fitting in a 1/8" piece of wood to reinforce the joint? Wouldn't take much set up to do, and if the edges don't show, you could get away with ragged instead of flush.

Old Guy

[CW]

I have used the bicuit into the outside corner. Works well.

[Greg Esres]

Thank you. I'll play around with this.

[Old guy]

Modify your biscuit joiner?

Old Guy

[imp2aca]

If the biscuit is wider than the joint surface, you can cut/sand off the excess of the biscuit after gluing, and it should be strong enough.