How would you?

[Scoly2803]

Building a mirror frame for my son. Dimensions are 88"x36" with mitred corners. Will be walnut with stain and clear shellac. This will be assembled at my house and carried to his.
I am concerned about the miters seperating if just glued. Have considered splines and/or pocket screws from the bottom.
Thoughts or suggestions?
Thanks
Steve

[cabinetman]

Building a mirror frame for my son. Dimensions are 88"x36" with mitred corners. Will be walnut with stain and clear shellac. This will be assembled at my house and carried to his.
I am concerned about the miters seperating if just glued. Have considered splines and/or pocket screws from the bottom.
Thoughts or suggestions?
Thanks
Steve

How are you planning the frame? Is it basically just mitered corners and a rabbeted back edge for the mirror?
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[atgcpaul]

You definitely want to reinforce those miters. That's a really big frame that
has to a hold all that glass.

Cutting splines will be a challenge because of the size, but probably doable if
you make a decent jig.

Biscuit joiner would be my next choice if you have one. If you can't register
off the face of your frame--because of a profile, then it's very important that
your frame pieces are the same thickness. If you register off the back and
your pieces aren't equal thickness, the faces won't be coplanar.

I've reinforced frames using pocket screws, too. The important thing is
to immobilize that miter (glue it first and let it dry) then screw it home. If
you screw it together while the glue is wet, the miter could slip. You also need
enough meat on your frames because of the entry point of the pocket screw
drill bit.


Paul

[cabinetman]

You definitely want to reinforce those miters. That's a really big frame that
has to a hold all that glass.

Cutting splines will be a challenge because of the size, but probably doable if
you make a decent jig.

Biscuit joiner would be my next choice if you have one. If you can't register
off the face of your frame--because of a profile, then it's very important that
your frame pieces are the same thickness. If you register off the back and
your pieces aren't equal thickness, the faces won't be coplanar.

I've reinforced frames using pocket screws, too. The important thing is
to immobilize that miter (glue it first and let it dry) then screw it home. If
you screw it together while the glue is wet, the miter could slip. You also need
enough meat on your frames because of the entry point of the pocket screw
drill bit.


Paul

I wouldn't use either pocket screws or biscuits. A half lap miter, or a splined miter would be my choice for the joinery.
.

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OR, a splined miter:
.

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[Mr__Bill]

Many old mirror frames were reinforced with braided picture frame wire laced on the back. I expect this was an after the fact thing. If you hang the mirror from the bottom with the wire going through screw eyes on the sides then the weight of the mirror will hold the sides tight and the bottom will hold the mirror weight and not the joint of the frame sides at the bottom. This is not to say that the corners should not be reinforced is some way but hanging this way will add to the life of the mirror and frame. This of course assumes the mirror will be hung on the wall. If it's going on a pivot stand then I would add some diagonal support at the bottom.

Bill

[Scoly2803]

Thanks for the responses.
Frame is pretty simple. 3/4" thick by 3" wide. Will have a slightly rounded outside edge with either 2 or 3 equally spaced grooves. It will not be supporting the mirror just framing it. The two short ends will have about a 2" dado that will go over the mirror while the long top and bottom will only have around a 3/4 dado for the mirror. This is due to the size of the mirror and a 90.75" wall for it to hang on.
Sorry, I should have stated much of this in the original ?
After looking at the design I notice that pocket screws are probably out. Just not enough meat to work with.
Splines are sounding good. With walls on either side of the mirror they will not show, to bad, but will add that additional strength that I feel I need for transporting. Just want to be sure the mitres stay together till I get it hung.
Thanks again. Really appreciate all the help.
Steve

[crokett]

Another option for reinforcing it is to glue up the miters as-is, then rout a key into each miter and glue in an accent piece that spans the miter and locks it together. Sort of a half-lap idea. I've seen it done with bow-tie shaped pieces as the key.

[chopnhack]

I assume that the mirror would be transported separately, if so don't forget to temporarily tack supports on the back side of the frame so that it doesnt rack while being shipped/handled.