Mitred frames

[paulc]

hello forum,
I 've made a large oak mirror frame - 100 x 70 cm - with mitred corners and its housing some quite heavy 4mm glass , the joints are just glued - Is this sufficiently strong or do the joints need to be reinforced in any way.
Thanks , paulc.

 

[Travis Byrne]

Hello Paulc
That mirror sounds pretty heavy and mitered joints are about the weakest joints going. If it is not finished yet, I would think about a spline and if the joint is already glued, I would put a dowel pin in joint from the side edge. A 1/4" dowel will strenthen the joint considerable. Let it extend about an inch into the opposing side.
Hope these ideas helps
Travis

 

[MikeW]

hello forum,
I 've made a large oak mirror frame - 100 x 70 cm - with mitred corners and its housing some quite heavy 4mm glass , the joints are just glued - Is this sufficiently strong or do the joints need to be reinforced in any way.
Thanks , paulc.

Hi Paul,

Another option is to cut a slot in as the below picture shows. The "key" gets glued in and is very strong--and can be done after the frame is glued up like yours with either hand or power tools.

Take care, Mike

 

[George_N]

Considering that the frame is already made any advice might be a bit academic. Mike's idea of using a key or spline is certainly certainly one that can be applied after the frame is constructed and, if a contrasting wood is used, it can be made into a design feature. I would probably use a biscuit joint to strengthen the mitre rather than dowels if I wanted a hidden joint, but then I have a biscuit joiner and no doweling jig. Pocket screws at the back might also work and could maybe be applied after glue-up to add strength.

 

[Jaco]

If already glued up, a spline.
I made similar frames, Beech, for my boys and complete with mirror and hardboard weighed in at 14.5kg's.
Used a biscuit in each corner. Have a biscuit bit for my router.

To hang it i used a chain at the back and i gave each boy a rawlbolt.
All hardware on the back is brass.
8) 8)

 

[paulc]

Great advice, thanks alot,

The key looks great Mikew , I have no band / fret saw to cut a 'key' and don't have great confidence in making one of an exact thickness by hand. Don't want to cut into the already glued up frame and insert a ill fitting key . I don't want to use plywood, Can you get veneers of 4-5mm?

Cheers, paulc

 

[DaveL]

Paul,

If you know what you need then I could run you off a suitable bit of timber for the key.
I don't have a very wide selection of wood but if you tell me what you are looking for I will have a rummage to see if I have a bit.

 

[Benchwayze]

If already glued up, a spline.
I made similar frames, Beech, for my boys and complete with mirror and hardboard weighed in at 14.5kg's.
Used a biscuit in each corner. Have a biscuit bit for my router.

To hang it i used a chain at the back and i gave each boy a rawlbolt.
All hardware on the back is brass.
8) 8)

I would also go in through the back with a small dowel or peg, long enough to go through the spline, but not break through the face. Both sides of the joint line. This helps prevent opening up of the mitre. I never had a heavy frame split yet, but that's not to say it couldn't happen!
John