Mirror door frame

[thomashenry]

Have made bathroom medicine from 18mm oak, and now need to make the door. Will be a mirror door, hung inset on butt hinges. Door size will be 66x56cm. I'm wondering how thin a frame I can use for the door. I'd like to make it from as thin stock as possible - I was thinking to try making it from 20x20, with each corner being a single dovetail, rather than a wider frame with M&T joints. Of course, I'll need a rebate on the back for the mirror. Maybe this won't be strong enough?

 

[thomashenry]

Have made bathroom medicine from 18mm oak, and now need to make the door. Will be a mirror door, hung inset on butt hinges. Door size will be 66x56cm. I'm wondering how thin a frame I can use for the door. I'd like to make it from as thin stock as possible - I was thinking to try making it from 20x20, with each corner being a single dovetail, rather than a wider frame with M&T joints. Of course, I'll need a rebate on the back for the mirror. Maybe this won't be strong enough?

Bit of a search on the forum dug up this

"He also suggests that frames should be of a light section only, since the glass will keep the framework square and rigid, and the plywood back will strengthen the jointing. "

Suggests that I could probably try a 20mm frame.

 

[Sgian Dubh]

For the most part, if I'm making relatively lightweight frames to carry mirrored glass, whether they be doors or mirrors to hang on a wall I aim for about 22 mm thick. Generally I'd suggest you go for about the same as in the example below. I wouldn't expect the mirror to hold the frame square, rather, I aim to allow the mirror to float freely. Aiming to make the mirror (or clear glass if making a door) an integral structural element to aid squareness means a tight fit within the rebate, and this has a chance of causing glass breakage either at installation or later in use. I use M&T construction for the most part, but sometimes simply mitre the corners and reinforce with a cross grain key as seen in the following links. Slainte.
http://www.richardjonesfurniture.com/Be ... rrors.html

 

[MikeG.]

......... I'd like to make it from as thin stock as possible - I was thinking to try making it from 20x20, with each corner being a single dovetail.......

I don't think a dovetail is the right joint in that location. I would be doing a bridle joint, personally, or a mitred bridle if the thing needed a fancier look.

 

[thomashenry]

For the most part, if I'm making relatively lightweight frames to carry mirrored glass, whether they be doors or mirrors to hang on a wall I aim for about 22 mm thick. Generally I'd suggest you go for about the same as in the example below. I wouldn't expect the mirror to hold the frame square, rather, I aim to allow the mirror to float freely. Aiming to make the mirror (or clear glass if making a door) an integral structural element to aid squareness means a tight fit within the rebate, and this has a chance of causing glass breakage either at installation or later in use. I use M&T construction for the most part, but sometimes simply mitre the corners and reinforce with a cross grain key as seen in the following links. Slainte.
http://www.richardjonesfurniture.com/Be ... rrors.html

I think I got my terminology wrong. I meant to refer to the width/height of the frame, rather than the depth. so for example, on a kitchen cabinet frame and panel door, I'd use a 70mm frame, whereas here I want to use as small a frame as I can - a 70mm frame would take away too much real estate from the mirror.

The depth (thickness? Sorry, am never sure what words to use when referring to the various dimensions of wood) can be up to 22mm, so no worries there.

 

[Sgian Dubh]

The mirror in my earlier post is roughly 800 mm tall by 500 mm wide. The sections making up the stiles are ~ 42 mm wide X 22 thick. The top and bottom rail are obviously wider. I wouldn't advise going much narrower than the 42 mm width for any of your door framing parts. If you do some sums you'll see that there's not much difference in the overall m² between my frame and the one you propose, i.e., ~0.4 m² for mine and ~0.37 m² for yours (0.66 X 0.56), so not far away from each other really in the weight of glass, assuming you're going to use 6 mm thick mirror glass as I did. 6 mm thick glass weighs just under 15 kg per m², so you could have about 5 kg of glass in your proposed door.

That's a fair chunk of weight to be supported by a frame as delicate and slender as you're perhaps considering. Slainte.

 

[thomashenry]

Perhaps it's not a direction that would be approved of, but what if I fixed the glass into the rebates using some kind of glue/fixer? Then the frame would get the benefit of rigidity from the glass?

 

[Sgian Dubh]

Perhaps it's not a direction that would be approved of, but what if I fixed the glass into the rebates using some kind of glue/fixer? Then the frame would get the benefit of rigidity from the glass?

I don't know why you would need to do that, but I suppose you could try it. You're describing a medicine cabinet with a door, but you're worrying about making a 'too small' mirror. Even if you allowed 100 mm all round for framing you would still have a mirror roughly 560 mm tall X 460 mm wide. Is that too small to view yourself? Or are you concerned about some other issue, e.g., the visual bulk of the framing? Slainte.

 

[thomashenry]

Perhaps it's not a direction that would be approved of, but what if I fixed the glass into the rebates using some kind of glue/fixer? Then the frame would get the benefit of rigidity from the glass?

I don't know why you would need to do that, but I suppose you could try it. You're describing a medicine cabinet with a door, but you're worrying about making a 'too small' mirror. Even if you allowed 100 mm all round for framing you would still have a mirror roughly 560 mm tall X 460 mm wide. Is that too small to view yourself? Or are you concerned about some other issue, e.g., the visual bulk of the framing? Slainte.

Exactly this. The medicine cabinet is actually recessed into the stud wall, only projecting out 20mm from the tiles. The idea is that it almost looks like a mirror hung on the wall, rather than a cabinet. I want to keep the frame small for aesthetic purposes , rather than practical ones. This is why I'm trying to look into ways to keep the frame small - and gluing the mirror into the frame is perhaps one way I can achieve this.

 

[AndyT]

One way to achieve rigidity with a fairly slender frame could be to add a backing board behind the mirror. This can also make everything look tidier when the door is opened.
This thread has some old diagrams assuming use of solid wood, you could probably get something even stronger with ply:

traditional-mirror-framing-t88530.html

 

[MikeG.]

A little mirror like that need only by 4mm thick, too. That will keep the weight down somewhat.

 

[Sgian Dubh]

A little mirror like that need only by 4mm thick, too. That will keep the weight down somewhat.

True, he'd probably end up with somewhere just north 3kg of glass working with the same dimensions.

My rough and ready reckoner is to allow 5kg per m² per 2 mm of thickness, therefore, 4 mm thick = ~10 kg/m², 6 mm thick = ~15 kg/m², 8 mm thick = ~20 kg/m², etc. It's not spot on, but it's close enough for most common glazing weight calculations I've needed. Slainte.

 

[deema]

Backing board as already suggested with the mirror stuck in. Use proper mirror adhesive or get the mirror backed with a liner and use any adhesive / silicone. Stick the frame to the backing board.

I would never just have a glass mirror in a bathroom that’s not stuck to a backing board. If it breaks, glued to a backing board ensures that it’s held and not in pieces on the floor.

Personally I like a plane mirror with no frame, get the edges buffed (or chamfered and buffed) when ordering if going without a frame.

 

[MikeG.]

Chamfering adds a lot to the price. Buffing the edges you can do yourself with a diamond plate. I've been through this very recently.

 

[Hornbeam]

You could fit the mirror from the front of the frame and secure it with a beading. That way you could have fairly wide rails/stiles
ian