Large frames >A0

[girlfromkent]

Hello all,

I have realised I need to get more comfortable with making bigger frames. I'm 5'2" and work mostly alone, so a large part of my discomfort is literal and physical. But, I realise, that part of it is a lack of confidence that is rooted in my 'see how it goes' approach.

A few questions...

GLAZING
I know that Artglass/TV manufacturers advice for frames over 1m is to go up to 3mm glass, but the increase in cost is substantial. Do you all tend to stick to this as a rule, or would you happily go up to, say, 1300 or 1400 before insisting on 3mm?
Same question for accrylic, which thickness for which size? I just ordered some 2mm cast for a frame 1170 x 925, but now that I've got it, it doesn't feel rigid enough. Will it be OK?

MDF
Same question really as for glazing - which thickness at which size?

BRACE / SUBFRAMES
I have limited woodworking equipment in my workshop, but have made cross braces and subframes when needed. It's an on the day 'how does this feel' approach though, rather than anything organised. How do you make your subframes as standard? Do you typically use subframe moulding, stripwood, other frame moulding? Do you just add a cross bar, or a full sub? Do I need to buy a pocket jig?

All other suggestions for how I can stop dreading the big stuff greatly appreciated.

Thanks,
Megan

[prospero]

Glass is stronger than you think and going thicker can work against you. As well as the cost, the sheer weight can
create other probs. Better to make sure the glass is sitting 'comfortably' in the frame. The frame should be flat
with no twists. The glass should be cut cleanly with no chips on the edge and no lumps/bumps under the rebate.
Also it should not be too tight. A knock to the frame will go through to the glass.


I'm reasonably tall but sometimes life is a challenge with big frames. You have to be quite cunning even to flip big
over in a tight area.

xmas2018_9.jpg

[Justintime]

Glazing:
The standard manufacturer's/supplier's advice is regarding when you go over 1m2 or have a long thin piece of glass. I would advise sticking with their advice! Even more so if you are using spacers and the glass doesn't have the support of the rest of the package/sandwich. I'm not a believer that the cost is an issue, it costs what it costs for the right materials for the job. Weight is however often an issue, which is where choosing acrylic might come into the equation. The thickness of acrylic is then the consideration to prevent flex!
When you see how much flex an entire sheet of 915mm x 1220 2mm glass has, when you try and turn it over on the table single handed, you'll see why you'd want to go to 3mm.
I would suggest 3mm acrylic for that size.
MDF - If in doubt go thicker
Subframes - have a look at Rose and Hollis A345, A350 and DR1840, various thicknesses. A pocket hole jig once set up makes the job easier and more accurate. Saying that I still don't have one and manage fine (but am always being told by a friend that I should have the stupidly expensive table version because it's so good! )
Dreading the Big Stuff - Find a reliable friend who will come in when you need. Someone who understands how to assist and focus on a simple task like turning over a large piece of glass, fitting it into a large frame. (Not the chatty and accident prone kind). Each part of the process is as simple as on a small frame it just takes a lot more care, a lot more time and an extra pair of hands. You have to clear the decks down for a big piece. You may want the mounts on one table, the glass on another, the frame somewhere safe within easy reach, same for the backing board.

[JFeig]

As a person who had a serious back injury many years ago as well as a senior citizen I found and use an electric winch to lift heavy items on and off the table similar to the one that I am attaching:
https://www.harborfreight.com/440-lb-el ... 60346.html
I have several size 2 and 4 ended straps as well as a glazers suction cup that attaches to the hook. My work bench is on wheels so that I can move the bench under the hoist when lowering a heavy item onto the floor. The hoist is attached to a beam in the ceiling of the basement. It can also be attached to a homemade tripod.

Necessity is the mother of invention.

[JKX]

Regards backing and mountboard too.

8 ply mount board for both aperture mount and under mount is a good idea when things start getting a bit big for 2mm glass. If cutting apertures in thicker board is problematic then deep wrapped bevels or a double mount with a slip between mounts, is even better.

Why not move away from Mdf altogether, purpose-made boards like artbak and corriccor are much better, then when size becomes an issue again - use foam board, foam board as well, or cross-braced fluted polypropylene. Big doesn’t have to mean heavy.

Glass - personally over about 1 sq m I’d skip 3mm glass and go to acrylic, but then if conservation and/or anti reflection, it starts getting expensive, and at the right thickness for over 1sq m it’s going to be far more than glass anyway.

Truvue conservation clear and museum is 2.5mm thick though, so that may be suitable for slightly over 1sq m. It does depend on things like spacers, mounts and inner frames though.

Your 2mm acrylic is only good for smaller things when safety or shipping is a factor.