Bed Clip concepts

Magnets have a "currie point" at which they lose magnetization.

For anyone else who thinks of that, I looked it up and it looks like even in the worse case (certain types of rare earth ones) it's >300 Celsius, so we're way beyond fine.

Magnets seem very appealing now that you mention it. The only problem I might see with it is that if you want to have the securing mechanism underneath the glass platform, as opposed to the side of build platform (meaning you need wings extending off the aluminum bed; the wings would be were you add the magnet) 

Airspace would be a big insulator between the heated bed and glass.

The problem with having it directly under the glass platform is then there will be an airspace between the heated bed and the platform. This could be compensated by adding a aluminum template to increase heat transfer from the bed to the glass, or by drilling into the aluminum base to add the magnets.

I could see this being part of an full bed upgrade, where you build a new aluminum plate which some depressions, so you can still level the bed, and simultaneously upgrade the platform a half inch in each dimension (so far as it's possible to move the printer head beyond the 6*6 platform) and also upgrade the heater with some nichrome wire.

The .6mm tabs from a feeler gauge might be good for this.  They already have a hole drilled at one end.

Drilling holes into the glass plate to place magnets above the leveling screws might be worth looking into as well.  In this case you would need to cover the tops of the magnets with Kapton or something.  That might not work too well by itself though, there isn't much friction between magnets and metal to keep the plate from sliding.  Magnet to magnet would be stronger.

There is a massive amount of room behind the bed on top of the wooden platform. I'm going to get glass that is too long in the y direction and utilise this space to have my mounting points.

I ended up buying a picture frame from target which had a bit of glass about 210mm x 150mm for a couple of dollars. I was thinking you could glue some L shaped brackets onto the front of it so it wedged onto the front part of the bed, then have some magnets at the back to hold it down. That way you only have to worry about the alignment of two out of the four points.

Works fine. You can see the way I have it at the moment. It just sits off the back almost perfectly. I thought about putting it sideways to get a bit more area, but figured I should at least try get some decent clips sorted out for it first. I must say though, I'm so happy with how the prints are sticking on the glass, and how easy it is to pull them off again!

I just used between 2 and 4 springs: see photo!  Very simple, inexpensive.

Attached is the setup that I use with the wood clothespins.

Don't mind the mess of parts... I need to clean and add to my ABS glue stash.

As you can see , the pins are only on the front of the machine.  When I finally get around to adding acrylic sides and a front door, I'll need to shorten the pins a little, but not too much.  They're enough to keep the mirror on the bed with the kapton there so I guess it's a neat little work around.