Mounting glass - Batch box heater

[hobbitman]

Best method, things to avoid when mounting glass window in metal door ?

Have a metal door with a 4" x 7" window to mount. Just cemented 1/2" fiberglass rope seal around perimeter of window opening (on metal door). The glass edge sets on the center of the rope right now. Just have it laying on top of the rope to check alignment. Not sure what the best method for securing the glass is from here. A tight fit or allow for some movement ? Need some input from experienced door fab makers.

[martyn]

You must allow for movement, the metal will expand and contract, ceramic glass will not.
The glass is normally laid on top of rope and held on the corners with small spring clips.

[fiedia]

There is useful information here: donkey32.proboards.com/thread/2464/door

As martin pointed out, you can not bound glass with metal or bricks. Thermal expansion will break the bound. You have to let some clearance. Glass fiber gasket is used to tighten glass/metal junction.