Circular windows

A opportunity arose for me to undertake some circular work. The window in question had been re-glazed approximately 10years ago.
Unfortunately the glazier did not measure the bend correctly and had to fit the glass ‘off centre of the bend’. This resulted in the glass having to be forced against the rebate and pinned.In turn this meant that the glass was under pressure to spring back to its original form. There is a certain amount of give in curved glass but it will always want to return, just like a spring.
This pressure to spring back resulted in the glazing bead between the two pieces of glass to break at the joints. I suspect when the glazier formed a mould for the replacement glass he/she took measurements from the inside and did not include the depth of the rebate. The piece was 24mm short on the length, the precise depth of both rebates.
I fashioned a new mould by taking out the second piece of glass which fitted correctly and transferred this shape to a piece of plywood.
The glazing bead between the two pieces was repaired using Oak tenons that were slipped into mortices that I cut out and glued.
Once I had the replacement piece back from the manufactures’ it was a simple case of fitting.
There is always a moment of anxiety when offering up a bend but this one fitted like a glove.