[TR] Broken Windshield

[Frank Fisher]

as i recall...and im old
first thing to be done was to build a polished steel buck.the glass would be cut to shape.then carefully clamped to the buck and put into an oven where the glass was heated until it slumped and settled on the buck. this is why you often saw distortion.after the hot slump the glass was allowed to cool slowly for annealed or quenched quickly with "cool" air for tempered glass. very little tempered glass went into laminated car windshields.
it required 2 bucks one for the outer light and one for the inner light.both having slightly different radi.smart folks developed bucks with a crank that could change the curve slightly if it was not a compound.
then one light of glass would have the PVB inter layer placed over it. it would have been slightly oversize for the size of the glass.
carefully 2 guys would place the second light of glass onto the first glass & PVB so that the edges lined up properly.touch at one end and kinda roll the glass into place.
manual roller firm but not heavy across the glass.
there would often be small air pockets visible at this time. and even today in manual lines you still see some small air pockets at this stage.

the PVB is not intentionally sticky but does cling enough to hold the glass together now
the assembly then as now went into an autclave stacked on edge.
steam is pumped into the autoclave and pressurized to force the 2 lights of glass together. the hot steam softening the PVB and allowing it to absorb the small air pockets that may have been present and take up irregularities in the curve difference of the 2 glass lights..
allow to cool gently.
knife off the laminate that was oversize.
its funny how the PVB sucks up some of the small air particles. i have often though that's why we start to see bubbling around the edges of old laminates.
there are i believe, some old time fabricators who can still make laminates this old way but i expect they want big bucks.
im not sure when better automated machinery took over. it had to have been after the war. to start producing cars at the rate we did this was not an efficient process.
today we are messing with "cold bending" glass. trying to get it to take shape using less energy. but like vacuum formed insulating glass we are only in research and development.
we recently ran a series of tests on some glass products here with general contractors, architects and building owners present.one contractor noted it was the boring day he had spent watching a test.





      From: Randall <TR3driver at ca.rr.com>
 To: 'Triumphs List' <triumphs at autox.team.net> 
 Sent: Thursday, November 19, 2015 1:43 PM
 Subject: Re: [TR] Broken Windshield
   
> Is it possible to have this repaired 

Sure, it's possible.  First you melt the glass down ...

Which leads me to an odd question : Does anyone know what the manufacturing process would have been back then?  Roll the glass out
flat and then curve it during the tempering or laminating process?

Randall Y.




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