Bullseye Decklight

[NB Alnwick]

Some may remember that, not long ago, Richard kindly machined the West System resin that I had used to set Alnwick's bullseye decklight in the front deck hatch - the relevant topic is here.

 

The result proved less successful than I had planned. After mounting the decklight and refitting the hatch cover, Jane and I retired for the night and were soundly asleep beneath it when we were awakened by a loud bang at about 2:00 a.m. - just after it had started to rain! Subsequent examination revealed a massive semi-circular crack in the bullseye glass just inside the built up resin. And, yes the crack was letting in water - initially just the occasional drip but the as the crack extended round the circumference of the bullseye this was bound to get worse - so we quickly implemented our equivalent of Sarah's Pyrex bowl!

 

I can only conclude that the cold rain had caused disproportionate contraction between the glass, the resin and the steel that were all bonded together. It is the glass that has failed and the resin bond is still sound and quite solid. The cracked glass will now have to be removed and this will not be easy because it is very firmly set in the resin.

 

Plan B is now on the drawing board . . .

[bizzard]

Some may remember that, not long ago, Richard kindly machined the West System resin that I had used to set Alnwick's bullseye decklight in the front deck hatch - the relevant topic is here.

 

The result proved less successful than I had planned. After mounting the decklight and refitting the hatch cover, Jane and I retired for the night and were soundly asleep beneath it when we were awakened by a loud bang at about 2:00 a.m. - just after it had started to rain! Subsequent examination revealed a massive semi-circular crack in the bullseye glass just inside the built up resin. And, yes the crack was letting in water - initially just the occasional drip but the as the crack extended round the circumference of the bullseye this was bound to get worse - so we quickly implemented our equivalent of Sarah's Pyrex bowl!

 

I can only conclude that the cold rain had caused disproportionate contraction between the glass, the resin and the steel that were all bonded together. It is the glass that has failed and the resin bond is still sound and quite solid. The cracked glass will now have to be removed and this will not be easy because it is very firmly set in the resin.

 

Plan B is now on the drawing board . . .

Looks like a cohesion problem between the three materials, The resin not flexible enough,or you bolted it down a touch unevenly.

[Chalky]

Try to get hold of some of the PU adhesive that's used to glue in car windows. It's designed to allow a certain amount of movement that occurs in all car bodies due to them flexing on uneven roads.

[Chertsey]

Oh damn. I'd better put that idea on hold then.

[alan_fincher]

Oh damn. I'd better put that idea on hold then.

It probably wouldn't have happened if it had been fitted the other way up!

 

[:tongue_in_cheek_smiley:]

[Chertsey]

It probably wouldn't have happened if it had been fitted the other way up!

 

[:tongue_in_cheek_smiley:]

I was thinking of inverting mine to dome-down mode as it fouls the slide at present, which probably hasn't done it any good. But above all I just want it to stop leaking!

[NB Alnwick]

I will try and post some pics tomorrow - I have now removed the bullseye and found that most of the 'flange' had disintegrated into a multitude of shards leaving just the centre part intact. There was no evidence of failure on the part of the resin which continued to support the glass and there is no evidence of uneven pressure in the final seal. I am now working on 'Plan B' . . .

[bizzard]

I fitted mine about 10 years ago. Cleaned everything thoroughly with white spirit first then bedded the bulls eye and brass bezzel down in Glaziers silicon. Its never leaked.