Patt743 Lantern Lens Shatter

[righttoe]

Hi Guys, We have recently had a Patt743 shatter its lens and fall from the rig in huge sections. The boss will not replace the lanterns due to cost ;) and has said to get mesh guards fitted somehow!

 

So far I have found out by searching that the mesh can be no more then 25mm spaced between gaps, anybody know where or how I would get this sort of thing and any other things I might need to consider?

 

Mike

[Brian]

So far I have found out by searching that the mesh can be no more then 25mm spaced between gaps, anybody know where or how I would get this sort of thing and any other things I might need to consider?

Garden centres.

[GregB]

PM sent.

G.

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[dirkenstein]

We have recently had a Patt743 shatter its lens and fall from the rig in huge sections.

 

That's, um, unusual. In other words, none of ours ever did that. Did something (scenery?) hit it or was it cracked to begin with? Are you sure they're not missing the little tubular metal spacers on the helical focusing shaft which prevent the lamp carriage and reflector from being moved too close to the lens? What about the spring clips that hold the lens in? I assume they're still original?

 

Some of ours have slightly chipped fresnel edges, but they've never developed cracks in the body of the glass.

 

Just trying to make sure you're not trying to cure a symptom by putting mesh in front of the lens, rather than the underlying problem.

[Andrew C]

That's, um, unusual. In other words, none of ours ever did that.

I've seen it; several years ago. From the 1st floor in an Abbey, about 40' down to the plywood chair that 1/2 the lens stuck into ;)

[Brian]

... 25mm spaced between gaps, anybody know where or how I would get this sort of thing and any other things I might need to consider?

And remember that 25mm is the maximum so if you can only get smaller that'll do just fine.

[dirkenstein]

From the 1st floor in an Abbey, about 40' down to the plywood chair that 1/2 the lens stuck into ;)

 

Ouch. I hope the chair and venue were unoccupied at the time. Is this more common than I thought in older fresnels, or some sort of defect specific to 223s/743s? I'm thinking about the up-rating of 743s to 1000W from 500W 223s and the potential thermal consequences of that. Are mesh guards considered a requirement these days in new fixture designs?

[Brian]

Are mesh guards considered a requirement these days in new fixture designs?

Obligatory in a fresnels case if the unit is to be CE marked.

[righttoe]

Right better source me some mesh then, thanks guys for your help!

 

I have done a bit of searching as to why it shattered, and it is due to heat change and expansion I think, our theatre can get very cold onstage during these winter months and it might have been due to rapid cooling of the lens, or the more lightly option ive been told is on a Patt743, unlike newer fixtures then lens has solid metal mounts, not letting the glass expand in some cases, which in turn would have started to crack the lense!

[TomHoward]

As an alternative can you put a Lee 130 / Clear in all the lamps - would this be seen to be robust enough by most members here?

[WiLL]

As an alternative can you put a Lee 130 / Clear in all the lamps - would this be seen to be robust enough by most members here?

 

 

In a word. No. Seeing as a 743 lens is about an inch thick a chunk of that would have sufficient weight to take the gel out of it's frame. Also if the lens is hot then if it did sit on the gel it would soon melt through anyway, adding hot plastic and possible fire to the hazard list.