Make:

The reminds me of an episode of Secret Life of Machines, only the bottles themselves were the lamps, not just shrouds around another bulb. I suppose you'd just need some filaments and a vacuum pump and some patience.

When you do a project like this how can you find out the material properties to a certainty? So if you accidentally leave it on when you go to work it doesn't melt or catch fire.

Where do you look up how much heat is generated from a certain wattage bulb, and what the melting point of those old computer cables?

Melting point for food grade HDPE is going to be around 135 degrees centigrade (275 F). If it's the really cheap thin stuff it could be as little as 120 degrees C (248F). As for calculating the heat generated by a lamp there are so many environmental factors associated with that calculation the best method for a Maker would probably be to experiment using a housing similar to that which you would want to use. I wouldn't use anything stronger than a 25W lamp in this type of enclosure and even then a compact fluorescent would be a better bet.

TMIV - he uses GLASS milk bottles.

But if you're curious, you can look up most calculations and material properties from www.engineering.com. they're a pretty good source for basic stuff. Other than that, I look in the manufacturers website or datasheets.

The bulb heat can be calculated also - basic thermodynamics. The necessary wire thickness can be calculated by the wattage and voltage being used - if computer wires are thinner than your needed gauge, don't use them!

For some reason I read it as being plastic too instead of glass, my mistake. I've seen outside Christmas lights made from PE bottles of different colors and I guess that stuck in my mind a little.

so basically you made
http://www.gnr8.biz/product_info.php?products_id=221

Hey, I actually didn't realize until now that my lamp had been posted up here - cool.

I did take into consideration the melting of the materials, and because of that, I've only put in very low wattage bulbs. It originally contained CFL's, but I couldn't actually find any that were dim enough for my tastes. So I ended-up using 15-20W bulbs in each fixture, which don't get very hot, and have a nice warm light.

I admittedly don't have any engineering basis for this - but I've left it on for hours and it's still bearable to touch. This is good enough for me.

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