Cutting glass bulbs

[pope_face]

Has anyone ever tried to cut or drill the back of a solid-glass headlight or something? I've got a cool old-style foglamp I want to stick on my truck, but it's a solid glass 6V bulb. I would swap out just the bulb itself, but it's an awkward diameter (4 3/8"), and the housing is fairly shallow. So, I want to see if I can cut or drill a hole in the back big enough to stick a small bulb in there, like an H1. It doesn't have to sit perfectly or anything, I just want it to put out some light. Only issue is, I'm not sure if the glass will shatter if I try to drill through, and I'm not sure if it's pressurized. There's a couple rubber/plastic plugs in the back where the leads for the filaments come out, so I might try pulling those out first.

 

Anybody have any ideas on how to go about this? I'd rather not shatter the glass, but if the back cracks it's ok. I just don't want to destroy the front of the glass, cause I have no idea how I'm going to replace it.

[datzenmike]

Glass is tougher than a steel bit. Possibly an abrasive disc on a dremel or maybe a carbide tip. Anything that cuts ceramic tile might work. Also glass is an extremely poor conductor of heat. Cutting will generate heat that will collect in a small area and cause this small area to expand and crack. Can be done, easy does it.

[flyerdan]

Any filament type bulb will have a hefty vacuum in it to keep the filament from burning up in an oxygen rich environment. Breaching this without catastrophic failure is unlikely. For drilling in glass, Harbor Freight has some tiny diamond hole saws for that purpose, build a dam with clay or caulk and use kerosene for a coolant / lubricant pool.

[pope_face]

Alright, well I decided to bite the bullet and just do it...

 

I started off by wrapping the lens in packing tape so that everything would stick together in case I accidentally cracked it, grabbed a small wire cutter, and went to town on the leads out the back of the bulb. I wore big gloves in case the glass cracked or exploded. There was a little nib between the two leads, and I ended up cracking it off as well. Turns out it was hollow, so there was a little hole in the back of the bulb, which meant no vacuum. Got the leads out, and managed to put a hole in the back big enough to mount an H3 bulb. Ended up breaking a big chunk out of the back, but it means I can slide the bulb in and out easily. Rinsed the inside out with rubbing alcohol to get it clean, stuck in the new bulb, taped it down, and mounted everything back together. Now I've got a fog/flood lamp with a bulb that can be easily swapped. I'll show pictures when I have a chance to load them.

[fastdadd]

i know its to late but for future referance...i have drilled holes in bottles use a mason bit and a steady supply of water with easy pressure on the drill letting the bit do all the work