posted 04-19-2005 02:31 PM ET (US)        

When you disassemble the ebay fixture you soon realize the two lights are completely incompatible. The ebay light has an extra internal piece of stainless that prevents the OEM lens holder from seating. The extra piece can be removed but that leaves no way to attach the OEM lens holder. The threads for the screws to hold the lens holder on are in the extra piece.

My idea now is to drill and tap two new holes in the 'pulley' portion that acts as the base for the lens holder. I bought #4 machine screws and a tap. Using a drill press and oil, I drilled two holes successfully but then realized one hole was in the wrong location. While attempting to drill a third hole, I noticed the drill bit was getting dull. Just as I was about through the bit broke in the hole. After a lot of effort I was able to remove the broken bit from the hole.

Tapping threads into stainless is difficult. I knew this was risky because a #4 tap is quite small and could break before the threads are cut. I got 3-4 full threads tapped in the first hole before the force increased to a point where I thought I better stop. I was making progress on the second hole and got to a point where I didn't want to push my luck any further. When I checked the threads I found I didn't have quite as much as the first hole so I thought I would try to get another 1/2 thread or so - big mistake. The tap broke in the hole. Now I'm screwed, how do you get a broken tap less than 1/8th of an inch in diameter out of a hole in stainless? As a dentist I happen to have a dental drill in my basement. Dental drills turning at 400,000rpm should cut through anything. Six dental drill bits later I had a hole drilled down the center of the broken tap. The tool steel was brittle enough that I was able to pick the tap out in pieces.