On 2015-02-28, dpb wrote:
On 02/28/2015 3:31 PM, Christopher Tidy wrote:
...

Here's what they aren't (because I've tried and they don't fit):

- #6-32 UNC
- #8-32 UNC
...

I notice you've listed no numbered UNF in the above...that'd be my
firstest guess sight unseen...

Well ... first off -- the pitch he measured is within 1.7 % of a
32 TPI thread, and given the stated uncertainty of that pitch
measurement, it quite likely *is* 32 TPI.

However, the diameter is a bit large. 6-32 should be a 0.138"
clearance hole, and what he has is a bit fatter than that. But I'm not
sure about the diameter being any particular standard number size. Some
manufacturers in the US were using non-standard proprietary threads just
to keep a captive market.

Any clue as to where the lamp came from? Given the wide range
screws that he tried, I suspect that the lamp is currently in the UK. :-)

Enjoy,
DoN.

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