Bridgeport quill stop thread

[pgram]

Hi all,
I own a Bridgeport mill, and I wanted to add a quick stop for the quill limit bar. All the quick stops that I found, on eBay and elsewhere, are threaded 1/2 20 Tpi but my Bridgeport quill stop bar is threaded 1/2 26Tpi. I asked around, but nobody was aware of this 26Tpi option. Does anybody know of this variant?
Thanks,
Paolo from Italy

 

[Martin W]

Maybe it is a metric quill stop? M12x1 has 26 threads per inch I believe.
Martin

 

[RandyM]

20 tpi = .050 stop travel per rev.

26 tpi = .0385. .0385 x 25.4 = .977mm stop travel per rev. Basically 1mm travel per rev. Still not quite metric.

 

[pgram]

I found that Adcock-Shipley built my Bridgeport in the UK in September 1968. All threads are Imperial, so I can assume that the quill limit bar is 1/2 26 Tpi. Maybe it was an Adcock-Shipley variation. Consequently, the so-called "educated" quill stop, sometimes available on eBay and threaded 1/2 20 Tpi, will not fit.
I will not try to make one, and I'll spend the saved time dismounting the table and cleaning the ways and gibs encrusted by 56 years of neglected murk.