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2PR & 6PR thread sizes.
- Thread starter RichardB
- Start date
My notes say use a 5/8" x 18 tpi Conduit which is 55 degrees but hard to find. Fits 2Pr vickers & tank & 6Pr 7 cwt & 40mm Bofors. Check before using.
A 5/8" x 18 UNF is 60 degrees and removes some metal from the V in the threads, but still works if you are re-tapping the primer threads to clean them.
The No 281 thread should be left hand but I do not have one to check diameter and threads but should be 55 degree form?
A 5/8" x 18 UNF is 60 degrees and removes some metal from the V in the threads, but still works if you are re-tapping the primer threads to clean them.
The No 281 thread should be left hand but I do not have one to check diameter and threads but should be 55 degree form?
If it is 5/8” x 18 tpi BS Conduit, there are used taps and die currently on eBay in the UK.
www.ebay.co.uk/itm/224773317218
www.ebay.co.uk/itm/205004524200
www.ebay.co.uk/itm/224773317218
www.ebay.co.uk/itm/205004524200
TimG is correct as 6Pr 7cwt is 7/8" x 14 threads Whit and is an odd size. My error in my thread book . Sorry.
The 5/8" x 18 tpi conduit IS correct for 2Pr Vickers, 2Pr tank and 40mm Bofors.
If the threads only need a clean then use a thread file or hand scrape with an 18 or 14 tpi tap of smaller diameter to remove rust. It saves buying a starter of finish tap.
Primers are usually only threaded for 1/2" approx. depth so easily cleaned.
If 6Pr threads are bent or badly damaged then retap with a 7/8 x 14 UNF which will remove metal but the No 15 primer still screws in nicely and nobody notices the thread difference.
The 5/8" x 18 tpi conduit IS correct for 2Pr Vickers, 2Pr tank and 40mm Bofors.
If the threads only need a clean then use a thread file or hand scrape with an 18 or 14 tpi tap of smaller diameter to remove rust. It saves buying a starter of finish tap.
Primers are usually only threaded for 1/2" approx. depth so easily cleaned.
If 6Pr threads are bent or badly damaged then retap with a 7/8 x 14 UNF which will remove metal but the No 15 primer still screws in nicely and nobody notices the thread difference.
