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Parker Hale threads
Posted: Tue Mar 08, 2016 1:22 pm
by ovenpaa
Does anyone know what the thread of the screws used to hold the PH17 sight in place on a BSA might be, yes I know it is piece of string type question however I am at a bit of a loss as to what it might be. It appears to be 48TPI and the major diameter of the screw is around 0.136"
Re: Parker Hale threads
Posted: Tue Mar 08, 2016 2:55 pm
by TomH
I would think it's a specific gunmaking thread used by BSA/Parker Hale before the adoption of British Standard threads and used thereafter on the "if it aint broke" principle.
Re: Parker Hale threads
Posted: Tue Mar 08, 2016 4:14 pm
by North Star
Check this out. It looks like it could be an obsolete thread?
http://www.practicalmachinist.com/vb/ge ... ad-223456/
Re: Parker Hale threads
Posted: Tue Mar 08, 2016 6:24 pm
by Alpha1
4BA
Re: Parker Hale threads
Posted: Tue Mar 08, 2016 7:01 pm
by Doz
Alpha1 wrote:4BA
4BA is only about 38.5TPI
Re: Parker Hale threads
Posted: Tue Mar 08, 2016 8:05 pm
by Alpha1
Re: Parker Hale threads
Posted: Wed Mar 09, 2016 6:09 am
by dromia
Ask at Norman Clark's, surely they will know.
Re: Parker Hale threads
Posted: Wed Mar 09, 2016 7:44 am
by ovenpaa
Dromia, good point as they certainly should know. I have to move the little P17 sight from one rifle to another and it would be nice to duplicate the fixings 1:1 however by the sound of it the chances of finding a suitable tap as opposed to having one made are not good.
Re: Parker Hale threads
Posted: Wed Mar 09, 2016 8:16 am
by bigfathairybiker
Try
http://www.tap-die.com
Mark
Edit: Just an idea, are shotgun beads.136x48tpi?
Re: Parker Hale threads
Posted: Wed Mar 09, 2016 12:41 pm
by Alpha1
I asked the clever guy at work he thinks It must be a odd one.
The nearest is M3 but considering its age may be not.
M3 48tpi x .13