# Surefire E-Series Head screw thread size ?



## J.D. (Dec 13, 2006)

Hey,
first sorry for my bad english.

im looking for the size of the surfire E-Series Head screw thread, because i want to dirll the thread deeper in the head.

i hope screw thread is the correct translation and you know what i mean.
(but i guess the english is very bad and nobody understand me )
thanx 
Jan


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## LifeNRA (Dec 13, 2006)

Your english is fine and I understand you.

Welcome to CPF.

Wish I knew the answer for you but I am sorry I don't.


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## highorder (Dec 13, 2006)

the thread is a 13/16-20tpi nominal. the major diameter is around .810"

good luck extending the threads. they dont make a tap that size, and lining up a single point tool is dicey at best.

perhaps there is another solution to your problem?


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## mahoney (Dec 13, 2006)

They do make taps that size, they are usually in among the sizes listed as "special thread taps" I bought mine from Traver's Tool, and I think MSC has them as well. I don't know where to source them outside of the USA, but my tap came in a box that said "made in Czech Republic" so they should be available in Europe somewhere.


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## highorder (Dec 13, 2006)

holy crap, they DO make taps that size! I stand corrected.

http://cgi.ebay.com/13-16-20-TPI-NE...ryZ58226QQssPageNameZWDVWQQrdZ1QQcmdZViewItem


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## J.D. (Dec 14, 2006)

thanks guys for your help ! 
my plan is to install a LE in the e2e head like McGizmo did it with the porsche 
in this thread and so i think i have to extend the threads.
greets,
and again thanks for your quick help 
Jan


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## J.D. (Dec 14, 2006)

thanks for the ebay link,
i´ll try to get some.


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## Anglepoise (Dec 14, 2006)

J.D. said:


> Hey,
> first sorry for my bad english.
> 
> im looking for the size of the surfire E-Series Head screw thread, because i want to dirll the thread deeper in the head.
> ...



Before you go out and buy an expensive tap, consider this.
You are modifying a thin wall part. 20 TPI is a medium thread and will require
a huge strain on the thin wall part to extend the thread. How will you hold this delicate part without damage by scratching or ,God forbid, collapse of the part?

Any machinist worth his salt, will be able to chuck the part and match up the thread and single point the extension. Once the matching is done, the extending of the thread can be done by revolving the chuck by hand and removing a few thou at a time making sure the cutter is fitting the exsisting thread grooves PERFECTLY.

Now machining costs are very expensive in all countries but this is not a complicated job and you might know a friend etc etc.
Good luck


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## PhotonFanatic (Dec 14, 2006)

Or you could send it to Anglepoise and he can do it for you. 

For the appropriate charge, of course.


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## highorder (Dec 14, 2006)

those taps are cheap, but that part is indeed quite thin. turning by hand with a SPT in a lathe is safer, but slow..


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## J.D. (Dec 15, 2006)

I´ll show you the results


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## Ganp (Dec 15, 2006)

Hi J.D.

Have you done this yet?

I did mine this way so I could revert back to the original lamp if needed ... not that that's likely  

I'm very interested to see your results - good luck  

Colin.


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## J.D. (Dec 16, 2006)

Ganp said:


> Hi J.D.
> 
> Have you done this yet?
> 
> ...



not yet, first i have to purcase the tap.
and the problem is i have to odrer it from the USA.
this part is very hard to get in europe.

by the way - your mod is excellet:goodjob:
Jan


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