C8 extension tube info.

Thom2022

Enlightened
Joined
Dec 12, 2016
Messages
224
Hey guys.
So I've recently built a new style
Convoy C8 into an XHP50.2 power house. I didn't want to run 2 18350's because the run time would be appalling and at 8-10A draw on turbo then i feel this would seriously stress even the best 18350's. So the hunt for an extension began.
Fast tech stock one but it 'doesn't fit' the new style C8's and there's some serious debate about what C8 style lights it does fit.
Well I've made one fit perfectly with some filing and some 'tactical cross threading' (I've bodged the s**t out of it).
On the FT extension the threads are not square cut and are the wrong thread pitch by a hair. But if you have a file and a dremel then you can get a perfectly flush, watertight and secure fit.
The method.
On the external thread side of the tube file off all except 2 threads, you want to leave the 2 threads closes to the end of the tube untouched,
On the internally threaded end of the tube you want to do the same thing but leave the 2 deepest threads untouched.
Because the extension is of poor quality compared to the host and the threads are tapered not square they will easily deform to the same pitch as the hosts square cut threads without any damage to the host.
Just slap a ton of grease on the threads for their first mating and then tighten by going 1/2 turn 1/4 back and repeat until tight and flush.
I also want to add I REALLY tried the strip the threads when I did this, I got 2 strap wrenches and cranked hard on the two tubes and the wrenches just started slipping.
The anodising of the convoy C8 host and FT tube is as damn near perfect as I could hope for.
Unfortunately I don't have pictures to upload as I can't be bothered signing up to a hosting site for 2-3 pictures.

Hopefully this will be useful to someone.
 

fivemega

Flashlight Enthusiast
CPF Supporter
Joined
Jan 28, 2003
Messages
5,154
Location
California
IMG_0894_zps74m3syqm.jpg


I recently made number of these for customer and few for myself.
Instead of using extension tube, I made 2x18650 tube with full grippy knirled body for use with XHP70
However, helpful information.
Thank you.


Edit: These are normal threads and not newer style square threads. So will fit older style C8
 
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NitrousZ28

Newly Enlightened
Joined
Jan 16, 2021
Messages
3
IMG_0894_zps74m3syqm.jpg


I recently made number of these for customer and few for myself.
Instead of using extension tube, I made 2x18650 tube with full grippy knirled body for use with XHP70
However, helpful information.
Thank you.

@fivemega sorry to dig up an old thread, couldn't PM you. I am really interested in having one of these made; how much?
 

Senna Fan

Newly Enlightened
Joined
May 18, 2020
Messages
11
Are these for the convoy c8? Do you still have any left? If so, what’s the price? Thanks.
 
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Senna Fan

Newly Enlightened
Joined
May 18, 2020
Messages
11
Are you ever going to accept p.m.’s again? I keep trying but it says you reached your limit and need to make room to receive new messages.
 

Senna Fan

Newly Enlightened
Joined
May 18, 2020
Messages
11
I just re-read this thread then checked my c8+. It has the newer square threads. Any chance you might do a new run to fit these threads? 🙏
 

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