Are there reputable members or places that do custom cnc and tube boring service? I need a few flashlight tubes bored to fit 18350 and tubes shorten.
If you switch back to basic Antenna channels and use a converter box, you might be able to watch all 7 channels on an old CRT…
Jokes aside, there was someone in Washington state who does boring for surefires and elzettas. I’m not sure that those EagTacs have enough meat to bore with while retaining structure…
Whats their contact or post?
I’ve been looking, gimme a bit…
people have had good results with Vinh, owner/operator of SkyLumen54@gmail.com
I read this person was hit or miss on his work. If anyone can share any other reputable alternatives
If you’ve got some calipers, it would be good to measure the current inside diameter of the tube and the outside diameter of the O-Ring grooves to work out what thickness the aluminium body is in these places- I suspect you might not have enough material to remove c.1mm from the inside of the tube.
The Surefire 6P which used to be “the cool thing” to bore to take 18650s had, very thin wall thickness at the O-Ring groove after boring.
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The tube will be shortened with new threads on that part. The wall is 1.76mm in thickness.
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if the body tube is 20.5mm thickness, that’s usually the outermost portion. in the image, there seem to be portions that dip in at LEAST 0.5mm radius, so AT LEAST 1mm diameter, leaving you with 19.5mm Outer Diameter to bore. Playing it safe, take another 0.5mm, giving 19mm.
taken from that same spec sheet:
Inner Diameter UP to 17mm, but you want an 18650 cell in there, likely 18mm +0.3mm to 0.6mm for wrapping, branding, stickers, etc.
From the apparent deepest outside part of the body (the Oring grooves are probably deeper than that) to the expected bored ID, that’s 19.5mm minus 18.6mm. That would leave you with 0.9mm DIAMETER on a good day, or roughly 0.4mm diameter on a bad day. Your oring grooves probably wouldn’t exist anymore, as @gravelmonkey cautions.
**that means 0.45mm walls, or 0.2mm walls. If you estimate or measure other numbers, definitely correct me if my estimates are off.
Here’s how the walls of a d25a2 mini look, roughly 0.5mm or 0.45mm walls.
Back in the days when I was a regular lurker on the other forum, the name Oveready was mentioned quite often.
If my memory serves me right, they even had a boring service. Their standard size for 18650 was 18.6 mm.
I do my own boring, using an adjustable reamer. Takes a lot of time and some elbow grease.
But it gives me much pleasure when the battery softly slides in (not drops with a clunk).
How thin were the walls at the o ring groove?
Its going to be a tight fit if I want to make it work. Doing measurements with my digital calipers ill have about 0.6. I have a d25c I would also like to bore out that has a bit more to work with no dips in the tube to fit an 18350.
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Looking at how minimum the available surface to work with, I would rather move on, buy, or mod or maybe cnc another /a new light than to risk that Good 'ol light.
Just my two penn’orth
Cheers 
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I do hope you find a good precise service! Sorry I can’t be of more help…
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Goog suggests remaining wall thickness on these 6Ps was only 0.5mm.
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Just a heads up. SkyLumen (Vinh) is great. However he just farms the boring service out to a machine shop. I’ve had a 6p host bored using him and the quality was not as good as what I’ve had done in the past from a true flashlight enthusiast that does it themselves. Not saying anything bad about him, great guy and been around forever but not many know this.
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One potential way you could accomplish this is to find an 18350 tube and tail cap that will work from another light. and then you just have to create larger threads in the head end to accept the larger tube. Good luck trying to find that tap. Or you ream those threads out and JB weld things back together. Although JB weld is not conductive. So you would have to have some good thread engagement.
Edit.
Aluminum zinc solder.
I have always had great service from Vinh and great gear too - but admit I have not had him bore any stuff for me.