Why dual/tri/quad bore on mag?

[rizky_p]

I just got 4D tube bore up at local mill today to increase its inside diameter, now 4 Sanyo 2700 will fits across nicely. I know that all if not most dont do diameter bore but instead does a dual/tri/quad-bore instead, can i ask why? is it has something to do with total integrity of the tube? did i do anything stupid by boring out the inside? And when heavily dual/tri/quad bored the thread also get easten up, in case of quad-bore would the tailcap still screw in nicely/tightly?

TIA
Rizki P.

 

[DonShock]

You're thinking along the right track. It's possible to do a light full bore job to get 4AA to fit without getting in to the tailcap threads. But if you want three 17mm cells to fit, the bore will go into the tailcap threads so a tri-bore is needed to leave enough threads to still let the tailcap screw on. And a dual bore for 18mm cells has the same problem.

 

[rizky_p]

You're thinking along the right track. It's possible to do a light full bore job to get 4AA to fit without getting in to the tailcap threads. But if you want three 17mm cells to fit, the bore will go into the tailcap threads so a tri-bore is needed to leave enough threads to still let the tailcap screw on. And a dual bore for 18mm cells has the same problem.

ah i see, how much can you take the inside without making it too thin in case of dual/tri/quad-bore? can i still do the dual/tri/quad-bore after my initial full boring?

thanks.

 

[Jesus Hernandez]

You can still dual or tri-bore your host. The Full-bore will take care of the quad-bore.

 

[LuxLuthor]

Jesus does excellent bore work!

Just one other approach if you had someone do a diffuse bore below the threads, and you want to put tri-config setup of "A" or "17xxx" cells; or bi-config of 18650 cells....you can mark 120° or 180° respectively, and just gently sand down a groove in the threads with Dremel drum for the batteries to get past.