I’d guess it’s more a failure of two things — repeatability and accuracy — so their tolerances are so wide that Lego-ing doesn’t work reliably.
Even assuming they’re using lathes that allows them to specify exactly what thread that lathe produces — how many operators, on how many different lathes, on how many days, are going into this production?
Seriously, these have to be beginners. Once someone’s competent to make truly interchangeable parts in mass production — that operator is going to be working on something more important than cheap flashlights.
Thank goodness, since that might be a nuclear plant or aircraft.
We’re getting the “training wheels” stage of industrial learning.
Quoting from the A6 thread at Thu, 09/10/2015 - 15:22
See follow-on comments in that thread for more on tolerances and how you need really tight specs.
I posted a long quote on using micrometers that included:
There will be some variation — and the variations add up to this kind of problem when parts meet or don’t.
My new BLF A6 legoes with the UF-2100. The uf-2100 tailcap works on the A6 tube and head but I can't get the A6 head to light up on the uf-2100 tube/tailcap.
I have successfully legoed the black and silver Ultrafire 504b and Uniquefire L2 heads, bodies and switches with the whole Solarforce lineup. I don’t have them myself, but the Spiderfire stainless steel P60 hosts should also lego well.
I just saw a “read somewhere” note that the MtnElectronics spacers (2 different ones) for the S2 and S2+ may also fit some other lights.
Anyone know for sure?
The A6 BLF clip fits the original Convoy M1 very well. Will post a picture later.
The clip for the Roche F6 fits the Convoy S2+ really well (even better than on the F6) and it is super sturdy. However it is not a deep carry and I don’t know where these can be bought separately.
Tailcaps: the tailcap of my red Convoy S2+ fits and works correctly on the battery tubes for both an Eagle Eye BLF-X6-SE and an Manker A6. (only checked one of each)
The tailcaps for both of those black lights are too tight — they start but won’t screw onto the red Convoy S2+ battery tube.
As noted above — the tolerance for variation is so large on these that a sample of one isn’t proof of any general claim about what fits what.
I’d guess somewhere there are three bins — heads, body tubes, and tailcaps — and whoever assembles the lights just keeps fishing until he finds a complete set and calls it good.
It’s the Goldilocks approach to flashlight construction. Some are too small, some are too large, some are just right.
That’s an oversimplification — threads have to be defined by several different numbers — spacing, depth, slope of the cut, maybe more. We don’t get that kind of precision.
(Or we get the seconds, if there are some that good)
Has anyone checked the threads for the retaining rings? I don’t know if those are done to any standard or not.