Hey BLF, I bought a BLF A6 XPL based on info from this site a few years ago and have recommended many to friends since. I take care of mine carefully however in the process of switching batteries the other day the rear screw-off cap has somehow disappeared. I’m completely at a loss so figure I need to buy a new one. I’ve hunted around on this site but can’t find the button and screw-on cap for purchase. Below are a couple of the options I’ve found so far:
Hey mate do you have the retaining ring that holds the tail cap in place?
Thanks for the super fast response. just so we're on the same page I think it's easier if I share a picture of the remaining torch
- https://www.dropbox.com/s/qlcruxa8vy11zih/MVIMG_20181229_154721.jpg?dl=0
No worries welcome to BLF!
Oh that’s a tough one lol.
Banggood have this assembly but i am not sure if it will fit. Some one will chime in and answer i guess. There are parts from other lights that lego on the BLF A6.
Any one want to chime in if this will fit? Actually some one wrote in the reviews that it fits the BLF A6? Then some one else wrote it won’t fit the S1 which is the same as the BLF A6 lol. According to Banggood the 18650 tube is the same fit on the S41, S42, BLF A6, S1 so it should be okay.
Check here. I will give it a read also.
Thanks again I will buy that part and report back after it arrives in a month or so 
You can probably get a new A6 for under 20 USD. That price sucks for just the tail cap.
I had a link through my email it has the price of the A6 for 18.69 USD i will link it here but it may not work. You can also try M4DM4X deals he should have a discount for the complete light.
M4DM4X deals
The tailcap of the BLF-A6 fits the Astrolux S41.
I have not tried the opposite (screwed on clips etc) but I don’t doubt it will be the same.
Uhm, no.
S41 S42 and S43 are the same threads as Astrolux S1.
The A6 uses slightly smaller diameter.
So a S1 or S41 tailcap will fit loosely, but i guess it’s better than nothing…
Well, you stand corrected, and I stand double corrected. :person_facepalming:
Trying to cause minimal damage to the ano I have pried the clip off from the A6 body.
The tailcap of the S41 fits rather loose on the body of the A6 (you are right about that).
But the threads of the A6 body are too short to reach the retaining rings in the tailcap and in the head.
(we’re both wrong, the light won’t/can’t be turned on with this combination).
This reminds me of why I use the A6 seldom/never.
The original plan for the A6 was the ability to lego with the BLF X6 SE.
But the machinist cut the first thread with a rather unique size (read: too narrow and too short).
Instead of doing a re-run they apparently decided to adapt all other threads to this wrong one.
You could probably jam a washer as a spacer between the retaining ring and switch to add some height to the retaining ring if it almost fits.
I think they changed the BLF A6 tube lengh after a few runs? Mine is from the first batch i think so i can’t be sure. Banggood advertises the spare 18650 battery tube fits all the lights A6, S1, S41 and so on.
It’s only a minute gap. So I can use (a piece of) a bend paperclip. But that does not look very professional.
I have a roll of 1mm Nickel plated (or was it Tin?) copper wire for that sort of thing.
And if it’s not enough i use the copper core of installation wire.
There’s always a way to fill a gap like that.
Ideally they would stock some spare parts for us to buy.
Uhm, no.
They are both exactly the same diameter. Measured. Absolutely interchangeable. Two A6, two S1 and two S41. And one more spare S41-tailcap.
Not owning a precise instrument to read female threads I did some Q&D measuring with a set of calipers.
Object of interest were the short tubes of S41 and A6
The interconnection of the threads was perfect. They use the same pitch, but the diameter …
S41 length: 36.95mm - diam.tail: 21.75mm - diam.head: 21.75mm - weight: 11gr
A6 length: 36.45mm - diam.tail: 21.45mm - diam.head: 21.45mm - weight: 10gr
A6 original 18650 tube - diam.tail: 21.40mm
In my case the S41 tailcap has a relatively loose fit on both A6 tube(s). But that’s only mechanical.
Both the long and the short tube have shorter threads at the tailcap side than the S41 tube does.
This means that A6 tubes are too short to make a connection between the S41 head and tailcap.
Not by much but …… a gap is still a gap.
Uhm, wrong.
A6 has a smaller diameter threaded section than S41 / 42 / 42 and S1
Yes, the larger ones can be screwed (a bit loosely) onto the A6 tubes, but not the other way around.
But maybe they changed it and it’s the same now?
I don’t know that.
I highly doubt it though.
Definitely no. I’ve measured with my caliper, thats exactly enough. And they are all the same. But: all bought in the last three month. Perhaps that’s the reason.
I bought them the moment they were released. Lots of start-up problems with the A6 (August 2015).
Literally none with the S41, but I put a few tiny nylon washers under the screws that hold down the LED PCB.