I ordered a few SK68 clones from ordinaryworld2009 on eBay. I payed approximately $4 each shipped. Since I haven’t used an SK68 before I can’t compare it to other models, but here is what I’ve seen and measured:
Cree XP-E emitter rather than Cree XR-E or Osram whatever shown in listing.
3 mode, as described (High / Low / Strobe) with next mode memory
metal ring rather than o-ring for focusing
Focusing feels somewhat gritty, but about as smooth as can be expected with the metal ring. The metal ring keeps the light fairly snug in the unfocused position.
When rotating the head the sharpest focus is not achievable in all positions. (something in there is a tad uneven)
On one of two lights the thin o-ring used between the two halves of the head was sticking out and mangled from assembly. See pics 4 & 7
The way the star is retained in the pill was a little strange to me. The star sits loosely on a ledge with a big 12mm hole in the middle, wires run up to the star through that. The XP-E has a large white plastic centering piece clipped onto it. A metal washer stacks on top of that, then a plastic retaining ring is friction fit into the pill around the edges, holding the metal ring down against the white plastic centering piece. There is no grease anywhere of course.
Tailcap current measurements with a (well-used + fully charged + rested) Duraloop:
High - 1.7A
Low - 0.4A
Strobe - 0.8A
Physical measurements:
Lens opening diameter - 18.1mm
Head diameter - 25.8mm
Driver diameter - 15.0mm
Driver overall thickness - 4.3mm
Driver ledge diameter - 14.9mm
space under driver diameter - 13.7mm
hole under LED star diameter - 12.0mm
friction / spring ring slot diameter - 20.3mm
friction / spring ring slot height - 0.8mm
friction / spring ring [itself] thickness - 0.7mm
LED star thickness - 0.8mm
LED star diameter - 15.8mm
white plastic retention ring outer / inner diameter- 17.1mm / 14.5mm
metal retention washer outer / inner diameter - 17.0mm / 5.7mm
LED star ledge diameter - 15.9mm
When I measured the ledge for the LED star ledge I’m not sure that I didn’t measure the tiny bevel at the bottom. The diameter just above the <0.1mm tall bevel may be 16mm or so, I think a 16mm board may sit nicely if you sand the bottom outer edge.
The next mode memory was a problem, so I decided to do add a resistor and get that fixed! Putting a 100k resistor over to the cap next to the inductor worked, but not well. It took over 5 seconds of off-time to reset to “high” mode. Swapping the 100k for an 8.2k did the trick. Now you can switch modes comfortably with about a 0.3s or less press. A 0.7s long press will definitely reset to high mode.
Stock:
100k 0805 resistor with dental pick:
100k resistor stacked on top of cap next to 2R2 inductor, yielded slow reset:
8.2k resistor stacked on top of cap next to 2R2 inductor, yielded good reset (<0.7s):
“
”
another view of 8.2k stacked on top of cap next to inductor:
I got stupid and tore the a pad off the R270 resistor. It looks ugly now because had to solder to the top.
thanks for the overwhelming amount of pics :-) Interesting that it looks Sipik branded and 3 modes, I was only aware that the 'original' Sipik only comes in 1 mode.
They don’t seem half bad. After I ordered 2x of them I ended up ordering 2x more about a week later in the hopes that I’d have 4x identical SK68’s. I figure that no matter how bad they are, at least any required modifications shouldbe the same for all of them [before they become gifts / etc]. We’ll see whether I get away with it since I ordered them a week apart…
Werner, have you seen any other SK68 teardowns w/ an XP-E? The plastic spacer seems to be there in order to pad the little XP-E out to about the same dimensions as an XR-E w/ it’s ring. I didn’t realize that the disk + big white ring was a standard retention mechanism for these, but it appears that that is the case: SK68 & Clones Teardown
bentrinh’s got 3 different drivers there, none the same as what I received! I’m curious about whether the components are the same, but I can’t tell from the pics.
I have seen a lot, but almost every new lot has different things. So I mentioned the white ring, which I have seen before, but not on a sk68. The last AA zoomies I bought were the two dollar zoomies from wallbuys, which I even like more.
Trust me you have a good one there. 3 mode and xpe, if the fins are not to sharp and the tailcapboot(so many photos but never the tailcap…) is decent than it is perfect. A solid pill would be better but this doesn’t matter for these cheapie lights.
As mentioned above the “original” sipiks had just one mode and a solid pill. I have one clone which has no sharp fins, just around the head like on a normal light. There are some which can’t tail stand because the tailcap is different, some have the metal ring some o rings, some have a oring on the pill…there are so many variations
That’s how I remember a xpe sk68 clone:
By the way those calipers look different too…from which material are they made and why?
You’re right - I totally neglected to take any pictures which show the switch-boot side of the tailcap. Next time I’m working on that stuff I’ll do my best to add a couple of pics of the tailcap / switch boot assembly for completeness. I spent a good few minutes fooling with the tailcap while I was taking the other pics. I couldn’t figure out a good way to disassemble it and just went on to the next thing.
The boot itself seems to be 13mm (caliper jaws would not fit into recess far enough to get a great measurement). The light tailstands fine / easily. Fins are far from sharp, they feel pleasant. I’d like to make an extra-large tailcap so that this light would be a suitable gift for my grandfather, who I do not expect to be able to handle the stock one. It’s too small for him to take off and the button is not exposed enough for him to press. He doesn’t need it to tailstand, but I can’t just cut off the wall around the boot or neither of us would be able to unscrew the thing!
I don’t feel like the hollow pill is really important at these drive levels. The super-thin MPCB is possibly a more important problem, but I’m not really worried about that either. I’ll probably put some thermal grease on the interface between the MCPCB and the ledge it sits on though.
The calipers are 150mm carbon fiber ones from Control Company - http://www.control3.com/3415p.htm The website lists them as non-conductive. I’ve read that carbon fiber is supposed to be conductive along the weave, but I can’t find any exposed weave on my calipers and IIRC I tested them with a DMM and found them non-conductive. They are very lightweight and I’ve found that they need to be zero’d MUCH less often than the 150mm steel calipers I bought from DX.
Hopefully somebody will come along with the specifics (it may take a lot of searching to find it), but somebody mentioned using the tail cap off of a SK78 (I think, unless it was a 73) makes it a much better and it works well as a swap between the lights.
Tailcap disassembly is hard and there are no cheap spare boots in this size available so you have to be careful if you dissassemble.
But this is not necessary as long as you just use it in stock configuration.
I consider the one SK68 I’ve tested to be “weak” but AFAIK that’s intended behavior. Based on tailcap readings the LED should be getting between 1.5 and 2.0 watts. From what I know about 1xAA boost drivers that seems reasonable.
The thread bump reminded me that I wanted to get a tailcap reading on 2xAA. I went ahead and did it just now, ~0.98 amps on 2x NiMH. Subjectively it seemed a tad brighter.
I spent a good few minutes fooling with the tailcap while I was taking the other pics. I couldn’t figure out a good way to disassemble it and just went on to the next thing.