502B to C8 converter

Hi all,

I have several UF 501B/502B type flashlights, as well as a few cheap C8’s from aliexpress (http://www.aliexpress.com/product-fm/568428226-5pcs-Freeshipping-UltraFi…).

I like the build quality and body of the C8’s. They produce really nice throw, but they have plastic reflectors, and of course for that price, the LED is not so bright. I’ve unscrewed them and found the pills to have different diameters to the 502B. According to my measurements, the C8 pill has a 22.5mm diameter thread while the 502B has a 20mm diameter thread. Since I have a bunch of these cheap C8 bodies, I was wondering what it would take to mount the P60 pill into the C8 body? Is that advisable? Since they’re quite cheap, and I have 5 of them, I don’t mind damaging one in an experiment. Does anyone sell thread converters that enable the P60 pill to be mounted inside the C8 head?


Why not just xml pill and alu reflector for c8?

link: KD C8 pills and reflectors


Please enjoy your time here, chah!

Thanks for the link rockspider. Basically,i have a bunch of 502b’s and want to be able to share parts. I also happen to have a spare 502b pill that I’d like to use in the c8 if it’s possible. those pills in your link do also look like good value.

There are $15 c8’s on aliexpress, adding together the cost of the $6 c8 body plus $11 pill comes out slightly more.but the kd pill does look quite interesting. Thanks.

Manafont, KD and DX all sell separate C8 reflectors. I have several for XRE/XML and XPG emitters, both smooth and OP. I’ve seen them for under $3 up to $6 each.

Does anybody know, do the flashlight manufacturers deliberately make the parts such that we cannot share parts easily between flashlights? I find that almost nothing from one flashlight I have can be re-used on another so far. The threads don’t match. I would have thought it’d be easier and cheaper from a manufacturing standpoint to keep the body and thread diameters the same, and just change the head, for example between the C8 and 502B or between the 501B and 502B.

I like the idea of adaptor rings, that would be cool.

Unfortunately, I doubt many manufacturers would agree. They make lights because they want to sell them. They would rather sell a compete light for a bigger profit than streamline things to make parts interchangeable.

Aside from that, one thread or tube size is the same as another to a machine, and without communication and the desire to work together for uniformity then it will never happen. Makers use what works best for them within the design parameters and budget considerations.

A few manufacturers make some lights that lego. Not every buyer cares or wants that. Most just want a light that works.

Makers cater for both to a degree.

Something else to consider, innovation requires rethinking design to incorporate new inventions and technologies and better design principles.

If makers kept everything interchangeable, we would still be driving T model Fords for example. Quaint, but I don’t really want that.

A lot of internal parts in iights are interchangeable, just not quite as easily as the lego ones. If you really want custom, learn about these parts, grab a soldering iron and have some real fun :slight_smile:

You’re asking a bit too much for all lights to be compatible with each other. It’s like expecting cars to all have interchangeable components. It’s just not gonna happen.

As it happens there are pills specifically made just for the C8 available on KD and DX.

I just ordered 3 empty pills for my C8. I ordered them from lck-led for $4.14.

Figured I could put 3 different leds in there and swap them around to see how they work. Maybe an XTE, some kind of red cree, maybe an XML U2 or nichia 219?

Thanks all, for the comments and links. Some counter points:

1) I would have thunk that to drill a 20mm thread you need 1 tool. To drill 20mm thread and 22.5mm thread you need 2 tools. Wouldn’t standardizing (thread diameters) save the manufacturers in terms of equipment cost and maintenance? I think it’s more hassle to say “let’s change the thread diameter on our next product” than to say “let’s re-use the same thread diameter on our next product”.

2) I agree that not every customer wants parts that lego. However, there are some that do. If it saves cost on manufacturing, and it opens up to a larger market, that would seem to benefit any manufacturer that does it.

3) I’m not asking the manufacturers to change. I’m just trying to understand the manufacturing and marketing processes and why design choices are made the way they are.

4) I don’t feel it is quite analogous with cars. There are improvements in one engine design over another. I’m not sure that a 22.5mm thread is an improvement over a 20mm thread. One looks to be as good as the other.

The place I can see that it involves extra effort to standardize (as you pointed out) is between manufacturers, where one has chosen one diameter and a competitor has chosen another diameter. Then the clones come along and they need to match both diameters. So they buy the tools that can do both diameters. I think this should be the main cause for lack of standardization, especially in thread diameters. But even then, a single manufacturer has products that could have the same thread diameter, but for some reason, don’t. The only thing I can think is that they don’t want us to lego them, maybe force us to buy a replacement, rather than reuse parts from another torch.

From what I understand, it probably has more to do with the way Chinese manufacturing works.

I know a lot of complex items, like small engines and chainsaws, are not manufactured all under one roof. Many parts may be outsourced to specialised factories then assembled into a complete item elsewhere.

Same with electronics, one company manufactures capacitors, another resistors etc.

When you want to build something that uses these items, you don’t tool up to make every single component. It’s just not efficient to do so. You may spec certain items to a certain standard, or just go generic and cheap.

Same with cast items that require foundries and machined parts that can be made from standard tube sizes. Then there is heat treating and finishing applications like anodising. Parts that require special treatment like reflectors and glass lenses.

You start with a design you like, then look for ways to make it work under a certain cost. The higher the sale price, the higher quality you can build into manufacture.

Below a certain level, then close enough is good enough. As long as the item works. When follow up orders are made, profit is taken into account. Perhaps you can save a few cents on each item by making some part/s differently, or the factory you source them from makes them cheaper and is different from the previous one.

Chinese production centres are like little cities with dozens or even hundreds of manufacturers. It’s almost a miracle that they make anything complex that works as well as it does.

They don’t just have a factory producing flashlights. A machine shop makes machine parts. One day it’s flashlight tubes, the next it may be small engine parts.

Orders are processed as they come in. Every new production run requires re-tooling. One size is the same as another to a machine. Say perhaps, that you find a source of 25mm alloy tube stock that is 2/3 of the price but a slightly different size to your last run. You have a renewed order for fifty thousand flashlights. What would you do? The thought that previous customers might want to swap parts with the new model does not come into it. Unless of course that is a design parameter.

The way most people see flashlights as throw away items reinforces the concept. Bin the old one, buy a new one. The new one is probably going to be better in some way, brighter or more efficient. Shiny and new. Smaller or lighter. And cheap enough not to matter.

In those circumstances, who cares if the threads are different. You got a good deal on some tube stock and that improves your profit margin. Maybe you got a good deal on some machine tools for thread cutting that aren’t quite standard and only work with the matching cutting tools. You buy them too, because it improves the bottom line. Price. Who cares if the threads you make don’t fit anything else but the lights in this weeks production run? Cheap and cheerful :slight_smile:

I have seen $200 dollar garage jacks thrown away because of a leaky $5 seal. They use non standard seals and you can’t buy a replacement here to fit. Thats not even getting into the different thread standards. There are quite a few as it is.

Ultimately, it’s a result of cost cutting during manufacture. Sometimes it’s different standards. Sometimes it’s just lack of care. But without it, we would not have these lovely cheap lights.

Thanks Pretzy, what you say makes sense.

For complex items, I’m sure that what you are saying is how it’s done. I work in the hard-disk drive line and the outsourcing you describe is what happens.

Flashlights could be simple enough to make the whole thing (except the LED) under the same roof. Perhaps the american brand flashlights are done that way, and so they charge a premium for it.

It would not surprise me if that’s the way chinese manufacturing occurred. On the other hand, if a flashlight manufacturer made an investment into the tools needed to create the body, they might save money in the long run by eliminating the outsourcing company from the profit chain.

I really like the build on the cheap C8’s, only the LED’s are not that bright, which is why I want to change it :slight_smile: Build quality is good and the pieces screw together smoothly and snugly, the clickie switch also feels nice and sharp. I can’t imagine how they make a profit at $6+ apiece. They must be clearing stock. I’m a cheapo, and will wait until someone is clearing stock on C8 pills. But thanks all for the links provided so far.

Flashlights are mostly made under one roof due to their simplicity. There are photo tours of the factories if you search hard enough on the web. Romisen, tank007, Fenix, etc. The more legit budget brands aren’t really all that different from more premium one. However, we here on the forum are known for scraping the bottom of the barrel for diamonds in the rough, and the fun is in the journey.

If that’s the case, do you happen to know the reason why they might choose different thread diameters in similar models of flashlights, like the 501B 502B and C8?

These lights and their parts are often clones of name brand ones. For example, the C8 has the same reflector as the Lumapower MRV. 502b’s use surefire p60 sized drop-ins. Different origins, different sizes.

The UF 501,2,3,4 models are based on the SureFire P,C and Z lights which all use a P60 standard drop-in, bezel and tailcaps. The UF made lights approximate the SuF mechanical specs so some parts will fit and others will be loose or too tight. CNC programming also specifies allowable tolerances for parts work, so the body tube may have good thread size at the bezel and loose at the tail cap and meet QC requirements.

Interesting information.

But still curious if anyone knows why the original flashlight manufacturer might choose different specs for subsequent models of flashlight. Is it convention to change specs so they have a “new” product to sell, is it because they can save costs somehow like pretzy suggests, or is it to prevent the parts from being shared between them?

I know the 501B and 502B don’t use the same tailcap because I have them. I also have the 504B and it has the same thread diameter on the tailcap as the 501B, but you can’t share between them, because the depths of the tailcaps don’t match.

It’s kind of surprising. Amongst the 501B, 502B and 504B’s that I have, the 501B seems to be the brightest and I use it the most. The 502B is not so bad, I use it from time to time, but the 504B (I only have 1) has a problem with the head. When I unscrew the head, I can’t get the reflector out of the bezel. I can get the pill unscrewed out of the reflector (with difficulty, because the reflector rotates inside the bezel), but the reflector is lodged inside the bezel. I think the bezel should unscrew in one more place, because there’s no way the reflector could have gotten in, but I can’t seem to unscrew it. So I don’t use the 504B, and it’s an XML-U2. It was also the most expensive amongst the three types, although at $20 it was still cheap.

When I told the seller I had a problem with the head (I had another problem of the flash-light intermittently changing modes, stepping down from the brightest mode before I tried unscrewing the head. I checked the battery, it wasn’t because of that), he was kind enough to send me another drop-in. Unfortunately it hasn’t solved my problem with the stuck reflector. But at least now I have a spare P-60 drop-in, which I would like to fit (the pill) into the C8’s if I could :slight_smile: So now you know why I’m interested in this.

What you’re saying makes no sense. The 501/502/etc all use interchangeable drop-ins that fit quite loosely.

I’ve got some that don’t screw all the way down because they are too tight . . sucks to have some I can’t test with the 501 aspheric.

This picture shows what I meant.

  1. The top left photo shows the 504B body on the left, the unscrewed head in the middle, and the replacement drop-in on the right
  2. The top-middle photo shows the same from above
  3. The top-right photo shows just the head. The springs on the bottom of the pill are visible sticking out the bottom (this picture should be rotated 90 degrees clockwise)
  4. The bottom left photo shows that I can unscrew the pill from the reflector, but the reflector is still stuck in the bezel
  5. Bottom middle shows a view looking up at the bezel, the reflector doesn't come out
  6. The view of the reflector stuck inside the bezel from the front.

I think the head should unscrew in one more place to get the drop-in, but it is screwed so tightly that I cannot unscrew it.