Fraternal Seoul Twins?

One of our Forum members asked me to make a custom light for him:

- 1xC cut down/re-thread Silver Mag
- setup for single 18650 LiIon cell
- USWOH Seoul (emiter)
- semi-custom Al heatsink
- M. Bulk BBflex Driver

So I decided this was so cool, why not build two of them?




But I am getting ahead of myself here. As always, I have "tons" of pictures to share about the whole process ...


Cut metal to length, make even:



Cut new threads (thanks again to Mac for teaching me his straight cutting method!):





Clean the edge to protect the o-ring:



Test the fit:



Now do the same thing twice:





Here are the two BBflex drivers from Mr. Bulk, after I removed the switch (which will be replaced by the modified Mag's switch):



Here are the semi-custom heat sinks I am using for this project, based on some parts that I got from MirageMan (thanks again dude!):



Here are the Seoul emiters in their new resting place (remember these must be isolated from the actual heatsink!):



The next step was to modify the switch to be momentary only (normally open) which is what the driver needs, but that by itself has so many photos that I am doing it in a separate post as a mini tutorial for those interested. Here are some teaser photos:




EDIT: Here is the link to the switch tutorial:
https://www.candlepowerforums.com/posts/2355490#post2355490


Here I am soldering the driver to the LED:



Taskled (the manufacturer of the BBflex driver) states that one should be careful with potting the driver as it might affect its functioning. I still did not wanted to have the driver loose inside, so I used some epoxy just to keep it in place, safely attached to the underside of the heatsink:



Once secured, I solder the heatsink/driver to the wires coming from the modified switch (battery, switch, and GND):



I then applied thermal compound to the heatsink before pushing it in place:



Once done, to keep the heatsink from moving, I used a little bit of epoxy to keep it in place:



I am of course using my own LiIon cell spacers with built-in o-ring (original idea from FiveMega):





Of course, for the spring to make contact, the bottom of the tailcap must not have the anodize/paint:









ITS ALIVE !!!



The silver one is the one built on order, the "other" one will be put for sale in the forums tomorrow

Will

Nice job Will! I love the 1 x 18650 and/or "C" lithium ion form factor. Glad to see those heat sinks being put to good use :thumbsup:.

A couple questions for ya...

Why not just slide the body into the chuck and part the body off in the lathe then face the edge to leave a perfectly square end? Also what is the "straight" cutting method? Do you not use the 29.5 deg compound slide method? Just curious.

Mirage_Man said:

Why not just slide the body into the chuck and part the body off in the lathe then face the edge to leave a perfectly square end?

Click to expand...

Since I have the band saw I find it easier this way, as parting is not one of my favorite operations

Mirage_Man said:

Do you not use the 29.5 deg compound slide method? Just curious.

Click to expand...

That is right, I do not use the 29.5 deg compound method. Hopefully Mac will chime in to help explain it better than I do, but straight cutting simply works extremely well, and you get excellent threads (as you can see in the pics).


Thanks again for all of your help :thumbsup:

Will

Nice work, Will.
:thumbsup:

wquiles said:

Since I have the band saw I find it easier this way, as parting is not one of my favorite operations

Click to expand...

Gotcha. I guess when you've finned as many heads as me parting becomes second nature. :sick2: :laughing:

wquiles said:

That is right, I do not use the 29.5 deg compound method. Hopefully Mac will chime in to help explain it better than I do, but straight cutting simply works extremely well, and you get excellent threads (as you can see in the pics).

Click to expand...

That's cool, I understand. You're just cutting both sides of the V at the same time. I was taught to use the 29.5 until the last pass. Then I bring in the cross slide in a few .001" for the final pass to clean up the back side of the thread. It really doesn't matter how you get there as long as you get there .

What is the length of the modified body?

cnjl3 said:

Nice work, Will.
:thumbsup:

Click to expand...

Thanks!

tattooedwhitetrash said:

What is the length of the modified body?

Click to expand...

At least for the 18650 cell, the length of body by itself (without tailcap of course) is about 4.6 and 4.7 inches, but this is not ubber-critical due to the spring :naughty:

Will

Very nice job, Will. I always enjoy your pictorials and your attention to detail.

BTW - that little blue/purple job looks familiar.

Kirk

Thanks Kirk

Will

Here is the link to the switch tutorial:
https://www.candlepowerforums.com/posts/2355490#post2355490

Will

Does anyone have a cad or dimensional drawing of the aluminum heatsink shown here? I would like to turn one on my lathe?

I no longer have these lights (both of them sold already), so I can't go and try to measure these dimensions for you at this point. However, if you have a "C" Mag body and a Seoul emiter you can pretty much engineer one without too much trouble. Let me try to help with some points/suggestions:

Some key dimensions that I feel are critical are:
- the small alignment circle used to center the emiter. Also keep in mind that the base of the emiter needs to be electrically isolated from the actual heatsink. If you don't have a circle (or some other trick) to center the emiter, then you will need a centering fixture to get the emiter perfectly centered (I did that for my McG45 - link below)

- the height of the base for the emiter, relative to the top of the Mag tube. If it sits too low, even with the head screwed all the way in, you will not be able to bring the LED into proper focus. Also, the emiter "tower" needs to be high enough that the bottom of the reflector will not hit the heatsink before proper focus is achieved.

- Of course, the OD of the heatsink is critical, but as long as it matched the ID of the Mag C tube, you are set. Plus this is one operation in the lathe where you can take a "little" bit of material, leave the heat sink on the chuck, try to see if you can get the Mag body to fit, if not, you can take a little bit more, etc.. In general I would say that a tight fit is much better than a loose fit, otherwise the heatsink will move up/down somewhat, causing out of focus conditions, etc.. I have also been toying with the idea of a small screw on the side of the body (through the top of the threads, but recessed enough ) to properly secure the heatsink, but I have not done so yet ...

- Now, if you want to house an LED driver on the under side of the heatsink opposite of the LED, then you need to "hollow" the under side of the heatsink with enough space to fit your driver (or to "pot" it if you are doing that as well).

I have done other custom heatsinks for the C body, like this one where the emiter had to be "very" deep inside the C body, due to the 45mm reflector being so deep:
https://www.candlepowerforums.com/threads/131800&highlight=McG45

I definitely encourage you to build one from scratch - that is how you learn a lot about this hobby

Will

Thanks for the information. I've been lurking around for awhile, I'm new to the hobby so all the information I can get is greatly appreciated. This is going to be my first mod and should be fun.