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  1. #1
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    XM-L Sled Light- Mattthemuppet-style.

    I thought I'd start a new thread, as Matt's old thread was about a single XP-G light.

    I've got a light in progress using Matt's housing and sled idea.
    All I'm waiting for now are the electronics.



    The top row shows:
    -Lexan outer cover- to be siliconed in place.
    -1" tubing main housing, still to be cut to length once I measure final electronics.
    -L-shaped bracket, which will get 3M Dual-lock on the bottom and velcro over the top. The light should mount well on a helmet and tilt nicely with this. It may also sink some heat.
    -End cap with obligatory fins.

    Bottom row shows:
    -Regina reflector, to be cut down (Also an 18mm DealExtreme reflector on the way to try)
    -Mini-Sled cut from 1" tubing- it's a nice tight fit in the back of the housing.
    -Waterproof momentary switch
    -Magicshine cable with cable gland stolen from old cell phone charger.

    Still awaiting:
    - XM-L emitter on a 20mm board, which goes on the front of the sled. Probably take forever from Dx, but they say they've packed them for shipping.
    - L-Flex, which goes on the back of the sled front, behind the XM-L. - probably take 4 days from Taskled.
    - Protected batteries and charger - already have 1S2P holders

    The end cap will be JB welded to the back of the sled, to allow an O-ring seal between sled and housing for easy 1-screw disassembly.

    Matt was kind enough to send some heat sink too, which I may mount later if needed.

    I should have parts for more lights after this, once I decide whether I prefer the XM-L or a Quazzle triple.

  2. #2
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    I like it (obviously )! This is the light I would have built if I'd known what I know now back when I didn't know it

    a 7mm drill is perfect to make the Regina fit the XM-L (going up from 4mm I think in 0.5mm steps) if that helps - just upgraded one of the LEDs on my (now) old twin XP-G light to an XM-L.

    Looking forward to the finished product and obligatory beam shots

  3. #3
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    I think you will have thermal bottleneck that limits the light output. If I understood you correctly you plan to mount LED on one side and driver on other side of 1.5mm aluminium profile that is mounted to the rectangular body that works as heatsink. All the generated heat must be transferred to the body via narrow 1.5mm bridge. Even if you cool the body of the light, the LED and driver will still be at elevated temperatures. If the temperature is too high, Lflex will dim the light to save the driver and LED.

    Thicker sled might help. Or separate sled for driver.

    Arne

  4. #4
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    Quote Originally Posted by arnea
    I think you will have thermal bottleneck that limits the light output. If I understood you correctly you plan to mount LED on one side and driver on other side of 1.5mm aluminium profile that is mounted to the rectangular body that works as heatsink. All the generated heat must be transferred to the body via narrow 1.5mm bridge. Even if you cool the body of the light, the LED and driver will still be at elevated temperatures. If the temperature is too high, Lflex will dim the light to save the driver and LED.

    Thicker sled might help. Or separate sled for driver.

    Arne
    Thanks, I've been wondering about that. I'm thinking of an L-bracket inside the sled for the L-flex if it turns out to be a thermal problem, as long as there's enough room.

  5. #5
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    OK, L-bracket made up for the L-flex, which will be mounted with thermal tape to the bottom of the sled and screwed together. Now, should it be thermally coupled with the front of the sled as well, or should I leave a small space between the sled front/XM-L and the L-bracket/L-flex?

  6. #6
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    I'd leave a gap or stuff something non conductive down there (rubber washer, electrician's tape) to give it a bit of support.

  7. #7
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    I've decided to use 1.250" tubing, 1" ID. 1/8" walls w/ exterior fins cut w/ a table saw. That, along w/ an "accessory wing" for the lflex, should make the heat dissipation a non-issue. The sled and accessory wing will use 1/16" square tubing. The larger exteriror housing should also make the build much easier. The housing should be approximately 43.5mm X 31.75mm. I have everything but the driver and xm-l but should get them both this week from George and Cutter.

  8. #8
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    A progress report of sorts- I JB welded the back plate on the sled, and did a trial assembly with an o-ring between the back plate and body.
    The tension required to compress the O-ring was enough to partially de-bond the back plate.
    The whole idea was to allow for a tight seal with only 1 screw, and easy dis-assembly.
    I was hoping not to have a tightly bonded sled that's a b!tch to remove for tinkering.
    ODTexas's design is much simpler, potted up with JBweld, but it's never coming off.

    I think I'll have to use black Gasket Former silicone instead of an o-ring between back cap and body, which can be a bit messier. I'll need to lubricate the body so the back plate/sled is easily removable.

    So far, I'm not sure the back plate idea is worth the trouble. It was a fair bit of fiddling to prepare and align, with holes and fins, even if it does look cool.
    The secondary bracket for the L-flex should be fine in the sled.

    It's looking like a build with a Quazzle triple and no back plate might be less work, if you're looking for a quick and simple build.

  9. #9
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    Could you use a plastic end cap to enclose the end?

    http://www.lowes.com/pd_41848-37672-...e|0%26page%3D3


    You would have to relocate the switch to the top maybe, but the power wire could still feed through the end cap.

  10. #10
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    Quote Originally Posted by Ofroad'bent
    The whole idea was to allow for a tight seal with only 1 screw, and easy dis-assembly.
    I was hoping not to have a tightly bonded sled that's a b!tch to remove for tinkering
    just sealing the back with a thin bead of silicone just inside the lip is really easy (push in, wipe off excess, all done) and it comes apart easily too. Then all you have to do is peel off the old silicone and add a new bead. I've done several like that and taken a couple apart, and it hasn't been a hassle at all.
    Last edited by mattthemuppet; 02-25-2011 at 07:12 AM.

  11. #11
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    Quote Originally Posted by KBARK
    Could you use a plastic end cap to enclose the end?

    http://www.lowes.com/pd_41848-37672-...e|0%26page%3D3


    You would have to relocate the switch to the top maybe, but the power wire could still feed through the end cap.
    The main point of Matt's sled design is that all the electronics are on the sled. An end cap and a relocated switch would work, but would need a different design. I am also counting on some heat sinking from the back.
    I think the sled would be easier to make without the back cap.

  12. #12
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    Woo-hoo, got the L-Flex. It fits behind the front of the sled OK, but since I added a secondary bracket to mount the L-Flex within the sled I will need to grind a deep groove almost all the way through the base of the bracket to allow it to fit. I'll get some pics once it's mounted.

    I got the battery case wired up too.

    My XM-L and stuff should be here soon- DX says it shipped last week.

  13. #13
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    I am using the larger aluminum for the housing which has an ID of 1" and I still don't see how I am going to cram it all in w/ the interior of the switch and all. It all fits fine, in theory and on paper.....There's just not alot of room for error. I'm really glad I am not using the smaller tubing!

  14. #14
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    Quote Originally Posted by Andy13
    I am using the larger aluminum for the housing which has an ID of 1" and I still don't see how I am going to cram it all in w/ the interior of the switch and all. It all fits fine, in theory and on paper.....There's just not alot of room for error. I'm really glad I am not using the smaller tubing!
    Here's my modified L-flex bracket, which will sit within the sled with the base facing backwards. It will attach with the same screw that holds the sled to the body.
    There's a cut-out for the L-flex, and one for the cable gland too. Things will be a bit tight but it should all fit

    I think using 1.25" OD square tubing to make a longer sled inside the same 1" OD housing would give more room to allow a bracket to face forwards, and then no mod will be needed to fit the L-flex. Picture a 2-seater sled.

    Last edited by Ofroad'bent; 03-03-2011 at 07:38 AM.

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    I was able to shave off some of the sides of my lflex in order to fit it in my square tube housing. I tested it and it still seemed to work fine.

    I'm still waiting on a 2600mah battery to be delivered so that I can finish it up.

  16. #16
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    Well, the Dx fairy delivered my batteries and charger, but still no XM-L

    Here's the battery pack wired and ready to waterproof


    Here's the charger modified


    Charger and battery pack after mods:


    And then the fiddly bit- soldering up the L-flex and fitting it and the bracket in the little "2-seater" sled.
    A longer sled would be nice.


    Ready for XM-L LED.
    Last edited by Ofroad'bent; 03-07-2011 at 09:47 AM.

  17. #17
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    looking good I take it that, even though you said you're waiting for the lflex, the fact that you have one wired up means you're waiting for the XM-L? Looks like it all fits in there surprisingly well, if a bit fiddly.

    BTW, if you're ever in need of a good strain relief/ cable gland material, Sugru is fantastic. It's some kind of magical silicone rubber blend that's hard but flexible. I used it on all 4 of my new XP-G lights and it's been holding up well on mine.

    looking forward to the finished product!

  18. #18
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    Quote Originally Posted by mattthemuppet
    l

    BTW, if you're ever in need of a good strain relief/ cable gland material, Sugru is fantastic. It's some kind of magical silicone rubber blend that's hard but flexible. I used it on all 4 of my new XP-G lights and it's been holding up well on mine.
    http://www.instructables.com/id/How-...ru-Substitute/

    shows how to make a similar product for a LOT less $

    Basically acetic curing caulking silicone and corn starch. Just helped my son with a science project and we used it to make some casts from home made molds. The stuff works great - just make sure you squeeze out any air pockets - but that's typical of any similar potting type compound.

    cheers,
    george.

  19. #19
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    cool, thanks for the tip George! I have five packets left (1 packet did 4 cables plus one kitty face), but when it runs out I'll definitely try this. I wonder if this could be used to encase and protect LiPo batteries?

    I also make a lot of silicone molds for a table top game I play, which is pretty damn price ($30/lb), be interesting to try this for making molds too.

  20. #20
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    Quote Originally Posted by mattthemuppet
    looking good I take it that, even though you said you're waiting for the lflex, the fact that you have one wired up means you're waiting for the XM-L? Looks like it all fits in there surprisingly well, if a bit fiddly.

    looking forward to the finished product!
    Thanks, fixed it - I have the l-flex but not the XM-L LED.
    Last edited by Ofroad'bent; 03-05-2011 at 03:37 AM.

  21. #21
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    georges80, thanks so much for the tip on the Oogoo - Sugru substitute. That deserves a sticky all by itself.

    borrower
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  22. #22
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    Quote Originally Posted by georges80
    http://www.instructables.com/id/How-...ru-Substitute/

    shows how to make a similar product for a LOT less $

    Basically acetic curing caulking silicone and corn starch. Just helped my son with a science project and we used it to make some casts from home made molds. The stuff works great - just make sure you squeeze out any air pockets - but that's typical of any similar potting type compound.

    cheers,
    george.
    Interesting. Dentists use all kinds of silicone putty and pastes of different consistencies for super-accurate impressions. They are 2-part ones that set in 3-6 minutes. They do tend to come only in brilliant colours. I have a ton of pale blue 2-part putty that expired years ago but still works.

  23. #23
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    Light's done! The Dx Fairy delivered.

    Here's the finished sled with XM-L LED and Regina reflector. I tried a Dx reflector but found it too diffuse for a headlamp. I like a thrower!



    Here's the body. It's so compact I added a heatsink. I also used 1" aluminum for the mount for more heat sinking.



    Here it is all assembled on the helmet.


    And here's a bit of a close-up. Looks like something from Tron.


    Total 54g, or 63g with the mount.

    Observations:
    It runs pretty hot on 3A, so I'm going to add another heat sink to the bottom.
    On 3A the beam hotspot is about as bright as my Quazzle XP-E, but with more spill.
    I may try a Larua RS in there for comparison.
    Last edited by Ofroad'bent; 03-15-2011 at 08:31 AM.

  24. #24
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    looks really tidy, I'm impressed! Glad DX came through for you, takes a fair bit of forethought and patience to deal with them.

    has the thermal protection tripped at 3A while riding, even slowly? That's the most useful test for me as most of our high powered lights will trip eventually in still air.

    if you want to remove weight, you can always trim the bracket too.

    oh, and another thought - this would be ideal for a remote switch on the side of the helmet, something using an old Taskled switch and some sugru, for example..

  25. #25
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    Quote Originally Posted by mattthemuppet
    looks really tidy, I'm impressed!

    has the thermal protection tripped at 3A while riding, even slowly? That's the most useful test for me as most of our high powered lights will trip eventually in still air.

    if you want to remove weight, you can always trim the bracket too.

    oh, and another thought - this would be ideal for a remote switch on the side of the helmet, something using an old Taskled switch and some sugru, for example..
    Thanks, Matt. I just got the light assembled last night. The trails are covered in ice right now, so no riding for a while. I set the thermal trip to 70C, so we'll see. I may need to dial it back to 2.5A max. The light gets warm, but maybe that's the heat radiating out from the thin aluminum more than with a heavier light.

    The bracket's oversized because I am hoping it will act as a further heatsink. Rather than fins, I thought a wide but thin bracket would add a couple of square inches, so I didn't even round off the bit that sticks up.

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    I am so stealing that bracket design...

    Question: do you think if a copper washer was placed between the light body and the bracket, that we would see a net gain in heat transfer since this should allow air to reach the part of the bracket and light body that are currently touching? Might be an insignificant gain, but it would be at zero cost (well maybe a cost of one cent). I say copper, since this should keep the heat flowing to the braket, which is currently a good heat sink as it is.

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    Double-tap

  28. #28
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    Quote Originally Posted by P220C
    I am so stealing that bracket design...

    Question: do you think if a copper washer was placed between the light body and the bracket, that we would see a net gain in heat transfer since this should allow air to reach the part of the bracket and light body that are currently touching? Might be an insignificant gain, but it would be at zero cost (well maybe a cost of one cent). I say copper, since this should keep the heat flowing to the braket, which is currently a good heat sink as it is.
    Funny you should say that, because I had exactly that thought. I was wondering if there could be corrosion issues between Al and Cu.

    There's thermal paste in between the bracket and body, but I'll be looking for copper washers or spacers.

    I was also considering a U-shaped bracket, with 2 bolts instead of an L-shape with one.

  29. #29
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    I've thought about taking a copper disc (not a pre-1982 copper penny, and not a post 1982 zinc penny, because that would be wrong), sanding it thin, drilling a hole in it, and filing it to a slightly smaller circumference.

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    Forgot to add- the bracket will attach to a helmet and a headband with 3M Duo-lock on the bottom of the bracket, as my current one does. The outer velcro's a backup.

    Another possibility is to just remove the bracket entirely and use Duo-lock on top of the helmet, as Scar does with the larger Amoeba light, but I'll lose the heat-sinking.

  31. #31
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    ah, figured your bracket might be like that for a reason. I'm not sure I'd be able to resist drilling a few holes in though, old skool mtb-style

    I've never been a huge fan of the scar style mounting - it's cheap and simple but

    a) I don't like lights on top of my helmet, how ever little they weigh, as I often clout my head on over hanging branches

    b) I vary the tilt on my helmet light (same bracket and velcro set up as yours) depending on type of trails - closer in on single track, further out on fast fireroad descents

    I'd keep it personally

  32. #32
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    Quote Originally Posted by mattthemuppet
    a) I don't like lights on top of my helmet, how ever little they weigh, as I often clout my head on over hanging branches

    b) I vary the tilt on my helmet light (same bracket and velcro set up as yours) depending on type of trails - closer in on single track, further out on fast fireroad descents

    +1 on a

    +1 on b.

    I also find that the fatigue factor has me adjusting the aim upward toward the end of a ride as my head hangs lower

  33. #33
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    Where Al, Cu and water meet there WILL be galvanic corrosion. So if you never ride in the rain, fine. Troutie's experience says 1/8" Al is good enough for a fire wall, then maybe an Al disc with a diameter of half bracket width would allow good thermal path into the backet AND allow the side of the light and inside of the bracket to be radiative surfaces. Copper's only about 60% higher than Al in thermal conductivity, a trait best used close to the LED to spread the heat out ASAP into the heat sink and light body. It also helps if it lines thin Al bodies. If I were to try Copper here, I would coat it thinly in Silver Epoxy to keep water a few molecules away, but I am not sure that will be enough. Pitting of the light at the contact point will be the risk. A little bit will tell you to go the Al washer route.

  34. #34
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    Quote Originally Posted by BrianMc
    Where Al, Cu and water meet there WILL be galvanic corrosion. So if you never ride in the rain, fine.
    OK, aluminum washer it is, and perhaps swiss-cheesing the mount too. We race in the rain, snow, mud, salty road slush, even have to swim rivers with our bikes at times so galvanic corrosion's definitely a problem.

    You know, the whole beauty of Matt's idea is that you can build a pretty decent light with only a drill press, hacksaw and file, and $100 worth of parts including battery and charger, and if you want to upgrade emitter or reflector it's only a single bolt to undo.

    The main challenge is just sourcing all the little bits and pieces.

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    Where did you get the battery holder from? It looks good.

  36. #36
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    Quote Originally Posted by biggusjimmus
    Where did you get the battery holder from? It looks good.
    It's the eBay one in this posting on the sticky parts supply list:
    Sticky request: DIY parts suppliers, vendors, etc.

    Probably overkill with protected cells. Good price for a protected holder with wires and free shipping- it's the same one Batteryspace sells.

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    add an aluminum bolt for extra weight loss and added heat transfer.

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    biggusjimmus, PM me re: battery holders... I might be able to help you out, as I'm local.
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  39. #39
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    Added a second heat sink, an aluminum spacer between mount and light, and even swiss-cheese drilled the mount's upper surface for more heat dissapation. Kinda cool industrial look to it.

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    Second heatsink: Did you test the light and it was a tad too warm, or did you opt to bring the area of air contact per watt up?

  41. #41
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    Quote Originally Posted by BrianMc
    Second heatsink: Did you test the light and it was a tad too warm, or did you opt to bring the area of air contact per watt up?
    A bit of both, really. I haven't tested the light much yet, but some early indoor burning showed the light warming up to the touch. It's a gift for a friend, and I've suggested that if it doesn't trigger the 70C heat warning and dimming, we can remove one or both the heat sinks.

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