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  1. #1
    Hack Racer
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    Cutter Electronics MR11 Kit into Marwi NightPro Housing

    I finally completed my project. At first I toyed with the idea of doing what Gilbo did and making his own housing, bracket, mount, etc etc... I had looked up all the various part numbers from various catalogs (digikey, mcmaster-carr, and even purchased the aluminum). Then I saw this thread Yet another 3xCree MR11 kit

    and thought, damn that is way easier than making everything myself from scratch. I purchased the light kit from an online bicycle store for under 100 bucks + shipping. It was easy, quick and the dimensions seemed perfect for what I was after. Plus the Cutter housing wasn't available at the time I ordered the light. If it was I would have probably just purchased that and called it job done.

    Here is how I built it up.

    picture 1: The kit
    picture 2: Cutter Electronics MR11 Fatman 3XCree LED kit w/ heat sinks stacked in correct order
    picture 3: The various internal parts laid out
    picture 4: PCB installed into it's heat sink
    picture 5: PCB heat sink flange, ID of Flange is slighter smaller than PCB board, and hence will secure the PCB against it's heatsink.

    See next post.
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    Last edited by Cheers!; 12-04-2007 at 08:48 PM.

  2. #2
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    More pictures continued.

    Picture 6: Note the 1/16" hole in the middle (this will allow you to remove the PCB should you need to with a soft point). Note also the recess (PDF with detailed drawings will be attached further down). The recess allows the top of the PCB to be flush with the heatsink surface.

    Picture 7: Wired Up. This picture was my 1st prototype. I did not put any cutouts on the heat sinks and hence not can not dissassembly without cutting the wires. Note the use of heat shrink. Try to source this from electronics shops, if you don't know of any, Canadian Tire, Pep Boys, Autozone will have some (expensive at auto parts store 2 bucks for a little versus 50 cents for a lot at electronics store). Do not use electrical tape as it will create a mess over time when it gets gooey.

    Picture 8: Another shot of the wiring. Note that the PCB faces towards to the back of the housing. The PCB heat sink's back sits against the back of the LED heat sink. Note also that a thin film of artic silver (thermal compound for CPUs) was applied to the back of the PCB to the heat sink, and against mating surface of heat sinks to other heat sinks and also to the housing. The heat sinks are machined to an OD that is .0002" of the ID of the light housing.

    Picture 9: Shot of the various peices in order of assembly (left to right). Flange is the very bottom, Then PCB heat sink (note PCB faces back of housing). Then LED heat sink, then LEDs, Then lens, Then cover+oring from Marwi.

    Picture 10: You will need to file down the copper PCB that the LEDs are mounted to to fit into the ID of the light housing. Becareuful not to scratch the LED. Use Isopropyl alcohol + Qtips to clean all surfaces before closing it all up
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  3. #3
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    More Pics.

    Picture 11: Note when you have all the heat sinks installed into the housing + lens and all and everything wired up, the lens will stick out. This is good. This will allow the Marwi flange for the housing to compress the Oring (supplied with marwi light) to compress the lens and create a slight seal for moisture. If you are going to paranoid or want to ride in the rain in the dark (you are crazy). You will need to find some Grey RTV http://www.permatex.com/products/aut...sket_Maker.htm

    and seal the plastic base with the black aluminum marwi housing. Marwi does not seal that part of the light housing. That is where water will get in.

    Picture 12 + rest: I'm a weight weenie, so I care about weight. There is also the annoyance of a heavy light head on a helmet, so weight was a concern for me.
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  4. #4
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    The battery is a 6V 4000 mhA NIMH battery from Marwi. I have bench tested it and it will run bright for 2 hours and 10 mins (new battery, full charge). At around 2 hours 15 to 2 hours 20 (not sure exactly) the light will dim, and the light will not run hot. I believe the battery at this point is pretty close to dead as the PCB can't draw the amount of current to keep the voltage up.

    Note for wiring: White wire from switch = positive. Connect that to +ve terminal of PCB (fatman). Black equal negetive.

  5. #5
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    The attached 3 PDFs are the drawings you will need to replicate what I have done. It is important that this be done within the tolerances specified on the drawing. To conduct heat, the surfaces must be nice and flat with each other and provide good contact.
    Less is more for the thermal compound, as the idea of thermal compound is to fill in the micro voids on the two surfaces to increase surface contact to conduct heat. Too thick of a thermal compound layer and it will at as an insulator rather than a conductor of heat.
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    Last edited by Cheers!; 12-04-2007 at 09:59 PM.

  6. #6
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    3rd PDF file (zipped)

    sorry MTBR.com only allows 19.5KB PDF files... but they allow like 500K pictures... I don't understand why...
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  7. #7
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    Comment on heat generated. When I first turned on the light in 15 mins the light ran HOT. HOT enough I could not hold it in my hand without juggling it around with my other hand. I used a mini USB fan and point it at the light. Once I did that it was cool to the touch for 2 hours at full discharge. So it is clear that the heat is able conduct from the LED/PCB to the aluminum heat sinks to the housing.

    I did not choose to wire in a 2nd switch + resistors to allow for reduced current operation of the light (Fatman feature). I wanted to keep the unit nice and simple. Plus two hours is good enough for 2 laps at a 24 endurance race.

    To improve on this light (ideas):
    -Run a 7.2V NiMH pack. You can order preassembled packs from Digikey.ca (panasonic cells 4200 mhA). The closer the pack is to (3X3.7V=11V) The more efficient the lights will be. Meaning you can get longer run times.
    -Run a 7.2 Lithium Ion pack from battery space or all batery (tenergy) w/ 6000+ mhA. This would probably get you 3 hours to 4 hours run time at the weight of the above 7.2V NiMH pack.
    -Go and buy the Cree R2 bin release for these LEDs
    -Add extra switch to allow to toggle light levels.

    Sorry no pictures of beam shots. I'm not very good with cameras but it's the standard MR11 Cutter Electronics Cree Fatman setup. http://www.cutter.com.au/proddetail.php?prod=cut756

    You could probably source everything independantly. Buy the Kathod Lens from Kathod USA, the LEDs from an electronics supply house (buy the tabbed LEDs, not the PCB mount in this case). Driver from TaskLED. In this case you would increase the thickness of one of hte aluminum heat sinks to compensate for the missing copper PCB the LEDs are mounted onto by Cutter. The thickness of copper peice that the LEDs are mounted to by cutter is: 1.58 mm or .0625"
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  8. #8
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    Further note: The wire I used was stranded 22 AWG wire.

  9. #9
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    Nice setup!

    I have a Q?

    Do the 3 little legs of the optic fit in the holes of the MCPCB or do they just sit on top of the holes?

    Cheers

  10. #10
    I spelled Knievel wrong
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    Very sweet! Nice work on the heatsink, you've done your homework! I've developed a similar conversion for Turbocats: LED Turbocat Conversion
    That headunit is really light weight considering the amount of aluminum you crammed inside. Are you running it at 700mA as set by Taskled or did you increase the drive current? Looks like you've found another good host for the Cutter kit, well done!

    I've actually tried to source these components independently to avoid the shipping nightmare that Cutter presents (2-4 week shipping to the US w/no tracking system). The distributors that I've talked to cannot get that optic from Khatod for some reason, but can get the 25deg flood optic. It is hard to mount bare Crees directly to a heatsink because they are not electrically isolated on the bottom of the LED. If you can pull it off though, it is the best option for heat transfer. Keep up the good work!
    Last edited by StevelKnivel; 12-05-2007 at 06:24 AM.

  11. #11
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    Have you contacted Marubeni? It looks like they have optics similar to the Khatod, it's just that you have to fax in orders rather than just being able to click. They'll do orders as small as three of any product.
    Train 'til you puke. Cheat to win. Party like a rockstar. We miss you, Jan!

  12. #12
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    Quote Originally Posted by jeep
    Nice setup!

    I have a Q?

    Do the 3 little legs of the optic fit in the holes of the MCPCB or do they just sit on top of the holes?

    Cheers
    The 3 little legs of the Khatod lens does fit into the MCPCB. They also protrude past the MCPCB. On the drawings I updated the LED heat sink for a recess so that it would not interfere. The pics you see here are my 1st and 2nd versions which I did not make properly. I ended up filing the legs shorter so that it would be flush on the back side of the MCPCB. The updated drawings will require no modification to the lens.

    Actually I lie... For some reason there is a tab on the plastic lens that prevents it from sitting into the housing. I think it is where the plastic stopped pouring during manufacture. I used a small file to file away this tab in order for the lens to fit into the housing.

  13. #13
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    I completely forgot. You will to make TWO PCB HEATSINK FLANGES and stack them up. I forgot I had measured the depth correctly, but couldn't do addition and subtraction.

    So make two PCB HEAT SINK FLANGES, or just double the thickness up for that one (that is what I did in the above pictures). I'll see if I can update the CAD model/drawings later today.

  14. #14
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    Cheers,
    The tab on the Khatod lens is actually a locating tab. I filed it off mine, along with trimming the posts to be flush with the MCPCB.

    Did you keep the original switch from the Marwi housing? If so, how did you set it up? I guess I assumed it was a momentary switch...

  15. #15
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    Quote Originally Posted by rockymtnway
    Have you contacted Marubeni? It looks like they have optics similar to the Khatod, it's just that you have to fax in orders rather than just being able to click. They'll do orders as small as three of any product.
    Marubeni doesn't have a triple optic for the Cree lamps. Also, the triple optics that they list on their site are all MR-16, not the MR-11 that the Khatod has. I'm guessing that Cutter got a bunch of custom optics made by Khatod (in fact, Mark mentioned that they are getting a tighter optic in as well, don't remember what the angle was).

  16. #16
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    Quote Originally Posted by StevelKnivel
    Very sweet! Nice work on the heatsink, you've done your homework! I've developed a similar conversion for Turbocats: LED Turbocat Conversion
    That headunit is really light weight considering the amount of aluminum you crammed inside. Are you running it at 700mA as set by Taskled or did you increase the drive current? Looks like you've found another good host for the Cutter kit, well done!

    I've actually tried to source these components independently to avoid the shipping nightmare that Cutter presents (2-4 week shipping to the US w/no tracking system). The distributors that I've talked to cannot get that optic from Khatod for some reason, but can get the 25deg flood optic. It is hard to mount bare Crees directly to a heatsink because they are not electrically isolated on the bottom of the LED. If you can pull it off though, it is the best option for heat transfer. Keep up the good work!
    Thanks for the compliments.

    Actually I did not adjust anything when I slapped it all together. My multimeter broke so I just hoped for the best. I should really check it though. I'm hoping Cutter Electronics set the correct resistance on R1 for the current draw of Fatman. What happens if you increase the drive current? Will the light run brighter?

    The khatod optic part number (spot, according to Khatod rep it is 10degree spot) is: PL60006
    It is not even in their catalog yet. You will need to email them directly to place the order. You can order the optics from: http://www.optomarket.com/isroot/Opt...atic/index.htm

  17. #17
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    Quote Originally Posted by dnlwthrn
    Cheers,
    The tab on the Khatod lens is actually a locating tab. I filed it off mine, along with trimming the posts to be flush with the MCPCB.

    Did you keep the original switch from the Marwi housing? If so, how did you set it up? I guess I assumed it was a momentary switch...
    dnlwthrn, I kept the original switch. It is momentary ON OFF switch. When pressed down, there is voltage, when pressed down again it is Off. The white wire is positives, the black wire is negetive. I basically cut the wires before the crimp for the halogen ceramic base and spliced in 22AWG wire (solder + heat shrink). It was kinda difficult as the wires left over were kinda short.

  18. #18
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    So how do you use that switch to power the system? The Fatman doesn't use a momentary switch to control power... (the reason for my question in the first place). I also got the kit with the Fatman, but now am kind of wishing I would have gotten a Maxflex instead.

  19. #19
    I spelled Knievel wrong
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    The switch in the Marwi is not a momentary switch, but rather a normal latching push on/push off switch. A momentary switch is only on while you are pressing it, otherwise it is off.

  20. #20
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    Sorry i meant to say it is not momentary. i

  21. #21
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    Gotcha. That makes sense now. For some reason I thought the Marwi had a momentary switch setup to give you different light levels. Have never seen one in person...

  22. #22
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    Very nice! Get a test ride in yet? Let us know how you like the beam. 10 degree can be a little narrow, but it might work out great. Thanks for sharing pics and info.

  23. #23
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    Any ideas on how to get something like this off the ground without access to a lathe? I found some good deals on used lights but I haven't found anything to use as a heat sink. TIA

  24. #24
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    Fatman connected to aluminum heat sink?

    How did you connect the fatman to the heatsink with-out any electrical problems, conductive, inductive, capacitive, ETC?

    Thanks

    DFH

  25. #25
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    Quote Originally Posted by dirkfh
    How did you connect the fatman to the heatsink with-out any electrical problems, conductive, inductive, capacitive, ETC?

    Thanks

    DFH
    The back side of the farman has no exposed traces. The only thing exposed are some solder points for wiring hook up. I drilled out areas and slotted them out with a hand drill and Drexel to clear these solder points. I didnt show it in the pictures as I had not done it yet. The locations and sizes is indicated in the zipped PDF. In addition I went to the computer store and bought ceramic based thermal compund which does not electrically conduct. The PCB heat sink flange also does not make contact with any traces or ecletrical components.

    To the previous poster I think it would extremely difficult trying to get .0002 to .0005 inch tolerances without anything but a lathe and proper tooling. You could take my drawings to a machine shop and they will have no issues making it.

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