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  1. #1
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    Octagonal helmet light with single XML and Aspheric

    Having a little bit of octagonal bar left over and having the aspherics arrive from Ahorton I have started to make a little helmet light with an single XML driven from an Lflex.

    I still have to machine up a retainer bezel for the aspheric but first I need to work out what the focal length is so I might need to machine the step for the aspheric a little deeper yet. I have it set at 15mm at the moment so I will see how it goes.

    I am still tossing up having the Lfex in an alloy puck incorporated into the battery pack since there is no need for it to be in the light as it has no temperature monitoring. This is the cell I might use is this HobbyKing R/C Hobby Store : Turnigy 5000mAh 1S 40C Lipoly (Single Cell) as it has a high discharge rating and I will make a carbon fibre housing for it incorporating the Lflex to keep it all safe.

    Here's the progress this morning. My wife has written me a list of jobs so better do those if I know what's good for me

    Housing chucked up in the soft jaws



    Mounted aspheric sitting in the retainer groove

    Last edited by brad72; 01-06-2012 at 06:29 PM.

  2. #2
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    I'm pretty sure the lflex has temp monitoring. It better as I have one to put in my mini 6 up XPG bar light.

  3. #3
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    Quote Originally Posted by Vancbiker View Post
    I'm pretty sure the lflex has temp monitoring. It better as I have one to put in my mini 6 up XPG bar light.
    Yep, your right vancbiker. It's a stat led it doesn't have. Now to re-think the design. I can still tag the Lfex on the rear of the light by making an end cap or just take a punt that I won't fry the led and keep it in battery back. Too many decisions for a Saturday morning

  4. #4
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    Regarding Stat LED on LFlex, check down the forum for George's recent announcement of LFlex V3 which now has the Stat.

  5. #5
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    Quote Originally Posted by brad72 View Post
    Yep, your right vancbiker. It's a stat led it doesn't have. Now to re-think the design. I can still tag the Lfex on the rear of the light by making an end cap or just take a punt that I won't fry the led and keep it in battery back. Too many decisions for a Saturday morning
    I always thought the V1/V2 of the lflex had a stat led...then i read georges post about V3
    That will teach me to not read all the gumpf on georges site!

    Brad, you've got problems...how many lights have you made in the last 4 weeks or so

    I should really put the aspherics i have to use, but i might wait for the B3flex..

    Looking good as always Brad..

  6. #6
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    Quote Originally Posted by Goldigger View Post

    Brad, you've got problems...how many lights have you made in the last 4 weeks or so
    It's an addiction maannn..........Perhaps I just need more sex ...maybe 7 times a week would do it or maybe I should shoot for 10 times then 7 won't seem so bad

  7. #7
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    the focal length from base of the lens to base of led cavity is around 12.5 mm depending on thickness of the led star .for an xml
    this will give you an impression of the die with no spill not good on its own as a useable biking light imho.
    to get more spread its best to go closer to the led to defocus

  8. #8
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    Quote Originally Posted by troutie-mtb View Post
    the focal length from base of the lens to base of led cavity is around 12.5 mm depending on thickness of the led star .for an xml
    this will give you an impression of the die with no spill not good on its own as a useable biking light imho.
    to get more spread its best to go closer to the led to defocus
    Thanks for that Chris. I'm using the 20mm stars from Cutter so I will work around the 12.5mm. That should work well as it will make the aspheric sit further into the housing. Just need it get dark so I can have play.

    The worst part is clocking up the housing in the 4 jaw each time I make a change. Perhaps I should bore out the shoulder and use a removable sleeve that I can trim to size to get the desired focal length.

  9. #9
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    Quote Originally Posted by brad72 View Post
    Thanks for that Chris. I'm using the 20mm stars from Cutter so I will work around the 12.5mm. That should work well as it will make the aspheric sit further into the housing. Just need it get dark so I can have play.

    The worst part is clocking up the housing in the 4 jaw each time I make a change. Perhaps I should bore out the shoulder and use a removable sleeve that I can trim to size to get the desired focal length.
    why not thread the cavity and have a threaded insert then you can micro tune the focal length

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    Great idea, thanks mate. Now to cut some tool steel as I don't have threading tools at home.

  11. #11
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    I cut a 40tpi thread into the housing and made a small collar to match for the lens to sit on. This means I can now infinitely adjust the aspheric from 11 - 15mm from the led pcb base.

    Great idea of yours Chris.

    Mooloolaba Prawns and Beer also helped to make the job more enjoyable.

    Here a picture of it

    Last edited by brad72; 01-07-2012 at 01:05 AM.

  12. #12
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    Well I got the light powered up tonight and it is amazing how the beam changes for 12mm - 15mm focal length. What I will do is take a picture at each 1/2mm so everyone can see teh difference and so I can decide which I like the best.

    Preliminary tests seem to show that the focal point between 13-4 and 13.8mm gives the brightest beam when shining on a big tree about 80 meters away. Because we have a full moon at the moment camera shots will be a little difficult but I'll see how it goes.

    Might be time for another beer to ponder the results. I cannot believe that 1 led can give such a bright light.
    Last edited by brad72; 01-07-2012 at 02:02 AM.

  13. #13
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    You've deffo earned that beer... brilliant (pun intended) work!
    The study du jour: can one's reputation be artificially inflated by simply putting a request for rep in one's sig?

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    Really nice job on the threading ,- as a new lathe owner (well the lathes not new) can you point me in the direction of how to do the threading. I know a little bit about threading its just how to get the threading up close to the shoulder inside the casing.
    I know its a bit OT. sorry.

  15. #15
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    Ok, so i managed to take a few beamshots (still need to video them into 1 image) and the 13.5mm distance gave the best result. Interestingly shining the light against a wall the 13.5mm is the point where the led die is perfectly focused on my light. Defocusing the light by increasing the distance makes the light noticeably dimmer but defucusing towards the die only slightly decrease the brightness.

    Capnahab, welcome to the forums and congrats on being a new lathe owner. If you check out this post Triple XML Bar Light MK2 and see posts 63 and 69 I put up a video and an explanation to another forum member about threading. If you want more info PM me and I'll be more than happy to help. As for threading towards the base of a blind hole you just need a cutting tool that has the thread cutting edge right at the end and make sure you go really slow so you can stop the lathe without overrun just before the tool hits the base, then back off the tool, reverse out and repeat until the thread is the correct depth.
    Last edited by brad72; 01-07-2012 at 03:01 AM.

  16. #16
    help with the zip please
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    Nice one Brad. How are you going to stop the thread from "rattling" away from the aspheric causing the focal length to change? Will a bit of locktite be sufficient?

  17. #17
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    Quote Originally Posted by emu26 View Post
    Nice one Brad. How are you going to stop the thread from "rattling" away from the aspheric causing the focal length to change? Will a bit of locktite be sufficient?
    Yep, the red super thread locker should work but the heat might make it soften and let go. Now I know what is the best focal distance I might make a 13.5mm high collar and fit that. The other option would be a M2 cap screw coming in from the side and locking against teh inner ring. That way I can still change the focal length if required.

  18. #18
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    Great idea for the threaded adjustment. Another thing I need to learn!

  19. #19
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    Quote Originally Posted by piesoup View Post
    Great idea for the threaded adjustment. Another thing I need to learn!
    I can thank Troutie for that idea but it works really well for fine tuning the beam

    Here is a Gif of the different focal lengths that really show how going away from the focal point of 13.5mm drastically drops the output from the light. Being my first gif please be kind. Next time I need the light on a tripod also.

    The tree is at 85 meters. My camera was set at f4 but the exposure time was only about 3-4 seconds so the shots are a little dimmer than what I saw.


  20. #20
    help with the zip please
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    Nice one Brad, now you just need to be able to make it trail adjustable from 12.5 to 14mm in .5mm increments, then you can adjust the beam depending on what type of trail you are on

  21. #21
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    You could make the font bezel longer so that it has a thread that threads into the main housing.
    Above the thread one or two groves for an o-ring.
    Nerl the front of the bezel so you can turn it to adjust. Put a nice dollop of silicone grease on the o-rings, should keep it easy enough to turn. But the resistance of the o-rings should provide enough resistance to stop it turning on its own.
    I can knock a drawing up if my explanation is bit Crap..

  22. #22
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    The o-rings and silicone solution should keep it water proof also.

  23. #23
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    Emu, GD and Bravellir, great idea with the adjustability. I'm going to have to machine out the lens pocket a little as at the moment is it size for size to stop the lens from rattling. I think I 'll keep the 40tpi thread because 1/2 a turn is about 0.5mm in focal length change. Going to a smaller larger tpi would make is too sensitive. The only downside is do i make the bezel hexagonal or round? If hexagonal I guess and 1/8 of a turn would match up to the rest of the body .

    I also have to change the orientation of the because at the moment when mounted the the points are at the top and bottom and I want them flat. Something I overlooked when drilling the power cable hole and mounting the led.

    Then a splash of colour I suppose. If I make a carbon fibre mount I might ano is gun metal grey (although not a colour per se). That should look alright and go with both my red and grey helmets. (got to look good out on the trails)

  24. #24
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    Looking good brad. Where did you get the aspheric lens from?

  25. #25
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    Quote Originally Posted by cytoe View Post
    Looking good brad. Where did you get the aspheric lens from?
    Mate I got if from Ahorton over at candle power forums. See this link
    Ahorton's sales (Lenses, headlamps ...)

    If you are in the USA then this guy is a distributor of them Aspheric Len's sale USA/Canada
    Last edited by brad72; 01-09-2012 at 06:39 PM.

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