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Thread: Gemini XP-G

  1. #1
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    Gemini XP-G

    I built a new basic twin XP-G light for a friend to use on the road. It uses Ledil LXP Real Spot optics to give a good throw for the sort of average speeds we are doing on unlit country roads in our area of Essex, UK.

    It uses a cheap Kaidomain 1.2A controller and XP-G R5 LEDs so should output somewhere in the region of 700+ lumens and run for about 2:15 hours on a double 18650 battery pack.

    Any questions, please feel free to ask.










  2. #2
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    looks very tidy, nice job!

  3. #3
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    Are you going to anodize it?

    You just have to love the four jaw chuck and the patience required. Well done, very nice work.

  4. #4
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    Quote Originally Posted by yetibetty View Post
    Are you going to anodize it?
    A "friend" advised me what to say in the event that question came up but I don't want to get banned by the mods.

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    Excellent bit of lathe work again! So much more visually appealing than the typical round lathed bodies.

  6. #6
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    Quote Originally Posted by OverTheHill View Post
    A "friend" advised me what to say in the event that question came up but I don't want to get banned by the mods.
    Sorry but I just couldn't resist
    What did you use to get the nice finish?

  7. #7
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    Quote Originally Posted by yetibetty View Post
    Sorry but I just couldn't resist
    What did you use to get the nice finish?
    Yeah, it made me laugh!

    Wet 'n' dry to get rid of the worst marks and then fine grade wire wool. An old boy gave me that tip a long time ago...

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    Very nice!

    Could you describe to a novice lathe user like me how you parted off the light from the block? What tool? And is the back plate press fit or threaded?

    Are you going to protect the ledil's with anything?

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    Beautiful design OTH. Your mate will be very happy.

    Your lathe work is always very impressive. I can never find enough scrap to keep the 4 jaw balanced. Out of curiosity what spindle speed are you running with the offset turning?

    Glad someone else asked about the ano because it saved me asking. We keep raising the bar and making rods for own backs
    Last edited by brad72; 03-21-2012 at 03:58 PM.

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    post error

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    Thanks Brad ..... knew about the ruler trick on a cylindrical piece ........ but ........... where would you put the ruler on OTH's piece of art nouveau perfection? Flat sides, off-centre curves, sharp corner at the largest diameter point etc?

    I've never tried to part off a "large" piece like this on my little Cowell's watchmakers lathe, could be pushing it's capability ... guess there's only one way to find out

    Edit: Brad's post went AWOL. Hope it comes back otherwise my reply looks bonkers!

  12. #12
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    Bobblehat, You have a Cowell's watchmakers lathe? May I ask which model you have. I have a Taig micro lathe but would love a Cowell's.

  13. #13
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    Nice light OTH, if those country roads in Essex find there way to Hertfordshire...I know someone who has a ano setup

  14. #14
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    Sigh, I'm so jealous of the blokes who have access to that kind of machinery and the skills to use them.

    If I could do that sort of thing I would build a light that would heat up the tarmac in front of me and give the oncoming drivers an instant suntan.....

    Anyway, back to reality and I'd just like to say what a nice light OTH and what a first class product you have created there.

  15. #15
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    Quote Originally Posted by Bobblehat View Post
    Thanks Brad ..... knew about the ruler trick on a cylindrical piece ........ but ........... where would you put the ruler on OTH's piece of art nouveau perfection? Flat sides, off-centre curves, sharp corner at the largest diameter point etc?

    Edit: Brad's post went AWOL. Hope it comes back otherwise my reply looks bonkers!
    I usually only have to use the ruler once to get the correct tool height and will keep my shims with the tool at all time so I know when I put it back into the tool holder everything will just right. If I had some spare cash I would get a quick change tool post as this makes things much easier.

    For OTH's beautiful work you need to use a dial gauge to get everything square. The two flat edges of the housing need to be at the same distance from the lathe centre line then you offset the bar stock to get the radius of the curved part. Then it is quite easy to loosen 2 of the jaws, flip the part over, check things again with the dial gauge and cut the other side. Once you have done it a few times it gets really easy. And if you stuff up , just call it the Picasso light I'm sure we all have lots of those

    .
    Last edited by brad72; 03-21-2012 at 06:54 PM.

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    Very nice OTH. I don't have the patience with manual machining so program a machine to do it. Hats off to you for the lathemanship (if that's a real word??)

  17. #17
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    Thanks for the compliments guys but the techniques are not as difficult as it first might seem. I posted the following diagram on my last effort (The Zombie) in case anyone else wanted to understand the method. As long as you have a 4-jaw chuck and a dial gauge it is pretty straightforward.



    brad72 has explained the technique pretty well. As far as parting off the lump at the end, well I don't! I just hacksawed off most of it and then faced the rest off flush prior to boring out the back end for the controller and wiring.

    The backplate is just a tight-ish fit which is glued in with JB Weld. It isn't actually a flat plate but more a bored-out cylinder about 5mm in total depth to give a bit more surface area to glue into the back section of the body.

    I balance the offset workpiece with a couple of steel lathe tools (see Pic 2 of OP) as I don't have any suitable lumps of scrap laying about either. As far as spindle speed is concerned I only have 3 speed options on the Myford ML7 lathe I have so I use the middle speed which is about 350 RPM I think.

    I haven't protected the optics with anything, they are just glued in place with silicone. The light in general isn't fully weatherproofed so wouldn't stand a good soaking but hey, who rides in the rain? I've used the same technique for several of my lights and haven't had any problems yet and have actually been caught out in showers a couple of times.

    I hope that answers most of the queries but if there's anything else you would like to know please feel free to ask.

  18. #18
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    very, very nice OTH.

    Well done.

    Clearly your skills are far from over the hill

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    Quote Originally Posted by yetibetty View Post
    Bobblehat, You have a Cowell's watchmakers lathe? May I ask which model you have. I have a Taig micro lathe but would love a Cowell's.
    It's the forerunner to the ME90. Looks just like the ME90, very well made machine. I'll PM you later, to save going OT on OTH

    OTH ..... thanks for the info ..... I'd be tempted to part off with a saw too! I'm a novice lathesman ....... (I like that word, deesta)

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