BLF recoil über-thrower

In the first drawing i limited the diameter of the mirror to where it was 45°, for a full 180° reflection.
That’s how i found the focal point.
In the new drawing i just used the same, but limited it to about 145° by cutting off some of the rim of the reflector.
So the focalpoint is more or less accurate in the new drawing too.
But, the drawing is for reference only, because i didn’t know how to draw a perfect parabole.
I tried, but it’s apparently almost spherical (concave)…

Yes it does, but it’s only a thin fin.
I will calculate how many % it would block when it’s 2mm wide.
Probably less than 2%.

The reason for making or buying a recoil style light like this is for the Beam shape in particular. Yeah, it’s not the perfect setup, but the beam is so cute! I have the 007 and I would want to try one that was smaller and not as bright.

Been considering doing this for quite a while, I've always wanted a long range spotlight like those HID throwers.

The only issue is that the LED surface area is much larger than what a short arc would be, and far less lumens too.

That leads to a large spread and less intense beam, unless you use a really large reflector.

If I do this I will be watercooling the LED, because the distance of the copper "arm" is too long to provide good cooling for a high power LED running at 12 amps or more.

There are some good reflectors from edmund options for $50-100 that are 12-24" diameter and have a short focal length. Problem is that edmund optics import costs are extremely high.

I've ordered a lens from them before and it the COD was more expensive than the lens itself. Can't imagine what it would be like for a 12" or 24" huge box....

http://www.edmundoptics.com/optics/optical-mirrors/focusing-concave-mirrors/large-parabolic-reflectors/1364/

Another option is this guy that makes acrylic parabolic mirrors for sun collection, not sure how accurate the parabola is but the 24" and 37" deep parabolics seem pretty good quality, and shipping within the US is cheap.

http://greenpowerscience.com/SHOPARABLOICHOME.html

The larger the diameter, the tighter the beam will be. This is really important if you plan to use a large LED like XHP70, SST90, SBT140, or something like that which has lots of lumens.

I'm not sure how large you're planning to make yours, based on the image I would guess 6-12". I am interested if anyone can find a good cheap parabolic reflector below 12" with an accurate parabola.

Remember that the smaller the mirror is, the more accurate the parabola needs to be, and the smaller the LED die needs to be. XP-L HI or dedomed XP-G3 would be optimal IMO.

Best surface brightness (lumens/mm^2) I have found so far.

My idea entails an XP-L HI or an XP-G2 or 3(dedomed) or maybe even a hard driven XP-E2?
I was thinking about 4 to 5 inch diameter reflector.
Finding good ones that are deep enough to take 145° of light is indeed the problem…
…that is, when you’re on a tight budget…
For this to get built by the hundreds i think they would have to be custom made in China to make it affordable.
I fear this is where this idea will cease…
I’m hoping for someone here with the right connections with Chinese manufacturers.

I think a cheap and good reflector from china will be very hard to find...

The smaller you go, the more accurate it needs to be if you want a good beam.

I highly suggest you install optical ray tracer to test that the reflector properly focuses light, since usually the only information given is the depth and diameter of the reflector. http://arachnoid.com/OpticalRayTracer/

Also, a big problem with getting stuff from china is that even though it is low price they usually have a minimum order quantity and you can't get something unless you buy a set of 50 or whatever.

But search around, test the mirrors with the ray tracer and see if you can find a decent one at a good price.

You need to find something like this, but cheaper: http://www.edmundoptics.com/optics/optical-mirrors/focusing-concave-mirrors/precision-parabolic-reflectors/3096/

$300 for a 4" mirror is way too expensive even for me...

Might I suggest having a play at this site :student:

For cooling how about miniature heat-pipes, think of an upside down Mercedes symbol, you could use three or four in line for one support and use two of these for the top two supports, with the third (bottom) support just being 1mm flat copper.

Just throwing it to see if it sticks :wink:

Cheers David

Edit, forget the three or four miniature pipes (expensive) however they do 2.5mmx8mm for laptops fairly cheap.

Even if you guys could find a suitable host and reflector, won’t the placement of the led with big limitations on heat transfer limit the Amps the led will be able to endure?
And thus limit the beam intensity - throw of the light?

If a light like this can use 100% instead of roughly 75% ot the light for the spot, but the led can be driven at 75% of maximum, where’s the benefit? (other then beam characteristics).

The heat transfer will indeed be the big limiting factor, so just one arm would probably not suffice. Maybe the “Mercedes” star design would be best?

Interesting idea, bu waiting to see whether it can be turned into a practical design.

Grtz
Nico

I think some of you underestimate the thermal conductivity of a copper boom.
But we could opt for a bar across the reflector, so it goes both directions to the head.
A ‘mercedes star’ will definitely look nicer but is much more complicated to construct from one piece.
I think i will change the drawing to have a copper bar in stead of a boom, doubling the thermal conductivity.
But you should also consider that an XP-L can run 3 Amperes on a ‘normal’ aluminum MCPCB, which is absolutely not ideal.

It's honestly not that conductive due to the distance the heat has to travel, liquid cooling work work far better but cost far more.

Maybe if you can find some heat pipes from china that would work a lot better? They transfer heat a lot better than just solid copper.

Hmmm… I guess i overestimate the copper boom…
What’s in those heat pipes anyway?
I assume you mean those copper tubes used in laptop cooling etc…

Heat pipes have some sort of liquid inside

If I remember right a bar of 3 heatpipes of about 5x6mm could cool my 85W Laptop CPU they were like 15cm long

They are used in big cpu coolers because they can transport heat a lot better than way thicker solid copper

I am sure a bar of 3 smaller heatpipes can easily handle 20-40W of LED power

8x2.5mm Heatpipe
https://www.aliexpress.com/item/1PCS-LOT-YT257-Flat-Copper-Heat-pipe-100-8-2-5mm-Laptop-CPU-GPU-Video-Card/32732898661.html?spm=2114.01010208.3.10.2tHVLI&ws_ab_test=searchweb0_0,searchweb201602_2_10091_10090_10088_10089,searchweb201603_1&btsid=06e24f7f-d7e2-4aaf-ad55-47d434e59670

Cool! :+1:
(pun not intended)

It will only need one pipe to handle a 50w light as roughly half is converted to light and half generated as heat, a 8mm x 2.5mm pipe will handle that with room to spare, however I would suggest two for rigidity and also the cooler a led is the more efficient it is.
Have a read of this pdf from Digi-Key.

Cheers David

Still that much?
If an XP-L HI is used at 6A @ 3,9 V, would that not mean a total energy of 23,4 Watts of which the majority is transformed into light?
Please correct me if I’m wrong, these kinda calculations are not my strong suit.

So maybe one small copper bar with one small heat pipe inside?

Grtz
Nico

The reflector that I’m checking out atm is a cheap plastic reflector used in those optical illusion discs, like this one: http://www.ebay.com/itm/Toysmith-3-D-Mirascope-6-Inch-/162165285686?hash=item25c1cde336:g:5XQAAOSw9NdXq7Kw The focal length of this reflecor, as EasyB noted, is short, just as needed for this kind of set-up, just a bit above the edge of the reflector. I have a 6 inch version that I’m trying out, but there is a 9 inch version that should work better and have better throw. But here in The Netherlands I can not buy one for cheap, in the States they are plenty available. I think that optically the reflectors in these toys are not bad (or they would not work for the optical illusion) but I suspect that the surface does not reflect optimally, there’s more light loss there than is desirable.

In a test set-up with a XP-G2 S3 3d dedomed and direct drive (I used a 14500 zoomie flashlight without lens, so as a mule), and blocking the outer edge of the beam so that a 90mm diameter section of the reflector is used, I get 310kcd. But it is running from an Efest 14500 and the flashlight and clamp are blocking quite some light, in a better build I expect over 400kcd from this. Considering that 90mm of the reflector is used, there is room for improvement, probably with a better reflector, but it is fun anyway to see the principle working so well.

Alright, if you guys manage to build a recoil thrower with active liquid cooling I’m definitely in :money_mouth_face:

Would a heat pipe behind the LED a good idea?

Apparently, yes.
I ordered one today, hope it will arrive soon so i can check it out.

…you mean with a pump and a radiator? :smiley: