Building a thrower - need a big reflector

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SMOKEU
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Building a thrower - need a big reflector

I would really like a big, high powered thrower but can’t justify the price especially as I don’t have any use for one other than as a toy, so I would like to build my own with an SFH55 emitter (loving that one in my Mateminco PD90S).

It doesn’t have to look good, doesn’t have to be particularly durable or waterproof, doesn’t have to be practical, and a run time of only 4-5 minutes will be all I need. Power shouldn’t be difficult as I have a few new 30T cells and BMS that I can make a battery with, and a few CC CV buck/boost converters.

The hard part seems to be the reflector. Even if I could buy a reflector from an especially large light such as the Mateminco MT35 Plus or similar that would be a good start, but I would like to go bigger still.

I don’t have much in the way of fabrication skills or a workshop…

Codec
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What’s your definition of big and powerful?

QReciprocity42
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If you want a large optical device that is cheap and easy to get, go for a Fresnel lens. It's also much easier to focus (more tolerant of inaccuracy) than a parabolic reflector. Hate to toot my own horn but I've done a thrower build and you might find the log informative: https://www.reddit.com/r/flashlight/comments/oh85u4/cheap_fresnel_throwe...

SMOKEU
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Codec wrote:
What’s your definition of big and powerful?

Good question – ideally something the size of those trailer mounted WW2 carbon arc search lamps. But I don’t have the space or wallet capacity for that.

But for now, a reflector diameter of at least 200mm (8” or so) would be nice. Then one day something much larger. I could probably afford to spend Mateminco MT35 Plus sort of money but it would have to be a huge improvement in power and throw, otherwise I might as well just buy the flashlight and not have to worry about building anything. It just seems to me that “large” flashlights are very poor value for money in comparison to smaller lights. I have a Convoy 3× 21A SBT90.2 and Convoy L21A CULPM1 (both are excellent lights that I’m very happy with), but anything much bigger seems to be a huge increase in price relative to the increased dimensions.

Codec
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I hear ya.
My 2X Shooter hits buildings at 800 metres plus, I’ve not tested further but I’m sure 1km with the naked eye can be achieved with the 365k lux it spits out.
It only cost me $116 dollars, and in order to beat that throw today (without going up to mega throwers) I’d need to spend twice as much and only maybe get 450k – 500k lux. Finding a large reflector could be an issue for you. Sourcing a large one was a big concern when the BLF GT was mooted. Not sure how easy it would be to find one today however.

SMOKEU
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That looks exactly like what I would like to build! I might as well build a small scale prototype first to make use of the emitters I already have before making one to a bigger scale, as the Fresnel lenses on Aliexpress look really cheap. Is there anything in particular I should be looking for in a Fresnel lens? I’m considering buying a small assortment of plastic square shaped ones to try them out as at least I don’t have to spend a lot of money straight away.

As for the emitter, I need to decide between SST20, CSLNM1, SST40, SFT40, XHP50.2, 519A that I have laying around…..

SMOKEU
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I’ve definitely noticed that reflectors tend to top out at a certain size based on what I’ve managed to find Googling. I’m wondering if they become difficult/expensive to manufacture after they get to a particular size, or if there’s just not enough demand for them to be manufactured in anything but very limited production runs for very specific uses.

Hoop
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You could get a Thor X Colossus and put an automotive HID bulb + 50W ballast in it. That would throw.

KaiDomain has an 86mm reflector but it’s not the smoothest.

Reflectors are often machined from solid, or electroformed. In both cases it gets more expensive to produce as the size increases.

Marc E
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SMOKEU wrote:
As for the emitter, I need to decide between SST20, CSLNM1, SST40, SFT40, XHP50.2, 519A that I have laying around…..

From a purely throw point of view the SFT40 and CSLNM1 seem like the only two choices here.
The CSLNM1 will be the ultimate thrower but given how narrow the beam will be in the build you’re planning the extra width in the SFT40’s beam may be more advantageous than the extra throw the CSLNM1 would give.

For all the others you might as well go with the throwier LEDs in a smaller build for the same throw.

kennybobby
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Take a look at grin’s threads, he has built some big reflectors and throwers, etc.

Now i used to think that i was cool,
drivin' around on fossil fuel,
until i saw what i was doin',
was drivin' down the road to ruin. --JT

Sirstinky
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You can message Astrolux on Banggood and ask for a MF04 reflector or MF05 reflector. Or email Lumintop and see if they’d sell you a GT90 reflector. They’d be mighty expensive though, $100+ with shipping.

Or you could buy a cheap flashlight with a big plastic reflector and mod it.

Codec
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Sirstinky wrote:
You can message Astrolux on Banggood and ask for a MF04 reflector or MF05 reflector. Or email Lumintop and see if they’d sell you a GT90 reflector. They’d be mighty expensive though, $100+ with shipping.

Or you could buy a cheap flashlight with a big plastic reflector and mod it.

Which would be $200 for us here in New Zealand

Sirstinky
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Codec wrote:
Sirstinky wrote:
You can message Astrolux on Banggood and ask for a MF04 reflector or MF05 reflector. Or email Lumintop and see if they’d sell you a GT90 reflector. They’d be mighty expensive though, $100+ with shipping.

Or you could buy a cheap flashlight with a big plastic reflector and mod it.

Which would be $200 to us here in New Zealand

Ouch! Any reflector over 90 mm diameter is going to be expensive. They’re hard to make and usually not sold separately so they charge a premium for them.

QReciprocity42
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SMOKEU wrote:
Is there anything in particular I should be looking for in a Fresnel lens? I'm considering buying a small assortment of plastic square shaped ones to try them out as at least I don't have to spend a lot of money straight away. As for the emitter, I need to decide between SST20, CSLNM1, SST40, SFT40, XHP50.2, 519A that I have laying around.....

The main thing is area--as large as possible, since the area of the lens is proportional to the intensity, whose square root is proportional to throw distance. Also aim for square or circular shapes, since rectangles fail to catch all of the light. Though my rectangular one cost $6 for a 2-pack, which is crazy cheap. Among lenses of the same size, aim for a shorter focal length--it makes your build more compact and makes collimating easier.

In terms of emitter: for max possible throw, go for CSLNM1 (as I did). If you have good heatsinking (which my build does not), SFT40 could be a more practical option--you won't notice the slight loss in throw, but will notice the brighter beam and 4x coverage area.

I've probably said it too many times but will say it again: a reflector this large is impractical. It is extremely difficult to perfectly center a large reflector around a small emitter and to keep it centered when you move the light. Even a small error will completely mess up your beam. On the other hand, a Fresnel lens really doesn't care about slight misalignment--it only results in the beam pointing in a slightly off direction, but does not mess up the beam profile or intensity. Also, using a Fresnel lens gives you the option to build a light that can be folded flat for transport (as I did), while you can't do the same with a reflector. And of course, there's the price...

An HID light would surely obliterate all but the best LED builds in peak performance, but they are expensive IMO and too complex for maintenance by someone who does not have extensive expertise in electronics, such as myself. They are also extremely power-hungry.

grin
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Glass Reflector https://a.aliexpress.com/_mLsHou8
These are first surface mirrors but they are not bad for the price. However cooling a recoil LED makes things more complicated. The cheapest way is one of these with an automotive HID. A retro reflector is a good idea as well

SMOKEU
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Hoop wrote:
You could get a Thor X Colossus and put an automotive HID bulb + 50W ballast in it. That would throw. KaiDomain has an 86mm reflector but it's not the smoothest. Reflectors are often machined from solid, or electroformed. In both cases it gets more expensive to produce as the size increases.

That Thor X Colossus looks OK but not locally available and shipping too expensive here.

I've added the KaiDomain 86mm reflector to my cart on Aliexpress, I think I will buy that AND do a Fresnel lens project light as well. 

 

Marc E wrote:
SMOKEU wrote:
As for the emitter, I need to decide between SST20, CSLNM1, SST40, SFT40, XHP50.2, 519A that I have laying around.....
From a purely throw point of view the SFT40 and CSLNM1 seem like the only two choices here. The CSLNM1 will be the ultimate thrower but given how narrow the beam will be in the build you're planning the extra width in the SFT40's beam may be more advantageous than the extra throw the CSLNM1 would give. For all the others you might as well go with the throwier LEDs in a smaller build for the same throw.

Looks like I'll be starting with the SFT40 then.

 

 

kennybobby wrote:
Take a look at grin's threads, he has built some big reflectors and throwers, etc.

Thanks, will do.

 

 

Sirstinky wrote:
You can message Astrolux on Banggood and ask for a MF04 reflector or MF05 reflector. Or email Lumintop and see if they'd sell you a GT90 reflector. They'd be mighty expensive though, $100+ with shipping. Or you could buy a cheap flashlight with a big plastic reflector and mod it.

I will give that a go, can't hurt to get a price at the very least. I'm getting a 3D printer very soon, I wonder if it's worth printing a reflector...

SMOKEU
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QReciprocity42 wrote:

SMOKEU wrote:
Is there anything in particular I should be looking for in a Fresnel lens? I'm considering buying a small assortment of plastic square shaped ones to try them out as at least I don't have to spend a lot of money straight away. As for the emitter, I need to decide between SST20, CSLNM1, SST40, SFT40, XHP50.2, 519A that I have laying around.....

The main thing is area--as large as possible, since the area of the lens is proportional to the intensity, whose square root is proportional to throw distance. Also aim for square or circular shapes, since rectangles fail to catch all of the light. Though my rectangular one cost $6 for a 2-pack, which is crazy cheap. Among lenses of the same size, aim for a shorter focal length--it makes your build more compact and makes collimating easier.

In terms of emitter: for max possible throw, go for CSLNM1 (as I did). If you have good heatsinking (which my build does not), SFT40 could be a more practical option--you won't notice the slight loss in throw, but will notice the brighter beam and 4x coverage area.

I've probably said it too many times but will say it again: a reflector this large is impractical. It is extremely difficult to perfectly center a large reflector around a small emitter and to keep it centered when you move the light. Even a small error will completely mess up your beam. On the other hand, a Fresnel lens really doesn't care about slight misalignment--it only results in the beam pointing in a slightly off direction, but does not mess up the beam profile or intensity. Also, using a Fresnel lens gives you the option to build a light that can be folded flat for transport (as I did), while you can't do the same with a reflector. And of course, there's the price...

An HID light would surely obliterate all but the best LED builds in peak performance, but they are expensive IMO and too complex for maintenance by someone who does not have extensive expertise in electronics, such as myself. They are also extremely power-hungry.

Excellent advice - I'll buy a few sizes with relatively short focal lengths. I'll start with a smaller one to test with first with an SFT40 then do a bigger one once I know what I'm doing a little more. 

Cooling is never a problem - I have dozens of old server heatsinks and powerful Delta fans and water cooling gear. I could even do a thermoelectric cooled LED (yes, I know that is silly but it would be fun! I've done it before with an SST40 + reflector I had laying around. Cooling power consumption for the TEC module was several times more than LED power consumption).

Now I'm really keen to get a BIG Fresnel lens and mate it to a SFH55 and pump 40-50A through it....

 

 

grin wrote:
Glass Reflector https://a.aliexpress.com/_mLsHou8 These are first surface mirrors but they are not bad for the price. However cooling a recoil LED makes things more complicated. The cheapest way is one of these with an automotive HID. A retro reflector is a good idea as well

Nice, some good ideas there

grin
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Very hard to print one

QReciprocity42
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SMOKEU wrote:

Cooling is never a problem - I have dozens of old server heatsinks and powerful Delta fans and water cooling gear. I could even do a thermoelectric cooled LED (yes, I know that is silly but it would be fun! I've done it before with an SST40 + reflector I had laying around. Cooling power consumption for the TEC module was several times more than LED power consumption).

Now I'm really keen to get a BIG Fresnel lens and mate it to a SFH55 and pump 40-50A through it....

Sounds like you have really good cooling, in which case you should go for a throwy emitter with large surface area (SFT40, SBT90.2, etc.). Another reason for going with a large emitter is that large optical devices (reflectors or Fresnel lenses) often do not have enough precision to correctly focus a smaller emitter like CSLNM1, but a large emitter can be focused well.

Just doing some back-of-the envelope calculations, SFH55 fully driven paired with a 30cm diameter Fresnel should give 5-6km of ANSI throw. If you can find a larger lens for cheap, things get very fun...another option is to get a bunch of medium-sized lenses and build a multi-emitter array with each emitter behind one lens.

Here's a thread about the SFH55, which suggests that it has half the intensity of SBT90.2. https://budgetlightforum.com/node/79830