Can not afford paint stripper 
It will have to go on a trailer that is a full sized carbon arc mirror. Apparently some cinema projectors are laser. I have 8x7w blue laser diodes I brought for some stupid project that wasnt smart to build. So I would like to go LEP or short arc. I also would like the light and driver to be easy to swap…the heat will be transfered to the drum using endermans method of coiling copper tube around it.
CNCman, being so excited I couldnt sleep thinking about a big mirror. Anyway I did some work on the the lights copper piston. So here is an update. The first drawing is still relevant just more detail on how I have made the piston.
The end on the piston has been filled with 45% pure silver solder and a recess for the LED machined into that. I was tempted to melt half a bar of silver bullion in there.
The brass is soft soldered with electronics solder so I can hold it in the lathe.
And this is the lead screw I have it is probably about 10 turns from end to end so I calculate I need 40rpm to give me 15sec from focused to full zoom. The motor there could be used but is only 1rpm and 24v. I have different motor and leadscrew ordered and it is a lot smaller. So I will wait for that but I was also thinking about just putting a knob through the backing plate so the leadscrew can be turned by hand. Because lets face it how often are you going to zoom in it is more for throw and is allows for that slight adjustment from focused to collimated.
For collimating light from an LED, you need an aspheric lens.
You want the whole lens to be focused at one focal plane, where the LED is.
With a regular (sperical) lens the light from a single point (like an LED) will not all leave in the same direction, some will converge and some will diverge.
A regular lens has a surface that is just a radius, part of a circle, while an aspherical lens has a complex equation that defines the surface.
The image above shows what happens with incoming light rays, to show that the normal lens has multiple focal points.
If you reverse the process, and put a single point of light emitting rays, after they go through the lens they will not all be parallel, some will go inwards and others outwards.
The aspherical lens fixes this to make them all parallel, which is called light collimation.
Thanks for clearing that up Enderman. So the lens I am using are mostly spherical. I think I had better build another test light with a different configuration to check the new information I have
Check this out!!! Just picked up this 36inch parabolic mirror from a carbon arc searchlight. Tonight I will have a play and take more photos
Awesome grin! 
There is one of these on my parents property with a 2 cylinder lister diesel, 3 speed gear box, the diff has been pulled out but is there. Last time I started it it ran like a dream. So i am thinking that would look cool with the search light mounted on the front instead of the bucket.
It is crank start but easy to crank and I can mount an alternator on the motor to charge a battery pack and run the light.
Damn I am very jealous of that mirror 
If your platform is this large, maybe all the disadvantages of short arc lamps will be less of an issue.
I cant believe I found it and only AU$400 and it cost less then the 11inch from the states, less than some of the lenses I have including fuel. It was well worth the 8hr drive there and back to get it.
I will go see if I can get some beam shots just holding an sbt-90 in front of it.
that’s some beautiful countryside you have there, and those rock cliffs are some interesting formations. thanks for sharing.
Awesome cliffs, pity they are too soft for climbing I have been looking at them for 40 years and you notice they well I notice how they have changed. That is on the edge of the wollemi and golburn river national parks.
well I just sat the mirror up on a chair and taped a spider of a smaller recoil to the tripod and stood it in front of it. Led is SBT-90 @ 12amp
W30
K75
Wowwwww
The first beamshot looks so interesting.
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OK , I understand better now.
So your build will be adjustable focus between the LED and your first plano-convex lens and also the big adjustment between those two together and the big plano-convex lens to create a Zoomie. I do see your collimator covering the LED also. 
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After you get it finished, may we get some dimensions from you for reference ? Nothing is better than working numbers ! 
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There has been much discussion on this subject over the years but very little experimentation that you are doing ” grin “. :+1:
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Keep up the good work and blaze the trail, we will follow you
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Breaking News: UFOs across Australian Skies sending energy beams to Earth
I should not have drawn the 2 lens that light will only have a single 150mm diameter lens with 177mm back focal length. I do have another lens combo for it but i will eventually build a light for them. I would like to have both lenses adjustable in my two element lenses. So for this light it will be 1 to make it simpler.
A couple of things have me puzzled one how to stop the piston spinning with the motor. Dowel or keyway im not sure. The other is how do I stop the led power cables getting caught.
Anyone can use my ideas I post here if they be crazy enough.
[quote=grin]
well I just sat the mirror up on a chair and taped a spider of a smaller recoil to the tripod and stood it in front of it. Led is SBT-90 @ 12amp
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WOW ! that is 
Looks like a comet 
Thank You for sharing with pictures
Be careful ! don’t let it get too hot !
I wonder how you could check the throw on it ? You would need to get a 800 meters away to check it !!!
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I can only run it for short periods of time so normally turn it on take the photo turn it off. I will do something about cooling very soon.
This was taken within the beam
The other thing it is a full moon tonight and you have all the ambient light from the town.
When the beam looks like that it is over focused of to far away when the led is too close it looks like a big fat column