casting reflectors

kramd · Apr 29, 2011

Hello

Im able to cast small amounts of aluminuim and Id like to try some reflectors for an XML. These will be for bicycle lights

I plan to use a 44mm or 22mm aspheric lens.

However, what internal shape for the reflectors? I can make the mould from plaster - so easy to shape.

alpg88 · Apr 29, 2011

if you using aspheric lens there is no need for reflector.
i,ve never seen cast aluminium reflectors, only cut on lathe, or stampped, you'll be the first one to cast, which i have no doubts you will be able to do, however you will still need lathe to give it final shape after, surfice wise, and parabola wise.

DrSwiger · Apr 29, 2011

alpg88 said:
if you using aspheric lens there is no need for reflector.
i,ve never seen cast aluminium refloectors, only cut on lathe, or stampped, you'll be the first one to cast, which i have no doubts you will be able to do, however you will still need lathe to give it final shape after, surfice wise, and parabola wise.

Looking at your collection. Those are crazy spot lights. Can you describe some of them?

alpg88 · Apr 29, 2011

DrSwiger said:
Looking at your collection. Those are crazy spot lights. Can you describe some of them?

i'll pm you the links, so we don't highjack the thread.

bitslice · Apr 29, 2011

Wouldn't it be more profitable to cast the whole lamp casing as a custom one piece heatsink and leave the reflector stuff to others.

You could have it fit your bars exactly rather than having to use a wobbly clip

kramd · Apr 29, 2011

This will be the housing aswell. Lens will fit onto the front, at correct distance. and slug of copper will bolt onto the back, so it may aswell be useful shaping the beam. It will also be quite big, and should work well as a heatsink.

I remember reading that an epiliptical reflector is needed for aspherics? (or none atall) either way with both of mine, 45 - 90 degrees would just be wasted light (0 being centre beam).

Although I have a crude lathe, this will be close enough in shape to be sanded/polished for the correct surface finish.

Walterk · Apr 30, 2011

Wouldn't it be fantastic if the reflector is the housing is the led mount !
AND you could step of that boring cilindrical housing of all common flashlights.
If you can, why couldn't you.

But for the reflector; casting could work very good.
You would have to make a counter-mould to sand and polish the reflector afterwards.
Besides freedom of design, its probably a little less efficient over buying a stock reflector.
For halogeen and xenon (xsa) reflectors often 99,9% alu grade is used.

MikeAusC · May 1, 2011

alpg88 said:
if you using aspheric lens there is no need for reflector. . . .

- unless you want to use compound optics for maximum efficiency - central part of the LED output focussed by aspheric, outer part focussed by reflector.

casting reflectors

kramd

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alpg88

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DrSwiger

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alpg88

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bitslice

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kramd

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