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Clive
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Re: Fresnel lens maybe...?
Clive "Max" Maxfield   7/9/2014 9:53:25 AM
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@slomobile: Whichever way you go, you might consider using a 1 1/16" Forstner or anular bit (ideally spun by a cnc mill for accurate grid placement)on the face of the hardboard to positively locate each brass washer.

That's not a bad idea -- I was already moving to using a CNC machine to drill the holes, because having them wander aroudn even a little will ruin the whole look of the thing.

slomobile
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Re: Fresnel lens maybe...?
slomobile   7/8/2014 6:43:43 PM
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Whichever way you go, you might consider using a 1 1/16" Forstner or anular bit (ideally spun by a cnc mill for accurate grid placement)on the face of the hardboard to positively locate each brass washer.  You can fine tune the depth to just barely capture the film/lens between washer and board eliminating the need for glue there.  A small bit of glue in the recess can unobtrusively secure the washer if needed.  The hole depth can also be used to adjust distance from LED to film/dissuser/lens.

Max The Magnificent
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Re: Fresnel lens maybe...?
Max The Magnificent   7/3/2014 4:37:41 PM
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@jb0070: The "filler disk" could asily be glue, or wood putty / paste...

Thanks for the suggestion -- in fact I now know exactly which way I'm going to do this ... keep watching EE Times for my next blog on this topic...

jb0070
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Re: Fresnel lens maybe...?
jb0070   7/3/2014 4:30:28 PM
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The "filler disk" could asily be glue, or wood putty / paste (or something similar --- does not nned to be a washer / metal / "finished product"). Both harden and can be glued easily, and allow for clean up" before assembly. This can also be done to "mount" whatever lens you fit into the hole.

Max The Magnificent
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Re: Make the Film Disk bigger
Max The Magnificent   5/8/2014 9:47:57 AM
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@AnSc.de: Make the film disk as big as possible to fit under the washer...

This is a variation on one of the approaches I was considering -- but I think it's a better idea than mine ... let me look into this...

 

AnSc.de
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Make the Film Disk bigger
AnSc.de   5/8/2014 1:22:29 AM
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Make the film disk as big as possible to fit under the washer.

Then you can glue it to the inside of the outer ring, so the unwanted glue on the inner ring is avoided.

Then you can use the space of the film disk below the washer to glue the washer in place without unwanted glue outside the washer. Or use here a ring of double sided adhesive film.

You still have to be careful with the amount of glue...

 

crude Inkscape sketch:

Washer with Disk and Glue

 

Max The Magnificent
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Re: Fresnel lens maybe...?
Max The Magnificent   5/6/2014 10:21:57 AM
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@jstabler: I suggest you make a filler disk with a center hole the same size as your brass washer...

This sounds like a good plan ... I'll add it into the mix ... I'm still looking at a variety of alternatives ... I'll be posting a follow-up blog when I make my final decision... watch this space :-)

jstabler
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Re: Fresnel lens maybe...?
jstabler   5/5/2014 7:27:02 PM
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I suggest you make a filler disk with a center hole the same size as your brass washer.  It doesn't matter what material you use, could be another very cheap washer.  Glue your translucent disk to the filler disk.  Glue your new assembly to the brass washer.  Glue the final assembly to the surface of your project.  If you select your glue positions carefully, the glue should be hidden when you are done.

Max The Magnificent
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Re: Fresnel lens maybe...?
Max The Magnificent   5/5/2014 2:29:58 PM
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@perl_geek: Two thoughts for the mass-production...

I'm currently exploring a variety of options. I must admit that the Fresnel lenses do look rather tasty -- but it depends on (a) how they fit in the washers and (b) if I can find a really low-cost source.

I have one on order at the moment so we can check point (a) -- depending on the result we can decide what oiur next move shoudl be.

perl_geek
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Freelancer
Re: Fresnel lens maybe...?
perl_geek   5/5/2014 2:25:27 PM
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Two thoughts for the mass-production; 3-D printer to create multiple copies at once, or a CNC machine to mill them. (Out of a large sheet, so lots created per loading.) At least the machine wouldn't get bored.

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