grins 8th annual old lumens machine made entry

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grin
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grins 8th annual old lumens machine made entry

Ok lets not think of this as a competition but a challenge. Now as most probably know ere I like lights that give you that crazy grin. Cool The best thrower would have to be a recoil but the big disadvantage is cooling the led that is on a spider. So I have been thinking you could go off axis, extremely expensive and near impossible to grind. The way I want to get around this is a reflex or cassegrain system. I know this works as I have a small plastic optic with this design. The reflex system has a primary parabolic mirror, a secondary hyperbolic mirror, it also needs an optic to shape the beam from the led for the secondary optic this this can be a reflector or lens. The other drama is matching the elements. So I want to see if I can build a reflex spotlight with matching elements. I am waiting for a drawing board to get here so I can do better drawings. I havent plotted the hyperbola yet but here is the basic geometry of the planned build.

The bezzel will be 180mm and under 200mm long. Light will come from SBT-90 and K75 driver so the battery pack can be 4s6p 30Qs.
So my personal aim is to learn a new skill and do something I havent done before. It also has to be a challenge because there is the opportunity to have input from some very switched on people.

Current stage the light is at

Edited by: grin on 10/11/2020 - 05:37
ReManG
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Whoa, this is pretty fantastic all by itself! Looking forward to the complete entry…

MtnDon
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Wow! How long did that take?

grin
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I have spent a few hours working out a process to cut them these ones are contoured, then smoothed with a radius tool and finally ground with a profile clamped in a tool holder. I have some high speed steel blanks that I intend to make a profile from to get a more accurate cut. Over the weekend I will see if my coating will be any good. I will update it this weekend

grin
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So I cut a hemisphere from aluminium and polished it up this sits over the led and acts as a stop/aperture/shutter to shape the light for the hyperboloid secondary mirror. Because I am hand making the mirrors need to have some way of protecting them with a coating. So a bit of research turns out that “mothers” ceramic auto paint protector is silica dioxide and titanium dioxide. I think a hotplate and vacuum is the go I have the vacuum pump butt no hot plate. But see how it goes.


The initial finish it will be repolished when I adjust the height and aperture.

Tally-ho
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That’s a nice entry, bravo.

CNCman
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We are all Grinning Big Smile

MRsDNF
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CNCman wrote:
We are all Grinning Big Smile

Yes to this.
Is 180mm diameter correct grin?

 

djozz quotes, "it came with chinese lettering that is chinese to me".

                      "My man mousehole needs one too"

old4570 said "I'm not an expert , so don't suffer from any such technical restrictions".

Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

 

MtnDon
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MRsDNF wrote:
CNCman wrote:
We are all Grinning Big Smile
……180mm ……?

Good size grin Smile

grin
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Thanks for encouragement Thumbs Up

MRsDNF wrote:
CNCman wrote:
We are all Grinning Big Smile
Yes to this. Is 180mm diameter correct grin?

I had a 170mm borosilicate 3D printer base for front lens and I can get 180mm diameter aluminium bar. Another reason I wanted the hyperboloid to be a decent size for making it.

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Have you considered cutting one of your huge mirrors to create off-axis parabolic mirror?

grin
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I did. But an off set parabolic mirror is a section of a full mirror and so even cnc they are offset in the lathe chuck. These have been ground with an acrylic profile and emery cloth moved between the mirror surface and profile like a feeler gauge creating the curve. So it is not possible this way. If this technique works well I will get a profile tool professionally made later because cutting them seems more accurate.

MRsDNF
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Oh Don. Blushing

 

djozz quotes, "it came with chinese lettering that is chinese to me".

                      "My man mousehole needs one too"

old4570 said "I'm not an expert , so don't suffer from any such technical restrictions".

Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

 

grin
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This is the result of my practice parabolic reflector.
One of the reasons to build a custom reflector is so that it can be tuned to the light source. Like if you were for some reason decided to cut your w30 up.



So now I wait for the 180mm billets to turn up. Tomorrow I will start on the heatsink and driver housing.

kennybobby
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So are the beam shots in pics 3 and 4 from the 75mm parabolic reflector with the emitter source held on a stinger as in picture 2? That puts a crazy grin on my face.

How did you do the polishing of the parabola? Aluminum oxidizes immediately when cut but our polisher folks can get a fairly nice finish using a pitch lap with alumina slurry.

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

grin
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The reflector in the photos is 140mm diameter and the beam shots are from the same one.
I sand it with a profile to 2000grit then use a buff once it is polished etch the surface with caustic then repolish. I am still not completely happy with the polish but it just takes a lot of time. I was looking at the laps just incase this wasnt going to work but it appears fairly accurate. So I dont think I will need it.
For a coating i have been experimenting with mothers car polish with silica dioxide and titanium dioxide. I also have the pure dioxides ordered and will expirment with baking them on under vacuum.

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Wow! This is a true laser beam. Shocked

Awesome idea and really nice test results, grin.

Did you run the SBT90 with the full current already for the fotos?

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Da beam is killa Thumbs Up
and great handwork

Regards Xandre

grin
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Skylight wrote:
Wow! This is a true laser beam. Shocked

Awesome idea and really nice test results, grin.

Did you run the SBT90 with the full current already for the fotos?

It Is a chopped W30 in the photos. The SBT-90 reflector has a much shorter focal length. You can see the difference between them.

MRsDNF
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LOL

 

djozz quotes, "it came with chinese lettering that is chinese to me".

                      "My man mousehole needs one too"

old4570 said "I'm not an expert , so don't suffer from any such technical restrictions".

Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

 

MtnDon
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Shiny!

CNCman
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Very nice mirror polish job !! Rarely see aluminum polished that good. Beer

Zandar
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 Subscribed and really interesting build! I'm eagerly following along.

 

pinkpanda3310
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Wow, that’s ambitious, making your own reflector. I love it Thumbs Up

  

grin
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Beer everyone Last year I took a gamble on a very different heatsink it paid off. This is a bit of a gamble not so much the main mirror but the hyperboloid Im not sure how accurate it has to be. There are a few things that might stump me. But it has to be different it has to stand out. For the OL challenge I want to build something I have thought about but havent done before. Anyway the 180mm billets turned up today and I had just got the geometry right.


So I cut that out and glued it to acrylic and roughed out the billet

I take the ridges off with a lathe tool then use 40grit emery between the profile and billet.


Few hours later it is starting to take shape I will make a new profile because the first is worn out.

MtnDon
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Thumbs Up
MRsDNF
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You have a lot more patience than I grin. Big Smile

 

djozz quotes, "it came with chinese lettering that is chinese to me".

                      "My man mousehole needs one too"

old4570 said "I'm not an expert , so don't suffer from any such technical restrictions".

Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

 

grin
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Well what a mission after nearly 24hrs I have this. The outside edge is a bit low but will be trimmed. Hot spot lookes good in the sun.

grin
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Chopped k75 in a testing jig


About 50m

pinkpanda3310
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grin wrote:

OOooh shiney…!

That spot looks really well focused. Good job Thumbs Up

  

grin
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Thanks PP,
I am surprised at how simple it was but I knew it was going to take time. I had it roughed out by sunday spent all sunday fine grinding/sanding from 8am until 11pm with a few hours break, then 6 hours polishing this morning. My arms feel like they are going to drop off. Started with 40grit emery then 240grit, then went to wet and dry 320 400 600 800 1200 1500 2000 then calico wheels first grey compound then brown and white, last was mothers aluminum polish. If there were any marks not removed I repeated the step before. I think the calico wheels would remove more of the finer scratches that are hard to see.

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