grins 8th annual old lumens machine made entry

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.

Oh Don. :blush:

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.

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.

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.

Wow! This is a true laser beam. :open_mouth:

Awesome idea and really nice test results, grin.

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

Da beam is killa :+1:
and great handwork

Regards Xandre

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.

:laughing:

Shiny!

Very nice mirror polish job !! Rarely see aluminum polished that good. :beer:

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

Wow, that’s ambitious, making your own reflector. I love it :+1:

: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.

:+1:

You have a lot more patience than I grin. :smiley:

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.

Chopped k75 in a testing jig


About 50m

OOooh shiney…!

That spot looks really well focused. Good job :+1:

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.