I have no Carclo 10623/10624 but frosting the 10622 with #320 grit SiC already fix the beam very well.
No, with only 4 LEDs, rotation will only make the beam’s hotspot weighted to one side. The LED’s die hot spot is too asymmetrical it requires at least 6 LED in rotation to get even beam pattern from a tight plain TIR optic. So far, the best fix is to use the tightest Carclo 10621 paired with Luminit’s 30° - 80° LSD.
- Clemence
If you refer to this, can you link retailers, where I can get it?
Another (non-flashlight) question. Did you consider getting an MCPCB manufactured for Optisolis, which has: 16 or 24 emitters, and can be configured into 4S4P (4S6P) or 8S2P (8S3P) for 12V or 24V voltage requirement. I think, if Optisolis is not the best for flashlight usage, it would be very tempting for ceiling light panels. If there would be such panel, I’d be a definite buyer for that (3-4 of these panels could nicely illuminate a bigger room).
Work in progress…. 
Seamless module you can combine it to make unlimited larger panel of light.
Yes, that’s the correct Luminit. Will put some in the store too. Try to contact Edward Udarbe in Luminit, he’s the marketing manager. But be prepare, it’s a very expensive, aerospace class diffuser. Luminit just launched the cheaper version for earth dweller like us.
- Clemence
It would be just perfect! Very good to get these good news! :+1: I just told my father about Optisolis, and this way of its possible usage about a week ago (and I told him, that I will contact you). You already read minds 
Aw. So this would be good for occasional custom builds, but probably won’t be competitive for using in a manufactured flashlight.
Is there 16 leds module https://www.lumitronix.com/en_gb/aventrix-4x4-v2-led-module-16x-nichia-757-leds-4000k-cri-80-31989.html
a quadtrix e21a or a quad optosolis 4000k for LEO use. which one?.
Easy Nichia E21A soldering on Virence VR16SP4 MCPCB
.
.
.
Part. 0 (forgot to make it, Kaybi made me shot this one)
Pre-soldering the Indium to the MCPCB
.
.
.
Part. 1
This is a quick and dirty video I made with one of the order. Sorry for the quality, it was hard working with only one hand.
The MCPCB was first pre-soldered with Indium at the LED pads. I simply add some flux (common water based Zinc Chloride) and ran the molten Indium balls until all pads properly wet and contained sufficient Indium blobs. Be careful! This nasty flux will corrode aluminum instantly in contact (above 50°C). I did all the soldering on my upgraded “deluxe” cloth iron hot plate. Temperature regulated and monitored to 160°C (+/- 5°C)
Next, I cooled the MCPCB and carefully placed the E21A in approximate locations. Reheat the MCPCB just enough until all the E21A stuck to the pads. Cooled the MCPCB, added some more flux and reheated the MCPCB. Voila! it’s done with minimal efforts.
.
.
.
Part. 2
Ultrasonic Cleaner post cleaning. The water based flux makes it very easy to clean all the flux residue leftover, even from underneath the LED! The liquid ingredients: distilled water, dishwasher surfactant agent, and some dirt from previous cleanings. I did final rinse in a clean water (using glass beaker submerged in the USC)
Result:
Perfectly centered!
- Clemence
Very nice!
Do I see some layers of asbestos cloth on top of the iron?
Nice work on the indium soldering!
Yes, I put asbestos cloth and then drywall on top of them for my palm rest for better control. As a side bonus it makes the iron heats faster, very effective insulator.
- Clemence
Hmm, isn’t that toxic?
Because I lost my rock wool insulating brick. This asbestos supposed to be temporary replacement.
- Clemence
Well , YOU make it look easy ! 
This is white asbestos which is the less dangerous form. As long as you don’t saw or sand the stuff, producing asbestos dust, you should be ok.
My (late) mother used to warm the croissants on top of an asbestos simmer plate on the stove. But I will more probably die from her chip pan: she never replaced the fat for 20 years, when the level got low she just added new fat.
So it’s like Beryllium Copper 
As long as I don’t saw or sand BeCu, I’ll be fine.
waiting for 16mm to be in stock again.
thanks.
If I were to solder 4 nichia 119’s onto an VR21SP4 would they be spaced correctly for a Carclo quad or because of how the LED’s will center on the pads will the led to optic cone spacing be wrong?
No, they won’t fit Carclo quad. But you can do it with E21A. They still produce great beam although placed offset from the optic center
[Clemence]
Clemence, have you considered making 3x3 E21A MCPCBs? Would be expensive but compatible with 7070 optics (aside from low height) and producing a lot of high quality light.
Yes, this is in my to do list since last year
[Clemence]