I don’t think I’ve sliced a 70.3 but I have sliced a 70.2, maybe 6000K (came with Thrunite T2), and it turned out great. My impression is slicing should work with 70.3 but maybe not.
It definitely should work with the 70.3 also. I’ve seen where others have done theirs and got good results.
It sucks that I essentially turned a good emitter into basically trash, but I can live with that. It sucks more not knowing what I did wrong. I used a 1mm thick washer, and ended up with what I thought was a decent nearly flat surface.
By my tests CCT drops, but DUV doesn’t change much. It seems to get worse unless sliced totally flush.
Edit:I’ve sliced maybe 20-30 of 70.3’s
And @crbnfbr
Did either if you also “dice” - cut away the phosphor layer adjacent to the LES? My understanding is dicing helps with the duv amd tint shift.
That’s interesting, I definitely didn’t get it totally flat. There is a bit of unevenness, but I didn’t think it would make such a big difference. I can try to smooth it out but I don’t have much silicone left to work with.
That at least gives me some idea of what happened.
I only sliced the dome off. Using the 1mm thick washer as a guide to run the razor across, but was finding it difficult get it perfectly flat.
Here’s info on dicing if you’re unfamiliar:
I found dicing makes these worse. Duv increases.
I’d be too nervous to try that dicing. I did follow a few links in that thread though. One I came across mentioned polishing the dome with some fine sandpaper. At this point I can’t make it any worse, so I think I’ll give that a try.
edit: Well I polished up the slice marks, but the duv didn’t improve any. I’ve attached a couple pics after polishing. At this point I’ll attempt to “dice” it too, not expecting any improvement but just to try it out.
I don’t know what’s up with the solder mask on the mcpcb, it started coming off right next to the led while cleaning after reflow, and it’s only gotten worse.
Why do people slice 70.3 HD if 70.3 HI exist?
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A 70.3 HD is not a 70.3 HI, but it can more or less be turned into one via slicing, and since people can’t simply pull LEDs out of their… hat.
That makes sense if you have one in a flashlight you like, but Haukkeli apparently sliced 20-30 of them. That seems to be somewhat on purpose. Is there any (relevant) advantage of a sliced 70.3 HD over a 70.3 HI?
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I as far as I was knew slicing is supposed to lower the CCT and duv. I’ve seen many times people have done it successfully, but apparently I did something wrong.
Mostly I’ve been building different lights and have been spending some money trying to find good bins. Usually buying 2-3 from different sources hoping the best.
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I re-modified my C8 that I built around 10 years ago. It had an XP-L HI and was a great thrower, but I rarely used it.
I read way above (from ebastler) that the high CRI 5700K 70.3 HI from Simon has good tint, so I debated whether to just buy a new 70.3 HI C8 or buy the parts separately. The new C8 was only $2 more vs the parts, but I’m going to use the existing driver for another flashlight so I guess that saved me another $11. 
A very simple build. I just had to pick off a solder blob next to the LED and lap the MCPCB. I’m always surprised that the LED boards are not more flat. Here it is when I just started to lap it, and then at the end.
I’m really impressed with the 70.3 HI! The beam is very nice with the OP reflector and makes my C8 much more usable. And I agree with what @ebastler said, it’s a great tint-free and tint-shift-free cold high CRI 70.3 HI emitter.
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Another good 70.3 HI from Convoy is the 4000K r70. I have one in my TS22, and the 5700K r90 in an M21B.
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I can always find something around the house that’ll work. But whenever I throw away electronics or appliances I always take out the stuff I think I might find a use for later. Lots of copper lying around. I have a few extra chunks of copper pipe from idk where, some plumbing project or some cooling coils, I’ll squeeze those into a flat chunk in a vise or hammer them down so it’s just a chunk of copper, then cut and grind that to size.
I always have a handful of damaged mcpcb’s lying around too, where the solder mask came off or whatever. Can polish those off and use a few of those. Or if I find an old penny. Canadian pennies were 98% copper until 1996.
It is an issue isn’t it. They should really fix that. I always forget how bad it is until I hold a noctigon or kaidomain board.
I’ve never sliced a 70.3 HD, but I have sliced several 50.3 HD’s and I prefer them to the 50.3 Hi’s. It lowered the duv on all of mine. I like the tint better.
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I never really used my SFT-40 M21A either. It was also an impressive thrower, but I always found myself using my M21B instead. Initially I was going to get the OP 10mm holed reflector, but I’m a sucker for a TIR.
Same here, I always save any chunks of copper and aluminum. I also have a bunch of CPU and other heatsinks I’ve scavenged from obsolete motherboards.
For the Americans, US pennies up until 1982 were 95% copper.
I must really not know what I’m doing when it comes to slicing XHP emitters. Several months back I had also tried my hand at slicing a 4500K 90cri XHP50.3 HD. Unfortunately, the duv didn’t decrease, but it didn’t increase like my XHP70 did. I probably should’ve learned from that experience and not tried slicing again.
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Idk what I’m doing right lol. My slices are not perfectly smooth. I don’t use a guide most of the time, just freehand. And it usually takes a couple slices. But it’s always worked.
I always use a brand new utility knife blade for every emitter. Sometimes 2 new ones if it takes a few slices to get right. Maybe that’s it? The replacement blades for my Milwaukee fastbacks I buy in packs of 100 so I can always slide out a brand new one, never used, still oiled from the factory, sharp as can be for each slice. That’s the only thing I can think of that might be making a difference but idk
I really like the sft70 in the m21b. I wasn’t a fan of the sft40 in it, I like the sft40 in the m21a, but the sft70 needs an OP reflector so you can’t get a ton of throw from it anyways, and it’s more lumens than the 40, so it works great in the m21b
I used a brand new Feather double edged razor blade. I’ve been saving a pack of them for when I get the ambition to wet shave again. So, it most likely wasn’t the blade causing my issues.
I sanded a bit more off the XHP70 and it appears to have lowered the duv a bit, but I still need to check it with the Opple.
