519A, Try Slicing!

Thanks. I’m considering replacing 219C 5700K for 519A 5700K. I do like 219C tint, but tint shift is particularly bad with the TIR I’m using. So I would also need to shave the 519A.
I already shaved lh351d. I’m wondering if it’s worth to order 519A to do it.
For measuring tint shift,I think you can take one measurement on hotspot and another one on spill.

Eh, I don’t think you need to get 519A LEDs if you’ve already got domeless/dedomed LEDs.

Side emitting enhancement silicone, especially domed ones, amplify by their nature any imperfect nature, and depending on the quality of the silicone used itself, it might cause further problems just by its addition.

I’ve done measurements in hotspot, corona, and spill. To my eyes, changes in CCT and duv both look bad. Especially if all three (hotspot, corona, spill) are significantly different.
The reflector/optic used can also make a big difference.

I just measured: 4000k 219c, 4000k 219b, LH351 5000k shaved, 519A domed and 519A shaved.

The domed 519A looked and measured the worst (not bad, but it is in good company).
The 219c and shaved LH351D were in the middle. These look good to me, even being picky on a white wall.
The best were the 219b and 519A shaved. These have very even CCT and duv.

FB

Thank you FB.

Like thefreeman’s LH351D slicing study, you just wrote the definitive guide to 519A slicing. This is a tremendous resource and one I’ve been hoping to see for a very long time.

What washer is needed for slicing?

Any type of metal washers should work. Ideally one that fits closely around the LED. And the washer should be smooth on the top so it shaves the dome off smoothly.

You can also sand the washer to make it smooth and to the thickness you want.

Here’s a custom one I made to shave down some SST-20 LEDs to just under 1mm:

@NeutralFan, would you be willing to make some of these custom washers and sell them?

I appreciate the suggestion BlueSwordM, but my efforts was to meet a specific need that I had. I have lots of washers and parts, but not really for selling.

Probably the best option would be to visit your local hardware store.

Here’s a pic of some of my parts I used to modify a rock tumbler for my son:

Ah I see. Thanks for the response.

Could you measure the thickness of your washer at the point that is the closest to the LED? It’d be nice if I could source some similar washers to make some high CRI superthrowers :smiley:

Feeler gauges are much easier than washers.

Huh, I didn’t even know these kind of things existed.

Thank Bob_McBob.

Or get a digital caliper so you can custom make your own washers.

I do have calipers, it’s just that you seem to have done the research already, so it’d be nice to have a starting point for thickness :slight_smile:

No research from me. I just sliced my SST-20s to the closest to the wires as possible (from what I could see) in order to improve the DUV.

FBsLights has done some great research for slicing the 519As!

I use washers that have a hole just big enough for the emitter (5 to 6mm).
I prefer fender washers which are large relative to the hole size. I have a selection I’ve gathered with various thicknesses. I’ve sanded them smooth them out and remove any burs.
Take your calipers to the hardware store and pick up a few. There is usually a range of thicknesses to you can find the right size washers in bulk, so you can pick and choose.

If you want a complete selection, take a feeler gauge set, and drill an appropriate size hole in the thicknesses you want.

Something like this:

https://www.amazon.com/Hotop-Blades-Feeler-Imperial-Measuring/dp/B06XHXJG31/ref=sxin_24_ac_d_hl?ac_md=1-0-T3ZlcmFsbCBDaG9pY2U%3D-ac_d_hl_hl_ac&content-id=amzn1.sym.c62cb81a-0a35-442f-8d53-cc7156305bbb%3Aamzn1.sym.c62cb81a-0a35-442f-8d53-cc7156305bbb&crid=CDIK1Z23L1CT&cv_ct_cx=spark+plug+gap+tool&keywords=spark+plug+gap+tool&pd_rd_i=B06XHXJG31&pd_rd_r=5a883799-157f-492f-a6ed-bb50c799e8bb&pd_rd_w=YKGBA&pd_rd_wg=CE4wr&pf_rd_p=c62cb81a-0a35-442f-8d53-cc7156305bbb&pf_rd_r=4YE31W65VDTKZSEJN9K6&psc=1&qid=1653878496&sprefix=spark+plug+gap%2Caps%2C251&sr=1-1-25fd44b4-555a-4528-b40c-891e95133f20

Overkill? Yes.
But you would have an almost unlimited selection of thicknesses.

Still playing with the thickness some. Adding a layer of silicone works just as you would expect. I’ve increased the silicone thickness to get higher CCTs. It is hard to get a nice smooth beam this way. It is better to slice to the preferred thickness the first time so you have a nice flat surface.

FB

Shim washers (DIN988), 3535 will fit into 5mm ones and with their 10mm diameter they usually fit onto most multiple LED MCPCBs without having to desolder other LEDs, if not it’s easy to remove a bit of material so they do. I have 0.1, 0.2, 0.5 and 1mm thickness and just stack a few to get any thickness in 0.1mm increments.

Don’t forget that the LED itself has to sit flush on the board. The slightest bit of “float” (ie, too much solder underneath) raises up the LED and you’ll be cutting unevenly at best, cutting too low at worst.

I’m surprised this is mentioned so rarely in dedoming discussions. When I do a traditional slice on an LED, I reflow it to a specific MCPCB with pressure from tweezers so it’s at exactly the same height every time. That’s the only way to be consistent about slicing height with a guide like a feeler gauge.

More emitters measured. All emitters behave about the same.

Emitter, CCT measured, duv measured

519A 2700k domed, 2660k, 0.0007
519A 2700k 1.4mm slice, 2564k, –0.0005
519A 2700k 1.2mm slice, 2445k, –0.0007
519A 2700k 1.0mm slice, 2273k, –0.0009
519A 2700k dedomed, 2138k, –0.0019

519A 3000k domed, 2993k, –0.0003
519A 3000k 1.4mm slice, 2907k, –0.0014
519A 3000k 1.2mm slice, 2770k, –0.0018
519A 3000k 1.0mm slice, 2607k, –0.0023
519A 3000k dedomed, 2388k, –0.0037

519A 3500k domed, 3423k, 0.0004
519A 3500k 1.4mm slice, 3319k, –0.0012
519A 3500k 1.2mm slice, 3196k, –0.0013
519A 3500k 1.0mm slice, 2999k, –0.0012
519A 3500k dedomed, 2709k, –0.0035

519A 4000k domed, 3779k, 0.0009
519A 4000k 1.4mm slice, 3663k, –0.0014
519A 4000k 1.2mm slice, 3478k, –0.0011
519A 4000k 1.0mm slice, 3329k, –0.0013
519A 4000k dedomed, 3027k, –0.0027

I can get a nice negative duv with CCTs from ~2150k to 5200k.

Happy modding!

FB

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