BLF GT (preliminary) modding thread

Do you have a donut hole in the beam or not? I hat a visible donut hole when I placed shims under the centering plate. It was visible even at 250m distances

Good info, If you find a perfect thickness I will pass it onto lumintop and see if they can make some updated centering rings.

Anyone else that wants to experiment with this be sure to post your findings as well, the more the better.

Luckily I have my friend’s GT in my hand so I will try focusing that too. That was even worse stock than mine. It only got 894000 cd. Now I have two workdays so I don’t have time for it but after that I will upload all results.

EDIT: I talked another hungarian forum member and he will send me his GT head too to measure it and focus it. So I will have 3 GT focus tests but all 3 is from the late February or early March batch because they all had same tracking movements around few minute differences.

Ok, so these are from the old reflectors, still good information to have.

I spend one morning messing with the center piece of my GT, made it both thinner and thicker, but never got rid of the slight donut hole, and the throw did not get better. I may have to look more precisely, but I first have to replace the ledboard screws with version that do not have a very round head but heads with a straight side, so that the center piece can be positioned exactly and keep the led in focus. But it takes too much time already, I will first wait for a new led to arrive…

I have been testing with my GT using a flat plastic piece placed under the original centering disc. I have cut it with the same shape of Lumintop disk but with a bigger central hole. (Similar to those in the picture of KawiBoy1428) I started with a thickness of 1.10 mm and I have repeated readings sanding it down to 0, 90mm, 0, 70mm and 0.40 mm.

The starting point is 1.203.000Cd using a boiling thinner dedomed XHP35 E4 HD.

Lux readings were taken at 10m. I have no more available length in my house but I will try to measure in the community garage at 15 and 20m this night, when the lights can stay off, without car transit. As it is only an experiment the readings are taken at the start of the light. Therefore, No ANSI

These are my results at 10m.

- 1.10mm: Ugly spot with blurred edges and a very marked black hole up to 5m. I did not mensure. It was obvious that the result would be bad.

- 0,90mm: Nicer beam profile with a more definite spot. The black hole from 4-5m onwards was replaced by a central area that, although irregular, was more illuminated than the rest of the spot. 1.092.000Cd.

- 0,70mm: More defined spot. Illuminated area in the center of the spot is regular. 1.229.000Cd.

- 0,40mm: Perfect and well defined spot. 1.299.000Cd.

I finished the sanding because I hurt my fingertip with the sandpaper. :TIRED:

I received my GT on February 23rd. I don’t know the date of manufacture

My luxmeter is a cheap LX1010B. I have hope that when I buy in the future a better luxmeter the results will improve.

This is the Led with the centering disc raised. Some dust after disassembling and assembling 50 times.

I blow the reflectors off with compressed air in situations like that and 90% of the time that is all that is needed.

I also use keyboard cleaning compressed air, but it’s over. I need to buy more.

To answer some questions.
I noticed if the reflector focused well and I’m getting the best numbers at 25-30m distance it will have a donut hole at 10-20m. If you get the highest lux readings at 10m then the light is over focused and even if you got high lux readings it will not throw as far as you calculate and it is noticable by eye. When I had a very tight hot spot at 10m the lux readings were lower than if I saw a little more corona and not very tight hot spot. Because of the reflector size this light need to measure at least 20-25m.
Earlier I saw that the beam looks like a cone as it going farther but now it looks wider and two days ago we had come clouds and I could see the hot spot touching them :smiley:

I opened the second GT yesterday and started with 3,3mm thickness centering ring. I only had time to measure this setup. This light earlier got 894 kcd with stock 2,5mm centering thickness. with 3,3mm I got 926kcd still best reading at 10m so maybe I need to go much higher in thickness than my light.

Measured at 10m, 15m and 20m after 30 seconds.

10m 1.237.000Cd

15m 1.284.750Cd

20m 1.272.000Cd

Great numbers! :THUMBS-UP:

I did that for a while as well. In the meantime i read that compressed air contains a small amounts of oil. So i wouldn´t recommend this any more.



Oil is generally only if you have an oil canister in the air line that is supposed to add oil to the air to lubricate tools.

If you do not have that then it will generally be pretty clean. It can have some water in the line if it has not been cleaned out regularly but if you spray it on the ground at first to clean out the line I have not had any issues.

That said if you want to be sure, just use a can of compressed air, it works just as good but costs more. If it the best option anyways, you know it will be clean.

Hi all,

I did an XHP70.2 swap. Its a de-dome and I also changed the driver to a mosfet. Came out pretty well. It’s got about the same range as before but over 8,000 lumens.
Since I had a total of 4 lights here I also did a few control tests.

Thanks for the nice comparison, the XHP70.2 mod (with TA driver) is in the planning for my GT also so I’m glad to see it performing so well.

About the lux-readings: I recently (link) compared the LX1330B luxmeter (which is the one I think I see you using) to my high end Mobilux meter (which should be as accurate as you can possibly buy in a portable meter) and my LX1330B meter at least reads the cool white 70CRI XM-L2 in my Sunwayman D40A 9% too high, and a (70CRI) 4500K led 7.5% too low. That is 16.5% apart, so the spectral error of the LX1330B alone could already account for the reading difference that you find between the cool and neutral XHP35 Hi emitters in your GT’s.

Great video and great results! Good to see my own numbers are backed up, yours are a lot better then mine actually.

Hopefully this should help lumintop see that making the XHP70.2 mcpcb is a worthwhile investment.

Yes, I have noticed these same things and about the same ratios on the cheap meters. The readings themselves are pretty good but they most certainty are effected by tint.

I have Anduril working on the BLF GT, in case that’s a thing anyone is interested in. Basic usage is very similar, but it has extra features compared to the original firmware. Granted, some of the extras are less relevant on a big thrower than they are on EDC-style lights, but some are still pretty useful.

Just thought I should mention it since it’s relevant to the topic.

This also means it should be pretty easy to get other interfaces running on the GT, since the library supports the hardware now.

Yes, this is on my to do list once I finish some other projects. I really want to play with Anduril just have not had time.