---------- Arc of Josiah---------

Great to see another of your creations! I love knurling. Just love it.

Nice work! The knurling looks spectacular and I can’t wait to see the final product.

You might consider running 26650 LiFePO4 cells to reduce the power slightly and have less voltage sag. I did that with direct drive on 3 XHP-70’s with terrific results, over 15,000 lumens.

Also looking forward to seeing what this XHP-35 does at those levels. I have components on the way to use with an LD-2 for a build I’m doing with one of these emitters, should be here today actually. I was planning 2A but now I might go a little higher… :wink:

Thanks for sharing, and for the words on Josiah. :slight_smile:




The way that knurl is created differs from most lathe work. Rather than cutting maternal away, what your actually doing is "pressing" the design into the metal. Doing so will actually increase the diameter of the part due to the peaks made on the knurl.

The hard steel wheels on the knurler have lines in them in opposite directions.


Typically you center the part between the two and run an "X" pattern on the part, but I have found I get better results ( especially on a long part) by running one wheel and then the other.

A close up of the result.




The driver is my version of the BLF DD FET driver. Here is a link for the boards and the parts list needed. If you use the parts for the standard 8.4V config with the zener diode etc, the only thing you need differently than what is in the list I provided is to change the 10uf cap from a 10V to a 16V.

17mm & 20/26/27mm single-sided DD/FET driver release: A17DD-SO8 / A20DD-SO8 / etc


RMM has some 16V 10uf caps and his boards may be 16V ready, but I dont know for sure.


I am just using the star off time firmware for this.

Nice work. The knurling looks fantastic.

Thanks for showing how the knurling is made. The tool and the knurling you created are just too . Sure seems like it would take a lot of pressure and consistency to get it right.

WOW!! Fantastic work! Thank you for sharing VOB. I dig the Grizzly

Excellent work really and it was interesting to read how knurling is achieved too. I wondered how it would be done in simple manner. I’ve never used a lathe but I can see how useful it can be for such work.

Another knurly beauty from VOB’s workshop. Looking forward to more lathe, and tooling info… very interesting.

Coming along nicely!

Quite a large update added to the OP. Including LUM 5-90 and more on the head.


Gr8 build man! Your reign has started!

looking good! :slight_smile:

I like the reverse tapered head. I dont think Ive seen that done in a light of that size before.

Thanks for the update. I'm glad l'm not a mini lathe in your hands.

that is a bad * club!

great work…

That is going to be one big light! Thanks for sharing it all :-)

About the abandoned XHP35: if at 2.5A the led is at its maxiumum output and 3.5A is well over its max , PWM-ing down from 3.5A will cause the led still to run at 3.5A, just switched on and off by the PWM, and so it will have the diminished output that goes with the 3.5A. In your battery set-up you need true current regulation to get the max out of the XHP35.



Thanks djozz. You could put what I know about driver science in a thimble so your probly right.

My theory on why I get improved stability by PWMing the current down like that is not because the LED cannot handle the 3.5A. but because the heat cannot dissipate quickly enough. I was thinking the off time allows the cooling time between pulses?

When I bench tested this emitter in my sphere I reflow soldered it to a very heavy duty copper rod and got this result.

Cree XHP-35 HI C4 Measured Lumens Cree Chart
500ma 675 641
1000ma 1177 1116
1500ma 1577 -----------------------
2000ma 1888 -----------------------
2500ma 2010 -----------------------


I wish I had recorded the numbers at 3.0 and 3.5 now, but I did not because even on the copper rod they fell like a rock.

When I put this in the 4x26650 light it gave me only around 1600 lumens ( I get around 1300 from de-domed XML2) hence my disappointment.

Now that I think about it 400 lumens does seem to represent a bit wider margin (20ish %) of loss than what I got from the XML test. However I think that in this case even If i would have been able to harvest a couple hundred more of those lumens the result would have been the same. For this light I wanted to reach for the stars and in a host this big a single XHP-35 just wasn't going to get me there.


djozz, what kind of margin do you typically get from a straight emitter test to an install in a light?

Off topic but nice work on the lathe, i had one just like it but i could not stand the plastic belt when u get in a jam lol

Thanks for the output numbers. These may actually be the first real life output numbers of the XHP35. At least I'm not planning a test. A maximum at 2.5A sounds logical because it is four XP-E sized dies in series, and 2.5A is about the max for the XP-E2 as well.

I must admit that I never directly tested that, most emitters die during testing, and the ones that have ended up in flashlights are running on FET-drivers, making it harder to measure the current. I will have a go at that one of these days.:-)