Gr8 build man! Your reign has started!
looking good! 
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.:-)
Knurling the tube must have been nerve wracking.
There are worse things, but you do have to keep it on track the whole way down. Since there is some slight flex in the center of the tube I actually increased the pressure slightly when I got to the center portion, and then backed it off a hair toward the other end. If it does come loose from the bar any the pattern can get off track and it can be tough to pick it back up again.
I put an XHP-35 in my M2X-UT Javelot back on Aug 10th running 4 Efest 18350’s in series. It’s showing 2456.4 lumens at start and 302.75Kcd for 1100.45M throw. I used the LD-2 with proper modifications for 4 cell and 3A output and am seeing 3.10A at the tail.
I’ll have to double check it as my notes don’t show a break down with run time, I’ll do that and see how it holds up.
A runtime test would be interesting on this mod. If the 3.1A is over the max you may actually see a temporarily increase of output when the LD2 gets out of regulation and the current goes down. :-)
Thanks Dale.
The 300k lux seems about right if the Dereelight has an AR coated lens ( the one I had was not), that would give around a 12% gain over what I was getting at around 256K.
I recall hearing you mention this light before and also that you have calibrated your light pipe off a couple of other people who get very similar results.
So this leaves me wandering if my sphere needs to be re calibrated or if your actually just kicking my tail.
Is there any chance you might loan me that light so I can test it in my box if I paid the shipping both ways?
If you dont want to loan it out I do understand.
I can do that, in all honesty this was one of those “challenge builds” that I built to see if I could, how it would act, and now that it’s done I wish I’d kept the Javelot in it’s small thrower trim. So I will probably end up setting it back up with the de-domed XP-L and FET driver to run on a single cell anyway. I just like it in compact form better.
Charging the 4 18350’s and I’ll test it, see how it goes over a timed run in my light box. Then I’ll box it up.
PM me your mailing address so I can get it headed your way. I’ll tape the end of the cells and include them so it’s the same test on your end that it is on mine. 
Should have test results directly…
Awesome Dale PM inbound. Thanks.
I have updated the OP just now with several new pictures.
With 4 Efest 18350’s fresh off the charger, it ran like this in my box…
Start 2332 lumens
30 sec 2125
60 sec 2039
120 sec 1925 and HOT!
Oh, and the cells came out after 2 minutes at 3.97V average.
I am really liking this. Nice work, and can’t wait to see it finished.
I have just added a second update to the thread for the evening. I think some of you may have a particular interest in this.
