FWIW, use a brass post on a 17mm driver in combination with a 26650 cell, No issue. 
Agree!
And could that not also be soldered on the inside to a braid as spring bypass? Would look very tidy.
Totally lost me on that one Miller! lol
The brass post is the diameter of the spring, typically, and enough length that the cell cannot possibly touch the retaining ring… this post replaces the spring on the driver, and as such, you must have a spring at the switch or you’d have a battery crusher style which could be compromised by a drop, breaking contact and rendering the light unusable.
I have, on an occasion, drilled a small hole in the brass post on the underside to line up with a through hole in the driver such that a wire could be passed through from the brass post directly to the emitter for best possible current transfer…
Ah lol I thought you means a brass cap over the spring
(Stealing pic here
yet you simply replace the whole spring with it , yeah lol I am on par
The Miller, I am not trying to argue. I am simply saying if a pill is made correctly and the proper spring is used on the driver…. there will be no issue no matter what battery is used. Or in place of a proper spring use a brass button like Dale suggested. 
The Cometa is only an example of complete failure in the areas mentioned above. Nothing was done correctly. :person_facepalming:
Sad, but true…………
Z1 hosts can be bought!
Thanks Jaxman!
First post is updated with this info. Thanks The Miller!
Paul/Jaxman is to thank
Let’s build some sweet lights that inspire and get the flow going for a next host!
Took my 2 Z1’s to the lake a week ago. Wanted to see what the difference in throw would be. Here are the results:
XML2 U4 1C on the left
XPG2 S4 2B on the right (old stock)
Both are dedomed
To the naked eye, they both look to be about equal brightness. The XML obviously has a much larger die so it produces a larger “square.” But side-by-side, the lumens on the trees look to be equal.
Those trees are about 600-650 feet away according to Google Earth.
What a great pic!
Ordered a host and so leaning to a large LED, this strengthens that.
I finally built my Z1 with HXP35-HI and 4S(16.8A) buck driver set at 2.5A.
Posted in the Modding thread.
Looks sweet! Looking forward to getting my fet and copper pill!
I ordered a Z1 “host” for myself the other day. 
It’ll be a couple weeks before I get it though.
Do you have any particular plans for it?
Oh, nothing crazy. One of my copper heatsinks, XP-L HI, and either a fet driver with a king kong or buck driver with 26350’s in the extension tube.
I just got back from testing my Z1 down in the ravine. Awesome!
The HXP-35 HI is about as perfect in this light as you can get. The throw is amazing when zoomed, lighting up the distance with full clarity, and there isn’t any annoying visible matrix.
When deployed in spot mode, it will easily illuminate the entire infield of a ballpark well enough to play. (I was standing at home plate)
Well Dangit! Now I’m gonna have to get a Z1 extension tube and another driver from Richard! 
Nice work Ouchy, always great to see such results.
I do love what’s coming out of this build, but you also have to realize that I have nothing to compare it to, such as the same Z1 host with an XPL HI. Besides the XHP-35 being 12V with four mini dies, I have no idea what the visual comparison and output would be between the two. Besides that, I’m impressed enough that I ordered another host last night.
Now I have to decide what to put in it.
Shame nothing comes close to the XHP70 lumen wise, if you can get over the windows advert it projects on full spot mode then its ideal.
XPL or the XHP35 direct drive would be sweet too.
My Z1 got an Luminus SBT-70 for the round die and it’s ensuing round hot spot. I like it, as I simply adore the way they build this emitter, but it’s not an absolute kind of light due to horrible inefficiency of this emitter. One thing I do not like is the blue rectangle from around the perimeter of the substrate. It’s normal for this light, not seen in a reflectored light (I have several) but the zoomed in image clearly shows it, even in the field.
