Im not sure you are right.
If we want to use various of different cells, we need to use springs.
If we have springs from driver side, and glue tube to the head, so cells are fixed and then screw tail with tail pcb, you will short cut 2 from 4 cells in 4S config and the only way to avoid this is tail pcb that can slide around incide tail (Klarus G30 and etc.)
If we have springs from tail side, and use fixed tail pcb (insulated from host) and cells that inserts from head side, we have same problem with some extra solutions.
If both - and + pads are on head side, we can use some extra part that is made from plastics and inside it - pad goes to host, + goes to driver and all extra space are insulated to prevent unforeseen short-cuts.
If both pads are on tail side, we can use same plastic insulator for intermediate cell connections and connect negative to host through tail pcb, positive should goes to tail pcb center with should be connected to some solid rod which should goes through center hole between cells to the driver.
All posted describes 4S connection and I think this solutions are much better that tail switch and big bada boom if it is on when you screwing the tail.
I am not totally sure what you were describing but I am also into a pile of buck drive data sheets and can’t really focus on it at the moment.
I was talking about the conversion that many have done to the SRK over the years where the battery tube stays fixed meaning it can not short at the front of the light.
The tailcap is then modified to allow the PCB to spin as you screw the tailcap into place.
Just like the Klarus G30 now that I look it up, that would seem to be the simplest option. Anyone can do it, particularly if the Q8 already had the screw hole machined into the tail cap and PCB.
K, just ordered the 17's and 22's, 3 each, 17's in 2 oz. copper. 
For $6 shipped, not much of a risk.
Curious how the 2oz version holds up, I forgot to change one of mine to that sadly.
Mine are supposed to be made on the 29th, curious when yours get done.
Last time I ordered I got them in like 5 days! lol.
Sometimes they upgrade to the express service, simply because they got room on an express panel our small boards fill in to. It's happened to me several times. The17's are nice in the thin size. I really don't think it makes much of a difference for us having the heavier copper, because typically the batt+ is connected direct from the spring w/bypass to the LED, and the other critical power path is batt- (grnd) to the FET input. When I piggyback a driver in, I make sure I got a nice wire connected from a good grnd point on the contact board straight to a FET input pin. I also sometimes will wire a jumper from the grnd ring to the FET, all depends.
I figured that was the case, these little boards would fit into lots of small areas.
I put in an order today as well. Scheduled for the 29th
Hi, I am new here (if you couldn’t tell from my post count!) I want to build the 17mm version of this driver, I am having trouble locating and selecting the correct items, I looked up the fet found choices on mouser but the size etc still gives me a list of values I need like gate voltage etc. Same with the resistors .10 and $1 ones in the same 603 size, not sure which to order! Thanks!
I know your feeling! I can say for resistors, I usually narrow down the options using these filters:
0603 package(or 0805, 1206 depending)
In stock
Cut tape
1% accuracy
Then I sort by price and choose the cheapest resistor that has the highest temperature range. At the low prices the temps are usually the same, but sometimes there is a low temp version in there and I usually stay away from those.
The price is usually .10 for one, but buy 10 for .25. Something like that.
Edit: I use a similar method for choosing other components, but yes, there are some basic values that you need to know. For fet, you need to know the size or package you want. Look for single n-channel fet ,best temperature range and for a low resistance.
There are a lot of things that go into choosing a FET in particular. The SIR800DP(?) is regarded as the best (and also expensive). You can search the forum to find discussions on a couple model #’s that suit our purposes as well.
Ditto the above, I just got my parts order for the drivers in today. After I build a few and make sure everything works I will try to make a shopping cart with everything you need.
I follow lightriders selections for narrowing down the selection to the parts that are at least the type I am looking for.
Thank you guys, I look forward to the cart. The last few builds I did I used MTN17DDm-NUV but this looks like DRJONES-H17F with Bistro, that seems like the best of both worlds. I wanted to try a 1+7+FET but I didn’t want to give up Bistro.
Just got in the 22mm's today. Look'n good/!See they are labeled 26 mm 
Hope to have a chance to reflow one tonight, we'll see.
LOL, opps. I will put that on the to fix list.
I am hoping to reflow one tomorrow.
My 2oz 17 and 22mm boards arrived today. Boards look great, but boy are those pads tiny. I knew they would be tiny, but didn’t realize how tiny they would be. I’ll see what 0805 parts I can get away with and then order the rest. Probably, won’t get around to it for a couple days at least.
LOL, yeah I knew the entire board would be tiny but seeing it in person really drives the point home. Dealing with it in software at 10” diameter, you forget how small it will end up.
I looked over the boards and they look good to me, a few minor things I will correct just because they annoy me (26mm printed on the 22mm, the FET resistors not perfect lined up ect).
Only thing that I noticed that was not how I wanted it was the copper pour not going all the way to the edge of the board. I know oshpark says in the specs that they won’t do that but PD seems to get them to do it on the tripledowns?
These should still work, just remember to solder them in place and/or add a soluder blob to make the ground contact.
PD, how do you get OSHpark to take the copper all the way to the edge of the board?
Luck, I guess? They seem to be getting more picky about their edge limits lately.
Hello my blf friends. For those fortunate that are with these driver boards on hand, is it possible to post pictures and test results please. For sure there are others blf members like me waiting some feedback to pull the trigger and order some boards to assemble. Is there a board layout revision ongoing, or can we order now? Thanks for additional information.
Didn't have a chance yet to reflow one, but fully buzzed out a 22 mm last night, and all looks good. Think I need to print out your pics in the OP since I don't have a screen handy by my bench. The labeling is tough to read, and in some places not so clear on what pads it labels. Even on the 22 mm board, real estate is super tight, and OSHPark's labels don't work well at those sizes.
I'm really confused now bout pad sizes and parts... Thought the 22 mm pads were all 0805's - I measured a few of them and they matched Richard's red board, accept for the 0402 resistor he uses of course.
Think you state in the OP they are all 0603 accept C1? Is this across all size boards? Weird because the pad sizes match exactly with Richard's, so was it common to use 0603 pad sizes then on all our common OSHPark driver boards? Didn't do more compares, but I got a ton of OSHPark boards laying around from several sources, in several sizes -- way too much unused, and looks like they will never be used now, with all these great new ones 
. It's a good problem I guess...
All of wights and my own boards use 0805, and Richard used to, but since he is using his own designs and his part picker machine he switched to smaller stuff.