I don’t think there’s any signing up.
Just follow the link and purchase. 
1 Thank
Hi Simon, are the threads in the S21A: “ACME” which are 29 degrees included or “ISO Metric trapezoidal” which are 30 degrees included?
And is the pitch 1.5mm or 1/16"? Could you provide the thread specifications?
I would presume it is ACME with 1.5mm pitch.
1 Thank
I believe all newer Convoys are square cut threads. My S21A, S2+ and M21B are all square cut. Older S2+ were trapezoidal threads.
The older s2+ had a truncated triangular thread, not trapezoidal. The S21A has a trapezoidal thread, it is not a square thread.
According to this review the S21A has square threads. To my untrained eye the threads also appear to be square on mine.
1 Thank
Thread angle can be difficult to determine without a comparator. If you take two S21A pills and interlock the threads you will see that they are not square.
When I take a 29 degree acme threading tool and insert it in the S21A pill’s threads, it appears like a perfect fit, but I am not sure if it is off by 1 degree included, which is the difference between ACME and ISO Metric Trapezoidal. As far as I know the ACME standard is the more common of the two, even in Metric countries.
I’ll add that almost everyone categorizes threads incorrectly. It’s kind of like how everyone calls the glass on a flashlight a “lens” even though it is not a lens, it is a window. I call it a window because the meaning of words matter to me. Surefire calls it a window as well: “Tough polycarbonate window resists impact.”
1 Thank
I took a closer look at under my S21A under a magnifying glass and it does appear to have a slight angle to the threads. You obviously know more about machining than I do. I just watch some vids on youtube and dream of owning a lathe and mill.
It is rubber button.
Yes, it’s on my list of plans.
3 Thanks
Sorry, I don’t provide data on this.
I’m curious about why you need this data, and I’ll see if there’s anything I can do to help?
I’m going to make a custom heatsink. It would save me a little time to have confirmation about the thread angle and pitch.
1 Thank
To measure it I’ll cut one in half and take some pictures and analyze them in CAD. Then make thread racks with different angles and pitches for comparation, until the fit is exact. Should take a few hours.
1 Thank
Too bad, Your first photo on Facebook showed a metal switch that compliments the design. Rubber is kinda step down
2 Thanks
I agree, I wish he had kept the metal switch.
2 Thanks
I think Simon should design ONE tailcap for all S2s that could use a lit or unlit rubber, or metal switch, and sell all the switch parts so we can customize it how we want. The existing metal switch design isn’t compatible with anything else. The lit metal switch could be made in an unlit version as well. It’d be nice if the height was fixed to the light could tailstand properly.
I was just about to buy one myself but reading this has made me think twice. I love the metal switches that come installed with certain S2+ models but I’m rather less keen on the illuminated versions that fit the rubber switch aperture - mainly because they compromise tail standing, I’ve tried various means of jiggering about to get them to sit flush but to no satisfaction.
I love the elegant design of this new Ti version but I do think the rubber switch boot detracts from that somewhat (actually rather a lot). I think I’ll stick with my plain Aluminium silver S2+ with it’s bare metal stainless steel switch.
Edit: I think I just convinced myself that a T3 Ti is the way to go 
1 Thank
It’s a beauty!
Great !! I’ll wait to buy the S21E then. Thanks
I want to love my S21E, but the temp regulation doesn’t seem to work. It will step down from turbo, but still gets too hot to hold after ~10-15 minutes.