FX Chrony V2 easy clamp
The clamping mechanism (or lack thereof...) of the FX Chrony V2 is not very handy, there should have been at least a knurled finger screw, so one does not need to get out the hexdriver everytime when attaching or detaching the chrony, or it should have a toolless spring type clamp.
And on top of that it is a pain if you want to use it for both picatinny and non picatinny equiped guns, one needs to unscrew the clamp with 4 hex screws, replace it with the concave part and rescrew the 4 hex's. And that time and time again if you have multiple guns with and without pica rails to chrony...
So room for improvement right?...
Then let's start off with a picatinny spring clamping system that does not require any tools to attach or detach...
For this you only need an M4 (meaning 4 millimeter) thick bolt with a locking nut, a piece of shrink tubing and a small spring. (ISO the M4 you can use an imperial size that comes close, it is not critical in size, as long as it is slightly thinner than the original (M5) because it makes the clamping mechanism work a little smoother when covered with shrinktube.
The shrink tube has a dual function: to prevent marring of the pica rail the Chrony attaches to, and to make the moveable piece of the clamp slide easier.
So when shrunk on the bolt you want to cut the shrink tube off long enough so it passes THROUGH the hole of the moving plastic clamp part, and if your spring has a large enough diameter it may be exending into the coils of the spring, but it does not have to.
The spring lives between the locking nut on the very end of the bolt and the plastic moving clamping piece. It goes into the hexagonal recess where the regular nut used to be but of course it needs to be wider than the hole the bolt passes through, so the spring compresses when the moving part is pushed towards the locking nut.
You got to figure out the exact length of the bolt depending on the size and strength of the spring used, and how hard you want the clamping force to be while still being able to "hook" and "unhook" the Chrony to and from the picarail. (This takes a little trial and error, but when you got the right length you can saw off or dremel the end off. Take your time when Dremelling, as you must not let ig get so hot to melt the plastic pieces nor the locking ring of the locking nut! (ans of course have the whole thing unscrewed from the chrony (by means of loosening the 4 hex screws on the side of the chrony) while working on it)
You need a selflocking nut so it will not work itself loose when operating the mechanism, or due to any recoil of the airgun. (you could use a regular nut with locktite instead, but that takes time to dry and makes it more cumbersome to adjust on the fly, if your clamp is just too tight or too loose)
Now how to make it user friendly to use it incidentally on a non picatinny rail equipped airgun?...
As it turned out, the FX concave piece has 4 holes, so it seems FX maybe intended something like I envisioned, but they didn't pursue it as it was more costly for them. Anyway it made life much easier for me to draw someting up that could be used...
4 small screws are used to join the "table" to the concave FX piece, (that is where FX made the holes already for me) and 2 screws are to join the small piece of pica rail to the table. (alternatively you could glue the 3D printed pieces together)
There are no extra holes or any other permanent deformations to the original FX hardware, so If ever wanted, everything screws apart, and nobody is the wiser!
Youcan find the whole text, with more details and pictures here:
https://www.airgunnation.com/threads/new-fx-pocket-wireless-chronograph-v2.1296659/page-4#post-1624575