Tips Wiki Paper Clip Sheer Pin Mod
From Heli-Wiki
This is a simple mod in where you replace the original sheer pin with a small paper clip. This allows the sheer pin to do what it is designed to do, and sheer off in a crash. The original pin is supposed to do this, but I find that it is too strong for the application, and never sheers off. The paper clip is much softer metal, so it ends up sheering readily in a crash. It’s still hard enough that I have never had one sheer on me in flight yet.
What happens is when energy is transmitted to something that can’t move, or something that cannot move fast enough, it either bends or breaks. What this paper clip sheer pin does is takes some of the force when it sheers, but also makes it so the head can spin freely on the main shaft after the pin is sheered and thereby reduce the amount of bending or breaking of parts, especially blade grips, center hubs, feathering shaft and main shaft.
It’s real simple, inexpensive, and only takes a minute. All the supplies needed are in the pictures. Take a small paper clip and cut off about 9/16” (14mm). Bend a small L-shape in it like the picture. Then what I like to do is pull the head off enough that you can see the hole. The hole usually lines up with a spoke on the main gear. I hold the spoke on the main gear for reference where the hole is, and then insert the pin. After you’ve got it pushed all the way in, bend over the other side, and you’re done.
This mod is also useful for crashes caused from radio glitches or other crashes where you cannot turn down the throttle on the heli (or if you left it in idle up and forgot about it in the heat of the moment). What happens is instead of the motor binding, and then surging, and then burning out your 3 or 4 in 1, instead the sheer pin just breaks and the shaft spins inside the head. This isn’t a complete protection, though it does help. I would still recommend the fuse mod in addition to this mod.
I got this mod from Choppersrule over on RCU. One other suggestion he had was to sharpen one end of the paper clip with a dremel tool so you can get it in easier.
When the paper clip sheers off inside, you'll need to take another paper clip and push out the pin that will be stuck in the main shaft. It's easiest to do this by leaving the swash plate on, but pulling the head up slightly so it comes off the main shaft, and then just poking it through.
mrasmm
PS feel free to PM me either on RCU or RCgroups if you have any questions or comments
