New piston jams against sector gear!
 

Alright, I've been playing with this for hours now and no luck. I've searched a bunch and lots of people have similar problems but they aren't quite the same, so they haven't really helped.



I've got a v3 gearbox (AK) and the stock gears and piston just went on me. I bought a set of King Arms Normal Torque Flat gears. Also grabbed a Modify Quantum piston (That's the one with the full metal teeth).

What happens is as soon as the teeth on the sector gear touch the teeth on the piston, it all locks up. With the gearbox apart everything moves nice and free.. I even put all the parts into the right hand side of the gearbox to see if there was a difference, but it still ran smooth.

I've tried shimming how I normally do, shimmed left, shimmed right, didnt shim at all, same deal every fking time.

It looks like the teeth on the sector gear try to push the piston up against the top of the gearbox and that's how it's jamming. No idea why. The stock piston works fine with the new gears.



So, what the hell? :confused: Any suggestions?

Amos Airsoft how to: AOE and the ARS MASK kit! - YouTube

Part of the way through this I talk about checking the angle of engagement... That'll be what you need to do.

Hm, interesting, but I don't think that's the problem either. On the Quantum piston that tooth is actually already removed and thus the engagement angle is perfect.

http://arniesairsoft.co.uk/news2/wp-...5/image147.png

You may be locking up on the 2nd last tooth, go through the gear motions like in the video.

The piston may be too far forward in it's resting state, take the spring out and leave the piston in. Then rotate your sector gear and actually LOOK AT what's causing the jam.

You aren't trying to run a full tooth sector gear with a half tooth piston, are you? Would explain the piston getting shoved up into the top of the mechbox as soon as they start to mesh....

Yeah. I did. As I said, what seems to happen is the teeth push the piston upward a bit and it seems to get jammed against the top of the gearbox shell.
Like I said it all works perfectly smooth with the gearbox shells apart, only does this once I put it back together..


I don't think so. The piston has shorter teeth but it's not a half tooth. That picture above isn't a very good angle but the strip of steel that goes alongside the teeth is actually even with the crest of the piston teeth, not the root. The sector gear rotates freely through the half rotation where the teeth don't touch the piston and I did make sure I had it shimmed so that the teeth lined up properly left to right.

Yeah....that might be causing the problem. It's acting almost like a half tooth piston. That strip of metal is way too close to the gears and might be jamming them up. Not much tolerance for where the sector gear sits on the teeth.
It would be much better if that strip was flush with the piston, not the highest point of the teeth.

The pic above is what I thought I saw which is here:

http://www.airsoftgi.com/images/airs...ntPiston_A.jpg

Which requires a half tooth sector gear (unless the teeth are wide enough and offset on the piston to accomodate the full width gear.) This is one of the many issues people come across with mixing various brands of parts together.

Maybe I'm just mis-reading things?

Well, like I said with the sector gear turned so the teeth are down, it seems to rotate okay and the teeth seem to engage without touching the metal strip. I just tossed in another piston I had given to me along with another gun, and although the teeth on it are worn, it seems to jam the same way.:(

Oh, I should add, it isn't advertized as a half tooth, and the sector gear I am trying to use is the same width as the stock one and the modify torque set I have.. not even the modify gear works with the modify piston. >.<


Could something be wrong with the shell???

What brand of gun, what FPS, what motor, what battery are you using?

It's an src gen iii pro, aiming for 420 fps with a g&p m120 motor on a 11.1 lipo 1600mah 25c.

If you are wondering whether the motor and batt are just weak, I doubt it.. but I can't even get it to pull the piston with no spring at all, so.

the quantum piston is _supposed_ to work with full tooth gears.

are your guide rails smooth (enough)? ...if things are a little rough use some lube (that's what she said).
I've seen (although my google-fu is failing me atm) some v3 users glue a spacer to the top/back (open side) of their piston to stop it from binding.
G&P m120's aren't the torque-yst motors around. if you have something else on hand, give it a go (although that lipo probably fixes that).

you could probably just bring it to a tech nearby, if not just for a fresh set of eyes.

Heh, yeah, its a cheap motor but I wanted something with some speed.. but that doesn't even matter here because it won't even pull the piston with an m90 spring. As soon as it engages the teeth you can feel it lock up. It pushes the piston up and even when I go to open the gearbox it is hard to open because there is so much force pushing back down on the sector gear. It's almost like the teeth on the piston are a little too low, or the gear is a little too high. So confused...