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Incomo

cyma M14 gearbox v7 locked

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Hey everyone!

 

I've just started with airsoft and I already encountered a problem which I can't seem to solve myself.

I hope I'm posting in the right section, sorry if not :-)

 

So, I bought a nice Cyma M14 or 'CM.032' the one with the long barrel. I read some good and positive reviews about the gun, I liked the looks and it was within my budget for a first gun.

 

7e06f6eb107ef3aa95934fceffab9d5d33325a3a.jpg

 

I bought it online, coming from Poland: http://www.taiwangun.com/en/cm-032-wooden-style-cm

 

The first few days it worked as good as I suspect it should be working. I had quite some fun shooting targets and stuff. I didn't even have to adjust the hop-up; it was set well by the testing team before shipping.

 

One morning however, it just stopped working. So I took it apart! I only heard a clicking sound which later on I discovered was from the motor-bevel pushing the motor away from where the resistance came - the gearbox.

The Cyma M14 uses a v.7 gearbox which looks respectively from the outside and inside like this:

(I cleaned out the green snotty grease and use something else instead now)

 

IMAG3378.jpg

 

IMAG3379.jpg

 

a little closer on the gears:

 

IMAG3380.jpg

 

and with the 3 gears taken out (+ the anti-reversal-latch):

 

IMAG3387.jpg

 

The motor:

IMAG3390.jpg

 

Also, I have no idea what the little wedge shape is doing on the 'bottom' of the last gear:

 

IMAG3392.jpg

 

 

I use the battery that came with the package, an 8.4V Ni-MH 1100mAh (not 1200 which the site I bought it from states)

From the motor itself I have no info, only that I can adjust the motor height on it's rear end:

 

IMAG3394.jpg

 

So what happens if I close the contacts is: A short moment of noise, which I believe is the motor and gearbox spinning and slightly putting pressure on the spring. Then the 'clack' when the whole thing seems to get locked halfway through the cycle.

I checked inside to see if anything was obstructing the movement but saw nothing I could deduce the cause from.

I tried adjusting the motor height which resulted in either the idle spinning of the motor or locking the entire thing.

Also, I tried to go through the cycle with only my fingers powering the 1st gear, which was impossible because of the high torque caused by of the spring compression. (is the motor really so strong that he can overcome that? :O)

 

If there'd be an internal jam, could it be the anti-reversal latch, the tappet plate, the piston coming out of his guiding rails? it all seems unlikely when I see how well the housing is closed. might it have to do with 'shimming'? (didn't have troubles the first few days though).

I fully loaded the battery before testing again but nothing's changed.

 

 

If anyone has any ideas on what could cause this locking, I'd be so happy to hear about it !!

(I can post more info and photo's if it helps)

 

Thank you :-)

 

Incomo.

Edited by Incomo

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First off, the "wedge" on the last gear is what actuates the cutoff lever. That is what allows the gun to fire in semi auto. When you switch to full auto, the cutoff lever is moved out of the way so that it does not interact with the wedge on the gear.

 

The first thing you need to do is get a new battery. The battery that came with the gun is very low quality, and more than likely, that is the reason your gun is locking up. Go to eliteairsoftbatteries.com and pick up an Elite cell battery. They are the BEST NIMH batteries for airsoft, and they are significantly cheaper than any similar size batteries carried by airsoft retailers. I would suggest a 9.6v 3300mah pack. The slightly higher voltage will give you a bit better trigger response, and the larger capacity will allow your gun to shoot longer on a single charge. That pack lasted all day for me.

 

If the new battery still doesn't fix the issue, then come back here and we'll go from there. But right now, the battery that came with your gun is holding you back, and I highly suspect that is why your gun is locking up.

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Thank you for the fast response, much appreciated! :-)

 

In the directions from the manufacturer it says I should charge the battery 8 hours long, assuming the battery is as good as empty to start with. I'm not sure how long it was exactly that I charged + the standard wall-charger that came in the box isn't a 'smart-charger' so I might have destroyed the battery already :a-blushing:

I'll post a reply in this topic once I've tried another battery.

 

 

 

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Is that just grease on your motors gear, or are the teeth messed up already?

 

It's not grease :s they're indeed already a little dented. might have been caused by trying to adjust the motor height to the point it started slipping, hitting the gear's teeth with that very surface.

With that kind of torque and rotational speed it might have scraped that bit off in an instant. I never tried this for more than 1 second whilst adjusting the height.

The 1st gear from the gearbox seems to be the sturdy one, no dents whatsoever.

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update: it's ######!

 

Figured it might just be the battery at first. Tried my brother's battery, since he recently got an airsoft rifle himself, using the same battery type as me.

It worked... but noticed there was no real power behind the BB's continuously. The fps ranged from decent to barely making an imprint on my target to just rolling out of the barrel :s

I considered that it could be the tappet plate's faulty movement and hence the little nozzle attached to it, which might have caused the air to be pushed away through the magazine feed from time to time.

 

So I opened my gearbox once more and was stunnned what I found there. The spur gear (2nd one) missed a tooth on the large rim :a-shocked:

 

Could this be caused by bad motor height, uncorrect shimming (I never changed anything there, just the standard 1 ring per bearing from the factory), an obstructing tappet plate... (even if in the unlikely event I reassembled my pieces uncorrectly, it wouldn't explain why it jammed in the first place aswell).

I'm completely clueless and will probably be buying an entire new mechbox instead of just a new gearset.

Edited by Incomo

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