WE scar tappet plate not resetting to correct place

[Alicks]

Hi all

 

 

I have just stripped, cleaned, re shimmed and re-assembled the V2 gearbox for my WE scar.

 

However when i have put it back together and test fired it the tappet plate stays retracted and comes forward when fired only to retract again.

 

When i put it together the plate is fully extended and can be pushed back and forward on its spring and runs along the tracks correctly ( i checked with a torch).

 

The only thing i can think of is the sector gear has quite a large molded chip on it not just the usual round peg, more like a crescent. Could this be causing the tappet to be pulled back most of the time as it is so large?

 

Or have i missed something important when putting it back together?

 

Also the piston doesn't reset to its original position at the front but stops at different stages of its run ( if you get what i mean). Is this caused my over-spin on the gears?

 

Many thanks

 

Alex

 

Edit: the sector gear's crescent looks like this one: https://www.airsoftworld.net/shs-tokyo-marui-next-generation-recoil-hardened-steel-gear-set.html

[Sitting Duck]

You do understand that nozzle retracted is nothing to be alarmed about in operation on its own....

By the time the first tooth on a 16 sector gear engages the pickup up tooth,

I would say the tappet is already drawn back 90% - at least 80% of its travel already.

By the time the piston is released - the tappet cam is at about 3:30 o'clock,

meaning it has only one quarter revolution before it begins to retract tappet plate again.

A little overspin - piston being retracted is fine but if after doing various tweaks you still are not happy

then an AB Mosfet should reduce it - but I wouldn't bother myself

If the gun is firing ok then the main problem is sorted

Nozzle retraction will happen in nigh on most guns - stop worrying about nozzle

see if piston is over well over half way retracted or double firing in semi - then you are running present setup too fast

stronger spring + SS if possible if that was the case

 

Gun fires - problem sorted - no worries

Think you will find your gun very likely retracted the tappet before you opened it up

unless AB mosfet that slows/stops the motor very quickly or you run it very slowly rof like 10rps

the box will run on a bit and retract tappet anyway

As said by the time the first tooth on sector gear engages the piston (AoE corrected btw) and just prepares to pull piston

The tappet plate is already @ 85% retraction

As guns cycle quicker with higher volts/juice, stronger motor etc... this over-run will increase

if you are pushing a stock gun into 20's you will get some over-spin and piston itself getting a little pre-cocked

If gun starts to fire twice on semi - you are pushing too much

20rps is fine with a tiny bit of over run or pre-cocking

25rps starts to over run a bit much & double fires

30rps deffo double fires and danger of Pre Engagement

so keep it moderate - to save storing gun with spring compressed or pre-cocked

use a lower/old/used battery that ensures the gun parks without piston /spring compressed

the tappet plate will be retracted in nigh on most guns unless AB or very slow speeds

[Alicks]

Thats very reasuring, cheers

 

on my other gun (the cheep CYMA keymod that you have) the sector gear only have a small pin so i have never seen a tappet plate getting stuck back before... was freaking me out as its the first time i have done my own tech stuff.

 

I took my cyma to a tech and he messed it up so badly that i have taken to doing it all my self, its still in pieces as i broke the moto connector on the wiring and keep forgetting to pick one up.

 

Will putt it fully back together tonight and put some rounds through it.

 

Didint want to put it back together only to take it appart... scars are awful on the selector switches!!

 

Many thanks

 

Alex

[Sitting Duck]

motor connector, try to strengthen the elbow - 90 degree bend with a bit of extra solder

not massive blobs - just a thin bit of solder inside n out on the bend

 

they can weaken so easily that they blow under load like a low rated fuse

or just snap when fitting to motor

 

HOLD UP THE CONNECTOR - if you don't then there is a chance solder can flow into connector itself

if that happens you won't get the bastid on the motor at all and will nee to cut & replace with another new connector

 

So fit, little crimp n solder connector, hold upwards, strengthen with a smidge more solder at the elbow - job done

(I have welded a few connectors - so like everything, we are still learning by our numerous mistakes)

[Alicks]

Good advice.

 

Cheers

[Alicks]

Fired scar up this morning and shoots like a dream. Looks like i was flapping for nothing.

 

How do you know if its shimmed and greased correctly? Is there a optimum sound i should be hearing? It has a pleasant wurring sound atm. But i dont know if this is the correct one.

 

Cheers

 

Alex

[Sitting Duck]

If it sounds like cat dying from a swarm of wasps = badly shimmed

 

if the motor gets very warm quickly the bevel is shimmed too low that the motor or pinion is ramming it against shims/bushings/bearings

though it would sound a bit rough - though a different rough sound to crap gears meshing badly....

 

remember to put a bit of grease on that poor motor's pinion too when you plop it all together

(I forgot about this but does need it the poor thing as it is going 10 to the dozen of all the gears in ya box)

 

bad shimming don't always sound rough, but motor getting warm quickly is a sign or blown fuses another

too low and you end up winding motor in more and more until the pinion is hitting the bevel's AR lugs on it

 

if it works, sounds decent = job done, I got a Galaxy MP5k once new from Poland and expected to find a dead cat inside

f*ck me it was ultra roughly shimmed - almost as bad as my first few boxes

 

chill - get out and hose some sods down - that is the real test or proof of the pudding is in the eating/shooting so to speak

 

ps - even a brilliantly shimmed box can sound like a bag of ol' bolts if the motor's pinion don't like the gears or rather bevel

I got a Dream Army motor - pah more like f*cking NIGHTMARE ARMY !!!

every box I put in sounds painful - gotta change that pinion gear one day I think

 

ya did fine if she sounds n shoots ok - really quiet smooth as silk meshing is not always easy no matter how well you try to shim everything perfectly - some gears and pinions are better/worse than others and some just sound a a tiny bit rough no matter what try

[Alicks]

Hoping to get out and about soon. But on crutches after tearing my meniscus in the left knee.

 

I have too much time on hands atm.

 

So its onto cyma m4 now.

 

Cheers

 

Alex

[Sitting Duck]

Hoping to get out and about soon. But on crutches after tearing my meniscus in the left knee.

 

I have too much time on hands atm.

 

So its onto cyma m4 now.

 

Cheers

 

Alex

 

At least you got ya gun running - so not all doom n gloom

and you got a scar to prove it - lol

 

soz - I'll get me coat

hope you are on the mend soon I mean

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Yep hoping wont b long :/