can you fluff up an AOE correction

[Mr Monkey Nuts]

So, new gearbox shell arrived and is built, sits nice, shimmed nicely sounds quiet and a really nice crisp rapid trigger ...... but its only shooting 190fps (.25) with a brand new lonex 110 spring.

Air seal cylinder - head = perfect, Head- nozzle = not brilliant, but still pretty good for a moving part.

Hop up seal seems pretty good no obvious leaks, (how do you test the hop up seal?) the pressure of air leaving the gearbox feel the same with barrel or without barrel.

Piston ring is new and seal well, gears are good condition, motor is a guarder infinity torque all running on a 7.4v 25c lipo, full of juice through 16g wire.

Now I did do an AOE correction on the instructions of the youtube video, I used rubber tap washers with a nice large bore, and needed approximately 5-6 mm correction, 2 teeth lost and almost perfect engagement.

The cylinder also has a large bore hole/ inlet approx 2/3 of the way down (430mm barrel) so by moving the cylinder head space in by 6 mm i have lost a fair amount of compression volume, could that account for 150+ fps loss? or have i fluffed up the AOE? is the rubber too hard?

Finally, when shooting on semi, the piston never returns to the same position and never to The head without the spring having a degree of compression.

I cant get another standard uncorrected piston until tomorrow, but do have a spare ASG ultimate cylinder I could try tonight.

I'm getting fed up now, it started fun, now I am getting bored of it very rapidly. I should have just bought a recoil and left it alone.

Opinions please? What am I missing? What have I fluffed?

 

[Samurai]

You can test the airseal between the GB and the hopup by plugging the hopup's bb feeding part (with your finger) and taking the end of the barrel in your mouth and blowing air in it. Best done with the GB and barrel removed from the gun. If not, it looks silly. Disengage the AR latch before doing it so the nozzle and the piston is in a forward position.

 

[RR01]

I think you've answered your own question. By loosing two teeth you have shortened the stroke quite considerably. I've done an AOE correction on one of my M4s and used very thin shims (about 1.5mm)(between the piston and head to achieve the correct result without having to cut any teeth. As you also have a vented cylinder you have probably dropped the volume of air under compression by maybe 25%, which should account for your loss of FPS.

 

[Mr Monkey Nuts]

now you have said that, I can remember reading it somewhere before. hop up seems to seal ok, a bit of a leak but a lot of resistance, so im happy with that for now untill i can get another mapleleaf hopup rubber.

Another thing I have spotted is the nozzle is always compressed and solid after shooting semi, is that normal? i never noticed it before. almost like its pre-cocked.

Do i need a delay chip maybe?

 

[AK47frizzle]

Like RR01 said, it's the teeth cut off, you've shortened the piston travel distance a lot.

190 fps with .25 is probs 240 with .20g, so it seems about right.

All you need now is a stronger spring.

 

[Sitting Duck]

AOE will not lose much overall fps - maybe 10 to 15fps

you never really lose any teeth like in short stroking

The first tooth on sector still picks it up at initial large pick-up on piston

The sector continues to pull the piston back and engages perfectly fine on the other teeth

even though the second tooth is missing and the 3rd tooth is shaved a little or a bit lower

The sector gear still picks up on the 4th tooth and continues on its merry way

What you have lost is the start/final resting postion of about 5mm from AOE

The actual piston is still being pulled back by 16 teeth on sector gear but the start/return is shorter

it isn't quite the same as short stroking which if you chop off 1 tooth that 3mm tooth is when the piston

is at its highest tension point and you do lose 15fps easily on each last tooth or two

From what you are saying it sounds like a mixture of seals on hop/nozzle perhaps

plus the cylinder is maybe for a 300 to 363 barrel

you say you have a 430 and I feel barrels in the 450mm region is getting close to max reliable

propulsion of air on a "normal" cylinder - 500mm + requires bore-up or the longer 19 teeth cylinder/piston

So feel that a 430 barrel would of needed very close to a full or very nearly full type cylinder

This build is made more difficult as it is a clean fresh build and still a lot of parts may not be perfectly suited

nozzles just on M4's vary anything from say 20.5mm to 22.5mm and that alone can be totally messing ya up

Worst thing is you got no fall back on how it WAS running ok-ish as in a box you are tweaking or upgrading

So a complete new build can be far more prone to compatibility problems than a previously tweaked one

Cylinder Ratio can leave you to lose about 60fps but as you are so way way down me thinks it is probably

also seal related to be that far out perhaps as well

Take all this crap with pinch of salt coz I am still learning as I go and very much a humble noob myself

 

[jcheeseright]

I'm with Sitting Duck on this one, with a 430mm barrel you probably want a full cylinder.

 

[Sitting Duck]

The cylinder also has a large bore hole/ inlet approx 2/3 of the way down (430mm barrel)

that is perhaps one area to look into on a 430mm barrel

really think ports should be futher back or full if ya did AOE and lost a little bit of final air compression

 

[Samurai]

By correcting the AOE you need to cut the second and maybe the third tooth, keeping the first.

 

[Mr Monkey Nuts]

Seals was the first thing I tried, they all seem to be pretty good. Certainly better than my g&g was and that still managed 320. I have a good rubber in my GHK so will strip that out tomorrow.

With the full cylinder in it's still only 210 FPS on .25

Tomorrow I will take the pads out completely and try again. And I may drop a 363mm barrel in to see of that makes any change. I may also back off the shims slightly, it may be slightly tight.

Thanks for the input so far, keep them coming!

 

[Sitting Duck]

Ya Lonex m110 should be putting you way over the normal 360fps-ish on .20's

(they are a quality spring - must be coz Lozart uses them - lol)

So that spring should be giving you out of this world propulsion really

(can't convert say 370-ish might be on 0.25's but gotta be near 300 min)

The whole Cylinder - Barrel volume Ratio is at best like an Oen University Maths course

even them quick calculator prgrams seem open to flaws & misinterpretation

each tooth is about 3mm in pitch so the full stroke would be about 48mm

(yeah maths bit of 2xradius x Pi x length is giving me a f*cking headache too)

plus all this is only ever a rough guide coz weird curveball setups present themselves now n then

Suppose why experienced GunSmiths stick to a certain "tried n tested" & compatible parts list

That optimum barrel - cylinder ratio setup is so easy to upset & go out of balance

with too much/little air volume giving you really f*cking odd weird results

Double check everything - sounds silly but ensure tappet spring is on correct way

pointing down to switch as it can drag on tappet plate if installed upside down

as you tried a full cylinder maybe see if you have a tiny slightly longer nozzle

or compare to nozzle especially how well it seals when pushed fully home into hop-up

try a shorter barrel too - soz to add more crap to try out but may produce different results

and then based upon these people may be able to accurately narrow it down a little more

(people way way way more experienced that this noob)

 

[Lozart]

I use shs super shooter springs but yeah an m110 should be giving plenty of power.

 

[Mr Monkey Nuts]

righto, its been stripped and tweaked, various cylinders, different hop ups and rubbers, different cylinder ect all to with minimal changes to the FPS.

However it just dawned on me I don't think its a compression issue, but a drive train issue. the tappet plate and nozzle always seem to be compressed even after shooting semi auto. Also when the gearbox is closed up it feels a lot of resistance on the nozzle and is slow to return foreward.

I opened it up after a few shots on semi and found it like this:



It looks like the tappet plate is just bending upwards and not pulling back as it should. I have tried a different tappet plate and another set of gears and it keeps doing it.

Ideas?

 

[jcheeseright]

can your tappet plate physically move any further back? looks like it's getting caught on the cylinder head.

 

[Mr Monkey Nuts]

Yes it can. the problem was it was misaligned, The spur gear was shimmed a smidgen too high, causing all the other gears to be too high, causing the tappet to rub against the GB shell, a re shim and a small amount filed off the tappet plate arm and it now moves freely in full range.

Still only 250fps. I'm done, all out of ideas and flips to give.

 

[Lozart]

Nozzle looks wonky too. Are you sure the nozzle is seated properly on the tappet plate?

 

[Sitting Duck]

nozzle does look a tiny bit pointing upwards as Lozart said

That is a QD box with microswitch, normally sold as complete units

though you can buy a bare APS box with 8mm bearings

Just saying coz you are trying to install parts that may or may not be truely compatible with that particular box

I would like to see a shs tappet/nozzle and "maybe" head in there as they are quite good all round cheap bits

that seem so far go in very well in most boxes.....

Yeah the tappet getting mashed like that ain't good - me thinks nozzle might wanna be a tad longer

(just coz nozzle length looks ok but the box or end of box "could" be sited sat 0.5mm further back

so you may be losing a good perfect seal on bucking)

check what others said about checking for absolute airtight seal on nozzle to hop

BUT you are getting there - now up to 250 - bastid new builds

 

[straffham]

Is the tappet plate new? And is it able to slide right to the front of the gearbox shell wall? I had trouble with an SHS one where the plate which catches on the cam on the sector gear was too large/wide, so in its rest position (against the sector gear axle) the front face where the nozzle sits wasn't quite at the front of the gearbox hence the nozzle wasn't sealing against the hop chamber. I had to file the tappet plate slightly allowing it to sit further forward which cured the problem (a longer nozzle would probably solve the same problem, if it that).

 

[straffham]

That is a QD box with microswitch, normally sold as complete units

though you can buy a bare APS box with 8mm bearings

Just saying coz you are trying to install parts that may or may not be truely compatible with that particular box

The ZCI shell does take standard fit parts aside from the fire selector and trigger mechanism (though microswitch is a std electronics part).

Problem is different manufacturers standard parts are not standard: for instance SHS tappet plates are slightly different to say G&G, which are slightly different to TM and so on, and the slight differences can add up over several components to the extent of affecting air seal right up to not being able to function due to parts jamming etc. Parts should all work together but its not always the case annoyingly.

 

[Sitting Duck]

is why I said a new build is perhaps the biggest bollock ache

at least if replacing old stuff and its crap after new parts, you can re-try the old stuff

(then compare new part to old (wise to check any bits before fitting I guess)

On a new build there is no 101% guarantee all $hit will work well together

tappet plates - had to trim one at back coz it came very close to hitting bevel gear spindle on a crappy SRC box

soz - got it wrong - SPUR gear not bevel - that thing majig one in middle I call it

nozzles - jeez there is loads of tiny discrepencies M4's can be 21 to 22 with a bit either way

but think SHS M4's are about in middle @ 21.47mm

(AK short 19.5 to AK long 20.5)

poor sod - I do not envy him one bit coz major trial n error but he is making progress it seems