Rcommend piston setup that can take some serious punishment

[Adolf Hamster]

well, time to ressurrect this topic.

i'm sure @Sitting Duck will be pleased (well sort of) to hear he was right, it's blown up again.

so since this thread it had the shs piston installed and i set the etu to safe/semi/3rnd in the hope of preventing future explosions.

which worked, for most of yesterday.... (it was shooting great, to many poor victim's consternation )

so the spur gear shredded on it's smaller gear then i suspect the resulting blast of the unloaded motor meant the pinion shredded part of the bevel.

the rest of the box seems fine, piston holding up well with just a little of the coating worn on the teeth. rest of the gears are ok and none of the bearings exploded.

so i'm wondering where to turn next, sadly as i have no electrical way of adjusting the rof short of either scrapping the etu and getting a titan, or scrapping the motor in favour of something slightly less high speed, either of which is more money than i'd really like to be dealing with.

mechanically all i can think to do is swap to bushings, as the piston is full-weight, i have no headroom to increase the fps, and i had the anti reversal latch still installed. gearing wise it was stock asg so i haven't been messing with ratios.

or maybe i should just accept my fate and start putting pennies aside for a polarstar

 

[Sitting Duck]

What motor was in there or you replaced the old grey 18k/blue 24k/orange 25k ifrit with

did you drop in a SHS HT or something ???

(which is 30k 16tpa like zci balanced/speed motor)

SHS HS is a 14tpa 40k motor

A zci torque is a 22tpa aprox 22k rpm motor which would probably be up your street @ 11.1v

& dial it back a bit

https://www.ak2m4.co.uk/internal-parts/motors-parts/zci-motor-high-torque-long

if bevel was shot you could replace it with a 9 tooth one from ak2m4 instead of 10 tooth

that would dial back say 10% rps aprox making say a 18:1 now a 20:1 gear ratio

https://www.ak2m4.co.uk/internal-parts/gears/zci-9-tooth-bevel-gear

But that bevel only dials it back 10% and feel you was likely going quite nutz 

Somehow you need to dial it back a bit

My gut reaction would be grab a 22tpa zci from Pete while he has them in stock

locate a std spur from a junk box of bits that works to get gears moving

check bearing under bevel for wear/play and perhaps if iffy replace with a bushing

fit a very thin 0.1 hex shs shim or something very thin under spur/bushing

not much else or a complete new gear set to throw shimming out

though check motor height/bevel etc...

chuck it back together with a once over and gun should be less insane or not so prone to wrecking

keep old fast motor for a 7.4v build

 

[Adolf Hamster]

it's an asg 40k, with extra fancy neodynium magnets, so yes pretty spicy (and pricey, hence wanting to keep it).

i do have an shs hs motor knocking around somewhere, or potentially could pillage the g&g high torque from the f2000 (which still isn't feeding, well, not on the field at least)

i guess my choices are keep upgrading the gearset/rest of the box until it can take the punishment, change motors, or just give up and go hpa.

but then i'll be tempted to drop that motor in the mg42 and we'll be right back to square 1

 

[Sitting Duck]

High Speed Motors run at 40 to 45k rpm with a 12 tpa producing lots of heat/amps/watts

really only for say 7.4v lipo

this in a stock gun will produce at least 20rps maybe 24rps

you might be able to run on modest 9.6v which is about the same as a beefy 7.4v

but not 11.1v lipo coz increase rps by 55% or x 1.55 and you are over 30~36rps

depending on G&G motor is 18k to 25k

grey are ferrite 18k ferrite 27/28 tpa,

so is blue but slightly better ferrite magnets & faster at 24k rpm (19/20 tpa maybe)

Orange is 25k neodym likely 18/19 tpa-ish

If G&G motor is grey and gearset is totally shot with no spare spur to hand

you could drop in a 16:1 replacement set - or at least the spur which is what alters the ratio from 18 to 16

(actually it is a con, 18:1's are 18.65:1 & most 16:1's are in fact more like 17.25:1 - so 16's are a con)

but if set is totally shot 16's would be worth considering over a 18 set if buying new

you got plenty of grunt running on 11 & ratio change is very slight like about 7% quicker

if running on 18k grey which is quite slow then might be an option if gears are shagged/no spare spur

a blue/orange - hmm might not need it with a snappier motor

Twenties is plenty, when you get near 25rps you get overspin but you got AB with ETU

but still overspin if quite severe the gun is talking to ya

more overspin from worn COL occurs but if all working OK & no worn COL etc....

if a reg gun is overspinning quite a bit without AB then the gun is screaming ease up trying to push it

so really 20rps to 25rps is limit unless you did homework like Short Stroking & all that crap on UK 350 gun

now 18k motor will produce about 12~13 rps on 7.4v

11.1v will get you 20rps on std gears or maybe 21.5 on 16:1

24k~25k will get you about 15rps on 7.4v aprox

11.1v will get you about 23rps on stock 18:1's and leave it there

These a rough but fairly accurate-ish figures depending on numerous factors

how good shimming is/isn't

wiring crap 18awg to mental 14awg

spring/barrel/compression & efficiency blah blah blah

mental 45c battery or mild 15/20c battery deans & f*ck knows what else.....

but roughly give or take a round or two a second

Ya gun won't destroy itself so quick

your battery will last longer

And your gun apart from running cooler, you shouldn't need to keep picking up bits of teeth every month or so

The gun is always gonna complete the cycle due to ETU

so it is very unlikely you can spam the trigger on semi faster than 20rps in real instances

but about 20rps to 25 rps or twenties is plenty the guns just run better

regular manual AEG's are much less prone to releasing the trigger too quickly & locking in dead zone

once you get to 20's the risk of dead zone due to bad trigger discipline really reduces

you can get a bit faster say 30's with a bit of SS work m120 spring etc....

well really 35rps but you wanna always dial back a smidge to not sail too close to the PME wind

you only need one misfeed on auto/burst to clog & slow piston's return speed and BAAAANNGGGGGGG

you are picking out teeth once again - not worth it going too nutz and too close to PME limit

I'm not clever - far from it

I've just done EXACTLY the same thing as you like many on here have learnt the hard way

Clever people would have heeded good advice but I thought nah I'm sure it will be OK....

So alas I ignored sound advice and found out through my own mistakes

But then again that is what wisdom - wise after the event is all about

Learning from our mistakes & that is one thing I am good at- making lots of mistakes...

but my fav I live by....

 

[Adolf Hamster]

hmmm.

having tried running it previously on 7.4 to test for problems (which turned out to be the cutoff lever but we were just throwing everything at the wall at that point) and the rof wasn't noticably lower. it wasn't catching/overspinning.

i do have a spare spur, but being from the original king arms box it's been through the wars and then some and not in great shape.

i'm leaning more and more towards just giving up and going hpa at this point, feels like changing motors and gearsets is throwing good money after bad.

maybe keep the 40k motor for the mg, as thats a gun i would be happy doing a ss/dsg build in.

 

[Sitting Duck]

Well it is up to you - the box is in bits anyway now

What is a new 16:1 set - £15 if you ask pete direct on here pm or fb

drop in a cheapo motor not so insane ferrite motor knocking around

11.1v running sweet and still got your asg mofo to drop in another gun

Then on the other hand you mentioned a Titan - ffs that thing is more than many of my guns original cost !!!

You just chose the wrong motor for the build that you needed to run on 11.1v due to etu

it plays up on 7.4v but 11.1 on a 30k motor is pushing it

(why some Krytac's that came with a 30k motor sailed close to PME in lower spring UK guns so fitted 20k motors)

you on the other hand fitted a 40k to run on 11.1v - no wonder you wrecked stuff

you just need a 20k~25k rpm tops motor on 11.1v and you will be golden

 

[Adolf Hamster]

Well it is up to you - the box is in bits anyway now

What is a new 16:1 set - £15 if you ask pete direct on here pm or fb

drop in a cheapo motor not so insane ferrite motor knocking around

11.1v running sweet and still got your asg mofo to drop in another gun

Then on the other hand you mentioned a Titan - ffs that thing is more than many of my guns original cost !!!

You just chose the wrong motor for the build that you needed to run on 11.1v due to etu

it plays up on 7.4v but 11.1 on a 30k motor is pushing it

(why some Krytac's that came with a 30k motor sailed close to PME in lower spring UK guns so fitted 20k motors)

you on the other hand fitted a 40k to run on 11.1v - no wonder you wrecked stuff

you just need a 20k~25k rpm tops motor on 11.1v and you will be golden

Click to shrink...

the logic behind a titan is the rof control, could tone down the full auto rof to prevent explosions while retaining the extra response for semi, but as you say mega pricey.

might give another motor a try and see if it works with the bad gear, one of the reasons the asg monster is in there in the first place was because the etu didn't like the (admittedly pretty worn out) motor that was in there.

i'll have to think, if i'm going to give up and go hpa it just means the m4 will be out of action for a good while before i get the funds together.