sector gear catching piston on return cycle V2 gearbox

[Whambham]

hi guys does anyone know how to solve an issue i have

the AOE is set up correct

the gun fires the sector gears pull the piston back and realease the piston on the last tooth

the piston shoots forward

but the sector gear on returning to the first position for the next shot clips one of the First teeth on the piston before the cycle is complete

thus instead of the sector gear going clock wise makes an anti clockwise cycle before the anti reversal latch catches it but not before the last tooth of the sector gear hitting the back of the pistion first tooth .

[Bachelarius]

Re: sector gear catching piston on return cycle V2 gearbox

It's called pre-engagement, you need to either fit a heavier spring, short stroking the gearset if necessary and work on making it easier for the piston to return, so lightening it by getting rid of the bearing or replacing that stupid massive marui style lump of metal that the piston head screws into with a regular, lighter nut and/or by swiss cheesing the piston if necessary.

Check that the piston moves smoothly in the case and it's not wedging or catching on the rails and apply a thin layer of lube to both piston rails and the tracks on the shell.

The piston needs to find it easy to travel AND be light to enable quick direction and speed changes (think back to physics lessons on momentum and acceleration and F=MA etc)

[Whambham]

Re: sector gear catching piston on return cycle V2 gearbox

awsome il stick in a heavyier spring .

[Kaladyr]

Re: sector gear catching piston on return cycle V2 gearbox

Just bear in mind that a heavier spring will increase your muzzle velocity, so make sure you don't go over limits.
If you do shove in a heavier spring then you could short stroke by a tooth or two to maintain the same muzzle velocity and that will ensure your piston is resetting fast enough.

[deanfirst]

What rating is the spring? M80?
Are you running a high speed setup?

[Whambham]

Re: sector gear catching piston on return cycle V2 gearbox

its an CA mp5 sd dont know what the old spring rate was but it was more than m100

it already has one tooth removed from the piston i belive it started when i changed the speing guide to a bearing one changed the piston to an poly one and the stock spring was very stiff so i changed to a m100 to be site safe and thats when the issue happened so il chanage the spring back .
the piston and no bearing and its a poly one also on that and its greased so must be the spring

motor is a CA high torque standard gearset

[sj_asc]

Re: sector gear catching piston on return cycle V2 gearbox

Corresponding tooth must be removed from the sector gear if you take from the piston that affect its stroke. With single sector gears this should come from the initial catch side (pick up tooth).

AoE optimisation is not the "be all, end all" mod for high speed, it simply remedies one of the many issues that show up a lot sooner when you up the cycle rate. Short striking must not be done without taking the spring rate in consideration and it's ability to keep the piston assembly in time. Cylinder type, in addition to barrel length and hop setting are also key areas that need looking over as they all affect the above. (posing from the dam phone again, sorry if a bit vague)

[Whambham]

Re: sector gear catching piston on return cycle V2 gearbox


Bit of an update i put in a stronger spring about m120

and swiss cheesed the piston

no pre-enagegmant on full auto but pre engaement on semi.

no i think its the motor even though its a Classic army high torque motor

i dont really want to go down taking teeth off the piston and sector gear unless its absolute.

could a stronger motor fix this

[BioSniper]

Re: sector gear catching piston on return cycle V2 gearbox

I notice that nobody has asked but:

How are you determining that you are suffering pre-engagement?
Is this a high ROF build? If so, how fast?

At normal speeds that people consider high (~25) with an M90 I've never seen pre-engagement so you are either running VERY quick, or your piston isn't returning as fast as it should.
Have you tried moving the piston in an empty but screwed together gearbox housing? You may find something like your piston guide rails are too wide (horizontally or vertically) and would be worth checking before you go modding the sector gear

[Whambham]

Re: sector gear catching piston on return cycle V2 gearbox

no its not a high rate of fire build

i have slided the pisiton and its not catching anything.

if i turn the piston upsite down and look at the teeth the middle teeth have marks on the oposite end of the tooth were their should be no pressure from the gear.

and when i press the trigger and fire in semi i can see the sector gear and spur gear go clockwise then anticlockwise on the return of the piston

[Kaladyr]

Re: sector gear catching piston on return cycle V2 gearbox

Have you left out the anti-reversal latch? Sounds distinctly like it, or that either that or the catches on the bevel are worn beyond use.

[Whambham]

Re: sector gear catching piston on return cycle V2 gearbox

nope the latch is brand new with the spring and with the gearbox open if i spin the spur gear the ant reversal latch works fine in thinking it might be a little bit of overspin im using a 9.6 volt and a high torque motor i might change it for an ics3000 ive worked on a few gearboxes but a CA mp5 has got to be the worst

[Kaladyr]

Re: sector gear catching piston on return cycle V2 gearbox

If the AR latch works then you shouldn't see the gears spin backwards. It's not binding on the spur gear when all closed?
A proper high-torque motor should be less likely to over-spin than a non-torque motor...

[Whambham]

Re: sector gear catching piston on return cycle V2 gearbox

well ive checked the weight of the old piston its 14 gramms new one was also 14 gramms worst thing is its causing the tappet plate to jam also as the sector gear goes backwards

[deanfirst]

Put both piston side by side, see if they are different in length.
I have a blue piston before, it's about 2mm longer than the Marui standard ones.

By the way I have a ics turbo3000 for sale.