ROF stuff

[CDN_Stalker]

Originally Posted by ILLusion

It's actually a pretty popular technique in Asia for their insanity-ROF guns. There are certain limitations you can push a gearboxes ROF before you start murdering the teeth. The solution is a short barrel (to allow a cylinder that's ported), removing final teeth on the sector gear, and possibly removing piston teeth (as required.) The result is a shortened piston-stroke. Less movement required = higher ROF. Pretty simple concept.

When you do this, consider the length of your inner barrel and where your cylinder port is. You may be able to remove more teeth off your sector gear. Or you may already be removing too much. Find out where your port is, where the piston head will be when compression begins, and which teeth are still connected between the piston and sector gear at this point. The teeth beyond this release point can be safely removed.

Yes, using a heavier spring will return the piston to battery faster - in normal guns. But when you begin to reduce the piston stroke, that can make up for issues of raking teeth. To be honest, I *think* you may be able to get away with a stock, M80 or M90 spring with such a setup. I'm not 100% certain as I don't have any hands-on experience, I only know the theory.

Easiest way to find out is to just pick the FPS you want, set it up and see if that ROF is acceptable to you. If it's not, reduce the spring tension till you find the velocity you like, run it for a couple thousand rounds and then check the piston teeth for any excessive wear. Biggest signs are the first three connecting teeth of the piston. (negate the 2nd one in your case since you're removing it.)

I'd actually recommend keeping the 2nd tooth intact. If you see it getting chewed up, then your ROF is too high for the spring. See if you're able to shorten the stroke more, and if not, then you should upgrade the spring rather than remove that 2nd tooth.

Fair enough, will add the info to my "knowledge base". Lol, thanks Bri.

[ILLusion]

Originally Posted by Down-side

yes the rest is completely stock... its a WELL MP5. And it shoots ok when its on semi.

Okay, if that's the case, then it sounds like you may be suffering from an extreme case of barrel suckback.

Ventilate your piston head to alleviate some of the barrel suck and report back on the progress.

FYI, piston head ventilation:



I don't know if Well guns come with pre-ventilated piston heads. If not, drill out the face so that the o-ring has ports to inhale and exhale. It will relieve the compression chamber of a vacuum on drawback, while providing a better seal on compression during o-ring expansion.

[Down-side]

Yup the well piston head is already ported exactly like the one picture above.

[ILLusion]

Did you remove the FIRST two teeth of the sector teeth or the last two?

If you removed the last two, you will need to advance the timing of your tappet plate. The tappet plate won't be chambering the BB before the piston is released if you removed the last two teeth.

[Down-side]

the last two.... I'm gonna fire it some more and see what happens... it shoots fine with a smaller 8.4 battery... but the bigger 8.4 seems to make it wanna mess up... i'll go mess with it again... video tomorow hopefully

[Down-side]

heres the video of the gun firing with my AK 8.4v battery.... it needs to be faster!!!

www.kinkairsoft.com/DSCF1638.AVI

[LUTNIT]

What ever happened to max highspeed gears, sector gear clip, systema turbo motor, and a 14.8V LiPo? I think it was Madmax that took a CA249 with no mods other than a 14.8V LiPo and his rate of fire was MUCH higher than that in the video (and his piston stripped after less than one boxmag I think.

[Down-side]

Originally Posted by LUTNIT

What ever happened to max highspeed gears, sector gear clip, systema turbo motor, and a 14.8V LiPo? I think it was Madmax that took a CA249 with no mods other than a 14.8V LiPo and his rate of fire was MUCH higher than that in the video (and his piston stripped after less than one boxmag I think.

umm... what?? obviously 14.8v is gonna be WAY faster then 8.4v... like i said i'm going to be getting a 10.8v battery soon. I'm not looking to impress anyone or break anything.... i just want it to shoot really fast...

[ILLusion]

It sounds weird. It sounds like there's no anti-reversal latch installed!

It's also not as fast as I've heard before.

My guess on why full auto isn't working is still because the BB isn't chambered properly before the piston releases. You need to advance the tappet plate engagement and release... or just get a new sector gear and remove the first 2 teeth, rather than the last 2.

[Down-side]

Originally Posted by ILLusion

It sounds weird. It sounds like there's no anti-reversal latch installed!

It's also not as fast as I've heard before.

My guess on why full auto isn't working is still because the BB isn't chambered properly before the piston releases. You need to advance the tappet plate engagement and release... or just get a new sector gear and remove the first 2 teeth, rather than the last 2.

There isnt an anti-reversal latch

And yes i know its not super fast... but its only running on 8.4v

And yeah i gotta buy the sector chip or try and build one myself.

What would removing the first two teeth do? Looking at it, it doesnt seem like it would make it shoot any faster than it did stock.

[ILLusion]

Originally Posted by Down-side

What would removing the first two teeth do?

The same thing as removing the last two teeth, except it happens at the beginning of the cycle, rather than at the end. That keeps you from having to mess with sector timing.

[Mud Gunner]

Originally Posted by ILLusion

Okay, if that's the case, then it sounds like you may be suffering from an extreme case of barrel suckback.

Ventilate your piston head to alleviate some of the barrel suck and report back on the progress.

FYI, piston head ventilation:



I don't know if Well guns come with pre-ventilated piston heads. If not, drill out the face so that the o-ring has ports to inhale and exhale. It will relieve the compression chamber of a vacuum on drawback, while providing a better seal on compression during o-ring expansion.

If you want to do this with a drill, do either four or eight and try to space them out evenly as possible....A little tip I thought I would share...

I can see you with one of these, you'll also be the guy carrying 12 hicaps wehre most carry 12 lo's

[Down-side]

Originally Posted by ILLusion

The same thing as removing the last two teeth, except it happens at the beginning of the cycle, rather than at the end. That keeps you from having to mess with sector timing.

Hmmm doesnt seem like it would.... because you want the sector gear to release sooner... not grab later... but i'll give it a try.

[ILLusion]

Originally Posted by Down-side

Hmmm doesnt seem like it would.... because you want the sector gear to release sooner... not grab later... but i'll give it a try.

Release sooner, grab later, what's the difference? Either way, the piston stroke length is shortened.

If you have 16 teeth and you remove 2 teeth, you end up with 14 teeth regardless of whether you take it off the front of the sector or the back. If you remove 2 teeth off the front, a 14 teeth sector gear is not going to make the piston travel 16 teeth.

In a semi-auto condition, yes, your piston is picked up earlier and released earlier than my scenario - you get faster initial reaction time. But how much faster? However much time it takes for the piston to travel the distance of two missing teeth, which doesn't equate to much at all. Barely a fraction of a second.

In my scenario, however, the cycle occurs later than your scenario, but doesn't have to deal with the timing issues related to the tappet plate, chambering of the BB, and piston release times. It's a more reliable setup because the air nozzle has time to settle and prepare for fire. Yes - semi-auto shots in this scenario don't release that fraction of a second faster than your current setup. However, my suggestion for this method is to support a setup meant for high ROF movement.

If you fire 500 rounds, the sector gear isn't going to spin faster if you remove 2 teeth off the front or off the back - the ROF stays the same, and so does the piston stroke length. The ONLY thing that's different is the cycle event timing.
In fact, the ROF should also be the exact same as a bone stock gun using the same battery pack! You haven't done any upgrades yet to increase your ROF besides using a bigger battery pack. The only thing you've done is performed a modification to *support* high ROF upgrades. You haven't done an ROF mod yet.

This is the purpose of removing teeth - to shorten piston travel. NOT to make it release earlier or pick up later or whatever, and it's definitely NOT to get higher ROF. However, it HELPS in achieving higher ROF through other modifications. It is a pre-emptive modification performed to prevent the destruction of internal components during extremely high ROF setups.

Shortening piston stroke does NOT equate to faster ROF. It only facilitates the modifications you would perform to get higher ROF - it prevents stripping and clashing of the gear/piston teeth. REAL rof upgrades are high speed gears, high speed motors, ball bearing bushings and bigger power supplies.



What I'm saying is: check where your tappet plate is when your piston is released. Has the knob on the sector gear released the tappet plate by then? Will the tappet plate return fast enough before the piston is released? Is it in battery with the BB chambered?
Run through the cycle manually. Take out the springs so you can watch the basic mechanical action without tension.

If the timing is close, it's hard to tell if the tappet plate spring is faster than the forward motion of your piston, and it's possible that the piston is firing off before the BB is fully chambered. Instead of worrying about this end-of-cycle timing, this is why you start the piston draw late and end at a normal time - rather than start the draw at normal time and end early. Changing the front is less complicated than changing the back, because there are less things happening at that time.

The chambering happens during the piston wind up. The firing occurs after piston release. Watch where these events occur in the rotation of the sector gear.

[AnakChan]

My setup on my CQB P90 :-

- 3 teeth taken off sector
- 1st (or last depending on how you look @ it) 3 teeth taken off piston
- 2nd (or 2nd last, depending on how you look at it) tooth taken off
piston
- SystemA Turbo motor
- SystemA M120 spring
- 11.1V/2150mAh LiPo
- Tanio Koba inner barrel to reduce FPS to legal Jpn limits

Setup ran fine for 6xwhole day games (approx 18-20,000 BB's?) before piston gears stripped :-

http://www.anakchan.com/gallery/Hobb...2_enterAlbum=1

Agreed mags couldn't keep up with mechbox setup. Actual ROF was as high as 34/sec but would love to test ROF from sound :-

http://www.airsoftmechanics.com/home...nt/view/24/30/