ROF stuff
 

Ok... i'm removing two teeth from my sector gear and removing the second tooth from my piston and i'm going to run a 9.6v or a 10.8v battery.

Question is what spring would be best? I dont wanna get one to powerfull because it will decrease the ROF. But i dont want one to weak because i'll mess up my piston teeth if it doesnt return fast enough.

Anyone have experience on this?

Never heard of it. Sounds like the fastest way to label your AEG as "FUC'T", but I could be wrong.

Yes its a possibility... but we'll see what happens... i'm a gun dealer so i can get guns for $60USD and i can get new motors for only $25USD... so i'm not to worried about it.

Ok, go for it and let us know how it goes, I doubt anyone around here has heard of such a thing before, and if it works well you'd be the first to educate us on it. Best of luck!

Low rated spring. Stock spring, M85, M90 and M100. Heard of this before. FPS will drop but insane ROF. Ask players from filairsoft.com for more details.

see thats what i was thinking too... but i remember somone saying use a high rated spring so that it returns to neutral faster so you dont risk tearing up the teeth on the piston.

From what I remember. Its not for high rated spring. Piston and gear will wear out fast. So it is suggested for low rated spring. If you are really into ROF why not just upgrade to higher voltage battery. 10.8v or li-po 11.1v.

I am upgrading my battery on top of these mods....

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.

well i just finished doing the mod... took me all of 20 minutes.
Its fast... but not as fast as i'd like it to be... 10.8v battery here we come!!

BTW... this gun has NO modification other than me taking off the second tooth from the piston and two teeth from the sector gear.

I'll take some vid tomorow

i just got it to fire so fast the mag couldnt keep up... hmm

What kind of mag are you using?

The fastest feeding magazines are Marui lowcaps and Magpul lowcaps.

i'm using a star 90rnd midcap

also i forgot to mention this is an MP5

But i'm thinking it could be somthing else because the BB's just kinda start spitting out and only flying about 5 feet....

Is the rest of this gun completely stock? And what brand is this mp5?

Does it shoot okay in semi-auto? Or does it shoot 5ft only in full auto?

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

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

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:

http://www.pbase.com/illusive_airsof...842/medium.jpg

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.

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

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.

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

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

www.kinkairsoft.com/DSCF1638.AVI

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...

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.

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.

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 :D

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.

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/

Just because you install that inner barrel, it doesn't mean your velocity will go down. Your BBs will just shoot wild at the end of their effective range, although at 380-400fps.

That inner barrel is only recommended for guns that will output 1J of power (328fps). An M120 spring far surpasses that.

As for the damage on your gun, the stripping of the initial tooth on the piston suggests either:
1. The spring is too heavy and providing too much resistance against the fast moving sector gear
2. The piston is still moving too slow for the sector gear and is getting the rear teeth raked

Scenario #1 is the more plausible of the two. Although, having it run for ~20,000 rounds with that setup is pretty impressive!

Hi ILLusion,

Ah..apologies, I should have been clearer :-). When I trimmed off 3xteeth off the sector and off the piston, I've created a shorter piston stroke (therefore increasing ROF). So with the M120 spring, I'm actually getting less than 328fps...in fact I'm getting 0.96J only.

Here's what I mean :-

http://www.anakchan.com/gallery/Hobb...2_enterAlbum=0

Note only 13xteeth on the sector, and the length of 12xteeth on the piston (but spaced out to an equivalent to 13xteeth - the 2nd was removed to reduce crashes).

You're right for the reason of the crash. Even though I've taken the 2nd tooth off, I think I still run the risk of crashes. I may consider removing the 3rd tooth too (or simply run with a lower voltage battery since my mags can't keep up with the mechbox setup anyway).

Not sure if removing the 3rd tooth is a wise idea - a lot of stress would be put on the 4th tooth.

Doh! That's why the last tooth of a standard piston is metal (which I filed off). Well let's see this time if it lasts ~20,000 rounds as well. Maybe I was just lucky with the previous one (same config). After this, I'll switch over to the Angel Hi-Speed Piston/Phoenix Hi-Speed auto shimming Gears (both 12th teeth setup as standard from manufacturer).

Cheers for your advice though ILLusion!