SystemA Turbo + 12V + bearings = helical hi speed gear crash!

[takatorikku]

Sugoi! buy a minigun. some of the good ones put out around 100/sec.

[Gryphon]

Originally Posted by AnakChan

Hi Gryphon, well I am new to airsoft so I don't know the physical/practical limitations, but I pick up the theory relatively fast. I just started getting into airsoft about 2 months ago - I can hear the words "go an enjoy the game first before tinkering with the components".

But by nature I like to tinker with parts, so that's a habit that's gonna be hard to break :-). Anyhow, whilst we're on the topic of physical/practical limitations, what would be the limitation? Say my goal is to achieve an ROF 30-40/sec. 10.8V? 9.6V?

Ok, fair enough! You don't necessarily need to be heavily invested into the sport if you've got a mechanical interest in things.

In all honesty, 30-40 RPS is unrealistic for an AEG because it's extremely abusive to the system. I don't see people running much faster than about 20-25 RPS (1200-1500 RPM) and even they have problems sometimes. For one, magazines can't always keep up at that speed especially hicaps and especially electric box mags. Second, the return speed of the piston/spring is proportional to the strength of the spring meaning that lighter springs don't uncompress as quickly. With a fast gear combination and high voltage battery, the sector gear will be beginning its next revolution before the piston has had a chance to return to rest against the cylinder head. Since the gear teeth are stronger than the plastic teeth of the piston this strips the piston teeth very quickly.

The solution then is to either slow the gears down by reducing their ratio with standard or torque-ups, or going to a heavier spring that will return faster. Since the gear ratio of speed gears is such that they spin faster at the expense of torque, this will put more strain on your motor and electrical system when they are under load and is very inefficient. Furthermore with high speed gears and a 12 volt battery, you would probably need to be pushing in excess of 450 fps or faster to get an acceptable spring decompression speed. Since you're using a version 2 gearbox it will crack the shell very quickly because they're not designed to handle that kind of stress.

I would try a 9.6V battery first and measure the ROF and see how that does. It will be an insane BB hose already and you'll be considerably extending the lifespan of your parts. You may even find that with high speed gears an 8.4V would suffice. If you truly want to go faster your only practical alternative are the classic guns that use an external gas rig since they don't have a complicated gearbox to contend with, and are fully capable of sustaining very high rates of fire close to what you're after.

Hope this helps, let us know how it turns out!

[AnakChan]

Hi Grypon, cheers for the tip. I think I will try the lower voltage option. I went to the store today and they recommended a few complicated options (one included filing down the last 4 teeth off the sector gear and using a hi speed piston). Makes sense but now getting complicated if I have to cut or file down metal.

They mentioned that flat gears are more durable and don't crash as easily helical. Thoughts about this opinion?

[ILLusion]

I agree with the short stroke piston option. It will greatly increase your ROF that way, and your chances of killing your gears are greatly reduced.

With a quality file, it shouldn't take you much time or effort at all to complete.

[Gryphon]

A Dremel with a cutoff wheel will accomplish that very cleanly in about five seconds.

[MadMax]

You would have to use a dremel to grind off teeth on a Systema set. They're case hardened and would probably make a mess of your file. Cool the adjacent teeth that you DON'T plan to remove by placing a damp piece of toilet paper on them when you grind off the last teeth. High speed grinding is a process which generates a lot of heat. You do not want to anneal (soften) the teeth you plan to keep by conducting too much heat to them.

After removing the teeth, thoroughly clean your gear with grease solvent. Assure that no metal or abrasive particles contaminate your new mechbox as they would greatly accellerate wear. It's good practice to thorougly clean your mechbox with each gear replacement as the gears which stripped probably cast off a lot of metal particles.

You will probably see a significant drop in fps with a short travel setup. It appears that in short barrelled AEGs, the accelleration time before the piston head closes the cylinder port is quite important. You will probably lose much of this precompression accelleration by using a short stroke setup. You will also be using the spring in it's low compression end (piston in the forward portion of travel most of it's time). Short travel setups require higher energy springs to output similar energy to long travel setups (work = force x DISTANCE).

[AnakChan]

If I pursue the short piston stroke option, would/should I stay with helical gears or move to flat?

[Greylocks]

I honestly think that unless you want to continue to butt up against some of the laws of physics, or throw away tons of cash, you really should stop trying to build a gun that cant possible work well.

There are definite limits on what an airsoft gun can do. It's a smoothbore shooting a light, round, plastic BB with air compression. What you want exceeds what the system as it is can give you. It's that simple.

Yes, there are ways to do it; all pretty much involve butchering a LOT of parts and will not work for very long.

Why dont you try and build a perfectly balanced and accurate gun that will work like a top instead? There are many good ways to do that.

This is my opinion, I just think you are wasting your time and money for a dream.

[AnakChan]

Hehehe..I've already gone through 4xSystemA gear sets & pistons (and piston heads). Actually, in all seriousness though, this is how I learn. I a sucker for details...Why and where does it crash? Why can it shoot 1000-2000 rounds before it crashes? Where are the strengths and weaknesses of helical gears (vs. flat)? Where's that "exact" balance between max features yet maintain stability/durability?

So whilst I don't have to commence my divorce settlement yet, so got some spare cash to experiment :-D.

Back to specific details though, I may try the Phoenix gears...their sector gears have some o-rings which may provide some "play" in gear meshing.

[ILLusion]

I tested a set of Phoenix gears

Don't really like them at all

They're extremely noisy and the metal is pretty soft. I'm running it in a mostly stock gun at 330fps and one of the spur gear's teeth cracked right off. There was no sign of stalling whatsoever. It still works fine, but it's just kind of annoying that such an expensive gear set doesn't perform so well. Sure, I save time not having to shim... but so what? It still performs pretty crap. I'd like to see if they really are good for as many cycles as they claim.

[Homewrecker]

Well at least he lives in Japan so the parts he's breaking don't even come close to what they cost here.
It must be nice to only have to run down the street everytime an AEG part is needed

[Greylocks]

I know, but it's still a bit senseless to toss money against the laws of physics. An AEG can only work so fast, no matter what. For what he wants, he may as well start designing mechboxes with a far higher piston capacity and built of steel.

He's doing what is called Destructive Testing with no real goal that I can see.

Creating indestructible mechboxes would be different, I know many would love to see that.

Right now, I only see a guy driving a Hummer because he can afford the truck and the gas. Sorry. All that proves is access to money and parts.

[AnakChan]

Well, Greylocks, you are entitled to your opinion, and despite your last 2 previous posts, I have been pleasant to you. People get into this hobby for various reasons and I have explained mine even though I don't really need to.

As for disposable income, yes I do have some which is my choice on how I wish to spend it. If we want to get specific about cars, I drive a Porsche C4 cab.

To -get back- to the topic, I did pick up the Super High Cycle Phoenix gears. The sector gear has fewer teeth, so no filing required. And the shop sales assistant said that it would go well with the Angel High Speed piston, but I'd need to go for an M130 equiv spring.

So that's what I'm building up now. Will update on it's status.

I truly do appreciate the technical advice I've received from various members of this forum. It has been a good learning experience.

[Gryphon]

Don't pay much attention to Greylocks. If you hang out here you'll quickly discover he rarely posts anything of value and is more often than not compared to a broken record, bleating the same cries over and over that no one wants to hear. A few years ago he'd actually contribute decent technical data as MadMax, ILLusion, and I have in this thread. Now, to quote Borat, not so much.

I'm waiting for the post where he tells you to get age verified and go to a game...

[MadMax]

How are the phoenix gears self shimming?

Unfortunately there isn't much experience here with 12v batteries and the SystemA Turbo motor, much less all that stuff and a high speed gearset. Is that the new super performance motor that SystemA just released?

I currently run a 11.1v Lipo 3Ah pack on a stock TM motor and gears pushing a 360fps spring in a P90. So far it has shown to be durable. I think I've blasted off over 10k pellets now. Unfortunately my chrony does not count rof, but I've found that a std cap mag lasts rougly 2 seconds (+/- 0.5s I figure) so that should work out to about 30ish rps. I'm not running that many upgrade parts, but I'm able to acheive a pretty high rof. I'm not sure that the "practical" limit of an AEG is all that low.

Still, it's difficult to determine how your setup is failing with the few symptoms you've listed.

What are you using for lubricant? It may be possible that your lubricant is failing at your pressure-velocity regime. Does your grease look filled with fine metal particles or is it generally clean except for larger hunks of teeth? If you see lots of fine filings, I would suspect that you are exceeding the pressure-velocity limit of your materials. If you see little evidence of fine wear particles, I suspect that you have a tooth fatigue issue so you're having a material strength issue. Do you see a funny "bite" mark in one of your piston teeth? I would guess that if the sector gear comes around too soon then you may see evidence of a bad meshing on a tooth close to the front one. What kind of wear do you see on the piston teeth?

Definitely do NOT use a tightbore barrel. If a bb jams in your barrel, it is highly likely that your piston will not return to full decock before the sector swings around to pick it up again. I don't know why this isn't an issue with stock guns, it may be because the sector doesn't move so fast in them.

Unfortunately e-diagnosis (coined by Illusion circa 2006) has very short limits. It's difficult to express in detail observed symptoms and it's also difficult to know what's important to describe. Anyone watch House (Hugh Laurie)? Imagine diagnosing an inexplicably sick patient with text only and no MRI. Damn, there aren't any pretty coworkers either. But I digress: Those limits can be expanded with very good photos, but not being to convey the very distinct sound and feel of your setup in operation is a significant problem. I have a feeling that you need to take a more gradual and systematic approach to your gun building. Dumping in all upgrade parts in one build throws a lot into the wind. In general, TM has very good mechanical engineering. They've obviously lifecycle tested their product significantly. When you dump in every upgrade under the sun, you get to find out how aftermarket manufacturers each (mis)interpret TM's original design intent. You will develop failures from the conspiricy of many small mistakes which is difficult to diagnose.

I suggest adding one component at a time while enjoying your gun in a gaming situation. Failures will occur, but you have a better chance of figuring them out as you might be able to correlate them to fewer changes.