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societyofrobots
07-04-2009, 06:35 PM
I'm working on a project this weekend and trying to CAD a gun into it. But I can't seem to find weight or dimensions of the *small* airsoft guns you guys used (the ones meant for RC tanks).

Also, how much volume and weight would say ~50 airsoft rounds be?

Hope someone can help!

lnxfergy
07-04-2009, 07:54 PM
Rounds are easy: 6mm each (there's gotta be an easy formula for a 3d array of them...), and typically most people are using the .12g weight.

As for the guns, I've found that the weight, minus hoppers = ~100g.

I have a rough Autodesk inventor 3D model of the guns... I could probably export it for you if I know what cad modeling system you are using.

-Fergs

07-04-2009, 07:56 PM
This is from the green Mato Toys tank gun - excluding barrel (since mine are just bic pens...)

These are complex shapes, but hopefully I'll give you enough to do some justice.

Weight: 70-81g (measured 4 guns)

Measurements from a couple guns _roughly_ averaged. These photos are GINORMOUS to preserve detail on both handwriting and gun pics. The gun pics cover-up the measurements, but that's so you can see where the points lie on the gun. Then there's just the measurements separate.

http://www.jlrdesigns.com/4sor/

Weight and size of BB varies by quality, type, and manufacture.

Typically, 6mm (.24Cal), but figure ~6.02 - 6.04mm. From that, you can figure out the volume, I'm sure. :)

Weight will vary from .12g to .88g. You'll be shooting .20-.24 or so. Nothing too much lighter. See: http://en.wikipedia.org/wiki/Airsoft_pellets#6_mm_pellet_weights_and_their_usag e

societyofrobots
07-05-2009, 09:00 AM
Both of you guys are amazing! =)

And actually, I *do* have Inventor. What version you using? (so that I know if its compatible with my v7 at home, or 2010 at work, as v7 can't read 2008 and above)

And two more questions. I know it'll be obvious if I had it in my hands, but I'm still in the design phase so I haven't made any purchases yet . . .

1) What does it take to fire a round? Would say a simple mosfet be all thats needed (single direction motor), or would I need a driver to reverse the motor? Does it have/require position feedback, or does it just relock/reload automatically after rotating a bit? Its just one motor that does it all?

2) How/where do rounds get loaded into these guns? I don't see an 'ammo-in' location =P
I read something about hoppers, but I also remember seeing gravity feeders, too. Can a feeder be purchased, or should I make one?

thanks!

lnxfergy
07-05-2009, 10:23 AM
Both of you guys are amazing! =)

And actually, I *do* have Inventor. What version you using? (so that I know if its compatible with my v7 at home, or 2010 at work, as v7 can't read 2008 and above)

And two more questions. I know it'll be obvious if I had it in my hands, but I'm still in the design phase so I haven't made any purchases yet . . .

1) What does it take to fire a round? Would say a simple mosfet be all thats needed (single direction motor), or would I need a driver to reverse the motor? Does it have/require position feedback, or does it just relock/reload automatically after rotating a bit? Its just one motor that does it all?

2) How/where do rounds get loaded into these guns? I don't see an 'ammo-in' location =P
I read something about hoppers, but I also remember seeing gravity feeders, too. Can a feeder be purchased, or should I make one?

thanks!

I'm actually still using Inventor 6.2 cause it runs really well on my laptop :) http://forums.trossenrobotics.com/datacenter/cad-files-5/tank-gun-inventor-part-142/

The motor only runs in one direction, it pulls back a plunger, and then a series of partially-flat gears allow the plunger to be released. I'm currently using an SN754410 to drive the gun since that's what I had on my board, but a mosfet would work as well. Position feedback = sorta. There is a switch that gets hit when the plunger fires the round. As for reloading, as the plunger pulls back, it opens the chamber to let another round in.

The rounds just enter right in the top of the gun, right behind the barrel. Most of us made gravity-feed hoppers out of tic-tac containers (see gdubb's gallery) or end-mill containers (see manny's CLYDE thread).

-Fergs

societyofrobots
07-05-2009, 12:47 PM
Hmmmm so that gun is ridiculously huge compared to my robot. Or my bot is ridiculously small . . .

Do you guys know if they sell guns smaller than this, or is this the basic size? I'm willing to accept a shorter range . . .

Considering its airsoft and no space is needed for combustion, any reason not to cut off 75&#37; of the barrel?

I think I'll just have to buy a gun and play with a bunch of ideas for ammo feeding. I have a lot of ideas, but worried about jamming . . .

lnxfergy
07-05-2009, 12:54 PM
I'm thinking your bot is crazy small.... Don't forget you'll need enough body space to hold your target plates, in such away that they wont collide with your legs...

-Fergs

ScuD
07-05-2009, 12:56 PM
I have plenty of ideas for small sized weapons, but they involve CO2 which puts me in the hardcore class.

Not a good thing ;)

Then again, chances of making it to the games are pretty slim, so I might as well build a few of these ideas anyway..

07-05-2009, 01:17 PM
Hmmmm so that gun is ridiculously huge compared to my robot.

What are you actuating the bot with?!?! Not hobby servos - the gun is < 3 5995's in volume...

societyofrobots
07-05-2009, 01:31 PM
What are you actuating the bot with?!?! Not hobby servos - the gun is < 3 5995's in volume...
You guys are forgetting I'm a skilled mechanical engineer :tongue:

The entire robot is designed to work on micro servos, and even smaller DC motors :veryhappy:

I made it small to keep the weight low, hence I can use smaller servos, hence smaller batteries, hence everything much cheaper :veryhappy:

And I run stress analysis simulations to shave every unneeded ounce of weight off . . . the entire thing currently weighs in at 2lbs and costs ~\$800. At least the current design!

Unless I can find a smaller gun, I guess I'll have to redesign it a bit . . .

ScuD
07-05-2009, 02:15 PM
This thread is worthless without pics!! :D

lnxfergy
07-05-2009, 03:44 PM
You guys are forgetting I'm a skilled mechanical engineer :tongue:

The entire robot is designed to work on micro servos, and even smaller DC motors :veryhappy:

I made it small to keep the weight low, hence I can use smaller servos, hence smaller batteries, hence everything much cheaper :veryhappy:

And I run stress analysis simulations to shave every unneeded ounce of weight off . . . the entire thing currently weighs in at 2lbs and costs ~\$800. At least the current design!

Unless I can find a smaller gun, I guess I'll have to redesign it a bit . . .

The camera and scoring plates are also gonna be huge on it... about how tall is this thing? (and is it a biped?)

-Fergs

societyofrobots
07-05-2009, 10:24 PM
I'm taking video of the entire design/build process. I'll start uploading in a week or so. I'll be sure to post a thread here.

The weight is now about ~3 lbs, \$800 estimated cost, height is 8" (without guns). I managed two guns on it.

Its a chicken walker, for mech combat next year. I just did torque calculations and found that my micro-servos are sufficient. =)

I might have to cheat and use smaller target pads, hehe =P
Hey it makes sense, big robots = big targets, small robots = small targets =P

CogswellCogs
07-05-2009, 11:20 PM
I have plenty of ideas for small sized weapons, but they involve CO2 which puts me in the hardcore class.

Is that true ? If we build a CO2 powered gun that fires Airsoft ammo at 350fps or less, can the Mech still be entered in the Airsoft class ?

robologist
07-06-2009, 12:17 PM
Is that true ? If we build a CO2 powered gun that fires Airsoft ammo at 350fps or less, can the Mech still be entered in the Airsoft class ?

Got a handy-dandy fps measurement device that can be easily transported to a competition to check mechs? Probably can be done, but should it be?

Additionally, given the same fps, different weight Airsoft ammo might impart different impact energy.

CogswellCogs
07-06-2009, 01:07 PM
Got a handy-dandy fps measurement device that can be easily transported to a competition to check mechs? Probably can be done, but should it be?

Yes, I do, but that's not really the point. Wouldn't this problem exist with commercial Airsoft products, too ? Don't those need to be chronographed ? I think a hopped up or spring powered gun could exceed the maximum velocity.

Additionally, given the same fps, different weight Airsoft ammo might impart different impact energy.

The rules so far don't make any distinctions about ammo weight. They just say "Airsoft BBs". I assume this means plastic BBs only, of course, but it doesn't seem to matter if they're .12g or .25g.

I was always operating under the "walks like duck" assumption. If your gun shoots Airsoft BBs and it meets the velocity restrictions than I figured it was an "Airsoft" weapon, regardless of the manufacture.

lnxfergy
07-06-2009, 01:45 PM
The 2010 rules are still in progress. The 2009 rules & guidelines were just that, quite loose guidelines, since we weren't expecting a ton of competitors the first year, and we weren't entirely certain what a mech would look like. The newer rule-set is much more explicit in it's language.

On this particular issue though, I think the 2009 rules were pretty clear (copied directly from mech-warfare.com):

Hardcore Weapon Class (http://mech-warfare.com/hardcoreclass.aspx) will use much more powerful weapons such as CO2 powered rifles, micro class rockets, and flamethrowers.

Hence, CO2 is hardcore only. The 2010 draft does insert the word "electric" in front of "airsoft" in the softcore class rules, as well as "plastic" for the ammo. While there is not a hard and fast FPS rule, we'll be spec'ing a mesh material that it should not penetrate. Frankly, anything remotely high-powered should be considered only for the hardcore class.

-Fergs

CogswellCogs
07-06-2009, 02:08 PM
I'll look forward to reading the 2010 rules. Can we start a thread to see what you guys are considering ?

lnxfergy
07-06-2009, 02:22 PM
I'll look forward to reading the 2010 rules. Can we start a thread to see what you guys are considering ?

There will be eventually, we're still ironing out some parts... Mostly it's the same, with clarifications on the language, updates for the different arena structure and revisions to the scoring system, and a few rules deemed necessary to combat mechs that can't move...

-Fergs

07-06-2009, 02:26 PM
Sienna had suggested joules instead of fps last year. Still a good idea, imho.

societyofrobots
07-06-2009, 09:20 PM
Sienna had suggested joules instead of fps last year. Still a good idea, imho.
How about "rounds cannot Pierce a Piece of Printer Paper at X distance"? P^4 rule. :veryhappy:

(going off-topic in my own topic, so sad . . .)

Sienna
07-07-2009, 05:14 PM
The only concern I would have over a CO2 bot in the entry class would be if it uses an electric solenoid or similar to control the flow. In which case, open the valve a very tiny amount of time to pass the chrono, open it longer in the game for a faster shot. A purely mechanical based (e.g., hammer actuated) I don't think there are any "dynamic" ways to cheat. (similar to an AEG, you can play with a hopup to reduce your velocity at chrono, but that is easy to spot if you tinker with it on the way to the arena.)

As far as a CO2 system being lighter then a LPEG / tank gun, I would love to see it to believe it. None of my CO2 pistols are lighter then a cheap walmart gun, and cheap walmart guns are heavy compared to a tank gun barrel assembly.

mannyr7
07-07-2009, 05:57 PM
The only concern I would have over a CO2 bot in the entry class would be if it uses an electric solenoid or similar to control the flow. In which case, open the valve a very tiny amount of time to pass the chrono, open it longer in the game for a faster shot. A purely mechanical based (e.g., hammer actuated) I don't think there are any "dynamic" ways to cheat.

What would be the advantage? The max range is what, 10 feet? Increased rate of fire? Target plates only allow scoring once per second anyway.

CogswellCogs
07-07-2009, 06:27 PM
I agree with Manny, here. From a practical standpoint, I'm not sure why anybody would cheat. From a moral standpoint, it's hard to imagine someone in the community being such a sleezbag. Maybe when the Mech Warfare prize money reaches into the tens of thousands of dollars :rolleyes:

The issue could be avoided by chrono'ing CO2 weapons immediately before the bout if it's really a concern. My thoughts are that if we can engineer a CO2 powered weapon that meets the safety standard, why not allow it ? An Airsoft BB traveling at 200fps will have the same impact regardless of the mechanism used to accelerate it. I also think CO2 may be a good way to power nerf rockets. Those would be cool addition to a battle.

07-07-2009, 07:05 PM
I will personally throw anyone caught cheating into the Bay.

There. That solves that.

Sienna
07-08-2009, 05:06 AM
What would be the advantage? The max range is what, 10 feet? Increased rate of fire? Target plates only allow scoring once per second anyway.
The only advantage that "cheating" with CO2 gets you is increased velocity (assuming that your barrel is long enough to hold the BB while the gasses continue to expand). (in practice, its probably not something to worry about, as anyone damanging bots because their gun is hot would also be noticed.) I guess I was just saying it is possible, not that there is a real tactical advantage.

The issue could be avoided by chrono'ing CO2 weapons immediately before the bout if it's really a concern.
Thats the only reason I brought it up, is because a certain design would be able to effectively cheat the chrono.

I also think CO2 may be a good way to power nerf rockets. Those would be cool addition to a battle.
Agreed here. And nerf rockets are nice and visible from an audience engagement point of view.

The competition might want two energy "categories" to do rockets effectively. Because of the rockets increased contact surface area compared to a BB, it should be safer to allow the rocket to possess more kinetic energy then a BB is allowed. (Say rockets with a contact area of >1cm^2 are allowed 2J, where BBs are allowed 1J, or something like that)

I will personally throw anyone caught cheating into the Bay.

There. That solves that.
Judge, Jury, Executioner :)
Are you sure you are not a robot from the future? :P

--

Don't get me wrong anyone, I am not saying CO2 = the evil. I think it would allow a more diverse weapon base.

Based on the videos I saw, it looked like bigger issues were insuring that mechs had more then one gun on them, and that they need to carry more then a tic-tac container's worth of ammo.

lnxfergy
07-08-2009, 09:46 AM
Based on the videos I saw, it looked like bigger issues were insuring that mechs had more then one gun on them, and that they need to carry more then a tic-tac container's worth of ammo.

Based on the videos *I* saw... it looked like we needed more people to stop screwing around with weapons systems and make mechs that can actually walk...

-Fergs

gdubb2
07-08-2009, 01:03 PM
uhhh... Yeah, what he said...LOL

Gary

DresnerRobotics
07-08-2009, 02:25 PM
We can screw with FPS Airsoft rules all we want, bottom line is if they can penetrate the nylon mesh we're using they aren't allowed. CO2 is not and will not be allowed in the Airsoft league. Its too unpredictable (as in, I'm not going to trust someones home made CO2 gun to shoot reliable FPS every time) and we can't have any accidents or damages occur at the event.

Later on, I'll be posting a link to where it can be ordered so participants can do their own testing. Anything stronger than a Defender is going to have to be tested onsite next year, and if you don't pass, you don't participate.

And really, unless you're building with RX-64s, good luck using anything stronger than the Defender.

Sienna
07-08-2009, 04:33 PM
Later on, I'll be posting a link to where it can be ordered so participants can do their own testing.
That would be nice.

Thanks Tybs

robokoi
07-10-2009, 01:41 PM
... if they can penetrate the nylon mesh we're using they aren't allowed.

Most heavily seconded!

Its too unpredictable (as in, I'm not going to trust someones home made CO2 gun to shoot reliable FPS every time)

No offense, but I'm not convinced that people's hacking of the electromechanical bits of the Airsoft guns wouldn't suffer from the same faults.

I will personally throw anyone caught cheating into the Bay. There. That solves that.

Why not tie them up in the arena and let the bots at 'em? ;)

DresnerRobotics
07-10-2009, 02:49 PM
No offense, but I'm not convinced that people's hacking of the electromechanical bits of the Airsoft guns wouldn't suffer from the same faults.

Uhh, there is most certainly more danger inherit with CO2 powered guns. Even if you upgraded the motor on one of the airsoft guns, you're not going to greatly increase the FPS, if at all. At most you're going to have a faster shooting gun, since the air pressure is more or less just spring powered on most of the electric airsoft guns, the motor isn't creating higher pressure in the chamber. With CO2, bigger bursts of compressed air are going to directly affect the FPS.

Ultimately, using CO2 in the Airsoft class isn't up for discussion anyway, as it's a safety issue. In the hardcore class, crowd safety isn't an issue.

darkback2
07-10-2009, 03:04 PM
I'm not sure I should get into this one...but I will anyway.

First of all, I thoroughly understand the desire to expand what is capable/allowable in mech warfare. The whole...what if I do this...

I think here there are a few different issues. Expanding the base of possibilities, and maintaining the safety of the event.

On the one hand, there have to be more alternatives than the heavy defender guns, and the slow tank guns. That said, The tank guns were fast enough to score hit points as shown by issy and bheka, and the defender guns were pretty darn impressive as shown by shadow scout. In the short demo match I had against him I couldn't get close to him because he would just spray at me where ever I went...that and my bots are both wicked slow... So...lets all start doing research...what other guns can we find? Is there a way to hack the defender guns so that they are a reasonable weight? Is there a way to hop up the tank guns so they are a reasonable speed?

As for keeping the event safe, so long as it has Andrews name on it, he has the final say...and he should for his own sake err on the side of caution. Its sort of like when the lawyers get involved...they almost always say no...because it is never in their interest to say yes.

Finally...CO2...once you add the tank, hoses and a reliable valve/switching mechanism...wouldn't that be heavier than an airsoft gun?

I don't know...but now we have some researching to do.

DB

Quantum
07-10-2009, 03:19 PM
Yea the motor is just the trigger. The way to increase the fps are springs. In a co2 gun its the spring behind your bolt. But you also have the potential for a big problem. CO2 guns have o-rings in them and if one of these go you could see your tank of gas being dumped. This causes condensation and if it were to happen near a circuit board I dont think it would make it.

CogswellCogs
07-10-2009, 03:21 PM
No one is disputing your authority to make the rules as you see fit, Tybs. We area all too grateful to you for setting up the competition on the first place.

I think your reasoning about the physics of the situation is not correct, however.

bigger bursts of compressed air are going to directly affect the FPS.

I'm not sure what a 'bigger' burst of CO2 means. The flow of CO2 is limited by orifice size of the solenoid valve and the pressure in the source, presumably a little 12g or 16g CO2 cartridge. The cartridge CO2 pressure will only decrease (unless the arena starts on fire or something). If software goes awry or the solenoid valve breaks, the orifice size does not change. It's small hole in a substantial metal manifold. What would happen is that the duration of the CO2 pulse would increase. Under normal conditions, the CO2 is stopped just as the projectile leaves the barrel. In the failure condition we're talking about, extra CO2 is vented after the BB has exited the barrel. It won't alter the velocity of the projectile.

Also, why isn't crowd safety an issue for the hardcore weapons ? Is the competion more solidly enclosed ? Is the audience physically removed from the competition ?

ScuD
07-10-2009, 03:50 PM
I too, would like to say that I most certainly am not voting to enter CO2 in the standard rules, I'm merely discussing here (as I'm least likely to ever compete).

Let's assume for a second here that only certified CO2 equipment can be used, for example a standard, store bought pressure reducer valve, with screw-on CO2 cartridges. It's widely used, safety is proven, and as Cogs explained, the only real "issue" is that all air runs out instead of coming in bursts, which in my opinion is only to the disadvantage of the bot facing the problem itself.

Now, one might also build his own spring powered airsoft cannon, one that's more powerfull than CO2 (for the sake of reason, assume this is possible) that'll mean he'd be ruled out before the match anyway, yet he too built a potentially dangerous machine.

Agreed, CO2 will most likely weigh more than the gearbox spring cannons, but I see it as a tank of power, with a versatility of weapons which can use this power.
Eg. a standard gun with high accuracy for one match, two fast smaller guns for a second match, foam rockets for a demo, etc etc.

Once again I'm just thinking of "keeping the roads open for improvement", in no way am i saying the rules should be adapted nor anyone do this or do that.
You want to build a CO2 gun? Build one! Heck, build 20! It's a hobby! Enjoy yourself! And if you happen to come upon a great new improvement that revolutionizes the game, all the better.
If not, at least you've learned a few new tricks.

You want to build a mech to compete in the wars? Print out the rules, and STICK to them. They're there for a reason.

DresnerRobotics
07-10-2009, 03:56 PM
No one is disputing your authority to make the rules as you see fit, Tybs. We area all too grateful to you for setting up the competition on the first place.

I think your reasoning about the physics of the situation is not correct, however.

I'm not sure what a 'bigger' burst of CO2 means. The flow of CO2 is limited by orifice size of the solenoid valve and the pressure in the source, presumably a little 12g or 16g CO2 cartridge. The cartridge CO2 pressure will only decrease (unless the arena starts on fire or something). If software goes awry or the solenoid valve breaks, the orifice size does not change. It's small hole in a substantial metal manifold. What would happen is that the duration of the CO2 pulse would increase. Under normal conditions, the CO2 is stopped just as the projectile leaves the barrel. In the failure condition we're talking about, extra CO2 is vented after the BB has exited the barrel. It won't alter the velocity of the projectile.

Also, why isn't crowd safety an issue for the hardcore weapons ? Is the competion more solidly enclosed ? Is the audience physically removed from the competition ?

I was under the assumption that a longer opening of the valve might create a more forceful shot. I'm certainly no expert on the matter however, but I do know that CO2 presents the possibility of a more powerful shot fired, and is unnecessary for the Airsoft class. It's much easier passing the safety tests at Robogames when I can demonstrate that the participants are using airsoft tank guns, or electric toy airsoft guns from Walmart, etc... and that they pose zero threat to penetrating the protective mesh. Regardless of how standardized and regulated CO2 might be, introducing it into that same environment makes the safety officials nervous and is simply not worth the hassle.

The hardcore weapons class takes place within the Ant weight battlebots arena, which is .5" lexan siding.

07-10-2009, 05:45 PM
Ideally, the CO2 is at p = p0 * exp(T/T0) if there is any liquid in the cartridge.

At room temp, about 315psi average for a short-fill typical bbgun cartridge at the start of the day. The psi will change, of course, with the volume of the _liquid_ in the tank, and dramatically with temperature as the volume changes. We really get ugly when we allow competitors to use unweighed tanks though. When we cross the hump of the ideal-gas PV above, we'll see that more than a thousand PSI might even accidentally occur from an overfilled bottle that has crossed the critical ~85 deg F.

But what happens when you siphon (accidentally or diliberately) liquid into the far larger chamber that is the barrel, especially a hot barrel? What happens when you build an intermediate chamber? The potential for mayhem becomes much greater. This, I suspect, was where Tybs was going without being able to fully express his concerns.

"Hot Guns" are a real problem out on the field because it really isn't as predictable as you make it out to be. If it were, you wouldn't crono in/crono out. And even with that, there are tricks to heating a gun up, leaving someone a nasty bruise, then cooling it back down for crono... That's why suspicious refs will pull a player off the field for hot gun reports on the spot, and/or crono right there at the point of the accusation.

It's a moot point anyway. If it's not to your liking, there are other better enclosed events where massive CO2 weapons are at play.

And in answer to your question about hardcore - the one hardcore competitor (Darkback2) fired-off his rockets in the full-on lexan lam battle box.

DresnerRobotics
07-11-2009, 01:55 AM
Reasons for not allowing CO2 in the Airsoft arena are also summed up nicely in this picture:

http://forums.trossenrobotics.com/gallery/files/1/7/7/8/mw-10.jpg

That said, I fear we've gone a bit far off topic from the original intent of this thread.