BFG Questions

[renegadecow]

Does anyone know if there's a patent on using a pneumatic piston as a delay mechanism for a flash/sound training grenade? I've sort of made a working prototype over the weekend on a whim which uses small handgun primers, an adjustable pneumatic delay and made almost entirely out of PVC save for the striker spring, primer pocket and some screws. My friends are convincing me to bring it to market but it's kinda too laborious for me to make on my own and don't know if that's even feasible on a legal stand point. Otherwise I'll need to switch to a more complex delay mechanism probably sourced from musical boxes.

[Stuey]

I'm pretty sure that's how Dynatex BFGs work, so it may well be patented?

[scorch]

Yeah, that's how the dynatec/vtg ones work.

[Baddbaz]

+1 to the above

[DrAlexanderTobacco]

It's certainly patented in the UK. The Dynatec design is basically:

 

• Pull pin, release spoon (drop corn flakes)
• Air in a chamber is slowly released through a tiny hole
• Once the pressure drops enough, a spring is released and the firing pin shoots up.

 

Amateurstuntman has a thread knocking around here somewhere where he took one apart if you want to look for it.

[paranoiddroid]

Where would you find the patent for it though? And surely any change in the material the size the shape where it is on the device will.mean the product is suffice tlk different. Sounds like an interesting project and the pc construction could lead to a lower price.

[renegadecow]

Is Dynatec the only one that make ones with a timer? I think I saw a diagram before and where I got the idea. But if it's different enough by design but only similar in principle like how many of those impact detonating ones are, will that put me in the clear? I'll put some pics up soon when it's done. Right now it looks like a pipe bomb cobbled in 5min out of a hardware store. Matrials wise I'm only down $5 with labor at about $40, less if proper machinery is used.

[Stuey]

Would the patent not be for the concept of a pneumatic delay element for a blank firing grenade? Thus you'd have to innovate something else otherwise be infringing on the patent?

[renegadecow]

That's where I'm confused. If it's the concept, there are other devices that use it like AI and VFC/Maple Leaf gas grenades which alo have their own patents. I think it's specific to the design like how a plethora of smart phones can all have a touch screen interface as it's the actual design of the individual phones which are patented. Otherwise I'll just make a few for personal use and have fun with it while I try to think of something else.

[JCheeseright]

a company in the UK called SWAT also make them, they're a direct clone of the Dynatec BFG, I can't imagine the patent is enforceable if they're getting away with it. 

[renegadecow]

Here's a test video:

https://www.youtube.com/watch?v=6mPgL1l69S0&feature=youtu.be

[Pepperisit12]

Really nice design in the video. As said above you might have a patent product if you are trying to sell. However surely you can make them to give to friends?

How long do you think the pvc will hold up to regular usage though?

Any particular reason you have gone for handgun primers and not shotgun primers that a lot of people use already. (unless I theres something I missed?)

[renegadecow]

Thanks. To cut cost down I used the primer pocket from a .40S&W case which I so happen to have a lot of as an insert for the screw on cover instead of having to make it entirely from scratch. The idea is to have different covers for different primers. I haven't tested it using an actual primer just yet though, will wait for that on the weekend when I play. But the combustion is completely external so I don't see any reason for it to blow up.

[Pepperisit12]

Would completely external combustion be a risk for burning your hand? I suppose it can't be any worse than a mk5!

Very interested to see how this pans out and keep us all informed of what you discovered about the patents and how you are going to proceed!

[LordElpus]

From what i remember... Dynatec sold the design rights to VTG when they were closing down however there is now a company calling themselves dynatex that appear to be exactly as the original Dynatec BFGs but i have yet to see any stink raised by swat over it

[renegadecow]

The flash hole is on top so if you were gripping it normally it shouldn't burn your hand. But I'll still need to find that out in actuality. At worst I'll need to make a blast shield attached to the cover but at least that way I can make it look like a real detonator and have the spoon attach to it instead of the body.

[scorch]

From what i remember... Dynatec sold the design rights to VTG when they were closing down however there is now a company calling themselves dynatex that appear to be exactly as the original Dynatec BFGs but i have yet to see any stink raised by swat over it

 

From what I can tell, the old guy that designed the first one is behind the new company and is totes BFFs with Zero One as he's been down at the last 2 GZ weekenders in the Z1 shop practically pressure selling to anyone polite enough not to ignore him and walk away.

 

At the last one, Z1 even gave him authority to knock a bit off the price if you bought it there and then.

[Rob15]

It's certainly patented in the UK. The Dynatec design is basically:

Any idea what the patent number is? I've never seen one published for the original BFGs, not even in the manual that came wiith them. Even if it was patented it's quite an old design so it's quite likely the patent has expired even if it had been extended to the full 20 years allowed.

 

From what i remember... Dynatec sold the design rights to VTG when they were closing down however there is now a company calling themselves dynatex that appear to be exactly as the original Dynatec BFGs but i have yet to see any stink raised by swat over it

Dynatex is the original manufacturer, but for some reason everyone started calling them Dynatec BFGs years ago.

 

To be honest a potentially old and expired UK patent would be the least of your worries, you'll probably have all sorts of legal issues with shipping them internationally and at least in the UK you'd have to satisfy the insurance companies that they're safe to use.

 

The AI and VFC grenades use an entirely different system to the Dynatex BFG so even if there was an active patent on the Dynatex BFG it shouldn't infringe on it, the AI and VFC use a compressed gas to operate, the BFG uses a vaccum piston.

 

If I remember correctly from looking at patent applications myself years ago you're not supposed to make details of the product public until you've at least started the patent application process and are able to put 'Patent Pending' on the product, not that a patent is worth much in airsoft, even if you had an international patent would you have the resources to enforce it in every country?

[Isamu]

AWESOME, RC! You never stop amazing people here

[renegadecow]

I imagine shipping would be a problem but I:

1) never really considered making that many (doubt if I can too)

2) you guys will probably want to support locally made nades (we just don't get any here at all apart from crummy CO2 ones that can cost a bit to run)

3) ship it unpainted and unassembled so it's just a bunch of PVC parts

4) make a 3D printable version

[Isamu]

Personally, if you ever decide to sell some of those, count me in for a couple

[Skarclaw]

 

Any new product in the BFG market is welcome. Maybe cause I only browse UK airsoft forums but it seems like we are the only country that uses them. It blows my mind that Americans *rickroll* about with those stupid thunderbees. For a skirmisher I would advise getting a BFG over a GBB...  The big gap in the market, IMO, is a lightweight BFG that can be safely thrown over arm. 

[renegadecow]

At its current weight (80g) I could say it's pretty safe to be thrown over hand, but there's the risk of mid-air detonation if you lob it high enough or time it short and a blast in the face is gonna ruffle up anyone's feathers. Will definitely need to implement a blast shield for that which will likely need to be metal and that's gonna increase weight as well. I can't understand he absence of BFGs in the US either and they're supposed to be the ones having a knack at blowing stuff up.

[scorch]

I'd rather play against a BFG than a Thunder B, given how bloody high those Thunder B grenades can jump when they go off.

 

I certainly don't want a spoon to the face.

[hotelkilo]

here is a diagram of a dynatex bfg which shows a cross sectional view of the two states.

 

 

when the pin is pulled and the captive lever is allowed to move outwards from the main body about 10mm it moves due to pressue on the sear and then releases the firing pin assy. initially the firing pin assy moves very slowly due to the tiny 'jet' opening and relative air pressure. when the firing pin assy gets to the larger opening in the main body the pressures equalise and it is free to continue moving under spring tension alone, and BANG

 

the length of delay is totally dependent on the tiny jet hole, if this becomes blocked then either no bang or a bang sometime way off in the future, if the bore of the jet is wider then the delay is much less.

 

a typical dynatex bfg has a delay of about 2-3 seconds, this can increase over time as the insides get dirty.

 

the cap/chamber allows the blast to vent up and out from the top of the device, away from the users hands should an nd occur. the cap/chamber can hold 12g short blanks or anything smaller with a suitable adaptor. dynatex bfg's used to come with a 9mm rimmed adaptor as standard giving the user at least two options for decibel level. aftermarket adaptors are pretty inexpensive.

 

(i know a previous poster described this mechanism already, just felt that the pic needed an explanation for any cursory readers)