Airosft AEG to HPA Mod Conversion

[jackssmirkingrevenge]

Hate to tell you this, but polarstar airsoft beat you to this about 2 months ago.

There do appear to be some similarities.

What irks me is that you would need to worry about air supply and batteries. I think the electronic system seems to work just fine, but it is too bulky and adds another logistical element.

Kuba, I know you love you 'lectrics but I think it's work looking into either a pop-off piloted QEV (though I think for airsoft and with HPA this is an unnecessary complication) or a direct pop-off valve.

Changing the strength of of the pop-off spring changes both power and rate of fire - lower strength means it fires at a lower pressure, so less fps, but at a higher rate.

Adding a flow control valve between the air supply and the valve can be used to compensate for these changes - it won't be as simple as flicking a switch, granted, but you can tune it for X setting to give Y fps and Z rps.

[al-xg]

Ah noo!
Was about to be sneaky and the spudfiles topic link

I reckon the whole circuit and batteries could be made to fit into the same space the AEG's battery fitted, even LiPos if it was uncased.
Or if you went for a mechanical solenoid control, even have the circuit in the gearbox, the batteries where the batteries went anyway.

There is a little bit of room for custom shaped bits...
http://kuba-t1000.com/minigun/obrazki/a ... x_view.jpg


If the was design use some form of pop off, any ideas for semi-auto selector ?

[jackssmirkingrevenge]

If the was design use some form of pop off, any ideas for semi-auto selector ?

Here's a thought - just use a proportional valve as the trigger.

As most of you might know some automatic weapons like the Steyr AUG do not have a selector but instead use a two stage trigger, light pressure on the trigger gives single shots while heavy pressure gives full auto. A proportional (ie the more pressure you put on it, the more flow it gives - like for example a blowgun) valve would give this same effect.

I think it would make a great "instinctive" trigger - when you're firing aimed shots at long range, you tend to be deliberate and slow with your trigger finger, but when you're panicked and squeeze the trigger hard, that's usually when you need as many rounds as possible downrange.

There is a little bit of roomfor custom shaped bits...

More than enough space for a trigger valve and "rattlesnake" type pop-off unit - no electronics or batteries to worry about, and all it would need is an adjustment screw for the pop-off spring to alter power settings.

For the M4 type carbine, you could easily remove the standard stock and replace it with a 13 or 48 cu paintball tank, giving you on-board air and no need for a backpack and remote line.

[al-xg]

Here's a thought - just use a proportional valve as the trigger.

Some MOSFET units used as upgrades on AEGs also replace the manuel select fire switch, so in that case realism isn't always the highest priority in airsoft. I do like the response of electronic triggers though

Remote lines have their advantages for weight and balance (they are often replaced by stocks for paintball), but due to the smaller calibre and energy the autonomy makes the use of smaller tanks more feasible.

[jackssmirkingrevenge]

I do like the response of electronic triggers though .

I think a pneumatic trigger would still have a good "feel" to it

Remote lines have their advantages for weight and balance (they are often replaced by stocks for paintball), but due to the smaller calibre and energy the autonomy makes the use of smaller tanks more feasible

A well made pop-off unit should only require a tiny amount of air per shot so a 13 cu 3000 psi tank set at 450 psi should suffice for several games before needing to be refilled, and it is compact and light enough to serve as a stock.

Kuba's design seems to work great and I don't mean to belittle his achievement but I feel there's a lot of room for optimisation, such as making the blow forward part more compact in order to reduce losses to dead space and further cut down on gas consumption.

quick and dirty before I miss my ride home:

[Kuba_T1000]

Thanks for all coments.
when I started this project I was thinking about using QEV and pop-off... but it was too complicated. The second reason was the price.
In current project I was able to simplify desing.

I like upper jackssmirkingrevenge's "sin_ttulo_980.png" picture. That's great idea. There are some difficulties about making guide for piston - it needs good quality of turning/milling.

Currently I'm looking for a mini-solenoid which can be hidden in standard Gearbox. Electronics I can made using SMD parts, so it can be miniaturized and also hidden in a gearbox - but I have troubles with searching for a mini-solenoid.

In my opinion the best option is full-stock for M4/M16 and hidding a solenoid into that stock. LiPo battery can be hidden in front grip and that's the best option for now.

[al-xg]

some difficulties about making guide for piston

Do you mean in the front section holding the thin part of the piston ?
It can be removed, I believe it's purpose was to prevent the spring from being the bumper, but If that slightly larger diameter on the piston was made longer it would do the same job.
The piston is supported at two points that are relatively far apart (over 1.5 times the max diameter), so the bearing surfaces don't have to be very long.
Otherwise you could just make it from two parts.

I have certainly seen shorter 3/2 1/8" valves (I have some back at home can't remember the brand though), have you tried direct acting ones instead of pneumatically assisted ? They should be more compact as they don't require the extra 3 small pistons.

Making a valve would out of the question ? I guess by that point you might as well make JSR's pop-off design. (Mmm actually you could just modify your solenoid valve to be direct acting, you could cut it's size down considerably)

[jackssmirkingrevenge]

when I started this project I was thinking about using QEV and pop-off... but it was too complicated. The second reason was the price.
In current project I was able to simplify design.

I don't think my design is terribly complex and anyone with reasonable lathe experience should be able to make it in sections - and you can't argue that completely eliminating the electronics doesn't make the project much simpler

[POLAND_SPUD]

have you tried direct acting ones instead of pneumatically assisted ?

unfortunately direct acting ones have much lower flow and higher power consumption

However it is a great idea, IF you modify the design of the blow forward valve into a 3 way valve and use a small solenoid valve as the pilot. That could be a neat way to minimize the size as you can get really small valves that don't have threaded ports

[Kuba_T1000]

I checked some solenoids and I've found a good one, which can be hidden in gearbox shell. I ordered it. The plan is: Milling gearbox shell for 1.5mm to insert there this solenoid (15mm thickness). Also I'll try to design a SMD version of electronics.

I'm thinking about buying a simple lathe... We will see...

[jackssmirkingrevenge]

I'm thinking about buying a simple lathe... We will see...

It's spreading

[LeMaudit]

I'm thinking about buying a simple lathe...

not my fault not my fault not my fault...

Good idea!

[Kuba_T1000]

So it is

[warhead052]

I have a theory that might work. What if you directly added a tube to the hop up where the bbs feed into, and then have a push button valve in the grip with a tube running to your air source? I am going to try it when a friends AEG finally gives out (its getting close so it will hopefully be soon).


Edit, heres a link of one that I found. http://www.spudfiles.com/forums/magazin ... 16205.html That should be it. Try that idea in the next one.

[POLAND_SPUD]

wow how much did you pay for that ??