Legacy's Guide to Building a High Speed AEG

So we can easily add 2 part epoxy and then moving the cylinder head back is then fine.
So it may improve feeding.
Doesn't seem too difficult either. Most people can use a drill, rotary tool and 2 part epoxy. And it is easy to plastic wield with a soldering iron. From what I can see it would only take about 30-40 minutes and then you never know, it may just work.

 

So I gave it a go. I used a gun that I have had feeding issues with for about 4 years. This gun has been such a frustration for a long, long time (Made up of all sort of parts that have not been totally compatible). Normally I could get it to feed up to about 20rps but once I change to a lower gear ratio, giving higher RPS, it would have feeding issues.

The mod was easy but a little bit more involved than what I originally thought. First I noticed that I needed to remove 2mm of the tappet plate guide rail in the gearbox. Then I built the front of the cylinder head up with NeedIt (a hardening clay). Also, filed and sanded the NeedIt so it would fit nice. Then I cut the cylinder down by 2.5mm. Next I put 2 part epoxy glue on the front of the tappet plate fin. Since the tappet plate moved back further I also had to remove a little from the rear of the tappet plate otherwise it would hit the axle of the spur gear. Since I had built up the front of the fin, I also had to make sure that the low part of it did not touch the spur gear axle otherwise the air nozzle did not seat all the way forward.
I also had to take half of a tooth off of the piston so that it would not get caught as the sector gear engaged.

Anyway, after doing it and putting in 13:1 gears, it was able to feed 29-30rps easily using just a high cap mag. The mod means that the air nozzle can retract an extra 2.2mm. This means that the air nozzle definitely was not in the way when feeding. It also meant that the tappet plate seated in time for the for the piston to move forward. So overall, I am happy with the mod. I will do this again as it seems to work a treat.

NOTE: All the gunk in the GB is from the filing. I will also be putting a mosfet back in it and also putting a hair trigger back into it some time.

 

So the 2 part epoxy came off the tappet plate. -Annoying as it was working a treat.
So I will today plastic wield some extra plastic onto the fin using a soldering iron and a spare piece of plastic from a selector plate. (I have done this many times on other plastic parts and it is stronger by far than 2 part epoxy).
If this does not work, does anyone know where to get a V2 tappet plate that has a bigger than normal fin?

 

Well the thing is, if a nozzle pulls back way to far, the second bb may drop in too much and cause a delay as the nozzle has to push the pellet out of the way to chamber the first one. I basically have 1.5mm extra movement forward by just sanding the face of the tappet and a tiny bit of material where the sector shaft hits the fin, this works for me because I use short lip packings, most guns have the packing lips in the way of the hop up feed tube. From my experience shs tappets tend to have too much material on the tappet fin. But that may be with a issue certain shells.

As for the cylinder head rotation lock pegs, I just drill out the holes a bit till the pressure is on the gearbox face rather than the pegs.

I am able to hit about 38rps without feeding issues with a high caps on my m4, people have been able to hit up to 65rps perfectly fine with high caps for ak and m4. There used to be a list of feed rates on ASM before it went down. Some used sector clips for the ssg builds.

I'll throw a video up in a bit on how I time my gearboxes and how I set them to feed. The only time I get miss feeds is when I forget to wind my mags.

Edit: https://www.instagram.com/tv/CCCde_wnueb/?igshid=ros9h132sa8k

Shooting video that has most recent part list too: https://www.instagram.com/p/CE0Vt2gnXGu/?igshid=9cvwrvr4x628

 

Good to see I'm not the only person that discovered the tappet fin and sector gear shaft thing. It can actually affect consistency significantly.

 

Check it out. 62rps at 1.1 joules. Awesome

In my previous posts I was working on the 13:1 gearset but then I decided to change to a 18:1 DSG. So I got a new cylinder head and redid my cylinder head mod so that it would pull the tappet plate back only 1.5mm more than normal. Also made myself another motor out of an Action Army motor Can and a JG M96 armature.
After putting my DSG together it now rocks. The DSG is now doing 62rps at 1.1 joules (0.25gm bb's). Not bad. Once I did the mod I mentioned above it made feeding way better. No misfeeds.
I know that my weak point is the tappet plate spring stretching too much. It was cut down to only 8 coils.
What I am going to do is investigate purchasing another spring off Aliexpress that has thicker wire (Does not need to be an airsoft spring. I will mod it to work). So a hard pull without stretching.

 

Also, that was done with just a cheap budget high cap mag. Nothing flash.

 

No. Sorry bad wording. It was just a standard cheap budget high cap mag. Feeds really easy after the mod on the cylinder head.
Though the more I use it, the less accurate it is. So my guess is the tappet plate spring is stretching. I am going to order a spring off of Aliexpress and then let everyone know how it goes.

 

OMG. Can you peel that dang plastic off your chrono already? My OCD is giving me a stroke.

 

I guess I have the opposite of OCD. Just haven't bothered.

 

So I now have 62rps at 1.1 joules. Does anyone else have an idea what I could do to increase the RPS. I do not want to bring the energy rate down. Mag is feeding great so I guess I could aim for more.
The only thing I could think of was to get one of the brushless motors from Shenzhen Chihai Motor Company. Would that give me more torque and motor speed?

 

Just increase the battery voltage?

 

I probably will do that but really I wanted to keep away from 14.8v. But that is definitely an option.
Any other ways of increasing rps? Or have I maxed it?
(To be honest, I can still change the bushings to bearings as well as swiss cheese the piston. But I want to see if people have other out of the ordinary ideas that may work)

 

Congrats on the success 1tonne, I haven't been on here in a bit but looks like your experiment worked and met at least most of your initial goals.

Regarding increasing RPS, there really is only two ways - minimizing losses, or increasing powertrain speed. Unless you have done an exceptionally poor job shimming and lubricating the gearbox which I doubt, that leaves only the second option as viable for significant gains. Running a higher turn motor on higher voltage to meet an RPM goal is going to run more reliably than a lower turn lower voltage motor system, assuming you can find a battery to fit. Same reason why I want to say most countries run their power grid at 220-240VAC instead of 100-120VAC.

You also mentioned 13:1 gears, if you're willing to redo the gearbox in 12:1 or even 10:1 that will net you additional theoretical RPS gains of ~8% or ~28% respectively with the same motor and battery, obviously will be less in the real world even assuming your motor is still in its ideal power band and the battery can supply the additional power required from a higher seen load.

 

I guess you could remove a few windings from the motor arm?

 

I would prefer not. I a number of motors and I have been swapping out the armatures with my best Can to see what would come up best. The setup I have now, came up on top. So I would not want to risk changing the amount of coils.

 

I guess you might be able to get a tiny bit more oomph by reducing the wiring resistance.

 

If it's to the point where that would make a difference, focusing on the connectors rather than the wire is more feasible. AEG wire gauges you're probably looking at the ballpark of 8-10mΩ/foot so probably 16-20mΩ per AEG wired up normally. Mini-Tamiya connectors supposedly have a contact resistance rating of 15mΩ, and genuine WS Deans Ultra plugs are supposed to be 0.2mΩ or so. Solder the motor wires on directly if you can.