More L85 plans!

[Airsoft-Ed]

Since I've got the externals nailed down and done barely anything to the internals, I feel a bit like one of those nob head boy-racers who stick a ridiculous body kit on their car and do nothing to the engine, so the extra weight puts them at a disadvantage.

Except I'm not at a disadvantage, 'cos I have got a barrel upgrade fitted, but that's all at the moment and obviously my body kit isn't ridiculous...

Screw you Finius.

But anyway, I want the fps consistency to be better, some shots occasionally fall short and it also very occasionally double feeds, so I want to address these issues.

Part of that might be down to the hop up consistency, so I also want to get a hop rubber that will work better.

I think a hard rubber instead of a soft, as the hop arm spring is quite weak, so the BBs are probably just pushing the hop about, I think a hard rubber might make that better, does that sound about right? Any hop recommendations? I tried a madbull blue rubber but it's too fat to actually fit in the hop unit with the barrel... Will getting a tighter barrel help with that? The outside diameter might be slightly thinner?

Lastly, I want to field it as a DMR running between 425 and 450 fps. Getting a tighter barrel will increase the fps without increasing wear on the internals, so I figure all the minor gearbox changes, coupled with a 6.01 barrel and maybe a spring that's 1 step up, so an M130, ought to put me in the 430fps sort of territory. Anyone disagree with that?

So, what do people think I should do internally to increase consistency?

I'm thinking of re-shimming the gearbox, thoroughly cleaning and re-greasing all the gears and lastly, upgrading the piston and piston head to get better compression.

Anything else I ought to do?

What parts do people recommend? I've never really delved this deeply into anything gearbox related so I'm not sure what parts are compatible.

Also, the double feeding issue... Something to do with the tappet plate? What should I do about that? I think it's a proprietary part so I don't really want to mod it until I completely understand what I'm doing.

Might leave that until the end, I guess there's a chance it might just sort itself out.

And finally... I've heard people talking about perfecting the angle of engagement for the best possible performance. I really don't understand how you can alter the AoE, surely the gears are always going to mesh the same? It's not like you can move them forwards or backwards... How do you adjust the AoE?

Thanks to everyone who can be bothered to read through all this and über thanks to anyone who actually offers any help or advice.

Cheers guys.

 

[TPI]

i know when i talk about AoE i'm not talking about the gearbox i'm talking about how high above i aim

 

[Airsoft-Ed]

I was under the impression it had something to do with how the gear that meets the piston grabs the piston with the first tooth. But I don't see how it can mesh any differently, I don't even get how it can mesh one tooth earlier or later because that would screw up how the rest of the gears worked...

 

[RR01]

I was under the impression it had something to do with how the gear that meets the piston grabs the piston with the first tooth. But I don't see how it can mesh any differently, I don't even get how it can mesh one tooth earlier or later because that would screw up how the rest of the gears worked...

Click to shrink...

What you are talking about is how the first tooth of the sector gear meshes with the teeth at the back of the piston. The ideal situation is to have the front edge of the sector gear meet the forward edge of the first piston tooth almost parallel, so you get full contact. If the settings are even a very small amount off then the first sector gear tooth will catch on the second tooth of the piston, either wearing it or, in the worst case, jamming up.

What is usually done is to remove the second piston tooth entirely, so that when the sector gear rotates it can make a clean contact with the first (rear) tooth on the piston. However, that also means that you need to ensure that the piston isn't either too far forward in the cylinder or too far back.

I've seen a thread on this somewhere (not sure where or even if it's this forum) that explains it in very clear detail. It's what is usually done on high speed setups, where the time taken for the gears to revolve can be quicker than the spring can return the piston to the front of the cylinder to re-mesh. There they will take out both the second and third teeth to overcome this. It works best on pistons that have plastic teeth, as they are easier to remove, but would work on metal toothed pistons as well. It's juist more work with a Dremel.

Just out of interesty, which make L85 have you got. I've got three, all Army, the main A2 with DD RIS that is the best, plus two A1's that have been put together from variously sourced spares. One is my back-up, the other is still being upgraded.

 

[Airsoft-Ed]

I've got the ICS one, don't suppose you'd be able to dig out the thread for me?

Thanks for the input.

 

[RR01]

I've got the ICS one, don't suppose you'd be able to dig out the thread for me?
Thanks for the input.

Click to shrink...

Had a look but I can't remember or find where I saw it.

I presume the ICS has the split gearbox (most ICS are), so it's at least a lot easier to work on the piston without having to strip a full gearbox to do it. The first thing to do is take the gearbox out of the receiver. Then you can see what's happening without the metal slab in the way.

What you need to do is rotate the gears until the sector gear is just rising into view but just before it actually starts to meet the piston. You might find removing the motor helps to turn it easier. Then lower the upper onto the bottom part, watching carefully where the back of the piston comes relative to the sector gear. Then move the sector gear very slightly until you can see it just starting to connect with the piston. If the piston is too deep in the cylinder then it will look as if the sector gear is going to connect whilst the first tooth isn't fully upright or almost upright (say at about 45 degrees). This will give poor contact. If it's too far back then the first sector gear tooth will be past vertical before it starts to engage. So the first step is to make sure that the piston sits in the right place. There are a couple of ways to sort this if it is wrong, but a properly set up gearbox should be correct from new.

If it is wrong then you can either use a thin slice of rubber or silicon on the cylinder head to stop the piston going too deep or if it's too far out you could very gently file down the head end of the piston. However, I'm talking very fine adjustments here. Going at it with a dremel would probably cost you a new piston.

Once you've got the point of contact in the right place that's the time to look at taking off the second tooth from the piston, That won't cause a problem, as by the time the first sector gear tooth has moved the piston far enough back you're already into the position that the third tooth is partly engaged anyway. My G&G CM16 gearbox has this done to it from new.

As regards your idea of turning it into a DMR, most sites would want to see some form of physical means of stopping it firing full auto (and some have a 400 fps limit on AEG DMRs anyway). You could possibly remove the fire selector switch, but that might not stop it going onto FA in error and you would have no means of releasing a jam if it stopped firing on semi. Only a trip back to the safe zone would solve that. You would also most likely need a high torque motor to turn the heavier spring, which will put a lot more stress on the working parts of the gearbox, if everything else isn't up to it. That said, when I was looking at upping the fps on my A1, I put an old spring I had lying about in it and had it firing at 475 with no problems, although I was only aiming for 330-340 max (so it came straight back out!!).

Hope this helps and if I can find the link I'll let you know.

Mike

 

[Airsoft-Ed]

Cheers Mike, I'll open the gearbox up at some point and have a look, it's probably already more or less right anyway.

The L85 gearbox isn't split, it's a once piece unit with the motor included. The motor and gearbox are supposedly rated to at least an M150 strength spring so it ought to take the heavier spring without any issues. The gears are all solid as well. Piston might need looking at but I'm upgrading that anyway for a better air seal.

As for the auto mode DMR thing, I know the people who run the site I play at quite well and I've advised them on certain aspects of marshalling etc so they trust me and I wouldn't ever break any fps rules anyway, especially since that law thing said that anything firing over 373fps on full auto was classed as an illegal firearm, or whatever it was.

Plus, since the gun runs a quick change spring and spring adjustment system, if I need to rush a bunker or whatever, I can actually change the spring in the field in under a minute, either the tension of it to reduce the fps, or just completely change the spring to a weaker one.

So, new barrel, new hop, new piston and piston head and maybe remove the second tooth on the piston after checking the AoE.

Any thoughts on the double feeding issue?

Any recommendations regarding the upgrade parts? I'm not sure which piston parts will be compatible. Might take a trip down to Patrol Base and have a chat with them about it.

 

[Deva]

Possibly this? Click the little red arrow thing if you want to see the whole post.

AOE stands for Angle of Engagement, and refers to the angle at which the sector gear and piston engage. In stock AEGs they engage at the wrong angle, putting too much stress on the first sector gear tooth and the first piston tooth. The angle of engagement is altered by adding a spacer to the cylinder head, which stops the piston slightly further back in the gearbox. This means that when the sector gear engages the piston, the teeth meet at a different angle, one which puts less stress on the teeth. A quick google will turn up some pictures which explain this clearly.

Click to shrink...

 

[M_P]

Do you want a list of what Finius did to his gearbox?

 

[Airsoft-Ed]

Cheers Dev, using spacers sounds pretty straight forward.

If you know what he did Marksman, then yeah that'd be great. I thought it was like a secret Finius recipe or something, I was waiting for him to contribute though.

 

[M_P]

My friend picked up a battered old ICS that he wants to fix up, so I asked Finius a while ago

here's what I've done, working from the front of the rifle to the back!
TK Twist Barrel, wrapped in teflon tape to minimise vibrations.

Madbull Blue Rubber and a Big-Out H-nub in the hop, I also switched out the hop-up spring for a harder one to make the nub press down properly.

Standard nozzle which I've countersunk using a dremel. I also shaved .5mm off the tappet plate to get a decent seal around the BB in the chamber. Glue the nozzle to the tappet plate and then give the nozzle a thin coating of tough nail varnish or something.

I've put a .5mm thick piece of brass tubing around the pickup for the tappet plate so it pulls back further to guarantee an effective feed.

Also done all the usual shimming/angle of engagement/piston shaving work. I've found that a piston with more metal teeth works but you have to pick and choose which ones work, you'll probably find almost any of them will need some minor shaving down to fit properly. Motor engagement has been adjusted too. I've got a Lee's Precision Engineering air-braked piston-head in there.

Wrapped teflon tape around the spring guide to reduce vibration for consistency and better sound.

I've set it to 320fps using a spring meant to only provide 300 (air-seal work adds about 20fps). I've wrapped the gearbox in aluminium-foil as much as possible without affecting airflow and function, including round the motor and cage. I've then wrapped EVERYTHING internally, again where possible, in teflon tape to reduce vibration and sound emission.

Generally, where they offer decent performance, stick with stock ICS parts and modify them to suit your requirements.

A lot of the work that needs doing is miniscule bits that take time rather than money. Have a look for a guy called Vindicare Assassin and his AEG DMR guide on google, that'll cover a lot of it!

Click to shrink...

 

[Airsoft-Ed]

Sh*t bobs.

It's like reading another language.

Counter sunk? What the hell does that mean? Lol.

I'll have to ask him about most of this, I just searched for the H-nub and can't find anywhere in the UK to buy one, that's probably the simplest part of the whole thing!

 

[Airsoft-Ed]

Just been talking to him about it. It all seems pretty simple and straight forward now I understand it. I only actually need to buy 3 new parts, the rest is just finding bits and bobs to use in a rather bodge jobby way, or fine tuning the stock parts.

I'm quite excited lol.

 

[Finius]

I'm quite excited lol.

Click to shrink...

He means in a sexual way, just so you all know...I tend to have that effect...

 

[Airsoft-Ed]

<_<