CYMA P90 full upgrade - Finished... For now...

[Prisce]

Proper engineers plaster there 👍🏻

[Asomodai]

Got a Delayer chip. Had to file it down with the Dremel a bit to fit onto the spindle.

 

 

I put the gearbox together, unfortunately the piston would rack all the way back and get stuck on the last tooth. Any ideas why this might be? The piston cant go back any further as it has hit the spring guide bearing. 

 

[Asomodai]

It lives! 

 

Had to tear out the ball bearing on the piston head as there was not enough space for the piston to come back all the way.

 

Does the gearbox sound ok from the video? I haven't really lubed much at all, just the cylinder set. The Air Nozzle and piston finishes firing in random positions, is that normal? It is currently running on a 8.4 Nimh and a weak motor so might sound off. Getting replaced with a 7.4V lipo on deans and a SLD 22TPA Neo motor.

 

 

[Asomodai]

Took it apart again, used lithium grease on the gears and piston teeth and silicon grease on the piston sides, head, air nozzle and spring guide ball bearing. Put her all back together and all seems fairly good. Air nozzle and piston don’t seem to want to regularly return to the same position. But that could be normal? No idea!

[Immortal]

Interesting project. Looking forward to seeing it finished. 

 

Alas I don't have any answers to your questions.

[Battle_Buddy]

Looks all very complicated 

can’t they just make these good out of the box? I don’t buy my Sony TV and immediately start taking it apart. 

[Prisce]

How many teeth does that piston have? And your sector gear?

 

Have you sorted your AoE?

 

Gearbox doesn’t sound terrible, but that air nozzle has me wondering. 

 

Looking back at the video of mine out of the shell it finished very similar each time.

[Asomodai]

3 hours ago, Prisce said:

How many teeth does that piston have? And your sector gear?

 

Have you sorted your AoE?

 

Gearbox doesn’t sound terrible, but that air nozzle has me wondering. 

 

Looking back at the video of mine out of the shell it finished very similar each time.

 

15 tooth piston, 16 tooth sector gear

 

Aoe is fine. I adjusted the motor height last night and it does sound a bit better.

[Prisce]

Hmm, think you may get a couple of feeding issues with the way that nozzle is going. 

 

If you place  your finger over the nozzle does it hold pressure or all leak out?

 

I think some of your parts may not be compatible. 

 

Not too familiar with the P90 box, but thinking about the V2 box I built I wonder if your tappet plate is catching somewhere. That or some of the parts may be slightly too tight on tolerances. 

 

Just checked mine again and it finishes the same place every time.

[Asomodai]

5 hours ago, Prisce said:

Hmm, think you may get a couple of feeding issues with the way that nozzle is going. 

 

If you place  your finger over the nozzle does it hold pressure or all leak out?

 

I think some of your parts may not be compatible. 

 

Not too familiar with the P90 box, but thinking about the V2 box I built I wonder if your tappet plate is catching somewhere. That or some of the parts may be slightly too tight on tolerances. 

 

Just checked mine again and it finishes the same place every time.

 

The compression is pretty much close to perfect. 

 

I just put it together and tested FPS. On an M90 it is doing around 315 FPS with 5 FPS variance with the hop off. Despite the nozzle ending up in a random place every shot, it appears to be feeding well with no missed shots. 

 

On a 8.4v NiMH battery and terrible CYMA stock ferrite motor its running at about 17rps

[Skara]

19 minutes ago, Asomodai said:

 

The compression is pretty much close to perfect. 

 

I just put it together and tested FPS. On an M90 it is doing around 315 FPS with 5 FPS variance with the hop off. Despite the nozzle ending up in a random place every shot, it appears to be feeding well with no missed shots. 

 

On a 8.4v NiMH battery and terrible CYMA stock ferrite motor its running at about 17rps

You'd need a fcu of some sort to make every cycle regular. I have no idea if there's such thing for p90s.

[Asomodai]

5 minutes ago, Skara said:

You'd need a fcu of some sort to make every cycle regular. I have no idea if there's such thing for p90s.

 

Does it matter if I don't have one? It appears to feed fine despite the nozzle being completely in the forward position before pulling the trigger. Its the first I have heard of this problem and other people don't have a FCU with a similar spec and don't appear to have a problem.

 

Maybe I need to swiss cheese the piston and put in a heavier spring. 

[Skara]

To be honest, it doesn't.

Airsoft guns have been working for 30+ years without them, and they will for another 30+

In the long run you may have troubles with the motor though, as it requires a lot more strength to pull the last mm of the spring, compared to pulling it from a more relaxed position.

This from a discussion I had earlier this morning with a teammate about pre cocking.

Swiss cheesing and heavy springs don't fix the "issue", as the anti reversal latch will always stop the gears in whatever position they are when the current is cut off.

 

I personally find this annoying as hell, but most likely it's because I'm too used to electronic triggers to even consider having a gun without one. They just make everything run so smooth compared to standard, all mechanical gearboxes..

[Asomodai]

56 minutes ago, Skara said:

To be honest, it doesn't.

Airsoft guns have been working for 30+ years without them, and they will for another 30+

In the long run you may have troubles with the motor though, as it requires a lot more strength to pull the last mm of the spring, compared to pulling it from a more relaxed position.

This from a discussion I had earlier this morning with a teammate about pre cocking.

Swiss cheesing and heavy springs don't fix the "issue", as the anti reversal latch will always stop the gears in whatever position they are when the current is cut off.

 

I personally find this annoying as hell, but most likely it's because I'm too used to electronic triggers to even consider having a gun without one. They just make everything run so smooth compared to standard, all mechanical gearboxes..

 

So considering I am getting a 22TPA SLD High Torque motor for Christmas. Maybe that will solve the issues? Its a stronger magnet so in theory there is less play in the pinion. Or am I still not following? I just installed an M100, Motor is really struggling now, though it seems as the nozzle is ending up in less random positions (though still random). 

[Prisce]

2 hours ago, Asomodai said:

 

The compression is pretty much close to perfect. 

 

I just put it together and tested FPS. On an M90 it is doing around 315 FPS with 5 FPS variance with the hop off. Despite the nozzle ending up in a random place every shot, it appears to be feeding well with no missed shots. 

 

On a 8.4v NiMH battery and terrible CYMA stock ferrite motor its running at about 17rps

Maybe it’s a quirk of a P90 box🤷🏻‍♂️

[Asomodai]

2 minutes ago, Prisce said:

Maybe it’s a quirk of a P90 box🤷🏻‍♂️

 

 

Well, come Christmas day I may have some time to install the new motor and see what happens. Going to change the connections to deans so I can use my lipo's as well. 

 

If it still doesn't work then I am going to have to go the whole hog and short stroke it. I really didn't want to have to do it, but considering how many new things I have had to do and learn in the past few days, this cant be much more of a stretch (he says)

[Prisce]

Short stroking is one thing that hasn’t appealed to me yet, it’s on the list of projects. 

 

DSG’d, try to get that magical 70RPS figure, short-stroke, Swiss cheesed piston, in an M4 pistol. 

 

Trouble is, I doubt I’d ever use it. I don’t use full auto at all, just want to build it to say I have.

[Iceni]

The air-nozzle finishing up in random places is nothing to do with a badly built box.

It's a combination of 2 things.

Mosfet without active braking, And a gearbox running a ROF that is closing in on the 2 shots on semi value.

Most ETU systems are also AB mosfet systems. It's nothing to do with been a microswitch, it's all about that active braking circuit that stops the over-spin. AB without an AR latch allows the box to roll backwards to settle as well. So the gearbox will always settle in the most neutral position.

I have a gearbox that will break the 2 shots on semi with a fully charged 7.4v lipo. I haven't bothered to correct it as after a few bursts it settles. If it didn't settle I'd switch to an AB mosfet. The air nozzle can end up anywhere in the cycle and it does 3 shots when out of a gun without a BB load!!!

It's caused because of the energy in the motor and gears. Heavy gears take longer to spin up, but also retain more energy and take longer to come to rest. More piston weight will actually help stop it, As the weight puts load onto the spinning gears with the spring. Reducing gear weight is a double edged sword. You get faster spin up time, and faster arrest time, but the whole system is less efficient on auto putting more drain on the battery.

The advantage of running close to the 2 shots on semi value is the gearbox acts more and more like a pre-cock system the closer you are to the 2nd shot. The over-spin in effect has partially drawn the piston and spring and has a much shorter distance to move. It's another reason my gearbox that breaks the 2 shot semi has been left untouched, because once you are into the flat discharge part of the battery the gun has instant trigger response, Then pre-cocks, Rather than cycling into a shot.

The disadvantage of this is I have to release the spring after a days play, to ensure it's sat at the correct position for storage. Otherwise my springs loose power at an alarming rate. I do this by shooting an 8.4v nimh that is close to discharged to just roll the gearbox over.


It's the same reason they lighten flywheels in racing cars. A lighter flywheel lets the engine gain and loose RPM much faster. So you have less time between gear changes and have more available power band per gear change. The disadvantage is fuel economy and it's easier to stall, as you have less potential energy saved as inertia on the flywheel.

[Asomodai]

On ‎24‎/‎12‎/‎2018 at 08:50, Iceni said:

The air-nozzle finishing up in random places is nothing to do with a badly built box.

It's a combination of 2 things.

Mosfet without active braking, And a gearbox running a ROF that is closing in on the 2 shots on semi value.

Most ETU systems are also AB mosfet systems. It's nothing to do with been a microswitch, it's all about that active braking circuit that stops the over-spin. AB without an AR latch allows the box to roll backwards to settle as well. So the gearbox will always settle in the most neutral position.

I have a gearbox that will break the 2 shots on semi with a fully charged 7.4v lipo. I haven't bothered to correct it as after a few bursts it settles. If it didn't settle I'd switch to an AB mosfet. The air nozzle can end up anywhere in the cycle and it does 3 shots when out of a gun without a BB load!!!

It's caused because of the energy in the motor and gears. Heavy gears take longer to spin up, but also retain more energy and take longer to come to rest. More piston weight will actually help stop it, As the weight puts load onto the spinning gears with the spring. Reducing gear weight is a double edged sword. You get faster spin up time, and faster arrest time, but the whole system is less efficient on auto putting more drain on the battery.

The advantage of running close to the 2 shots on semi value is the gearbox acts more and more like a pre-cock system the closer you are to the 2nd shot. The over-spin in effect has partially drawn the piston and spring and has a much shorter distance to move. It's another reason my gearbox that breaks the 2 shot semi has been left untouched, because once you are into the flat discharge part of the battery the gun has instant trigger response, Then pre-cocks, Rather than cycling into a shot.

The disadvantage of this is I have to release the spring after a days play, to ensure it's sat at the correct position for storage. Otherwise my springs loose power at an alarming rate. I do this by shooting an 8.4v nimh that is close to discharged to just roll the gearbox over.


It's the same reason they lighten flywheels in racing cars. A lighter flywheel lets the engine gain and loose RPM much faster. So you have less time between gear changes and have more available power band per gear change. The disadvantage is fuel economy and it's easier to stall, as you have less potential energy saved as inertia on the flywheel.

 

Thanks for posting! It actually puts me in mind of my F2000 which would always double fire on a fully charged 7.4v lipo. But would get better as the day goes on. Luckily the p90 isn't quite so close to the edge.

 

Does it matter if the piston ends up in a random place or is it a characteristic of the air nozzle in a random place?

 

My mosfets that I have spare are not active braking, but in my experience the gearbox likes to lock up on semi more with AB ones so I tend to stay away from them. 

 

I just installed the new neo high torque motor, on low charge it would cycle almost perfectly and the nozzle ends up mostly in the right place, once I fully charge it, it would act the same way as it did on the old motor. 

 

So I now need to make a decision, short stroke it and put an 120 inside and that might fix the issue, or leave it as it is. Unsure which way to go at the moment. It could potentially be a real BB hose if I wanted to on 11.1v. 

 

Cheers!

[Iceni]

3 hours ago, Asomodai said:

Does it matter if the piston ends up in a random place or is it a characteristic of the air nozzle in a random place?

Only matters for storage. Most gearboxes without AB finish with some pre-cock. For storage you always want the most neutral position to preserve the spring.

As for the motor and RPS. I like to have at least 1 reliable gun. And by that I mean a gun that isn't pushing any boundaries. Slightly underpowered 330 fps, And low RPS 15 ish.

It gives me the best fall back and loaner gun. On a loan out it's not going to cost me significantly on ammo (I always supply it if loaning), And it's not going to break itself. 

If the gun settles in a position you are happy with and the ROF is playable then pushing for more isn't a priority, Especially if you already own a couple of high ROF guns. The lower fire rate for me at least gives me something else to work with in game, I tend to use semi more and play for kills rather than suppression.

 

[Skara]

I switched back to 7.4s on my 2 main guns for two reasons:

Less ammo consumption, meaning I don't dump a lonex 360bb mag in 4 seconds, keeping me in the fight for much longer than with 11.1 fastbois. Useful for tournaments, I don't have to worry about reloading mags mid game;

Less stress on the gearbox, they're both below 328 fps as per our law, but they're reliable, meaning I can hold the trigger knowing I won't fire my piston and spring along the bbs..

ARP on the other hand needs to run on 11.1s -.- until I swap the etu for a titan -.-

 

Oh, btw, a gun that always stops in the same place will sound nicer

[Asomodai]

On ‎25‎/‎12‎/‎2018 at 16:18, Iceni said:

Only matters for storage. Most gearboxes without AB finish with some pre-cock. For storage you always want the most neutral position to preserve the spring.

As for the motor and RPS. I like to have at least 1 reliable gun. And by that I mean a gun that isn't pushing any boundaries. Slightly underpowered 330 fps, And low RPS 15 ish.

It gives me the best fall back and loaner gun. On a loan out it's not going to cost me significantly on ammo (I always supply it if loaning), And it's not going to break itself. 

If the gun settles in a position you are happy with and the ROF is playable then pushing for more isn't a priority, Especially if you already own a couple of high ROF guns. The lower fire rate for me at least gives me something else to work with in game, I tend to use semi more and play for kills rather than suppression.

 

 

I am unsure how I can make the sure that it would be in a mostly neutral position unless I take apart the gun everytime I use it. The Air Nozzle finishes in a random position to the piston. So even if the nozzle is all the way forward it is actually a little more likely that the piston is all the way back. I do own some high ROF guns already. 

 

15 hours ago, Skara said:

I switched back to 7.4s on my 2 main guns for two reasons:

Less ammo consumption, meaning I don't dump a lonex 360bb mag in 4 seconds, keeping me in the fight for much longer than with 11.1 fastbois. Useful for tournaments, I don't have to worry about reloading mags mid game;

Less stress on the gearbox, they're both below 328 fps as per our law, but they're reliable, meaning I can hold the trigger knowing I won't fire my piston and spring along the bbs..

ARP on the other hand needs to run on 11.1s -.- until I swap the etu for a titan -.-

 

Oh, btw, a gun that always stops in the same place will sound nicer

 

I am with you on this. I do worry that my midcaps wouldn't feed going so fast on 11.1v as well. But I would like the piston and nozzle in the right place... I am undecided. 

 

However in the meantime I have tackled the other big part of the build, electrics!

 

I had some fun with this. I only had a diagram for the P90 that would take into account if I had a single trigger contact on the mosfet. However mine had two contacts. I initially set it up for the positive motor wire to go to the full auto trigger loom and the trigger contact on the mosfet as well as the motor output on the mosfet to the same auto trigger contact loom. When connected up it just went straight into full auto. Went back to the drawing board and realised I just had to feed the trigger contact loom to the trigger contact part of the mosfet and the motor and battery straight from the mosfet. Easy when you think about it, but things were getting complicated because of the oddness of the V6 gearbox. 

 

It was really difficult to wire up the dual stage trigger with 16AWG wire as it was so thick, but just about managed it, I couldn't connect the trigger loom to the trigger contacts on the mosfet as the mosfet solder patch was far too small for 16AWG. I could have just gotten away with the original wiring as its just triggers but we live and learn!

 

I did overstretch the return trigger spring by accident... It doesn't seem to affect much, but I might want to source another if I can. 

 

I forgot to buy some wire crimps so I had to bite the bullet and solder directly to the motor which was pretty difficult because of the magnetism and the small area of contact. 

 

 

Here it is with a 30C 7.4V lipo in storage mode. This is also with the new SLD Neo motor. 

 

I did try a 11.1v and it broke straight through the double fire barrier on single shot. Ridiculous ROF! 

 

I also installed the Laylax extended Mag catch. Was it worth the money? Probably not, but will be damn useful for mag changes with gloves on! 

 

 

-------------------------------------

 

I have three  choices.

 

Leave it as is and finish up the project.

Open it back up put in the M120 and short stroke it by a couple of teeth and use 7.4V and take the ROF hit from what it currently achieves.

Or go with 11.1 and hope for the best. Thoughts?

 

I do need to re-chrono it since putting in the new M100, I have a feeling it might be slightly too hot as it is. 

 

 

Whilst I was at it, I extended my ARX160 wires and installed a Deans connector. 

[Asomodai]

Hard to see but because of the screws on the SLD motor, I was not able adjust motor height low enough. Had to get the dremel out and eat away at the gearbox. Gearbox sounds much better now!

[Asomodai]

Just tried what I thought was a heavier M120 spring but still getting the piston and air nozzle in random places. Either the Spring is only an M100 or/and I really need an AB mosfet or/and something else is wrong. Will chrono tomorrow to check the FPS. The spring is much shorter then the others I have, though feels a little stiffer. 

[Asomodai]

I have just tried it with an M120 spring, FPS is 404 FPS. Unfortunately the piston and nozzle still end up in random places. Could there be an underlying issue here? Would short stroking it help?

 

Or do I need to settle on an AB Mosfet instead?