M4A1 UPGRADE

Discussion in 'Gun Building, Modifications & Repairs' started by Xardass, Dec 7, 2021.

  1. Xardass

    Xardass New Member

    13
    0
    Hello
    I`m quite new to airsoft, started like 4 months ago with a cheap gun ~100$ M4A1 Cybergun
    The gun suddenly died and I decided to don`t send it to the warranty but to completely change it to another level.
    I started searching in the forums and on YT and I made a new build.

    Parts I used:
    SHS gears 16:1
    SHS bearings
    SHS double o-ring cylinder head
    SHS Cylinder
    SHS Aluminium 14 tooth piston
    SHS double o-ring piston head
    30k Boost motor
    Titan V2 advanced
    M120 spring
    Metal spring guide with ball bearing
    New tappet plate
    M4 Aluminium air nozzle (21.4mm)
    Battery Novritsch 11.1 2600ma

    Maxx Hopup unit
    Changed the inner barrel from 295 mm with Prometheus 6.03 407mm
    Hopup bucking purple Prometheus (soft)

    After all the integration process I encountered the first problem.
    At the first sight, my gun was not feeding properly. Because it was already Friday and I could not get a new nozzle till Sunday (airsoft day) I put a 2mm gasket between the gearbox and hop up unit.
    The good news was I could shoot with the original magazine but I could not with 120 midcap magazines. With midcap magazines, the bb was traveling around 15-20m and fall down (was like was unhoped)
    I will try to change the air nozzle but firstly I would like to get a few more opinions from people with more experience.

    After the airsoft day:
    If I shoot quite fast after around half magazine (350X0.25bb) the handgrip gets warm. Is that normal for such a build?
    The peak current measured by titan is 121.6A. Is that normal?
    I will attach photos with the old parts, with the failure spur gear, with the new build, an with titan statistics.

    defect spur.jpg hopup to gearbox nozzle.jpg hopup to gearbox.jpg new gearbox.jpg nozzle retracted.jpg old gearbox.jpg old parts.jpg titan statistics.PNG
     
  2. Ben3721

    Ben3721 Well-Known Member

    884
    459
    Is that a crack in the aluminum piston rear right hole? Aluminum pistons tend to bend or crack right there most the time unfortunately.
    A shs 14.5 metal rack plastic piston would be better.

    The issue with the feeding is probably because it's not pulling back all the way with that lonex tappet. A cheap shs one would do better. Or stock one.. Nozzle length and spacers aren't the best first approach.
    If the nozzle is a hair too short, sand the front of the tappet a hair. If it can't pull back far enough and there's room to move back, find a different tappet. Not a single part is to blame, they just fit together different with different brands of parts.

    Also the sector delayed chip needs less material on the pickup side.

    You should also look into radiusing the front windows to prevent cracking, and aoe correction of the piston with padding. Those three mods should help that build last much longer
     

  3. Guges Mk3

    Guges Mk3 Administrator Staff Member Administrator Supporting Member Lifetime Supporter

    8,780
    4,888
    Minneapolis
    Never run Aluminum pistons. They went away in the early 2000's due to aluminum not being able to handle shear stress, ie steel on aluminum...which material loses? The person who brought back aluminum pistons needs to be ignored.

    Your running a double bearing system (piston and spring guide side). Don't do that, you cause more stress in your mechbox in two ways. Your preloading the spring more and depending on the spring you may bottom the spring out (or nearly bottoming it out) and that will stress your electricals more...this is why you may be experiencing a high amp draw. Most M120 class spring that are built right only draw ~20A.

    Bearings were brought into the mechbox to address a design flaw. You don't need bearings if you buy a good hard spring and not a bad soft spring. Sadly...people don't know this history and just made assumptions that you need bearings on the head or the guide.

    In all honesty you threw to many parts for no "real" gain in performance. You could have just replaced the gears and used the stock parts with some efficiency tweeks and achieved the same thing with less cost and stress.

    In this day an age...due to the lack of manufacturing standards, any non-stock part will cause issues.
     
    Last edited: Dec 8, 2021
    mr. potatohead and Squad144 like this.
  4. Ben3721

    Ben3721 Well-Known Member

    884
    459
    I believe shs or aols brought back aluminum pistons. The reviews show a lot of cracking and broken racks. It's very interesting that aluminum can't handle the shock somehow. I'd imagine a plastic piston flexes a lot more than we want to know. But aluminum doesn't really flex much, it just stays bent a bit more every time until it becomes an issue, or until the rack breaks.

    If you got it off Amazon you could probably return it if it breaks or has any cracks. That's what I'd do.
     
  5. Guges Mk3

    Guges Mk3 Administrator Staff Member Administrator Supporting Member Lifetime Supporter

    8,780
    4,888
    Minneapolis
    It's not so much a shock issue, rather it's a sheering force issue. Good polymers is harder than hard aluminum alloys. This is why no stock AEG has never had Aluminum alloy pistons (hint look at the Japanese)...we figured this out in 2001.

    Sadly 20 years later and everyone forgot about them and honestly...some moron brought back AL pistons...

    The saying, know your history or you will be doomed to make the same mistake over and over again...applies aptly here.
     
  6. Xardass

    Xardass New Member

    13
    0
    The first thing I want to point out is that for me is actually the first time when I open an airsoft gun, so I'm not pointing out this build is a performance build. I want to learn from it and perfect it.

    Today my new air nozzle arrived and it seems the Maxx 20.75mm air nozzle solved my feeding issue.
    On the next component order, I will get a new polymer piston. Till then I removed the bearing from the piston and this weekend I will open the gun for AOE alignment.
    Today I just shoot 2 mags semi/auto to check the feeding. The main concern is that the current is still quite high. When I opened the gearbox I checked for possible errors and the shimming on gears looks fine (with all gearbox screws tight if I turn the sector gear with my finger it keeps rotating for a few spins) the piston moves easily with the gearbox screws tight.
    What can be the cause of that high current?
    Capture.PNG
     
  7. Ben3721

    Ben3721 Well-Known Member

    884
    459
    Did you get a chance to evaluate the aluminum piston for a crack? If the rack is sinking or busted it may show high amps from fighting to pull it back.
     
  8. Guges Mk3

    Guges Mk3 Administrator Staff Member Administrator Supporting Member Lifetime Supporter

    8,780
    4,888
    Minneapolis
    You dropped 20A by removing one bearing set? Wow...

    Got another motor you can try? You have a 30K Boost and the QC for those have been spotty at best.

    Also, did you do that gear spin test with the mechbox tightened down or just with the two halves together?
     
    Last edited: Dec 9, 2021
  9. Xardass

    Xardass New Member

    13
    0
    I opened the gearbox and I took the piston out for photos
    1AA1E874-DA3D-4AE3-8D9C-DBBCD2654480.jpeg 1AA1E874-DA3D-4AE3-8D9C-DBBCD2654480.jpeg 11E0E54F-D53A-4CF8-B26D-61CE3486F72F.jpeg FEBE3320-77D7-4F0B-B459-D628645D9381.jpeg 9CAA2785-D007-415A-8356-9497E32D3092.jpeg DE9C26F6-4F2B-46D7-8E25-BDA5156AAEF6.jpeg EF107247-8930-4333-B0F7-8292A7D48A27.jpeg 26D2D44E-634E-40CE-976A-3203BC9D6CB1.jpeg
    It seems it does not have any cracks, it has a mark on the 14th tooth (today i will shave half of that tooth when i will make the alignment) and I will also shave the rack where is scratch.
    Regarding the motor, I took the motor out and except the titan protects the motor (cuts the power after 0.3s) it gets warm after ~10 trigger pulls.
    Unfortunately I don’t have another HS motor to test the gun. I only have the original motor but I don’t have any information about it
     
  10. Ben3721

    Ben3721 Well-Known Member

    884
    459
    That mark you highlighted on the aluminum is from PME. Could have been a fluke jam or true pme from being such a heavy piston.
     
  11. Guges Mk3

    Guges Mk3 Administrator Staff Member Administrator Supporting Member Lifetime Supporter

    8,780
    4,888
    Minneapolis
    And that "ding" by the piston head shows why you should not use "Aluminum" for a part that moves a lot. If this would have been a POM piston...that ding most likely would never have showed up. The PME/Tolerance issue on tooth "2" was the cause for that most likely.

    This reminds me of another "Car" Analogy, don't use Aluminum in places where soft metals should not be used, unless it's designed right from the very beginning. Chevrolet Vega with the Aluminum Alloy Cylinder blocks "without" cast iron cylinder liners...yes...in summary it did not work as designed.

    I suppose if some made this exact piston out of Zytel...it would destroy the stock part fleece the new player market for pistons...and they wouldn't want to do that...I mean turning off the spigot of money would be silly.
     
    Last edited: Dec 10, 2021
    Squad144 likes this.
  12. Squad144

    Squad144 Active Member

    284
    76
    Ocean Springs
    You said it was a cheap gun? Stock gearbox? Yea I think I may know the problem for your high amp draw... take a look at where the bevel gear is positioned. What I have noticed in many cheap guns and even more expensive ones like the Classic Army Nemesis is that the bevel gear bushing (bearing) hole is positioned wrong. Ben actually found this same problem in the Retro Arms CNC gearbox. Now, how does this lead to high amp draw? Well this causes the pinion gear on the motor to contact with the bevel gear at a poor angle, decreasing efficiency and thus drawing an excessive amount of amps. Pair this with the problems Guges and Ben have pointed, this might explain why your gun is preforming as such.

    The best way to tell if your bevel gear bushing (bearing) hole is misplaced is quite simple. Just make sure that your have shimmed your gears correctly and these steps should work for you.
    1. Take everything out of the gearbox.
    2. Place the sector gear with it's shims and the spur (step) gear with it's shims into the gearbox.
    3. Close and screw shut the gearbox.
    4. Spin the sector gear with your finger. It should make no noise and be extremely easy to spin.
    5. Unscrew and open the gearbox.
    6. Add the bevel gear with it's shims.
    7. Close and screw shut the gearbox.
    8. Now when you spin sector gear, it should sound and feel just it did without the bevel gear inside. If it is louder and feels just a little more difficult to spin, then your bevel gear bushing hole is misaligned.

    Remember, perfect shimming really just means that the gears are not rubbing together or on the gearbox and have just about .2 to .1mm of up and down play.

    Unfortunately, if your have come to the conclusion that your bevel gear bushing (bearing) hole is misaligned, then the only way to fix this problem is to buy a new gearbox.



    Just as little advice, only change the parts that are needed. As Guges said above, there was no need to spend all that money on SHS compression parts if you could salvage what was stock. Instead, your put your money into a nice Tienly 35k or 40k motor. Those are both fine to use with 16:1 gears and an m120 spring.

    After looking at those stock parts, that plastic piston should be fine to handle a m120. Try using that. If it strips, then oh well. It is just a cheap nylon piston. Buy yourself a SuperCore or Magic Box POM piston.

    Another thing many newbies mess up on is checking their compression. Do not listen to (some of) those morons on youtube. You do not need to use your nozzle for compression test. You only need your cylinder, cylinder head, piston, and piston head. Put one finger over the cylinder head hole and just push the piston assembly into the cylinder. It should start compressing air once it reaches the port on the side of the cylinder. Increase pressure on the piston to ensure that no leaks are present. As for the nozzle, it only needs to fit tightly but not too tight on the cylinder head. Loose enough to slide easily but tight enough to not fall off when you invert the cylinder upside down. Yes an oring nozzle does help to keep the nozzle steady on the cylinder head but it is not needed for compression reasons. One of the laws of Fluid Dynamics says that a fluid will take the pathway of least resistance. Backwards is not the least resistance in an AEG compression system.

    Hope this helps.:)
     
  13. Ben3721

    Ben3721 Well-Known Member

    884
    459
    I think the bevel is leaning from the arl latch pressing on it before its closed. You'd have to see the outside of the shell to see if its a bushing placement issue.

    Most techs shim loose with slack around the motor tower anyways. Very few shim tightly enough to expose that problem.
     
  14. Xardass

    Xardass New Member

    13
    0
    Today I tried to make the AOE by adding some poly shims on the piston head. After the AOE I assembled the gun, shot a few bb, and checked the result.
    The current was the same so I decided to take the shims from the piston head out.
    I assembled the gearbox and put just the lower of the gun with the battery and I shot few times.
    On semi, the piston does not stop at the same point all the time. The big problem is that on auto the piston stops with the spring fully compressed.
    I leave a link with the video files:
    https://wetransfer.com/downloads/74416ec7b8e2400e06975a29cccae81120211210195007/83e203

    Tomorrow I will recheck the shimming and the problem pointed out by Squad144.
     
  15. Guges Mk3

    Guges Mk3 Administrator Staff Member Administrator Supporting Member Lifetime Supporter

    8,780
    4,888
    Minneapolis
    Firing in FA and the piston stops with spring fully compressed is "normal".

    This is due to the random points where it stops with the ARL and bevel gear interaction.

    This is why you always fire the AEG in SA before you put it away in storage.
     
  16. Ben3721

    Ben3721 Well-Known Member

    884
    459
  17. Xardass

    Xardass New Member

    13
    0
  18. Squad144

    Squad144 Active Member

    284
    76
    Ocean Springs
    Did it feel any different than when you only had just the sector and spur gear in? Cause you will feel a difference.

    It sounds fine on this end
     
  19. Xardass

    Xardass New Member

    13
    0
    no, it did not feel any different.
     
  20. Squad144

    Squad144 Active Member

    284
    76
    Ocean Springs
    Ok then your bushing alignment is fine. It is possible you have not shimmed your bevel gear height wise to your motor. That is as easy as placing shims on the top or bottom of the bevel gear.