Peeque's Tech Thread

Discussion in 'Gun Building, Modifications & Repairs' started by Peeque, Sep 12, 2017.

  1. aotsukisho

    aotsukisho Well-Known Member

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  2. LightIsRight

    LightIsRight Well-Known Member

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  3. aotsukisho

    aotsukisho Well-Known Member

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  4. Peeque

    Peeque Well-Known Member Supporting Member

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    Last edited: May 29, 2020
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  5. Peeque

    Peeque Well-Known Member Supporting Member

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    I bought a used CYMA CM.039c. I'm still not a fan of AK's but this one looks cool, lol.

    Stock* performance with 7.4v 1200mAh 25c. 360-365FPS with .25g, 12RPS.



    * Actual stock FPS was 380FPS. I replaced the spring immediately after receiving so it could be used at a potential game the next day.

    IMG_20200606_174106.jpg IMG_20200606_173350.jpg

    The wiring is quite janky. Why are there two fuses? Two sets of spade connectors as well. I wouldn't be surprised to see a nice increase in RPS and cycle time after re-wiring.

    IMG_20200606_175427.jpg IMG_20200606_174502.jpg

    The motor might be neo? It's able to hold up my hammer.
    IMG_20200606_182851.jpg

    That's all for now. I'll clean out the gearbox and all that jazz another day.
     
  6. Peeque

    Peeque Well-Known Member Supporting Member

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    Rebuild time!

    This guy needs a bath!
    JPEG_20200609_152820.jpg

    Ah, that's better!
    IMG_20200609_161003.jpg

    I polished the cylinder but it didn't turn out that great. I've got new metal polish on the way to try out.

    Before
    IMG_20200609_161136.jpg

    After
    IMG_20200609_162115.jpg


    Here it is all cleaned out and shimmed, AoE corrected. #14 o-ring, o-ring glued to air nozzle, bushings glued in place, rewired with 16awg and Dean's Ultra. I replaced the stock plastic spring guide with a steel one that I had on hand. Otherwise this is completely stock, just rebuilt.
    IMG_20200609_205922.jpg


    Rebuild test fire with 7.4v 1200mAh 25c


    355fps w/ .25g @ 1.4J & 12rps.
     
    Last edited: Jun 10, 2020
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  7. -Spitfire-

    -Spitfire- Well-Known Member Supporting Member

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    Definitely is neo. Pretty typical for VFC-style Cyma AKs.
     
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  8. aotsukisho

    aotsukisho Well-Known Member

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    Agreed, ferrous magnets are never silver-colored in my experience. Being able to hold up anything through the motor cage is a good sign, ferrous magnets have trouble holding their own weight up on anything stuck straight to the can
     
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  9. Guges Mk3

    Guges Mk3 Well-Known Member Supporting Member Lifetime Supporter

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    However that can be a N28 up to a N52...all of which are NEO magnets, but the performance value varies greatly.
     
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  10. Peeque

    Peeque Well-Known Member Supporting Member

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    It's on the weaker side for sure. It was just barely holding on to that hammer. If I wiggled it it would fall off. Maybe that was because it was still in the cage.
     
  11. Guges Mk3

    Guges Mk3 Well-Known Member Supporting Member Lifetime Supporter

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    Most likely N28...knowing China and ACM.
     
  12. -Spitfire-

    -Spitfire- Well-Known Member Supporting Member

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    Yeah, that cage definitely will make a notable difference.. That said, the hammer is also pretty heavy.
     
  13. Peeque

    Peeque Well-Known Member Supporting Member

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    So today I ruined an FLT bushing and possibly my bevel gear.

    I'm trying to figure out what is causing my gears to rattle so much so I started sound testing every gear one shim at a time. What if I make this looser, what if I make this a little tighter, what if I make it too tight? That kinda stuff.

    Well I start out on the bevel gear cause well it's first in line and I get to the point where I'm like frick this let's hear what it sounds like when it's way too tight. So I put on one extra .1mm shim. Just .1mm too tight y'all. Within 10s of this gear spinning the shell got super hot and then it made this terrible noise that you know can't be good.

    PXL_20200919_231307477.MP.jpg
    PXL_20200919_231321722.jpg

    Part of that extra shim is fused to my wonderful FLT bushing, and the other shim is straight up friction welded to the bevel gear.

    9/10 would do again with cheaper bushings.
     
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  14. Wingman703

    Wingman703 Moderator Staff Member Moderator

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    Yeah, when in doubt, too loose on the pinon is preferred over too tight.
     
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  15. Peeque

    Peeque Well-Known Member Supporting Member

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    Yeah I knew it would be too tight. I just didn't know this would happen so quickly. The rattling stopped and aside from the screeching from being too tight it actually sounded better.

    I've tried every combination of shims on the gear and no matter what it sounded like this. Maybe when I glued the bushings in they didn't sit completely flat and are slightly angling the gears? They all seem flat to me.
     
  16. Peeque

    Peeque Well-Known Member Supporting Member

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    I got a new gun! It's a Galaxy MP5K I yoinked for $80.

    PXL_20200930_195047866.jpg

    The battery space is indeed limited but the 2s Turnigy nano-tech's fit perfectly.

    PXL_20200930_201105434.jpg
    PXL_20200930_200825061.jpg

    These cheeky Gens/Tattu batteries I have for an upcoming drone build fit nicely in the grip. Their capacity is significantly lower at 550mAh compared to 1300mAh, but have a much higher discharge rating. They are 2s too, but Gens/Tattu has a 3s version that look to fit in the grip too.

    PXL_20200930_195331151.jpg
    PXL_20200930_195357741.jpg

    The grip has these little slots at the bottom. I could make a little cut out horizontally on both sides and print a cap that would work similarly to those on medicine bottles.

    PXL_20200930_202139411.jpg
     
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  17. interceptor

    interceptor Well-Known Member Supporting Member

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    Nice find - don't think I've seen one for a while. I can't remember - is the body plastic or metal?
     
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  18. Peeque

    Peeque Well-Known Member Supporting Member

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    It's some pretty sturdy plastic.
     
  19. Guges Mk3

    Guges Mk3 Well-Known Member Supporting Member Lifetime Supporter

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    I got a 1300 2S that would fit that grip.



    96x20x16mm are it's dimensions. I could have the factory fatten it to 3S.

    It is a 25C unit...
     
    Last edited: Oct 1, 2020
  20. Peeque

    Peeque Well-Known Member Supporting Member

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    The inside dimensions are 74x27.5mm but that bottle neck at the top starts ~60mm in so it would stick out ~36mm. I could print a box based on those dimensions and see if it will fit past that neck and go the full 74mm. I'm not sure what the ID shrinks too where the neck starts.

    Maybe I'll yoink one anyway and see if I can make something work. If not I'm sure I could use it with another gun.

    How much are they?