My King Arms Shim Test.

[Sarge127]

Yeeaahhh this was like my 2nd time shimming on my king arms the first method i used was from ATSKilo23s? guide starting from the spur gear and moving onto the yada yada. So i wasn't impressed no matter how many times i attempted to make it a little quiet so i looked for other methods and found the "Pinion to Bevel" Method without cutting or drilling into my new KA.

I don't knoooowww i made a short vid to demonstrate my first results I'll let you guys decide if its good or bad because im not 70% sure on how its supposed to sound.

https://www.youtube.com/watch?v=GuER9RulBcM

If you got any tips I'd appreciate it.

[pestobanana]

King arms guns usually sound terrible. When you get it shimmed properly all you should hear during testing is a hum. Check the motor tower fitment within the grip hole. Often it's far too loose and that causes poor pinion-bevel meshing. If that's the case shim the tower with heat shrink, get rid of the spring and use o-rings instead. I had to so that on a few KA M4s.

[wind_comm]

http://youtu.be/hGe-tPycrfw

this is what we all aim for when bevel/pinion shimming. don't sweat it if you can't get it perfect the first few times, it takes a while to get a handle on the whole shebang. getting it wrong is half the fun.

[Sarge127]

Well after spending most of the afternoon trying to shim it perfectly i concluded i blame the motor... I did the method perfectly i made sure the gears were shimmed as they should be and were able to spin freely upon screwing the gear box together and well i was surprised i got it right for once and i decided to call it a day and just test it out turns out it makes a screeching sound which anyone can hear. I don't know what i did wrong but it sounded good when i was testing it. The motor i use is a TM EG700 high torque.
>_> Gonna try and figure out what i should do now.

[pestobanana]

Did you check for play between the motor tower and the grip?

[Sarge127]

Yes indeed i did and no problems were to be found. Ok um here's a question. How many 0.1mm Shims should be on top of the gear? i but about at least 1 on the bevel and 2 on the others then worked on that set up.

[pestobanana]

Every gearbox and gear set is different, can't answer that question.

I did just rewatch the video on my computer with headphones, it sounds pretty normal to be honest. It sounded pretty bad when I watched it earlier on my phone.

Other people's guns sound quieter because mostly from the acoustic setup, not the gun itself.

[lurkingknight]

I find the videos and audio demonstrations of shimming to be a little difficult to trust. Mics do some really weird things to sound, and even video camera mics often don't represent the sound very well, not to mention the acoustics of the room you're filming/shooting in.

My guns sound completely different in person than on video.

[wind_comm]

in the first half of the video, are you testing the shimming with the cutoff lever installed? if the selector isn't all the way to full auto, the cutoff will engage slightly and create an intermittent click that I'm hearing.

Originally Posted by Sarge127

Yes indeed i did and no problems were to be found. Ok um here's a question. How many 0.1mm Shims should be on top of the gear? i but about at least 1 on the bevel and 2 on the others then worked on that set up.

as many as needed. bevel to pinion often leads to everything being shimmed SIGNIFICANTLY _higher_ than the spur method (had one gearbox where it was almost 1.5mm, yes millimeters, higher than the spur method most cases aren't nearly that extreme.) rather unlike what some people would forcibly tell you to believe, there's no preset amount of shimming in gearboxes, the tolerances are just all over the place and every gearbox will be different.

[Vivek92]

It is really hard to judge shimming from video/sound clips imo. Sometimes they are deceptively quiet, other times screechier then they actually are.

From what I hear it sounds good (there's only so much you can do about motor noise and piston slamming).