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Requesting shimming advice


Confederate842

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Dear fellow airsofters,

I am asking for advice in shimming a CA g36c. I have shimmed the spur and sector gears without problem, and they are held in position firmly and spin very nicely. However on the bevel gear, I have as of yet been unable to reach the same condition. My shimming either makes it a little to loose, where there is a tiny bit of slop, or to tight and there is a little to much friction. Both conditions make me a little uneasy, but it seems to be the best I can do. I have .2, .3, and .5 mm shims, and am wondering if any of ya have any advice.

 

Also,

*Is it better to have the gearbox shimmed a little tight or a little loose?

**Is it more of a factor since it's the bevel gear in question, as the gears are not flat and horizontal where they link up with the motor pinion?

***How does one check the line up between the bevel and motor pinon gears to make sure they line up well with each other? As soon as i slide the motor in, I no longer have line of sight from anywhere..

 

Thanks a ton for your time, any feed back is greatly appreciated.

-Confed

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a little slop is better than a little tight. a little tight will require your motor to work a little harder. if i cant get a gear just right ill always leave a little play. checking the motor and bevel gear is always trial and error. if its too tight gotta reopen and reshim. i always put a .1 mm shim on the flat side of the gear and go from there... though im doing that with my mp5pdw and it whines like a mofo...

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Did you completely screw down the gearbox? Screwing in one or two screws sometimes doesn't do the trick, on my ICS m4 I thought I shimmed stuff "perfect" but when I screwed everything in, the friction was massive and my gearbox was locking up.

 

That slight slop might be negated or slightly decreased if you screw it down. If the slop is very little, I'm sure it won't do much harm to your gearbox.

 

Now that I think of it, my bevel gear has some slop too... while my spur and sector gear are almost perfect. My gearbox sounds and works fine- you can look for my thread on gearbox noises and listen to a sample of it firing. I initially had a problem with motor adjustment.

 

 

I never tried it, but could you also file your .2 mm shims?

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Thanks Maxx, so whine = friction right?

 

Crunk, the only other screws I could put into are the two that connect the motor on the v.3. It does seem to tighten it a little; but I'm not sure if its my box getting tighter, or the pinion gear taking up some slack. As for the filing of .2 shims, I think I'd rather just wait for a shim package to make it to the house. Or are you talking about >.1mm shim washers?

 

Thanks to the both of ya,

Confed

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Whine may or may not be caused by friction. My gun was whining like crazy (actual recorded sound in a thread I made) when the gears were shimmed perfectly. It ended up being caused by my motor being adjusted improperly. My bevel gear was also too low, so I shimmed it higher. That solved my problems.

 

It seems like your bevel gear is fine. If adding the smallest shim creates too much resistance, I think you are done. Shimming needs to be great, but not 100 percent (tolerances are always an issue- sometimes there is .09 mm of slop that you can't do anything about).

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The motor forces the bevel gear towards the right (flat) side. Shimming on that side is more important. If there's a bit of slop towards the other side, the worst thing that can happen is that the bushing or bearing moves towards the gear by the tiniest amount. Minimize the amount of play, but don't lose your sleep over it.

 

I usually add at least a 0.3 mm shim to the flat side of the bevel gear, if possible. I leave the other side empty if I have to. If the room permits, I add even more to the flat side. Reason: If the bevel gear is able to move to the right, you'll have to screw the motor in for a correct mesh, but at some point you can't go deeper because the pinion bottoms out.

 

-Sale

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The motor forces the bevel gear towards the right (flat) side. Shimming on that side is more important. If there's a bit of slop towards the other side, the worst thing that can happen is that the bushing or bearing moves towards the gear by the tiniest amount. Minimize the amount of play, but don't lose your sleep over it.

 

I usually add at least a 0.3 mm shim to the flat side of the bevel gear, if possible. I leave the other side empty if I have to. If the room permits, I add even more to the flat side. Reason: If the bevel gear is able to move to the right, you'll have to screw the motor in for a correct mesh, but at some point you can't go deeper because the pinion bottoms out.

 

-Sale

 

Which side are you referring to? Strange, I had to shim my bevel gear very high (flat side with few shims) to get my gun to not squeak. To make sure the engagement is proper, I put together the gearbox except for the bottom half to give me a perfect visual of the motor/bevel gear engagement, to let me make sure the alignment is perfect.

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Crunkathon2k, it is possible that your anti-reverse steps were rubbing against the spur gear, which would imply that you had a bit too much shims on the left side (below) the spur gear. If possible, you should shim the spur gear as far to the left as you can.

 

The bevel gear doesn't need to be all the way to the left, but I add at least 0.3 on the right side. From there I work equally on both sides to keep it close to the middle. If you had a very wide gearbox, you could end up shimming all three gears too much to the side!

 

By the right and left side I mean the respective sides of the weapon. Just like a car has a left and right seat. The driver and steering wheel are on the left (except for the UK, Japan, Hong Kong and Malaysia). By "top" and "bottom" I mean the typical situation, where the left half of the gearbox is on the table and you assemble the gears on there, with the spur gear first. Shims on the right side end up on top of the gears, and the left side shims are dropped on the bushings/bearings before setting the gear on top.

 

Good to hear the info was helpful.

 

-Sale

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