[Guide] How to shim like a true mechanic

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Age
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[Guide] How to shim like a true mechanic

Postby Age » Sat Aug 27, 2011 10:51 am

***Photobucket is being a pita right now, so some of the pics have text and show where clearance is needed while other pics do not. It seems to change around. I'll try and find out what photo bucket's problem is, but for the time being please bare with me***

Well most of you all know what shimming is, if not just search, plenty of answers as to what it is.... although, not many answers or guides on how to do it correctly, so here is a guide on how to shim like a true mechanic. A lot of people will tell you to start with the spur gear, that is not correct. There is no mechanical application on the planet earth in which you start shimming in the middle and I can't fathom why anyone would. You always want to start on one side and finish on the end, you don't want to start in the middle then get caught up going back and forth between gears. You always want a nice and clean start to finish in your shim job. Do this correctly and your gun will not only function, it will function like it is suppose to.

I'm going to try to make this as simple, easy and quick as possible for you guys.

First, take the pistol grip with the motor and the end cap, then screw it onto the top half of your gearbox shell with only the bevel gear installed. If you have a v3, v6 etc. just screw on the motor and motor cage.

Adjust the motor hight so the pinion gear makes full contact with the bevel gear just like this (obviously it would be inside the gearbox, but this is just so you get a good view of the what it should look like).

http://i817.photobucket.com/albums/zz98 ... G_2886.jpg

Then, place enough shims of the top face of the bevel gear so that it has enough clearance to avoid grinding against the gearbox shell and meshes well with the pinion gear. The bevel and pinion should be making as much contact as possible without hindering the movement or causing to much pressure.

http://i817.photobucket.com/albums/zz98 ... G_2884.jpg

Now that the bevel gear and pinion gear are aligned and meshing properly, you can remove the motor and pistol grip or motor cage.

Now place enough shims on the bottom of the bevel gear so it prevents the bevel gear from riding to low.

http://i817.photobucket.com/albums/zz98 ... G_2891.jpg

Screw the gearbox shell together and test the movement of the bevel gear. If shims need to be removed or added, do so to the bottom of the bevel gear, not the top face. If you alter the shims on the top face it will effect the way the pinion gear meshes with the bevel gear.

Next you install the spur gear. Put enough shims on the bottom of the spur so it has just enough clearance so it doesn't grind against the face of the gearbox shell, the anti reversal latch notches on the bevel gear, and also the bevel gear's bushing or bearing.

http://i817.photobucket.com/albums/zz98 ... G_2908.jpg
http://i817.photobucket.com/albums/zz98 ... G_2897.jpg

Then put enough shims on the top of the spur gear to prevent it from riding up. Screw the gearbox shell together and test the movement. Add or remove shims from the top of the spur gear if need be.

Then install the sector gear with enough shims on the bottom so it has enough clearance from the spur gear and cutoff leaver, and also makes as much contact as possible with the teeth on the piston.

http://i817.photobucket.com/albums/zz98 ... G_2905.jpg
http://i817.photobucket.com/albums/zz98 ... G_2902.jpg

This is wrong. The teeth are not fully contacting each other.
http://i817.photobucket.com/albums/zz98 ... G_2909.jpg

This is correct. The teeth are fully contacting each other.
http://i817.photobucket.com/albums/zz98 ... G_2910.jpg

Then put shims on the top of the sector gear to prevent it from riding up. Screw the gearbox shell together and test the movement. Add or remove shims from the top of the sector gear if need be.

All the gears should have as little play as possible, yet spin freely and without hesitation. I take my time shimming, and I shim gears to the point where they don't move side to side at all, so you may mistake them for being to tight considering you cannot feel them move from side to side, however they spin incredibly well when you move them and you can't even hear them spinning. That's the kind of precision and high tolorances you want, so take your time a get it right.

All there is to it.
Last edited by Age on Sat Aug 27, 2011 4:40 pm, edited 2 times in total.
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SjKimber
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Re: How to shim like a true mechanic

Postby SjKimber » Sat Aug 27, 2011 11:12 am

upload pictures to flickr or imageshack?
great guide.
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Eric
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Re: How to shim like a true mechanic

Postby Eric » Sat Aug 27, 2011 12:20 pm

Great guide Age, but what about sector-piston meshing?
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Age
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Re: How to shim like a true mechanic

Postby Age » Sat Aug 27, 2011 12:26 pm

Eric wrote:Great guide Age, but what about sector-piston meshing?


Contrary to popular belief that doesn't do much. As long as its not dangling on an edge you're fine.
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Eric
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Re: How to shim like a true mechanic

Postby Eric » Sat Aug 27, 2011 12:30 pm

Still, you should add something about having people check to see that they're not meshing poorly. Keep in mind, people reading this for instructional purposes are likely not yet adept at shimming, and need all the help they can get. It's entirely possible to shim a gear in a way that it's just barely engaging with the piston, so it'd be good to put a small alert to watch for that. Aside from my opinion, I'm gonna message Faden asking for a sticky. This needs to be seen. Once again, great guide, and I like yo' gearz.
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SjKimber
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Re: How to shim like a true mechanic

Postby SjKimber » Sat Aug 27, 2011 12:46 pm

This is going to help out a lot of people :]
Last edited by SjKimber on Sat Aug 27, 2011 1:48 pm, edited 1 time in total.
KWA LM4, VFC M4, KWA m9
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Eric
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Re: [Guide] How to shim like a true mechanic

Postby Eric » Sat Aug 27, 2011 1:19 pm

Thank you, Age ;) . Faden's been asked to sticky, so it's in his hands now. I'll be referring people to this from now on.
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Re: [Guide] How to shim like a true mechanic

Postby koolaidz83095 » Sat Aug 27, 2011 3:52 pm

Good writeup; concise and to the point but without missing anything critical. Something caught my attention though:
Age wrote:Do this correctly and your gun will not function, it will function like it is suppose to.

Sorry for being an ass, but I don't think you typed out what you intended to say :lol: .
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Age
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Re: [Guide] How to shim like a true mechanic

Postby Age » Sat Aug 27, 2011 4:38 pm

Meant to say "your gun will not only function, it will function like it is suppose to. :lol:

Fixed.
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Re: [Guide] How to shim like a true mechanic

Postby Jonas » Sat Aug 27, 2011 9:24 pm

Thank god someone knows how to use Macro on a camera.
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