Shims?

How do you add shims?
What are you supposed to do?
I understand the goal is to make the gears not touch each other too closely.
You close the gearbox and spin the gears with your finger yes?
My question is how do you know when its perfectly shimmed?
how much resistance should there be when turning the gears?

TheOneNamedMike wrote:

How do you add shims?
Simple, you need to take the mechbox apart, then remove the bushings from the gears, The shims just slide right onto that axel
What are you supposed to do?
Shims are a very common way to space out mechanical things, in this case how far the bushing sits away from the gear. Legit airsoft mushings are barely a single mm thick and have a 2 mm diameter hole. So yes airsoft shims are different than what you buy at hardware stores
I understand the goal is to make the gears not touch each other too closely.
That, and reduce noise, also how tightly it is, too many bushings, a lot of friction, more wear on motor, and slower ROF/ Properly installed bushings, efficient motor use, less friction, quieter, and no draws on ROF.
You close the gearbox and spin the gears with your finger yes?
As I said above, yes this is a way you test the gears, to make sure the shims are not too tight. But you MUST screw down the gearbox to the appropriate torque so that the same weight put on the gears as if it were assembled in the gun
My question is how do you know when its perfectly shimmed?
When the bushings do not move, but you can freely spin the gears, almost without any effort at all
how much resistance should there be when turning the gears?
As I just said...NONE

Answered in RED

So you take OUT the bushings, and put the shims inside the hole?
Do you put shims on one gear and no shims on another?
Which gears HAVE to be shimmed?
Do you usually double or triple stack the shims?

No, the shims go on the axel, not in the hole of the bushing.

If it were a perfect world, no gear would need shimming. Just shim where it is necessary. Make sure your getting a complete gear meshing, but enough space between each gear so you could slide a small business card in between the overlapping gears. Don't put on just a stack of shims for each gear...its not that simple.
If you want the most accurate shim job. measure how much space you have to work with, and figure where each stack has to be thick, thin or none.

Ussually I don't put a shim on the spur gear if there is enough space between the mechbox shell and the side of the gear (enough space for a paper card)