shimming/grease help

[Wo1f]

right.. it was all going so well.. I got my fancy new super shooter cnc gears, kanzen bearings, my guarder teflon grease and my guarder shims.. I shimmed it to what i thought was perfection (shimmed to the bevel gear, no side to side movement and free spun for a few seconds all with the gearbox screwed tight) so i gave each gear and bearing a small smear of grease on the teeth and put everything back together. i tried giving it a spin again and it turned with my finger but didnt free spin at all. the grease was giving it lots of resistance. is this ok or not?

[Airsoft-Ed]

It's hard to tell from your description whether the resistance you're running into is down to the natural resistance there will be between gears. I've personally always struggled to turn a full gear set by hand when the shell has been closed.

 

Or if it's because you've added too many shims, restricting movement of the gears because they're being squeezed too tight by the gearbox.

 

Try adjusting all the shims by .5mm if you can. Then try again.

 

If you've added too many shims then once the gearbox is all screwed together you might notice a visible bulge around the area where there are too many shims.

 

Alternately, you could just try assembling the gun and firing it. If it all works fine and sounds normal then you're good. If there's obviously strain somewhere in the system, you'll be able to tell by the noise, then I'd say to try removing some shims. There ought to be enough left to right play to be able to feel the movement with your fingers still, but only just.

 

Check for all that stuff and reassess.

[Wo1f]

It's deffo grease related. I built it up and tightened the shell down and gave it a spin and it was spot on. It free spun for a few seconds. It was only after I took it apart again when I was happy with the shimming that I greased it and put it back together. The gears do still turn by finger it just stops the second my finger is removed. Il have to wait to test it fully built up as I'm having ascu problems. Thanks for the help.

[RR01]

It's deffo grease related. I built it up and tightened the shell down and gave it a spin and it was spot on. It free spun for a few seconds. It was only after I took it apart again when I was happy with the shimming that I greased it and put it back together. The gears do still turn by finger it just stops the second my finger is removed. Il have to wait to test it fully built up as I'm having ascu problems. Thanks for the help.

 

If you've tested it ungreased and it spun fine then greasing it (sparingly!) should make absolutely no difference to the gears ability to spin freely once put back together. I'd suggest you split the gearbox again and check everything is correct, by checking each individual gear on its own with the shims fitted, then put all three back (excluding the anti-reversal latch) and check that they all still spin freely. If you can get a finger in through the cylinder slot to spin them then a correctly set up gear train should spin easily for at least a couple of seconds.

 

You should shim the gearbox so that there is a small amount of side to side play once the case sides are screwed together (about 0.2 - 0.5mm) on each gear, a bit more on the bevel gear, as that is adjusted anyway once the motor is installed. Once it is set up like that then split the case to refit the cylinder, anti-reversal latch, spring, etc., making sure you don't loose or change any of the shim placings. Also, when you are setting up initially, make sure there is at least one thin shim under the spur gear, then make sure the sector gear has one under it that ensures the flat face of both gears doesn't rub together, as that can cause wear and slow down the spin rate.