Quick Shimming Question.

[LazzurusMan]

Do I need to have shims on both sides of my gears?

My bevel gear is too close to the pinion gear if I put even a .1 shim to push it closer to the pinion. I don't have anything thinner, and I'm not sure about letting the gear run on the gearbox itself.

[Pewpewpetie]

21 minutes ago, LazzurusMan said:

Do I need to have shims on both sides of my gears?

My bevel gear is too close to the pinion gear if I put even a .1 shim to push it closer to the pinion. I don't have anything thinner, and I'm not sure about letting the gear run on the gearbox itself.

You can, but I would avoid this at all costs. You have a few options, order some thinner bushings, sand existing bushings or change gear set and hope that it has a shorter vertical length. As I said it's not ideal to run without shims but it will work, also could run the risk of burning motor out due to increased resistance

[Adolf Hamster]

i tend to like having at least one shim on both sides, normally i'll start with 0.1 under the sector and then add to the top side.

 

same for the idler then i can set the bevel where it needs to be for pinion engagement, then if there's not enough tooth engagement between the beval and idler i'll push the idler/sector up by transferring shims as appropriate.

[Rogerborg]

We all have our own rituals, but I start by shimming under[*] the spur gear until it's just clear of the gearbox and not scraping on it at all. I've not had a gearbox yet which didn't need some shims under the spur.  Then I shim the bevel and sector to sit just above the spur and do spin tests with the gearbox closed and held in the same orientation, left-side down.

 

Only then do I put shims above the gears and hold the box upright or right-side-down.

 

I'd agree with wanting at least one 0.1mm shim on both sides of each gear to give a flat surface for the gear to spin on, unless there's literally no free play at all in it with no shimming.

 

[*] "under" with the left hand side of the gearbox on the bench, nozzle to the right.

[Adolf Hamster]

23 minutes ago, Rogerborg said:

We all have our own rituals

 

an equally valid point.

 

generally when i've shimmed the sector and more on to the idler if it's contacting with only 0.1 under it then it gets shimmed too (as well as shimmed to prevent contact with the sector)

 

ultimately if nothing is binding/jamming, everything spins smooth regardless of orientation and the bevel is in a good spot for motor mesh it really doesn't matter how you get there.

 

best boxes to shim are a&k lmg boxes, the open bottom might be awful design for preventing crap getting in but it sure does make visual checking of shimming a breeze.

[LazzurusMan]

Cheers everyone. Gears should be shimmed ok now with shims on both sides (still very loud, but I am running 11.1s), just gotta get new motor connectors as both broke during fitting.

[Rogerborg]

As Luke at Negative keeps noting, sometimes you just get noisy gears even with perfect shimming.  I've taken to using a tin of Carlube LM2 multi-purpose grease now, because it happened to be closest to hand one day, seems to work as well as anything else I've tried, and might be reducing noise a bit. Although, again, ritual beliefs.

[LazzurusMan]

38 minutes ago, Rogerborg said:

 I've taken to using a tin of Carlube LM2 multi-purpose grease now, because it happened to be closest to hand one day, seems to work as well as anything else I've tried, and might be reducing noise a bit.

Alas, all I have to hand is a very small tub of generic gear grease. Not a lot of noise reduction (or at least not last time I lubed any gears) but seemed to do the job it's supposed to do.

Onto the next step, aoe.

[Adolf Hamster]

8 hours ago, Rogerborg said:

As Luke at Negative keeps noting, sometimes you just get noisy gears even with perfect shimming.  I've taken to using a tin of Carlube LM2 multi-purpose grease now, because it happened to be closest to hand one day, seems to work as well as anything else I've tried, and might be reducing noise a bit. Although, again, ritual beliefs.

 

indeed, things like tooth engagement/backlash aren't really adjustable for airsoft gearboxes so sometimes they won't mesh right, plus ofc the tooth profile/face quality plays into it as well.

 

keep meaning to give helical gears a go but they seem to mostly be catered to high torque dmr builds than high speed builds, and the notation for the ratio is confusing.

 

plus box material, eg the harder material of an lct box makes for more vibration than the softer material of a jg box.

[Lozart]

On 11/07/2021 at 06:14, Adolf Hamster said:

 

indeed, things like tooth engagement/backlash aren't really adjustable for airsoft gearboxes so sometimes they won't mesh right, plus ofc the tooth profile/face quality plays into it as well.

 

keep meaning to give helical gears a go but they seem to mostly be catered to high torque dmr builds than high speed builds, and the notation for the ratio is confusing.

 

plus box material, eg the harder material of an lct box makes for more vibration than the softer material of a jg box.

 

Helical gears are a royal pain in the arse. IF you can get them shimmed right they are about as quiet as you'll get in an AEG, if not then they're the noisiest things on the planet!

[Adolf Hamster]

1 hour ago, Lozart said:

 

Helical gears are a royal pain in the arse. IF you can get them shimmed right they are about as quiet as you'll get in an AEG, if not then they're the noisiest things on the planet!

 

yeah, also heard they're pretty good at eating bearings thanks to the side thrust you get on them.

 

however it is my current mission- i've got the response down nice, just want to eliminate all the gear noise.