Greasing a grinder

[OneEyedMan]

My monthly trip to HF today yielded a cordless Hercules paddle switch grinder in the clearance section. It appears to be unused and is another tool I wanted to test out for employee use.

Before I used it I wanted to see if lubing the gears would quiet it down some. I’ve opened up my M18 grinders to redistribute the factory lube pile and this one had the same squirt of grease out of the way of most moving parts. I’ve never looked for grease specs relating to the kind of forces these gears apply and have no idea what’s used at the factory but assume it’s shoots for the bare minimum requirements.

I would guess some shear resistance is needed and whatever the opposite property of thixotropy is desirable. I spread what was in there on the needle bearing back of the housing and spread some more on the large gear and it did quiet the grinder noticeably. For future use I’d like to know if anyone has a good grease recommendation for grinder heads.

 

[bugzilla46310]

I put Lucas red and tacky in most everything around the house. When I replaced brushes on my 40+ year old 4” Makita angle grinder a few years ago, greased the gears on it also. Wouldn’t over analyze, though I often do!

 

[dnschmidt]

The best is John Deere cornhead grease which is thoxiotropic. It's a thin grease to begin will and goes almost liquid in shear. Once it stops being sheared it reverts back to being a grease. No matter what NLGI #2 grease, which is what most over the counter grease is, goes into a grinder 99% of it ends up on the walls of the gear case, like you mentioned, and very little actually does anything with the bevel gears.

 

[5ubtle]

There was a suggestion at Practical Machinist for "weed eater gearbox grease"

https://www.amazon.com/Stihl-0781-120-1117-Lubricant-B/dp/B007TK0TU0?tag=atomicindus08-20

The OEM grease inside my 20yo craftsman looked to be about NLGI #1, but it likely had less body when new. JD cornhead grease (made by Cenex?) is NLGI #0, and seems like a good suggestion.

 

[The Cobbler]

I used some very old water pump grease that I have on an angle grinder. it works well . but too much grease is no good too,