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Lubrication for Plastic Gears

14,738 5,475 March 9, 2011 at 03:09 PM
I have a scanner that has a motor that seems to be dying maybe. It is a gear motor and drives plastic looking gears (my guess is they are nylon) . They have some grease on them but its pretty dirty. My hope is that I can clean it up and apply new lubrication and at least get by a few more months till our new imaging system is implemented with a new scanner. My question is What to use for lubrication? White Lithium grease is what I am thinking?

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#2
Looked around, looks like this is what you should use.
Molycote PG75
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#3
It's almost always lithium-based grease, but sometimes it's silicone-based, in which case you should clean off all the old grease because mixing different types can sometimes result in a hard crust (it does with lithium and sodium greases). Automotive grease may be too thick. It's usually NLGI #2, not the lighter #1. If you use silicone grease, be sure it's grease only and not heatsink compound, which contains particles, like zinc oxide.
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#4
Quote from laloram
:
Looked around, looks like this is what you should use.
Molycote PG75
Quote from larrymoencurly
:
It's almost always lithium-based grease, but sometimes it's silicone-based, in which case you should clean off all the old grease because mixing different types can sometimes result in a hard crust (it does with lithium and sodium greases). Automotive grease may be too thick. It's usually NLGI #2, not the lighter #1. If you use silicone grease, be sure it's grease only and not heatsink compound, which contains particles, like zinc oxide.
Where could I find either of these 2 specialty greases locally? I know auto parts stores has Lithium Grease but would they also have the others? How about a Hobby/RC shop? Any other ideas? Keep in mind I need less than a gram of grease so I don't want to spend $20 on a 2lbs tub.

Thanks for the suggestions.
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Vague questions receive vague answers . . . . . .
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#5
Quote from LiquidRetro
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Where could I find either of these 2 specialty greases locally? I know auto parts stores has Lithium Grease but would they also have the others? How about a Hobby/RC shop? Any other ideas? Keep in mind I need less than a gram of grease so I don't want to spend $20 on a 2lbs tub.
Auto parts stores and real hardware stores (True Value, Ace, etc.) sell lots of different greases, including many from Lubriplate (assembly lube is OK). TV-radio parts supply houses, hobby electronics shops, and Fry's have the brands used in electronics, including GC Electronics and M-G Chemicals.
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#6
lithium grease huh.... auto parts stores sell that in a spray can for about $5.
Do you need grease though? Or oil? I understand the difference, but I've transitioned to a simple oil in outdoor applications which has surpassed my expectations.
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#7
Generally, on plastic gears you want lithium grease because it doesn't contain petroleum. Petroleum greases, oils and vaseline will have a bad effect on plastic gears -- seems to start the degrading process prematurely and cause them to break off teeth and start to crumble.

Back several years ago when I rebuilt a few VCR machines, all the manuals had big notes written in red telling the techs to only use white lithium grease to lubricate the plastic gears because petroleum grease would cause damage to the gears. I found this to be the case also (from experience) to use this white lithium grease on the plastic or nylon rollers used in window mechanisms for many older vehicles. Owners and shade tree mechanics had used vaseline or axel grease to lube these and the nylon or plastic rollers came apart. I always replaced them and used the white lithium after I saw the damage from the other lubricants.

I would be extremely careful when cleaning the old grease out not to spread it to areas you don't want grease to be in -- this could cause you to have troubles with your images. Same thing when adding grease -- use a toothpick or a Q-tip to apply the grease and keep it in the area it belongs.

I would NOT use any type of oil -- even if it isn't petroleum based -- because it is thin and won't stay where you want it around the gears. Gears meshing and spinning, even at a slow pace, will "sling" oil to areas other than you want it to be in. Or, it will just run off from gravity and leave the gears with no lubrication. Grease is thicker and stays put.
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Last edited by callpocket March 12, 2011 at 10:02 PM.
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#8
Quote from Dr. J
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lithium grease huh.... auto parts stores sell that in a spray can for about $5.
I'd worry about using spray lubes in a scanner or printer because the carrier solvent can let the aerosol travel far from the spot you want to lube. Applying the lube with a toothpick or Q-tip, as Callpocket said, is sometimes the only safe way to do it.
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