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To Grease or Not to Grease? (That is the Question)

HobbyMaker

Plastic
Joined
Feb 5, 2021
Backgroud
I have been working through a quick restoration of a Nuttall Lathe for personal use, and come to the stage of reassembling various components and I am keen to make sure they are lubricated correctly as they are reassembled.

A number of the components have zerk nipples for lubrication and over the life of the machine someone has greased each and everyone of these, including the ways(?). This intrigued me for two reasons: first my experience was using oil not grease on lathes (mostly to avoid swarf sticking to the grease), and secondly was the fact it was using zerk nipples.
As such I have done some googling and seems there is some debate but mostly people are recommending oiling via the zerk fittings.

Questions
  1. Is Oil not Grease the correct lubricant?
  2. If so should any components be greased or every fitting oiled or a mix of both? Should thread cutting gears be greased or the main bearing etc?
  3. I'm reassembling the saddle (see pictured) with the gear trains for the cross feed, thread cutting and autofeed. These all go through metal to metal bushings in the housing and there are galleries through the shafts (see pictured) presumably (?) for oil not grease. Whilst it is not very big RPM do the gear teeth need lubrication? if so what type?
  4. There is a main bearing in the clutch assembly (pictured) that looks to have been greased and I haven't pulled this apart yet but should this be greased or oiled also?


Any thoughts, Ideas, Links, wisdom would be appreciated :o
 

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For personal use, use oil on everything. Obviously grease was the wrong choice back then.. Gear train, look for a Shell grease called "Gear Coupling" grease, works well for exposed gearing. The clutch linkage, a dab of oil once in a while. Gearing in the apron, again, a dab of oil once in a while. There's plenty of threads here on what type of oils to use. Ken
 
My short understanding from a bearing mfg book (sorry, can't remember who) was that OIL is the lube. If you can keep some lube in the bearing by replenishing when necessary that's to be preferred. Grease is oil with a thickener so it doesn't wander off location. If you can't assure oil lube, use grease. Heat is ordinarily what kills bearings. Grease causes heat buildup so is rarely seen in high speed bearing applications.

Short version - oil if at all possible and grease if you must.

Yes, I hear the exceptions preparing to speak. Very high quality grease may be used in high speed precision bearings, but bear in mind that it's also metered carefully to not overfill and create unnecessary heat and applications like open gears need something to retain the lube.
 
Often people see zerks and assume grease gun.
Grease is just oil carried in a filler made of many things.
This filler releases the oil slowly over time and for some use not fast enough.
The stirring of the thicker is what makes for temp rise.

Many opinions, lore and usage. I am not a tribologist.
Those people are so weird and talk things hard to understand but one has to just love them.
Bob
 
Yes basically grease is just oil in a carrier, but oil NOT grease zerks were pretty common at one time. And grease in a location designed to use oil as a lubricant is just about the worst thing you can use. Yes it retains chips, but it also retains the inevitable wear particles just from using the machine. Oil tends to help float and wash any of that out and away from the parts bearing surfaces. Grease does the opposite. On a machine tool if the way oil is darkening or becoming black, it's a sure sign your not oiling often enough. Simply put, the cleaner you can keep the oil the longer the machine will last. It's exactly the same with internal combustion engines. Oil is obviously able to work in much more confined spaces and create that non optional wedge the parts ride on and that lessens the part surfaces contacting and creating that wear. The proper lubrication done at the correct intervals is the cheapest preventative maintenance you can do.

With today's cnc and on board timed and pumped lube systems it's probably far less true today. But with manual machines and manual lubing it's a safe bet far more machines were wore out from poor lubrication practices than wear from machining parts. Any machine tools that used cutting oil instead of flood coolant would be the exception since that helped keep the machines in a continuous bath of clean oil. And yes I do know lots of today's cnc machines do use grease in many areas. The difference is there designed to do so and are well guarded to keep any chip contamination out. In comparison to something like a car transmission, the change gears on a lathe are very lightly loaded. They still wear in use so you'd want the same effect oil provides of helping to wash out those particles and not keep cycling it back through the gears every revolution. Ok the grease is less messy, but do you want a cleaner machine or one that lasts longer? I've seen a few examples on Youtube mentioning they use grease on there hobby level machines. Not one of them has a clue about what there doing or they sure as hell wouldn't use it. When I was a lot younger and much more stupid I thought I knew better as well. Too long to go into here, but that dumb ass attitude cost me a $800 electric motor. Use some logic about the differences between grease and oil and it's pretty easy to understand why the lubrication type recommended in most machine manuals are almost universally for oil on almost everything. There are a very few areas on some machine tools where grease because of poor access might be the better choice. Around a clutch to keep lube oil out of it might be one. But I'm also not familiar with your lathe. What does your manual say?
 
Grease is often used as a quick and easy maintenance lube because It tends to lubricate longer than oil does, BUT that doesn't mean it works the same. Zerk fittings are designed to be used for any kind of fluid lubricant be it oil or grease and many manufacturers made use of them, but it's just become the common habit of mechanics every-ware to use the quick and easy lubricant (grease) in the quick and easy fitting (zerks). I don't think manufacturers often design new machines with zerks for oil anymore because now-a-days the go-to system for fast oil dispensing is an automatic lube pot.

When all else fails, consult the manual. Even if the lubricants in it are obsolete, a little bit of Googling will often get you a modern equivalent, or at least tell you what kind of lubricant to use. Unless your machine is 100+ years old, you shouldn't have to guess at it. Spindle oil, way lube, and hydraulic oil are not all the same. You don't have to go with name brand lubricants, but it's best to stick with the same type and weight of lubricant that the OEM states. Some lubricants need to stick to a vertical surface, some need to climb gears, some need to keep grit from sticking to the surface, some need to filter grit out. Different properties for different jobs. From my experience, most OEM manufacturers didn't have some lucrative deal with Big Oil to sell expensive lubricants. They used their experience and engineering to determine what type and weight of lube will be best for the job.
 
Hi,
There are Zerk Fittings, all over my BP Mill, but they are not for grease but Way Oil.

I took a cheap, Grease Gun, and made an Oil Gun.

Spindle oil goes in the head and flows completely through it, dripping down on the table, as designed!
 

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Hi,
There are Zerk Fittings, all over my BP Mill, but they are not for grease but Way Oil.

I took a cheap, Grease Gun, and made an Oil Gun.

Spindle oil goes in the head and flows completely through it, dripping down on the table, as designed!

Exactly! Many European machine tools have a unique, fitting specifically for push type oilers. The oiler tip has a concave radius. A quick web search will show importers. Using grease on these fittings is inexcusable.
 
Exactly! Many European machine tools have a unique, fitting specifically for push type oilers. The oiler tip has a concave radius. A quick web search will show importers. Using grease on these fittings is inexcusable.
Push oil and grease zerks are different shapes but somewhat the same.
Common use across the pond but for some reason these oilers are hard to find in the US and sure as shit some fool will hold a grease gun against it.
Then what to do? Flood it with oil? Tear apart the machine and clean?
Bob
 
Zerk fittings were invented in a time
where there was more intelligence in
the population of users than there is
currently. Keep that in mind when making
your ponderances as to what should be
put into them.

--Doozer
 
If made for grease what happens when you mix grease filler types? Some do not play well with others.
One can screw up oil weight and be okay. Mess this grease types and ......
Many think that grease is grease and whatever in the gun is good.
Bob
 
Last week I scrapped an old Cincinnatti mechanical drive Universal grinder.....the setup of oil pipes and little dripper nozzles inside the machine was magical.... all the bevels and worms oiled were in fine condition ,attesting to the effectiveness of drip oiling.
 
Just an update for anyone who's intrigued, I managed to track down a manual for the Nuttal lathe and it recommends a mix of grease and oil (I'm a little surprised also).
For the most part I have been sticking with oiling almost everything because I'm the only one using the machine and so any time it running it gets fresh oil but this does tend to run everywhere and need a level of clean up (nothing a rag can't solve). I could see this being less then practical in a old Tafe or school shop perhaps the reason for the use of grease.

Thanks Every One for the insights and ideas, always good to hear a few perspective on a problem

Nuttal Manual Grease Nipples.jpg
 
Having cleaned up a mill where the prev owner had used grease, I would not put grease anywhere they suggest- it accumulates dirt and chips forever and is tedious and messy to clean up. Excess oil drips away into the pan, or down the side of the machine and is easily wiped away; that ease of cleaning means the machine ends up cleaner overall.

For the nipples on my machines (ball oiler and zerk/alemite), I use a grease gun converted for oil- its fast and easy to run over the machine with the oiler and hit all the points. I guess the proposed grease/oil mix helps lubrication stay around longer- in that case I'd use way oil which tends to persist.
 








 
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