Does it really matter?

[Hauk]

As a beginner, it is sometimes hard to know what makes a difference, and what does not.

Exmpleoes it really matter what type of oil you use on the slides? I reassembled the crosslide on my lathe, and I ended up using some ordinary, rather thin oil.

I tried Molykote BR2 universal grease, but it is more messy and unpleasent to work with.

So, is the type of lubrication something that really matter on a lathe and oter machine tools?

Regards, Haavard H

 

[EL-CORAZON]

Hei Håvard ;D
I think that normal it is best to use regular oil..so that the chips( metall sponå ) don't stick to the bed

 

[Mainer]

It can matter a lot. You want the correct viscosity, for starters, especially for bearings. South Bend lathes, for example, typically have bronze journal bearings or something similar for the headstock spindle. The recommended oil has a viscosity of 100 Saybolt. Translating that into more familiar terms equates to about a #6 or #7 weight oil. If you put #30 in the bearings on the incorrect theory that heavier oil will be better...it won't be. The bearing shells won't get lubricated properly.

You probably also want a non-detergent oil. Detergent oils assume a filter is in the system to filter out particles in the oil. Machine tools, at least in "our" sizes, don't have oil filters. We want any dirt in the oil to precipitate out of the oil.

Another issue is water -- and another reason to NOT use engine oil. Engine oil is formulated to emulsify with water, because the oil gets hot, well above the boiling point of water, and the water will be driven out of the oil as it circulates. Machine tools don't get hot, so machine tools need an oil that is designed to precipitate water just as it precipitate dirt. Water in the oil can cause corrosion.

Way lubrication is another matter, but the type of oil is still important. "Real" way oil is formulated to minimize "stiction," the tendency of the oil to resist starting motion and hold, say, a lathe carriage from starting motion smoothly. And again, viscosity matters. Quite a few years ago I tried using straight #40 synthetic oil as way oil, on the theory that the #40 oil would float the carriage, there would be no metal-to-metal contact, therefore there would be no wear...Brilliant! Well, no. The #40 oil floated the carriage all right. The trouble was, the carriage floated so much that nothing kept it from moving side-to-side a few thousandths of an inch, which made accurate machining quite a challenge. I changed back to something more appropriate, and had much better accuracy.

You can buy the correct machine oils from places like www.mscdirect.com and probably www.travers.com or www.mcmaster.com. You'll probably have to buy a minimum of a gallon, but even a gallon isn't terribly expensive and will last you "forever."

If you're determined to improvise, use the correct-viscosity hydraulic oil. It's quite similar to machine oil.
The main thing is to get the viscosity right.

 

[Hauk]

It can matter a lot.

Thanks for the reply!

As I mentioned in the first posting I got myself some Molykote BR-2 universal grease.

I planned to use this for the bearings on my lathe, but does anybody know if this is a wise choice?
And could this grease also be used on the ways?

Regards, Haavard

 

[Blogwitch]

Haavard,

As Mainer stated, the correct viscosity is the key to all that relies on lubrication.

Way oil is a very good example.

To put it into laymans terms, each type of lubrication will have a different 'thickness' to it. That is, when it is there to prevent metal to metal contact, in the case of the correct way oil, it will have a running thickness of approximately 0.002" (0.05mm). Now if you use a grease, that might have a running thickness of say 0.004" (0.1mm). So if you set your gibs to your ideal 'feel', you will have a larger gap between the metal parts with the grease, and so if the grease gets displaced due to cutting pressures, you will start to get things like bad surface finishes and chatter.

Machine lubrication manufacturers go to great trouble to ensure that the 'correct features' are built into the lubrication. With way oil, it will be stickiness, so it doesn't run off angled or vertical surfaces, easy break out pressures, so that you get smooth operation of the metal to metal parts, and then the minimum film thickness to prevent metal to metal contact.

I over lubricate all my machines. I would prefer to have a dirty machine than a worn out one, and I have found that 20 pounds sterling will buy me enough oil to last me at least two years, maybe three. A small price to pay when compared to buying new machinery.

I asked my machinery supplier (the engineers, not the salesmen) what lubricants they used. They quoted me a 68 grade way oil, and a 32 grade hydraulic oil for general lubrication and gearboxes, so that is what my machines get.

In the UK, this is what I would buy if I needed some more.

http://www.chronos.ltd.uk/acatalog/1-Litre-of-Multispec-Slideway-Oil.html

http://www.chronos.ltd.uk/acatalog/5-Litres-of-General-Purpose-Lubricating-Oil.html


John

 

[steamer]

As pointed out by Bogs and Mainer.....no grease.

Grease will attract and hang on to chips and dirt and I would NOT recommend it on pretty much any lathe unless it's well sealed off from chips and dirt and was designed to run with grease.

Dave

 

[Tin Falcon]

The correct lube for machine tools is spindle oil for the spindle bearings way oil for the ways and gears. the machine manual should have a lubrication chart and recommendations for oil .
All the major oil companies of the world have there own blend and brand of machine oil.
Here is what i use
http://www.use-enco.com/CGI/INSRIT?PMAKA=505-1987&PMPXNO=945479&PARTPG=INLMK32

There are guy on e bay that will buy this kind of stuff by the 5 gallon bucket pack it in 8oz containers and sell it for 5 buck a bottle. but like Mainer said a gallon is 15-20 bucks and will last for years.

BP® Spindle Oil
BP Energol® SW is recommended for ways SW-68,

Shell has a lube finder program there well sight will tell you what to use on say a Bridgeport mill.
Tellus 22 for spindle
Tonna 68 for ways

 

[Hauk]

The patience with my (to put it mildly) basic questions is much appreciated. Without to access to forum like this I think I would have given up machining all together.

Best regards,
Haavard H.

 

[mcostello]

None of us here would know as much as all of us!

 

[Tin Falcon]

here is a chart that may help

http://www.farwestoil.com/crossreference.pdf
and as others have said viscosity is important . most vendors have a light medium and heavy version of there oils .Individual machine needs will vary depending on size spindle speed and some on design of the bearings ball taper roller or plain. a multy ton industrial machine has different need from a bench top lathe for example. the light to medium range should work fine for the home shop.
tin

 

[Ken I]

I am often asked - what lube would you recommend for such and such an application ?

My answer is always the same "Use what the manufacturer recomends".

Oil is cheap, failure is costly.

Unless nothing is specified or there is some compelling reason to do so, I see little point in deviating from the design by people who (generally) know what they are doing.

Ken

 

[Swede]

I do like Vactra medium for ways... it seems to have potent anti-corrosives in it as well, to keep the metal bright. I use it as a preservative on lathe chuck bodies and such when in storage.