Re: South Bend Spindle Oil

eddie.draper@btinternet.com
 

As oft repeated,

There is a list of S/B recomended oils in the files section.

Headstock spindle oil (A) is straight mineral oil ISO viscosity 22 cSt (CentiStokes, at 40 degrees C),
For other wick feeds such as the saddle gearbox and leadscrew, you won't go far wrong with ISO 32 either spindle or hydraulic oil,
And for the rest, oil cups that don't feed wicks, slideways, feed screws etc. a higher viscosity spindle oil.  I happen to have 220 cSt with a tackiness additive available, so I use that, except in the depths of winter (unheated workshop) when the 32 is used, although it doesn't actually need to be quite that gloopy and ISO 100 would suffice.

All you need to do is locate your nearest lubricants supplier in your local trade directory (in the UK, yellow pages or yell.com) and ask them.

Just a note on the units used here and in the chart below.

Saybolt seconds are a measure of kinematic viscosity, i.e. the ratio of absolute velocity to density.  It is measured using a fixed volume cup with a fixed size drain hole in it and timing how long it takes to drain the contents.  The more dense a liquid, even for the same viscosity, the faster it goes.  See also Redwood seconds.  In neither case can you use the number to perform bearing calculations direct.

The Stoke is a measure of absolute viscosity, centiStokes being more convenient for everyday use.  What it says on the label is how it performs in a bearing. 

Kinematic viscosity is tolerated in everyday use, simply because as a general rule the more viscous an oil is, the more dense it is, within a fairly narrow band, and it is easy to measure using a cup with a drain.  There have to be conversion tables to turn the seconds into coherent units for calculations, a bit like relating Brinell, Rockwell or Vickers hardness numbers to tensile strength.  Measuring absolute viscosity is quite a bit more complicated, although it can be calculated from kinematic viscosity and density, so long as your seconds to kinematic viscosity tables are accurate.  For fluid flow in pipes, you might as well start with kinematic viscosity, since Reynolds number which governs nearly everything includes the term anyway.

Hope this helps,

Eddie




On 6/7/2018 10:08 AM, Jim_B wrote:


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