[Beowulf] What is the right lubricant for computer rack sliding rails?

Lux, James P james.p.lux at jpl.nasa.gov
Sat Feb 7 09:05:47 PST 2009

On 2/7/09 8:17 AM, "Douglas Eadline" <deadline at eadline.org> wrote:

> To invite (incite) further discussion on RGBs questions:
>> Awww, y'all just don't understand.  The issue is WHY are
>> we lubricating rack rails?
> Indeed why use rails at all. If the answer to the following
> question is hardly and
>> I mean, how often do you pull a node in its lifetime?
> if your answer is not very often, and finally
> if you ask yourself: How much servicing do I do
> while extended from the cabinet? And you answer is little
> or none, then maybe you don't need rails.
> I have a 19 inch rack chassis in my basement (of course this
> is one of the few places I can make this statement and
> not be laughed off the list).

You have only one 19" rack at home? Our collective hearts go out to you, in
this, your time of need.

In any case, I occasionally get
> servers to test and I have two of my own. I had pieces of L
> shaped metal made that extend 2 inches under the server. They run
> the complete length of the rack and are easily bolted to
> the sides. I secure the server with the front screws (if at all).
> I may pull a server out several times a year and I put
> it on a bench, so I don't need to hold the server with rails.
> The servers slide easy enough, and there is no complicated
> detaching from the rails. Because it is like a shelf, the
> server can shift sideways, but if I fasten the front screws
> it holds them perfectly in place. For heavy servers you need
> to be careful and have one person on each side.

The tricky thing with the "rack rail" approach (which we use a LOT at JPL)
you give is that if the units have cases that are also full height, you
can't stack one unit directly above another, so you have to leave a 1U gap.
This is one of those cases where steel is a winner over aluminum, because it
can be a lot thinner than aluminum and still hold up the load.

> If anyone is interested I can post some pictures. I could
> even get some more made.

For casual use, 1.5x1.5 or 2x2 aluminum angle stock works well, and is
easily drilled for mounting to the sides. Steel (preferably galvanized or
otherwise passivated) is a lot more work.  You do need rails on the sides of
the rack to attach them to.  Unistrut (and similar products) works real
well, and is infinitely adjustable.

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