Ed sez: "BTW, again for gage-qualification-type work, granite can burr. They'll run a
hard Arkansas stone over the plate to remove them. They're really tiny, and
you can't feel them, but granite can turn up a microscopic burr."

Many years ago when I worked at Teletype Corp. They would periodically send their surface plates to
a lab for calibration, refurbishment, etc. This was when Telex and other "wire" comms. were
standard and electro-mechanical devices had very close tolerances. I suppose tolerances are even
tighter now, but electronic gauging has probably replaced the need for some surface plates.

Bob Swinney







"Ed Huntress" wrote in message ...

wrote in message
...
On Mar 3, 10:39 pm, "stu" no where just yet wrote:
I've just bought a "precision plate". I think its made from steel rather
than cast iron, but i haven't cleaned it yet. I doubt I will be using it
very often. It's covered with some sort of grease and waxed paper. Once
I've
used it I want to regrease it. Are then any "greases" that are better than
others for this? I've been told lanolin is the way to go.
thanks
Stuart

LPS 3 is like spray-on cosmoline, would be what I would use just
because I have it. I haven't seen cast iron surface plates for
decades, most everyone in the business has gone to granite, either
pink or black. No worries about rust or burrs with them.

Stan

Just for curiosity's sake, it's interesting to note that ribbed cast-iron
surface plates are still used at the extreme high-end -- for some gage
qualification work, and, until recently, at least, by ultra-precision
machine tool builders such as Moore Special Tool.

Cast iron has to be kept at a stabilized temperature for that work, and it
has to be high-quality castings that are fully annealed and artificially
aged, but granite can warp in unpredictable ways due to changes in humidity.
Of course, to those people, 3 millionths of an inch of warp is a disaster.
g



--
Ed Huntress