On Tue, 12 Aug 2014 12:54:51 -0400, Ed Huntress
wrote:

On Tue, 12 Aug 2014 09:27:26 -0700, wrote:

On Mon, 11 Aug 2014 19:09:37 -0400, Ed Huntress
wrote:

On Mon, 11 Aug 2014 15:38:46 -0700, wrote:

I have this old metal lathe. It's B.F Barnes and is at least 100
years old. It has that patina that a lot of old iron gets. Some folks
think this patina should not be disturbed. Other folks think the tool
should be made to look as close as possible to the original factory
finish. For this lathe I am of the mind that the patina should be
removed. I want customers to see what was possible 100 years ago. I
want the machine to appear new, or nearly new, the way it would have
looked in a factory where the machine was wiped down and cleaned every
night. So, opinions?
Thanks,
Eric

A new lathe, 100 years ago, would have had a scraped surface on the
bedways. That's probably gone. The look is very distinctive:

http://tinyurl.com/mmyyq2x

Re-scraping it would cost more than it's worth. But you may be able to
somewhat restore the *appearance* of the original scraping, depending
on the lathe's condition and what you intend to do with it.

Let us know if this it just for looks, or if you want to restore its
function as much as possible.
The lathe is now and will be fully functional. I will be making parts
on it. These parts will be just for my own enjoyment, not for paying
customers. The bed ways look as if they were made on a planer or a
shaper. Even under the headstock there are no scraping marks. I am not
sure how straight or worn the ways are but I can still see
longitudinal marks that run the length of both the carriage and
tailstock ways.
Eric

Some lathes were left just as the planer left them, but most from 100
years ago were scraped. Much later, they were often planed or ground
and then "frosted" with a scraping tool, mostly for appearance but
ostensibly to hold oil.

Longitudinal marks can be wear from grit, or maybe evidence of the
original planing.

The first thing I'd do is to lay a precision straight edge on the ways
-- the bevelled-edge type, if you have it -- and put a light behind
the straight edge. See how much "dip" there is from the front of the
spindle nose to the next 18" or so towards the tailstock end.

If there's a lot, just clean it up and use it as-is. If it's less than
0.001, it's worth considering running an Arkansas stone along the bed
to knock down any burrs. If you don't have a good stone, you can use a
really flat block of metal with some 600-grit wet/dry wrapped around
it.

This will horrify the purists, but it isn't going to make anything
worse on a 100-year-old lathe with a lot of "patina."

Getting the patina off is possible, but it depends. I'd start with
phosphoric acid (Naval Jelly) and coarse steel wool. But that stuff is
problematic on cast iron. Sometimes it leaves a layer of black oxide
that's really tenacious.

It may require hydrochloric (muriatic). If you use that -- outdoors --
I hope you're aware of the dangers. I haven't used it on cast iron but
I'm told that you really have to neutralize it carefully with baking
soda or washing soda, because of the surface porosity of gray iron.

On steel, it leaves a silvery but frosty finish. I think it's the same
on cast iron.

Good luck!
Greetings Ed,
The ways are remarkably flat and straight. The marks that look like
artifacts from planing are too regular to be waer marks. Especially
since the same marks are under the headstock. Any patina removal will
be done with oil and steel wool or something similar. I have decided
that since this machine is for my enjoyment and is not something that
only one exists of I will be making it look as close to the original
factory finish as possible. The thing was originally painted black on
the cast surfaces but I don't know if it was Japanning. I can buy the
stuff but it needs to be baked and costs way too much. Some nice black
lead based paint would probably be good too but there is no way I can
find any of that.
Eric