It should work on a good laser printer - resolution would be 600 dpi.

However I have never trusted them completely to be accurate for the overall
measurement.

A better option might be to find someone with a plotter.

I've done some Excel "graphics printing" like this, but not to such
precision, maybe 0.02 . I have found two things.

1- The Excel inch is not necessarily the same length as a printer
inch. There will be a scale factor to apply. I always determine
experimentally by printing  something in Excel scale then measuring the
print and calculating the scale factor.

2- That the X and Y scales don't always have the same correction
factor. i.e. printer X and Y resolutions aren't always the same.

3- Any paper feed variation can mess this up also.

The Mac & printers used to do a pretty good job, but I haven't
checked in a while.
Some of this kind of knowledgs seems to decay with younger
generations of engineers. I'm one, but an older, smarter one

1/600 DPI = .0016666... IPD

I've more or less come to the same conclusion and have built a procedure to
print a bunch of measurements. When I have a close one I'm homing in on the
closest I can get. I suspect that it alters with printers as well.

This is coming from trying to print a "mask" for the nut of an electric
guitar... Hence the need to go down so small. The thinnest string I've come
across is 8 thou.

When I was researching this I was suprised to see that there doesn't
actually appear to be a single exact measurement for a point. In fact there
are quite a few!

I understood that you
wanted to draw things with any and all locations within .005 of their
desired location. This is inconsistent with a .008 feature width.
I don't know what method you plan to use to transfer this to the
part, but I'm confident that defining the width of a nut string groove
which is .008 is too tight for a 600 DPI laser printout. This width
is 4.8 dots.
I've been 'playing' for a while and I do know that a notch that is
only microscopicaly too wide will buzz. I think they have to be Vee
shaped and if long, such as on the nut, the fret-facing side should be
guaranteed to be the narrowest - to guarantee pinching the string.
Sometimes, a piece of paper, forced into the notch by the srting
tension can cure the buzz.

Looking with a jeweler's lupe, the thin notch is really thin on the
Martin, but the bass notch is actually wider than the string. The
position of the peg is such that the string is pulled to one side of
the notch

On the other hand...Take the easy way out. Making it 5 x, turns that
8 mill notch into 24 dots width. Sounds better, but I don't really
know the required tolerance.

The nut slots *should* be just the width of the string, half the depth of
the string, and round at the bottom.
If they "pinch" at the fretboard side that prob means the other end is too
wide and the string will buzz... And there's more likelyhood of string
breaks.

If you put the string in the slot and move it from side to side then the
other end shouldn't move. If your bass string slots are too wide then I
think that thicker strings have been used at some time.

In my original message I said I wanted to print a "grid".. But this was
probably a bit misleading. What I'm doing is colour filling columns for 10
rows and then setting column widths and printing.

Looking at your terminology and subsequent responses, it seems
that your nomenclature may be confusing.
From an Engineering perspective,
"a grid pattern in Excel as precisely as possible down to about .005
inches" means that you're trying to create a series of horizontal and
verticle lines with each .005 inches apart... (which is roughly the
thickness of a hair)

A 600dpi printer will TRY to produce this, but it means that IF it
uses ONE dot for the line, ONE dot for the space, then ONE dot for
the next line, you've hit your .005 from OUTSIDE to OUTSIDE of the
lines...

Now, subsequent responses seem to indicate that you are actually
looking to make a grid in which the GRID LINES are .005 thick.
this MAY be possible, but I wonder if the printers, in their highest
quality mode, are using more than 3 pixels for a line.

I think if it's going to be at all possible, you're going to want to
use a printer that's a photo quality printer, that usually goes up to
1200dpi. Then, instead of using Excel's borders, just select to
print the grid lines (under Page Setup -> Sheet)