I have searched this group for information about obtainable accuracy or
surface grinders and have found some interesting information but have
not found an answer to my specific question. My question is what
maximum deviation from flatness should one expect to achieve when
resurfacing a surface grinder table? This is assuming the machine is
in good working order. The surface grinder in question is a K. O. Lee
Model 714 hand feed grinder with conventional ways, not ball ways. The
table has one V and one flat way, and the saddle has two V ways. The
spindle taper has no perceptible runout. The wheel hub has no
provisions for balancing. The area being ground on the table is 6" x
13".

I contacted K. O. Lee and the tech rep said .000050". I looked at
their website, and it indicates that "Turcite table ways and hand
scraped ways guarantee accuracies for work surface flatness up to
0.000050." Since they use the qualifier "up to", this statement
indicates to me that their best precision equipment can achieve these
accuracies. I don't believe these accuracies apply to a run of the
mill hand surface grinder, but I may be wrong.

The only information that I could find that addresses the flatness of a
surface grinder table is in Machine Tool Reconditioning. This book
indicates that the tolerance allowed in the longitudinal direction is
..0002" per foot of table length. The tolerance in the transverse
direction is .0004" in the table width. In my initial grinding I have
achieved a longitudinal tolerance of .00018" and a traverse tolerance
of .00046". I believe I can reduce these tolerances slightly with
further finish grinding.

I would like any feedback from those of you in this group that are
knowledgeable about surface grinding and the tolerances one can expect
to achieve from this type equipment.

I would also appreciate any recommendations on technique to achieve
maximum flatness. I am using a new Norton 7" x 1/2" 46J 5SG (Seeded
Gel) grinding wheel. The wheel is diamond trued to a sharp edge. I am
using a heavy mist coolant that seems to cool adequately. I
longitudinally feed quickly and use a cross feed of .0050. These
longitudinal and cross feeds are K. O. Lee's recommendation for manual
grinders.

One question that I have concerns wheel truing between finish passes.
My finish pass depth is in the range of .0001" to .0002". On the
completion of a finish pass the grinding wheel still seems to have a
sharp edge and is not glazed. What is the preferred practice for
maximizing flatness? Should one re-dress the wheel after every
complete traverse of the table? I find that if you re-dress the wheel
it is much more difficult to return to the point where you are taking
off between .0001 to .0002" on the first traverse. I usually err on
the light side which may result in many unnecessary traverses.

I also may try to use a larger 8" by 3/4" wheel. K. O. Lee recommends
using as wide a wheel as possible, because it provides a better wash
action. Any thoughts?

I know that I have provided a lot of information, but I want to provide
as complete a picture of the situation as possible. I have great
respect for the knowledge of this group, and all on-topic responses
will be greatly appreciated. However, please do not start a discussion
of what type of machine I should replace this one with. The long hours
of cranking the handwheels are therapeutic .

Ron