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

My KO Lee book specifies flood cooling, not mist. Temperature control is
critical, of course.

What kind of flatness are you getting?

GWE

wrote:
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

wrote:

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.

Just as a point to think about:
If your ways are bent (preferably in an arc) you can grind the table how
long you want, it will just have the same shape as the ways.


Nick
--
Motormodelle / Engine Models:
http://www.motor-manufaktur.de
Ellwe 2FB * VTM 87 * DLM-S3a * cubic
more to come ...

I'm wondering what you typical grinding job is and what accuracy you are
looking for and what you need and are they two different things...all those
zeros scare me! One of my techs was taking a piece to the surface grinder
and when asked why..."To make it shiny!"

(TOP POSTED THE RIGHT WAY!!!)

wrote in message
oups.com...
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

As I indicated in my original posting the variance that I am currently
getting is .00018" in the longitudinal direction and .00046" in the
transverse direction. These are the worst case variances. Some areas
are significantly better. In regard to coolant the K.O. Lee Rep
advised that I should get satisfactory results with mist coolant. Some
books I have read state that in many instances it is easier to obtain
proper cooling from a mist setup than it is from a normal flood setup.
Grinding wheels are porous and act as a fan. The wheels produce a thin
layer of air around the periphery of the wheel that forces liquid
coolant away from the wheel and starves the grinding contact point.
Special flood coolant nozzles have been designed specifically for
grinding to essentially scavage this air layer and allow the coolant to
get to the contact point. Most grinders do not have this special
nozzle. Because a mist system is pressurized it is fairly simple to
direct the spray directly at the contact point. The bulk of heat is
obviously generated at the contact point. Mist systems provide very
effective evaporative cooling which from what little physics I can
remember is a very effective heat transfer mechanism. The downside of
mist systems is that they provide little lubrication. It is my
understanding that this lack of lubrication is a surface finish issue,
not a cooling issue. Because in many grinding operations surface
finish is important, flood systems are popular.

wrote:



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.


Ron

I'm pretty new to surface grinding, but isn't a cross feed of .0050 on
the light side?

John Martin

I don't have a typical grinding job, but since I am grinding the
surface grinder table I want it to be as close to specifications as
possible. Following the table I will grind the magnet. Anything I
grind after these two pieces will never be more accurate than the
variance I obtain on them.

The indicator base was placed on the column in order to eliminate any
possible movement of the wheelhead. The measurement does therefore
confirm the flatness of the table which translates into the
straightness of the ways. The variances that I provided are
specifically for the table surface. Not coincidentally the variance
allowed for the ways is identical to that allowed for the table.
Checking the ways is a substantially more difficult process that
requires some significantly sized inspection equipment.

Although I assumed that I properly sparked out the surface, I probably
should take additional passes.

Do you have a manual or hydraulic feed machine? If it is manual, do
you take a larger crossfeed when sparking out?

It is the value that the K.O. Lee Rep recommended. Personally I think
that I got better results with a larger cross feed. One book advises
that you should feed about 1/4 of the wheel width but no more. This
would be .125 for a 1/2" wheel. I like .100 because it is one full
revolution on my handwheel.

I understand your point, but since I have no facility to check the ways
I can only indicate the table. This measurement then translates to the
condition of the ways. If I get the table into spec, the values of
which is my main question, then the ways are in spec.

wrote:
The indicator base was placed on the column in order to eliminate any
possible movement of the wheelhead. The measurement does therefore
confirm the flatness of the table which translates into the
straightness of the ways.

Actually, it doesn't. It just means that the distance is
repeatable at that point. You're still using the ways to
generate your measurement, so if your ways deviate you're
not seeing it.

I can't suggest a better method, mind you, unless it's to
use a surface plate calibration tool. I'm not sure if
that's a more useful measurement or not, but it would be a
better way to measure what you're _claiming_ to measure.
Personally, I think whether or not it grinds to a consistent
depth would be more useful... and this is what you're
measuring.

Perhaps someone else can improve upon my insight here...

--Glenn Lyford

wrote:

The indicator base was placed on the column in order to eliminate any
possible movement of the wheelhead. The measurement does therefore
confirm the flatness of the table which translates into the
straightness of the ways.

Consider if you removed the entire table and way assembly and instead mounted a
bicycle wheel below your indicator. Then turned your bicycle wheel and adjusted
it until the meter read zero deflection. Would you then assert the bicycle rim
is flat?

GWE

Is it really necessary to grind the table perfectly flat before tackling the
mag chuck?

I also have a KO Lee grinder (S714) and have only been planning to dress the
top surface of the chuck. Gotta resolve a scalloping problem first, though,
and that's long overdue.

BTW, can you convert "quick" longitudinal feed rate to something like inches
per minute, at least roughly? I've been half-heartedly trying to get a
handle on what sort of feed rate should be used.

Mike

wrote in message
ups.com...
I don't have a typical grinding job, but since I am grinding the
surface grinder table I want it to be as close to specifications as
possible. Following the table I will grind the magnet. Anything I
grind after these two pieces will never be more accurate than the
variance I obtain on them.

Did they recommend 0.005" cross feed or 0.050"? At 0.005" cross feed you
will be making over 1200 passes to get across the table!!!

Mike

wrote in message
oups.com...
It is the value that the K.O. Lee Rep recommended. Personally I think
that I got better results with a larger cross feed. One book advises
that you should feed about 1/4 of the wheel width but no more. This
would be .125 for a 1/2" wheel. I like .100 because it is one full
revolution on my handwheel.

My mistake, I missed a decimal point in my post. The K.O. Lee
recommendation was .050".

Maybe I am missing something, but I don't see the analogy. When I
indicated the table surface I zeroed the indicator at one point on the
table and then traversed the table back and forth and in and out to get
the readings over the complete surface of the table. I believe that
this indicates the flatness relative to the column. To use your
bicycle wheel analogy, if I held a bicycle wheel under a dial indicator
and moved it right and left and in and out, I certainly would know it
was not flat. Maybe we are saying the same thing in different ways.
All I am saying is that if you get an identical indicator reading over
the entire surface, then the table is flat and is traveling in the same
plane both longitudinally and crosswise. If the indicator readings are
not the same the problem can either be the table is not flat or the
ways are not correctly oriented.

I did not invent this test. It is how the K.O. Lee Rep told me they
make their check, and it is clearly spelled out in Machine Tool
Reconditioning.

In Machine Tool Reconditioning the process is to grind the table and
then the chuck. I would perform my to date controversial test and see
if your table is flat. My table definitely had some low spots. I
think that anything you clamp to a out of flat surface moves some
minute amount. I was amazed when I got an indicator that measures to
..00001" how little force it takes on a thick table top to get
significant movement. Beyond this I am totally unqualified to tell you
what to do.

I did get some good information from K.O. Lee about mounting a magnetic
chuck that may be useful to you. I think most people including me
clamp them down too tightly. You incrementally tighten both ends up to
10 ft-lbs and then tighten one end to 15 ft-lbs. This allows the chuck
to grow in one direction as it warms up.

In regard to "quickly" that is the instruction I got from K.O. Lee. I
recognize its relative uselessness. I think all you can gain from this
is that slow is not good. One of my books has a procedure on chuck
grinding and it states to use "a fairly rapid table speed (50 to 100
sfpm)." To make it easy use 60 sfpm. To achieve this you should cover
a 12" magnetic chuck in 1 second. If you are hand cranking this is
really moving. Hope this helps. I am finding that grinding seems to
be as much art as confirmed procedure.

craftsman,
I had the same thoughts when I bought a used Bridgeport. If I machined
a flat plate and measured from the mill head to the plate. I saw no
deviation, but placing a straight edge on it, I could see light under
the edge when placed across the plate, and when placed lengthways, it
rocked in the middle. Upon examination, I could also see wear on the
ways( the frosting was missing at the ends of the saddle). What I did
to understand what was going on was to place a surface plate on the
table and measure the distance between the top of the plate and the
head on 1" squares, ie measure each inch along the length of the plate,
move it 1" crossfeed and repeat the 1" measurements along that length.
What I found on plotting the data was that because of the wear on the
ways, the longitudinal ways were worn curved, with the ends of the
saddle worn down more than in the center. On the crossfeed, the ways
were worn dished. Using a 12" x 18" surface plate, from the center
of the plate to either end, 9", the ends of the plate were 0.004"
closer to the head than in the middle because of the wear. Crossfeed
showed 0.002" further from head on front and rear of plate than in
middle.
One thing you might do is take a surface plate and place it upside down
on the ground surface of your table and see if it rocks. If it does
not, put some marking blue on the plate and run the plate on the ground
surface and see where the blue transfers to the table, in the center,
or on the 4 corners, or?? That should give you an idea as to the true
flatness of the table surface.

wrote in message
oups.com...
snip---

I am finding that grinding seems to
be as much art as confirmed procedure.


You'll come to understand that all too well as you fail at projects that are
critical. Few experienced machinists make *good* precision grinders.

Harold

wrote:

If I get the table into spec, the values of which is my main question,
then the ways are in spec.

That's right.

Nick
--
Motormodelle / Engine Models:
http://www.motor-manufaktur.de
Ellwe 2FB * VTM 87 * DLM-S3a * cubic
more to come ...

wrote in message
ups.com...
The indicator base was placed on the column in order to eliminate any
possible movement of the wheelhead. The measurement does therefore
confirm the flatness of the table which translates into the
straightness of the ways.

No, it does not. No more than running an indicator along a mill table
confirms the squareness of the mill head. Look at it this way. If your
wheel is fixed (which it is) and the table rises and falls, the surface is
ground in a corresponding pattern, therefore yielding what appears to be a
surface that is flat. When you run an indicator on the table, all it's
telling you is how faithfully the wheel has followed the pattern, the ways.
It may or may not be flat, and most likely is not, especially if you're
using an older machine. . You can't check flatness that way--it should be
done by comparing on a surface plate of known flatness. Only then can you
discern the rise and fall of the surface, which then translates into
flatness.

Harold

"Nick Müller" wrote in message
...
wrote:

If I get the table into spec, the values of which is my main question,
then the ways are in spec.

That's right.

Nick

But only when the values are *not* established by checking from the ways as
has been suggested. All that tells you is how precisely the wheel has
followed the ways, whicy may or may not be straight and flat.

Harold

Harold and Susan Vordos wrote:

But only when the values are *not* established by checking from the ways as
has been suggested.

Oh yes! You even can't clamp an indicator near the wheel and messure the
surface. You need something independent from the grinder in all.
Either a touching plate, a ruler etc.

I had this setup in my mind, but didn't write it down.

Nick
--
Motormodelle / Engine Models:
http://www.motor-manufaktur.de
Ellwe 2FB * VTM 87 * DLM-S3a * cubic
more to come ...

Unless the longitudinal feed distance was always the same (long
production run) there is likely to be more wear near the center of the
ways, from frequent smaller jobs. The result is that the ways wear from
straight to slightly circular, the same way hand grinding turns a flat
blank into a spherical telescope mirror. If someone reground the table
it would have the same curvature as the ways. The thickness from the
ways to the table top is then constant, so an indicator on the spindle
head would show a constant reading, but the table top is NOT flat. I
think this is what the bicycle wheel analogy meant.

The cure is to check the ways with a straightedge or surface plate and
have them scraped to whatever accuracy you need and can afford.

My old $100 surface grinder is a good example. The ways are worn about
..015" deep from a long production run. I put shims under the ends of
the mag chuck to avoid bending it

jw

Mike Henry wrote:

Is it really necessary to grind the table perfectly flat before tackling the
mag chuck?

I also have a KO Lee grinder (S714) and have only been planning to dress the
top surface of the chuck. Gotta resolve a scalloping problem first, though,
and that's long overdue.

Before you grind in a chuck, make sure the table is free of burrs and clean it
meticulously, then put the chuck on UPSIDE DOWN and take a cleanup pass over the
bottom, and THEN turn it right side up and loosely bolt it down. Then get out
your dial indicator and set the long fence on the mag chuck so it sticks above
the rear edge of the chuck, and indicate on the fence and adjust the position
until the chuck is oriented correctly and where you want it, and only then
should you grind in the top face.

Quoting from memory from a KO Lee book I have somewhere -- GWE

Guess I'll have to dig up the MTR book and see what other useful info it has
on surface grinders.

Interesting suggestion about torquing down the chuck.

The feed rate you suggest correlates with my very limited experience -
faster rates seemed to give a better finish.

BTW, no one's mentioned the 5-block test yet so far as I can see. Place 5
blocks on the chuck, 4 at the corners and one at the center, grind the top
and bottoms of them, and then measure each. I think that K. O. Lee
recommends that in some literature I have but the user community seems to
have varying opinions of the usefulness of the test.

Mike

wrote in message
oups.com...
In Machine Tool Reconditioning the process is to grind the table and
then the chuck. I would perform my to date controversial test and see
if your table is flat. My table definitely had some low spots. I
think that anything you clamp to a out of flat surface moves some
minute amount. I was amazed when I got an indicator that measures to
.00001" how little force it takes on a thick table top to get
significant movement. Beyond this I am totally unqualified to tell you
what to do.

I did get some good information from K.O. Lee about mounting a magnetic
chuck that may be useful to you. I think most people including me
clamp them down too tightly. You incrementally tighten both ends up to
10 ft-lbs and then tighten one end to 15 ft-lbs. This allows the chuck
to grow in one direction as it warms up.

In regard to "quickly" that is the instruction I got from K.O. Lee. I
recognize its relative uselessness. I think all you can gain from this
is that slow is not good. One of my books has a procedure on chuck
grinding and it states to use "a fairly rapid table speed (50 to 100
sfpm)." To make it easy use 60 sfpm. To achieve this you should cover
a 12" magnetic chuck in 1 second. If you are hand cranking this is
really moving. Hope this helps. I am finding that grinding seems to
be as much art as confirmed procedure.

"Grant Erwin" wrote in message
...
Mike Henry wrote:

Is it really necessary to grind the table perfectly flat before tackling
the mag chuck?

I also have a KO Lee grinder (S714) and have only been planning to dress
the top surface of the chuck. Gotta resolve a scalloping problem first,
though, and that's long overdue.

Before you grind in a chuck, make sure the table is free of burrs and
clean it meticulously, then put the chuck on UPSIDE DOWN and take a
cleanup pass over the bottom, and THEN turn it right side up and loosely
bolt it down. Then get out your dial indicator and set the long fence on
the mag chuck so it sticks above the rear edge of the chuck, and indicate
on the fence and adjust the position until the chuck is oriented correctly
and where you want it, and only then should you grind in the top face.

Quoting from memory from a KO Lee book I have somewhere -- GWE

In this case the used grinder came to me with the chuck already installed
and it looks to have been that way for many years. I'm inclined to chance
just dressing the top as is. Maybe that's hour wise and days foolish,
though, from a time of use standpoint.

wrote in message
oups.com...
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.

I'm still interesting as to why you are so concerned about the grinder's
capability.

From a toolmaking perspective, .0002" flatness is virtually a joke in all
but the most critical applications. As you found out, it doesn't take much
to move .0002" if there are any forces acting on your work piece.

Further, you haven't even gotten in to grinding your work piece yet. It's
not hard to grind a part to .0001", assuming it's fairly stable.

Unless you're grinding very large work pieces (unlikely given the size of
your machine), you're probably not going to have trouble with the grinder.
More likely, in my experience, you'll have trouble with your work piece
flexing. While a good table is important, there are many other areas you
could have trouble with that will take far more time and be far more
aggrevating to iron out.

Just my $0.02 worth... It's like worring about which oil to buy for your car
before learning how to drive.

Regards,

Robin

On Wed, 27 Jul 2005 11:36:11 -0400, "Robin S."
wrote:


wrote in message
roups.com...
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.

I'm still interesting as to why you are so concerned about the grinder's
capability.

From a toolmaking perspective, .0002" flatness is virtually a joke in all
but the most critical applications. As you found out, it doesn't take much
to move .0002" if there are any forces acting on your work piece.

Further, you haven't even gotten in to grinding your work piece yet. It's
not hard to grind a part to .0001", assuming it's fairly stable.

Unless you're grinding very large work pieces (unlikely given the size of
your machine), you're probably not going to have trouble with the grinder.
More likely, in my experience, you'll have trouble with your work piece
flexing. While a good table is important, there are many other areas you
could have trouble with that will take far more time and be far more
aggrevating to iron out.

Just my $0.02 worth... It's like worring about which oil to buy for your car
before learning how to drive.

Regards,

Robin

Gads..for once I actually agree with the tyke.

Gunner

Liberals - Cosmopolitan critics, men who are the friends
of every country save their own. Benjamin Disraeli

I don't know where the logical place in this thread is to put this post
so I will just respond to myself. I want to thank Grant, Nick, Harold,
Bruce, Trains4, jw, Mike and anyone else I missed for showing me the
error of my "ways." No pun intended. I now better understand the
issue of indicating for flatness. The bulk of the responses concerned
the flatness issue, but I had other questions about grinding technique.
If anyone would like to "way" in on these, it would be appreciated.

I had another thought about determining flatness that I will run by
this august group. I am not sure about the practicality of the setup
so don't comment on it. What I would like to know is if anyone sees
any fault in the logic.

Say that I set a surface plate next to the surface grinder table. The
surface plate would be mounted on three toolmaker jacks placed in as
large a triangle as possible. I then mark three dots on the surface
grinder table, again placed in as large a triangle as possible. I
attach an indicator to a surface gage type base. The base of the
indicator would rest on the surface plate with the indicator point
alternately placed on the three dots on the surface grinder table. The
jacks under the surface plate would be adjusted until the indicator
reading is the same for all three dots. I believe this should make the
plane in which the three dots lie parallel to the plane of the surface
plate. I could then slide the surface gage with indicator around the
surface plate to take readings over the entire surface of the surface
grinder table. I believe that this would show the relative "flatness"
of the surface grinder table in respect to the plane of the three base
dots.

Comments?

Using the surface plate is definitely the way to go. You need an
external reference.

I would work the dial indicator from both surfaces. Start with the
dial base on the grinder and indicate to the plate in X and Y
directions: level the surface plate as needed so it reads zero at the
ends of the travels. This gets the surface close to the average plane
of the table motion.

Now you can put the dial base on the surface plate to indicate the
whole surface of the table. Check the table when it is in several
locations. Actually, you could remove the table and check the ways as
well.

Another test of the ways is to place a precision level on the table and
watch the bubble as the table is moved around. Check for cross-level
(twisting) as well. In this case, gravity is your external reference.

By the way Machine Tool Reconditioning has a whole chapter on grinders.
If you want to see ultra-precise, find a copy of Moore's "Foundations
of Mechanical Accuracy" where he describes how Moore jig grinders are
built and checked.

Bruce

Ron, your zeal is commendable, and as Harold puts it, you just might be finicky
enough to make an excellent precision grinder operator. :-)

I bought a little KO Lee grinder once, and ground in the chuck as best I could.
I get parts accurate to .0002" over 4" and that's just excellent by me. I
suggest you actually use your grinder for a bit before you go chasing gnat's
asses ..

GWE

wrote:

I don't know where the logical place in this thread is to put this post
so I will just respond to myself. I want to thank Grant, Nick, Harold,
Bruce, Trains4, jw, Mike and anyone else I missed for showing me the
error of my "ways." No pun intended. I now better understand the
issue of indicating for flatness. The bulk of the responses concerned
the flatness issue, but I had other questions about grinding technique.
If anyone would like to "way" in on these, it would be appreciated.

I had another thought about determining flatness that I will run by
this august group. I am not sure about the practicality of the setup
so don't comment on it. What I would like to know is if anyone sees
any fault in the logic.

Say that I set a surface plate next to the surface grinder table. The
surface plate would be mounted on three toolmaker jacks placed in as
large a triangle as possible. I then mark three dots on the surface
grinder table, again placed in as large a triangle as possible. I
attach an indicator to a surface gage type base. The base of the
indicator would rest on the surface plate with the indicator point
alternately placed on the three dots on the surface grinder table. The
jacks under the surface plate would be adjusted until the indicator
reading is the same for all three dots. I believe this should make the
plane in which the three dots lie parallel to the plane of the surface
plate. I could then slide the surface gage with indicator around the
surface plate to take readings over the entire surface of the surface
grinder table. I believe that this would show the relative "flatness"
of the surface grinder table in respect to the plane of the three base
dots.

Comments?

On 27 Jul 2005 12:55:10 -0700, wrote:

I don't know where the logical place in this thread is to put this post
so I will just respond to myself. I want to thank Grant, Nick, Harold,
Bruce, Trains4, jw, Mike and anyone else I missed for showing me the
error of my "ways." No pun intended. I now better understand the
issue of indicating for flatness. The bulk of the responses concerned
the flatness issue, but I had other questions about grinding technique.
If anyone would like to "way" in on these, it would be appreciated.

I had another thought about determining flatness that I will run by
this august group. I am not sure about the practicality of the setup
so don't comment on it. What I would like to know is if anyone sees
any fault in the logic.

Say that I set a surface plate next to the surface grinder table. The
surface plate would be mounted on three toolmaker jacks placed in as
large a triangle as possible. I then mark three dots on the surface
grinder table, again placed in as large a triangle as possible. I
attach an indicator to a surface gage type base. The base of the
indicator would rest on the surface plate with the indicator point
alternately placed on the three dots on the surface grinder table. The
jacks under the surface plate would be adjusted until the indicator
reading is the same for all three dots. I believe this should make the
plane in which the three dots lie parallel to the plane of the surface
plate. I could then slide the surface gage with indicator around the
surface plate to take readings over the entire surface of the surface
grinder table. I believe that this would show the relative "flatness"
of the surface grinder table in respect to the plane of the three base
dots.

Comments?
That would work. The best thing about this idea is that you are seeing
how flatness works. Once you get the basic idea it makes it much
easier to visualize ways to check your work. I like to draw
exaggerated pictures to show myself how things can go wrong. It's
always easy for me to draw something and assume that everything is
perfect. It's the error though thats most important.
ERS

Harold and Susan Vordos wrote:
wrote in message
ups.com...

The indicator base was placed on the column in order to eliminate any
possible movement of the wheelhead. The measurement does therefore
confirm the flatness of the table which translates into the
straightness of the ways.


No, it does not. No more than running an indicator along a mill table
confirms the squareness of the mill head. Look at it this way. If your
wheel is fixed (which it is) and the table rises and falls, the surface is
ground in a corresponding pattern, therefore yielding what appears to be a
surface that is flat. When you run an indicator on the table, all it's
telling you is how faithfully the wheel has followed the pattern, the ways.
It may or may not be flat, and most likely is not, especially if you're
using an older machine. . You can't check flatness that way--it should be
done by comparing on a surface plate of known flatness. Only then can you
discern the rise and fall of the surface, which then translates into
flatness.

Harold





Just use a precision level. Shim it up so the bubble is in the center
and run the table back and forth. IF its going back and forth over the
mountain of unworn metal of the ways in the middle of the travel you
will see the bubble go back and forth as you run the table left and
right. A cheap and dirty way to tell is with a laser pointer and a
mirror. Put the mirror on the middle of the table mounted upright and
aiming along the table, Clamp the laser pointer so it hits the mirror
and bounces off to a far wall. Now all you got to know is a little trig.


John

Cross feed per pass, fraction of wheel width is 1/10 for a hardness of
greater than 52 Rc and 1/4 for a hardness of 52 Rc or less, and a
table speed of 50 to 100 fpm. Rough cut 0.003, finish cut 0.0005 max.

Table 2. Basic Process Data for Peripheral Surface Grinding on
Reciprocating Table Surface Grinders page 1190 Machinery's Handbook
#26


--
The Road Warrior Hobbit

no -- it's NOT ok to contact this account with services or other
commercial interests
wrote in message
oups.com...
| It is the value that the K.O. Lee Rep recommended. Personally I
think
| that I got better results with a larger cross feed. One book
advises
| that you should feed about 1/4 of the wheel width but no more. This
| would be .125 for a 1/2" wheel. I like .100 because it is one full
| revolution on my handwheel.
|

Mungo Bulge wrote:
Cross feed per pass, fraction of wheel width is 1/10 for a hardness of
greater than 52 Rc and 1/4 for a hardness of 52 Rc or less, and a
table speed of 50 to 100 fpm. Rough cut 0.003, finish cut 0.0005 max.

The above data is almost guarantee to cause a train wreck with a small SG. - GWE

On Wed, 27 Jul 2005 19:07:08 -0400, john
wrote:



Harold and Susan Vordos wrote:
wrote in message
ups.com...

The indicator base was placed on the column in order to eliminate any
possible movement of the wheelhead. The measurement does therefore
confirm the flatness of the table which translates into the
straightness of the ways.


No, it does not. No more than running an indicator along a mill table
confirms the squareness of the mill head. Look at it this way. If your
wheel is fixed (which it is) and the table rises and falls, the surface is
ground in a corresponding pattern, therefore yielding what appears to be a
surface that is flat. When you run an indicator on the table, all it's
telling you is how faithfully the wheel has followed the pattern, the ways.
It may or may not be flat, and most likely is not, especially if you're
using an older machine. . You can't check flatness that way--it should be
done by comparing on a surface plate of known flatness. Only then can you
discern the rise and fall of the surface, which then translates into
flatness.

Harold





Just use a precision level. Shim it up so the bubble is in the center
and run the table back and forth. IF its going back and forth over the
mountain of unworn metal of the ways in the middle of the travel you
will see the bubble go back and forth as you run the table left and
right. A cheap and dirty way to tell is with a laser pointer and a
mirror. Put the mirror on the middle of the table mounted upright and
aiming along the table, Clamp the laser pointer so it hits the mirror
and bounces off to a far wall. Now all you got to know is a little trig.


John


The laser pointer method can be extraordinarily sensitive but
use TWO mirrors setup to be almost parallel.

Fire the fixed laser pointer beam so that it zigzags several
times between the two mirrors finally finishing off the end to land on
any convenient white card scale.

One mirror is fixed to the test surface and the second mirror
anchored to a fixed location. The angular sensitivity doubles at each
reflection so it doesn't need many reflections to reach scary
sensitivity!

Surface silvered mirrors give the best results but ordinary
vanity mirrors are usable if you are content with a few reflections.
Old hard disk platters are also usable but don't try to cut them - it
destroys the flatness.

The mirrors need to be a long way apart so that the zig zag
angle is small and the beams do not move beyond the limits of the
mirror surface as the table is traversed. There will a small movement
in spot position in the direction of the zigzag angle as the table is
traversed so the measurement must be made at right angles to this
direction i.e for up and down angular measurement the zig zag path
should be horizontal.

Jim