Ok I have my delta surface grinder up and running all looks good. I did a
small test plate and it seems to do the job. I have never used a surface
grinder so any tips, how to, or DON'T does would be good. not sure how fast
to feed, how much ect.

Take light cuts. I can't emphasize that enough.
I watched my boss blow up a wheel and take out a wall when feeding
around .010" on tool steel gear cutter bits. Don't force it. If the
wheel starts slowing down you are hogging off too much, reduce down
feed or cross feed or both. Oh yeah, never start to wipe off the water
on the magnetic table until the wheel has -completly- stopped. I lost
a couple of knuckle tops that way.
Your machine probably has a manual table feed so going too fast won't
be too much of a problem. The hydraulic table feeds can really force
things and the wheels can't take much of that.
Best of luck with it. 73 Gary

On Thu, 7 Apr 2005 20:08:53 -0400, "Waynemak"
wrote:

Ok I have my delta surface grinder up and running all looks good. I did a
small test plate and it seems to do the job. I have never used a surface
grinder so any tips, how to, or DON'T does would be good. not sure how fast
to feed, how much ect.

Feed as fast as you want..but only take off a few tenths (.0001) at a
time. Depending on wheel, and material, sometimes you can go fat and
take off up to a thousand..but you will likely wear the wheel fast and
get burn marks on your material. Plus the finish may suck as the head
bounces.

A heads up. The wheel needs to be dressed with a diamond dresser
(cheap) and aways...aways...aways start high. If you screw up and
start low..and hit the side of the workpiece..you could grenade the
wheel. Not a fun think even if it doesn't hurt you.

Gunner

Rule #35
"That which does not kill you,
has made a huge tactical error"

"Waynemak" wrote in message
...
Ok I have my delta surface grinder up and running all looks good. I did a
small test plate and it seems to do the job. I have never used a surface
grinder so any tips, how to, or DON'T does would be good. not sure how
fast
to feed, how much ect.



I strongly disagree with grinding instructions you've received. If my
opinion matters, here's a link
http://www.chaski.com/ubb/showthread...ssion&Number=6
5662&page=&view=&sb=5&o

that will take you to a site where grinding is currently being discussed.
My posts clearly state a procedure for grinding that is far superior, and
explains why. There is some very good information provided for anyone
that desires to learn to grind well.

Harold

On Thu, 7 Apr 2005 21:48:55 -0700, "Harold and Susan Vordos"
wrote:

5662&page=&view=&sb=5&o
This is a problem that can have so many causes that it's almost beyond
the scope of a post.

First, how are you grinding? Are you subscribing to the notion that
you should constantly down feed your wheel and take large swaths with
each pass? You'll never achieve what I consider a good finish by that
method. You must learn to grind in a different manor.

Are you grinding dry? Heat alone will give you more problems than
you'll ever be able to overcome. If so, no matter what it takes, get
your grinder running with coolant unless you're grinding small items
like punches. Grinding creates an enormous amount of heat, which must
be dealt with. The expansion of the work makes holding a tight
tolerance almost impossible, to say nothing of the poor finish you're
likely to get regardless of your effort.

Are you grinding soft materials? Cold rolled steel, for example? Soft
material never grinds as well as hard material, but you can get a good
surface void of waves when things are right.

To change how you grind, I suggest the following:

Think of your grinding wheel as a milling cutter, which it really is.
It is a multiple toothed cutter that will cut very best by using a
corner. Try grinding your objects by picking up, then moving over to
the edge and feeding down a reasonable amount. If you have .010" to
remove, and it will come off one side, take .005" and run across your
item repetitively, feeding the cross slide roughly .030"/.050" each
pass, allowing the corner of the wheel to take all the meat off. Take
all your passes in this manner, with no down feed until you're ready
for the next pass. By grinding in this manner, the wheel takes all the
meat off with the corner, leaving the balance of the unaffected wheel
to constantly spark the surface. That yields the best finish, and is
actually much faster than grinding by the plunge method. It creates a
shoulder on the wheel that must be dressed off when it becomes a
problem. You'll know when, because the wheel doesn't cut well. It can
be because it's gradually developed a tapered shoulder, or it's
loaded. Loading is usually caused by the wrong density of bond or
wrong hardness of wheel.

The very best scenario when grinding is that you grind both faces,
whether they require it or not. That way you keep stress in balance,
so the part tends to remain flat. Try to take equal amounts off both
faces, even when it's not necessary. Your reward will be flatter
parts. Don't take it off one side then the other, take a cut, flip the
part, take a cut, flip the part, etc., until you're to finished size.
That's the best way to achieve a good finish and a flat part. Your
final pass should be something like .0005", with a freshly dressed
wheel.

If you have a manual grinder, you're not nearly as likely to be happy
with this process as you might be if you have a hydraulic feed
machine. Unless you're involved in fine toolroom grinding, I highly
recommend you avoid manual machines. I've done some very difficult
toolroom grinding with several hydraulic machines, but can't imagine
grinding large surfaces with a manual one. You can turn on the
hydraulic machine and grind as I recommend while you're doing other
tasks.

Be certain that you have matched the wheel to the work at hand.
Aluminum oxide wheels for steel, always. Never silicon carbide. Using
a silicon carbide wheel on steel creates a glazed wheel almost
instantly, and that generally leaves a wavy surface. Too hard of a
wheel does the same thing, and a too soft wheel breaks down so fast it
almost always leaves a rough finish.

Wheels that are properly selected will cut without loading and leave a
decent finish, assuming your grinder has not had the motor replaced by
another motor (that has not been precision balanced), and has good
spindle bearings. Even a V belt can cause your finish to suffer. It
must run smoothly and not transmit any type of motion to the spindle.
The slightest vibration will translate into a poor finish. As little
as a few hundred thousandths variation show up as waves in your
finish. Use a hard wheel for soft material, and a soft wheel for hard
material. Wheels must break down at a proper rate (to stay sharp) in
order to achieve a good finish.

Are you running your grinder single phase? You're likely to never get
a good finish if you are. The uneven power pulses tend to translate
into the finish.

If you can provide more information I may be able to provide some
guidelines.

Harold

Excellent post Harold

gunner

Rule #35
"That which does not kill you,
has made a huge tactical error"

"Gunner" wrote in message
...
snip----

Excellent post Harold

gunner


*Blush*-----

Thanks, Gunner.

Harold

In article ,
Gunner wrote:

Several comments.
First this guy just bought a Delta toolmakers grinder.
Its is about as light weight as you can get, so advising the guy
to take 5 thou is very bad advice! Believe me, I own the rockwell
version of this machine and it won't do it! Period.

Second. This machine is not equiped with flood coolent. Mist
coolent was an option. I have never tried using coolent because
of health concerns but I'm sure it would work better. I have done
a lot of grinding dry with decent results. Definately a step
up from the milling machine.

chuck

"Chuck Sherwood" wrote in message
...
In article ,
Gunner wrote:

Several comments.
First this guy just bought a Delta toolmakers grinder.
Its is about as light weight as you can get, so advising the guy
to take 5 thou is very bad advice! Believe me, I own the rockwell
version of this machine and it won't do it! Period.

Second. This machine is not equiped with flood coolent. Mist
coolent was an option. I have never tried using coolent because
of health concerns but I'm sure it would work better. I have done
a lot of grinding dry with decent results. Definately a step
up from the milling machine.

chuck

Wouldn't some coolant options be healthier than the grinding dust?

I own a small lightweight (1500 pounds) 6x12" manual surface grinder. I'm not
real good at getting terrific finishes either. My grinder manual says to ease
the corners of the wheel with a dressing stone, and this helped quite a bit
for me. I've always gone with the .0005" downfeed, wide crossfeed, and I'm
going to try Harold's .005" downfeed, .020" crossfeed.

I hooked up flood coolant when I ground in my mag chuck. It somehow got under
my table and turned the way oil to jelly. I haven't tried coolant since. Most
of the things I grind are pretty little, though.

I'm also planning to try precision balancing my wheels. Eric Snow told me
recently that little grinders really work better with perfectly balanced wheels.

Grant

Harold and Susan Vordos wrote:

"Gunner" wrote in message
...
snip----

Excellent post Harold

gunner


*Blush*-----

Thanks, Gunner.

Harold

Harold, that is pretty much the way they taught me how to use a surface
grinder at work. I'm no longer in that department, but they grind several
HSS tools a day for the wickman multi-spindles.
Todd

On Fri, 08 Apr 2005 08:24:39 -0700, Grant Erwin
wrote:

I own a small lightweight (1500 pounds) 6x12" manual surface grinder. I'm not
real good at getting terrific finishes either. My grinder manual says to ease
the corners of the wheel with a dressing stone, and this helped quite a bit
for me. I've always gone with the .0005" downfeed, wide crossfeed, and I'm
going to try Harold's .005" downfeed, .020" crossfeed.

I hooked up flood coolant when I ground in my mag chuck. It somehow got under
my table and turned the way oil to jelly. I haven't tried coolant since. Most
of the things I grind are pretty little, though.

I'm also planning to try precision balancing my wheels. Eric Snow told me
recently that little grinders really work better with perfectly balanced wheels.

Grant
Yeah, but what does Eric Snow know?

"Chuck Sherwood" wrote in message
...
In article ,
Gunner wrote:

Several comments.
First this guy just bought a Delta toolmakers grinder.
Its is about as light weight as you can get, so advising the guy
to take 5 thou is very bad advice! Believe me, I own the rockwell
version of this machine and it won't do it! Period.

Second. This machine is not equiped with flood coolent. Mist
coolent was an option. I have never tried using coolent because
of health concerns but I'm sure it would work better. I have done
a lot of grinding dry with decent results. Definately a step
up from the milling machine.

chuck

The comments (in the post that was copied from a different site) were
directed to a person that was operating a B&S machine, not for the owner of
a Delta. However, everything stated still applies-------perhaps with a
lighter depth of grind. Regardless of how rigidly a grinder is built,
surface finish will be profoundly improved by the method proposed. Coolant
is a must-------it's not a luxury.

I'm not sure I understand your concern for using coolant and your health.
Are you suggesting it's healthier to breath the metal particles than some
mist? You want to remain healthy? Quit working with metals. There's
a given risk for those that do---------it goes with the territory.

When you suggest you've achieved decent results, try selling your results to
a QC department. It's all a matter of what you deem acceptable. My time
on grinding machines tells me that there's no way in hell you'll come close
to the results of grinding wet----and that includes holding dimensions.
Typically, grinding is close tolerance work--work that is rendered nearly
impossible when grinding dry. If, on the other hand, you have no clue
about working to tight tolerances, perhaps that's not a concern. For me, it
was. I'm afraid I'll have to put my years of experience in precision
grinding up against your opinion.

Harold

Wouldn't some coolant options be healthier than the grinding dust?

Its pretty easy to wear a half face dust mask to avoid breathing
the dust and to clean up aftewards.

I don't know how to deal with mist coolent. Seems like anything
wet would plug up a resperator pretty quick and you have to
deal possible machine damage by the moisture as well.

No doubt that coolent gives a better finish, but for a small
rockwell/delta toolmakers grinder (like I have ) your not going
to compete with a real surface grinder anyway.

To me it easier to deal with the devil that I know vs the
devil that I don't know.

chuck

"Grant Erwin" wrote in message
...
I own a small lightweight (1500 pounds) 6x12" manual surface grinder. I'm
not
real good at getting terrific finishes either. My grinder manual says to
ease
the corners of the wheel with a dressing stone, and this helped quite a
bit
for me. I've always gone with the .0005" downfeed, wide crossfeed, and I'm
going to try Harold's .005" downfeed, .020" crossfeed.

I hooked up flood coolant when I ground in my mag chuck. It somehow got
under
my table and turned the way oil to jelly. I haven't tried coolant since.
Most
of the things I grind are pretty little, though.

I'm also planning to try precision balancing my wheels. Eric Snow told me
recently that little grinders really work better with perfectly balanced
wheels.

Grant

Use good judgment in the depth of grind. My comments were (originally)
directed towards a much more robust machine, a B&S.

When you use my proposed method, do *not* modify the edge of the wheel.
That's no different from a wheel that has already done considerable work.
It's the corner of the wheel that does the work by this method. You want it
as close to a right angle as possible. It's when it becomes tapered that it
becomes necessary to dress the wheel.

One other thing. Again, my (original) comments were directed towards a
machine that is built for coolant. I fully understand your reluctance to
use coolant if you've had a negative experience----like running coolant on a
cutter grinder that is intended to be run dry. I obviously wouldn't
recommend coolant on dry machines---but I also wouldn't own a dry machine
when coolant was a *requirement* for good success. I practice what I
preach.

Harold

When reading the posts I realize the grinder I have will not take a .005
cut, however alot of the information very usefull. I think .001 is about the
largest cut I would want to make with this grinder, making small advances at
this depth gave very nice results. Sure it takes time but I don't have the
need for a 3000 pound machine for how often I will use this. Now its time to
find some other wheels and experiment. I sparked in the chuck and it seems
very accurate, and smooth.
Thank ypu for the great information and I look foward to any other posts.
"Chuck Sherwood" wrote in message
...
In article ,
Gunner wrote:

Several comments.
First this guy just bought a Delta toolmakers grinder.
Its is about as light weight as you can get, so advising the guy
to take 5 thou is very bad advice! Believe me, I own the rockwell
version of this machine and it won't do it! Period.

Second. This machine is not equiped with flood coolent. Mist
coolent was an option. I have never tried using coolent because
of health concerns but I'm sure it would work better. I have done
a lot of grinding dry with decent results. Definately a step
up from the milling machine.

chuck

On 8 Apr 2005 18:18:04 GMT, (Chuck
Sherwood) wrote:

Wouldn't some coolant options be healthier than the grinding dust?

Its pretty easy to wear a half face dust mask to avoid breathing
the dust and to clean up aftewards.

I don't know how to deal with mist coolent. Seems like anything
wet would plug up a resperator pretty quick and you have to
deal possible machine damage by the moisture as well.

No doubt that coolent gives a better finish, but for a small
rockwell/delta toolmakers grinder (like I have ) your not going
to compete with a real surface grinder anyway.

To me it easier to deal with the devil that I know vs the
devil that I don't know.

chuck
Chuck,
What Harold says. I sometimes will dry grind a small tool but it is
really slow compared to using mist or coolant. I just finished my
grinding room and it has two exhaust fans. But having even some mist
on the part will actually be better than the fines that come off of a
grinding operation. The water will get the fines to clump together
into larger size particles. I noticed this helps the amount of dust in
the air. Especially when grinding cast iron. Even with a mask you will
smell iron for hours after grinding cast iron dry.
ERS

"Chuck Sherwood" wrote in message
...
Wouldn't some coolant options be healthier than the grinding dust?

Its pretty easy to wear a half face dust mask to avoid breathing
the dust and to clean up aftewards.

I don't know how to deal with mist coolent. Seems like anything
wet would plug up a resperator pretty quick and you have to
deal possible machine damage by the moisture as well.

No doubt that coolent gives a better finish, but for a small
rockwell/delta toolmakers grinder (like I have ) your not going
to compete with a real surface grinder anyway.

To me it easier to deal with the devil that I know vs the
devil that I don't know.

chuck

What kind of dust mask are you using? Are you sure it will block the
particle sizes created by grinding?

Check to see if your table has stops. Otherwise you can crank the table
right off the ways, and oops, the table will kick up and smack the wheel!

Tony


"Waynemak" wrote in message
...
Ok I have my delta surface grinder up and running all looks good. I did a
small test plate and it seems to do the job. I have never used a surface
grinder so any tips, how to, or DON'T does would be good. not sure how
fast
to feed, how much ect.

"Harold and Susan Vordos" wrote in
:

I strongly disagree with grinding instructions you've received. If
my opinion matters, here's a link
http://www.chaski.com/ubb/showthread...discussion&Num
ber=6 5662&page=&view=&sb=5&o

that will take you to a site where grinding is currently being
discussed. My posts clearly state a procedure for grinding that is far
superior, and explains why. There is some very good information
provided for anyone that desires to learn to grind well.

I was beginning to think that I was the only person that grinds on a
surface grinder that way. I've got a question for you Harold. Have you ever
done any double disk grinding? I'm looking for a wheel supplier, and maybe
some advise. Very tight tolerance parts on a brand new very accurate
machine with auto sizing. I'd sure appreciate any help you can offer.

--

Dan

"Waynemak" wrote in
:

When reading the posts I realize the grinder I have will not take a
.005 cut, however alot of the information very usefull. I think .001
is about the largest cut I would want to make with this grinder,
making small advances at this depth gave very nice results. Sure it
takes time but I don't have the need for a 3000 pound machine for how
often I will use this. Now its time to find some other wheels and
experiment. I sparked in the chuck and it seems very accurate, and
smooth. Thank ypu for the great information and I look foward to any
other posts.

The power required is a function of the depth and cross feed. Reducing
either reduces the power required. Take .0025" and cross feed .010" and
you've reduced the power required by 1/2.

--

Dan

"D Murphy" wrote in message
...
"Harold and Susan Vordos" wrote in
:

I strongly disagree with grinding instructions you've received. If
my opinion matters, here's a link
http://www.chaski.com/ubb/showthread...discussion&Num
ber=6 5662&page=&view=&sb=5&o

that will take you to a site where grinding is currently being
discussed. My posts clearly state a procedure for grinding that is far
superior, and explains why. There is some very good information
provided for anyone that desires to learn to grind well.

I was beginning to think that I was the only person that grinds on a
surface grinder that way. I've got a question for you Harold. Have you
ever
done any double disk grinding? I'm looking for a wheel supplier, and maybe
some advise. Very tight tolerance parts on a brand new very accurate
machine with auto sizing. I'd sure appreciate any help you can offer.

--

Dan

Hi Dan,

Surface grinding:

My mentor had vast experience and was gracious enough to not only teach me
all methods, but wise enough to point out the pitfalls of using each one.
I have him to thank for what little knowledge I carry with me today.

It's been a very revealing experience to find that so many grind by methods
different form the one you and I prefer. I can say with total honesty that
grinding by my recommended procedure is the best way, hands down, assuming
finish is important. That would apply to even small, dry grinders.

Sorry to say I've never touched a double disk grinder, although I have seen
one. If by chance you manage to corner some information about one, I'd be
keenly interested in hearing what you discover. We had no need for one at
the missile facility, otherwise we'd have had one.

Harold

"Eric R Snow" wrote in message
...
snip----

.. Even with a mask you will
smell iron for hours after grinding cast iron dry.
ERS

Heh! I can't even machine it without smelling it for what seems eternity.
For some reason, there's something in iron (gray and ductile) that doesn't
agree with me, or at least my sense of smell. I used to run a job that
had ductile iron dogs, which were a part of a drive I used to build for
Seagrave Corp.. They were used for opening large doors, or gymnasium
partitions. I ran a vacuum cleaner off the back side of the spindle and
discharged outside to keep from breathing the dust. Half of the operation
was boring the parts for a large bushing. The vacuum setup was a natural,
with virtually 100% of the dust ending up in the vacuum.

Harold

"D Murphy" wrote in message
...
"Harold and Susan Vordos" wrote in
:

Hi Dan,

Surface grinding:

My mentor had vast experience and was gracious enough to not only
teach me all methods, but wise enough to point out the pitfalls of
using each one. I have him to thank for what little knowledge I carry
with me today.

I've read acouple of posts where you gave out good advice on surface
grinding and offhand tool grinding. We had similar teachers.


It's been a very revealing experience to find that so many grind by
methods different form the one you and I prefer. I can say with
total honesty that grinding by my recommended procedure is the best
way, hands down, assuming finish is important. That would apply to
even small, dry grinders.

The company I work for imported a surface grinder from Taiwan for a time.
We used to gring hardened 52100 steel to a mirror finish at the machine
tool shows for a demo. All you need is the right wheel, balance it, dress
it properly, and grind using the method you describe. Worked every time.
These weren't great machines either. They were better quality than I
expected but they weren't Mitsui's by any stretch.

I've been away from machining since '83, so I'm painfully behind in what's
happening today, including knowing anything about a Mitsui, but a friend
that is working as a mold maker was talking about one of them recently.
They're apparently a super nice grinder. Your comments on procedure
should be very enlightening for those that don't subscribe to what I call
*proper* grinding, verifying that which I've been espousing.



Sorry to say I've never touched a double disk grinder, although I have
seen one. If by chance you manage to corner some information about
one, I'd be keenly interested in hearing what you discover. We had
no need for one at the missile facility, otherwise we'd have had one.

Actually we sell one. We have had some issues with the wheel we are using
and the manufacturer hasn't been a lot of help. It's a CBN wheel and it
has been chipping out on the edges during cycle. The trouble seems to be
on parts where we are grinding single sided rather than double disk. I've
got some other projects where customers are wanting us to run a part and
I'm not comfortable buying another wheel from the current supplier at the
moment. I need to hold .0001" parallelism and .0001" flatness. Thickness
is wide open at .0003" total. I have to hold a 1.67 Cpk running these off
so there is no room for variation. When the wheel chips on the current
job the chip gets dragged across the wheel and my dimensions will jump
about .00006". sixty millionths may not seem like much but it's enough to
fail the run off. To say nothing about a very expensive wheel falling
apart. If you want to see the machine it's he
http://www.tsugami.co.jp/product/lapping/TVG4/TVG4.html
Unfortunately it's not in English, and we haven't added it to our web
site yet. http://www.remsales.com/
Dan

Wow! Very impressive looking machine, and a total surprise. The one I'd
seen had horizontal spindles with a carrier for the part which oscillated
back and forth between the two wheels. Very old technology, to be sure.
One of the jobs the shop was running with is was the slide portion of a
pistol.

I'm not familiar in the least with CBN wheels, considering they were not in
use when I retired from (commercial) machining. I gather that such a wheel
is more or less a necessity for the work at hand, but I'd be inclined to use
a different wheel, assuming that would be possible. You didn't mention the
material being ground.

Funny, talking about .000060" and having it be a concern. Yeah, it
doesn't sound like much to worry about, but when you have no tolerance to
speak of, it obviously spells the difference. I think it's hard for the
average machinist to grasp the concept of fine work. So much so that I've
commented more than once that it takes a special kind of guy to be
successful in the grinding department. Some guys never really make the
grade, yet may have years of shop experience.

About the chipping. I can't help but wonder if it's not being caused by
your parts chattering slightly. Your operation being a total stranger to
me, could it be that your coolant plays into the problem? For typical
grinding, the level of concentration of lubricant (in the coolant) isn't
critical, more for rust prevention than anything, but when you use machines
that rely on surfaces for support (like when grinding on one side only) it
could be you need more lubrication. We always ran a higher level of
concentration in the centerless grinder for that very reason. It's
interesting that it happens when grinding single sided, which prompts my
chatter question. My other suggestion would be feed rate, but without
understanding how the machine operates, I'm not sure I'd be in the ball
park.

I looked at the lathes offered by your firm. Sure makes me breath easier
to know that if I was really in need that there are still reasonable
machines on the market. I was particularly impressed by the one model
that offered 2,500 RPM at the spindle. I'm running a Sag 12 Graziano that
I bought new in '67, and I"m hoping it will see me through to my dying days,
but I'd not hesitate to buy something similar (new) if the need arose. I'd
rather it didn't come from Harbor Freight, if you get my drift!

Harold

"Harold and Susan Vordos" wrote in
:

Wow! Very impressive looking machine, and a total surprise. The one
I'd seen had horizontal spindles with a carrier for the part which
oscillated back and forth between the two wheels. Very old
technology, to be sure. One of the jobs the shop was running with is
was the slide portion of a pistol.

This machine is the smallest one they make. But you know how it is, the
smaller the part the smaller the tolerance. It's tough to see in the
photo but the fixtures are actually gears. So the parts rotate from the
inside of the wheel to the outside while rotating around the wheel.
eventually during the cycle all of the workpiece surface gets ground by
every bit of the wheel surface. The flatness and parallelism are really a
function of the bearings in the machine, and the machines ability to
resist deflection. The feedrate is determind by pressure, same as flat
lapping. The machine has auto sizing via an in process gage which is made
by Sony.


I'm not familiar in the least with CBN wheels, considering they were
not in use when I retired from (commercial) machining. I gather that
such a wheel is more or less a necessity for the work at hand, but I'd
be inclined to use a different wheel, assuming that would be possible.
You didn't mention the material being ground.

The one job we had trouble with we were single side grinding. The
material is 52100 low 60's Hrc. I can't remember exactly and don't have
the drawing here at home. CBN is the only way to do this type of
grinding.


Funny, talking about .000060" and having it be a concern. Yeah, it
doesn't sound like much to worry about, but when you have no tolerance
to speak of, it obviously spells the difference. I think it's hard
for the average machinist to grasp the concept of fine work. So much
so that I've commented more than once that it takes a special kind of
guy to be successful in the grinding department. Some guys never
really make the grade, yet may have years of shop experience.

To tell you the truth it's surprisingly easy to achieve these tolerances
on this machine. (When the wheel doesn't fall apart) One of the other
parts we did double disk grinding, we ran for 24 hours and had a total
thickness deviation of 1.6 microns and flatness and parallelism never
exceeded 1 micron. I'm willing to bet that if we re-cleaned and rechecked
the parts that were at the extremes we would find that the deviation was
smaller.


About the chipping. I can't help but wonder if it's not being caused
by your parts chattering slightly.

That's our current thought. The parts that the customer has supplied have
way too much variation, so the tall ones are under pressure and the short
ones might be jumping around as they pass beyond the edge of the wheel.
Either that or we have a bad wheel.

Your operation being a total
stranger to me, could it be that your coolant plays into the problem?

You might not be familiar with what we are doing but you're thinking is
dead on. The wheel manufacurer was certain it was the coolant. We were
using an equivelant to the one they sell. We then switched to their own
brand and the wheel still chips. They were claiming that the damage was
already done by the coolant we were using. Then I pointed out that the
lower wheel didn't chip and its flooded in the coolant. Hmmmm. Well then
you must have crashed the wheel. I'm telling you, that never happened. If
it did I would just get another wheel and get on with my life.

For typical grinding, the level of concentration of lubricant (in the
coolant) isn't critical, more for rust prevention than anything, but
when you use machines that rely on surfaces for support (like when
grinding on one side only) it could be you need more lubrication. We
always ran a higher level of concentration in the centerless grinder
for that very reason. It's interesting that it happens when grinding
single sided, which prompts my chatter question. My other suggestion
would be feed rate, but without understanding how the machine
operates, I'm not sure I'd be in the ball park.

Like I said the feed rate is controlled by pressure. We are starting out
at low pressure until we get to a point where we are certain that the
wheel is contacting all of the work. Then it shifts to a higher pressure
and then back to low as it finishes. The lubricity idea is interesting.
I'm going to look into that some more. When we are single side grinding
we are using hardened fixtures that ride on a hardened plate. The part we
are grinding locates on a shoulder in the fixture. So there is
opportunity for something to stick. The speeds are fairly slow though and
the flood of coolant is immense. I am thinking that we could re make the
fixture so that the workpiece doesn't come out from under the wheel as
the fixture rotates around. The problem then becomes we would have to
desin a dummy part for the in process gage. (this part is very small) The
double disk ground workpieces use a dummy part mounted on the periphery
of each fixture for gaging. These dummy parts are larger in diameter than
the part being ground.


I looked at the lathes offered by your firm. Sure makes me breath
easier to know that if I was really in need that there are still
reasonable machines on the market. I was particularly impressed by
the one model that offered 2,500 RPM at the spindle. I'm running a
Sag 12 Graziano that I bought new in '67, and I"m hoping it will see
me through to my dying days, but I'd not hesitate to buy something
similar (new) if the need arose. I'd rather it didn't come from
Harbor Freight, if you get my drift!

Thanks. I don't have anything to do with the "manual" side of the
business, but I can get knee mills and lathes at a discount for you if
you ever need one. The Harrison lathes are good quality of course, but I
have been pleasantly surprised at the 14x40 Nardini that we have at our
office. We have a small tool room and the home office let me have a new
Nardini. I would have loved a Harrison Alpha but for what we do the $$
don't make sense. The Nardini is a better machine than I expected,
cetainly better than most although not quite as good as the Harrison
manuals. I just can't get used to the "lay-out" of the thing. Small
complaint I guess.

Anyway thanks for bouncing this around with me. I've got a couple more
ideas as a result.




--

Dan

"D Murphy" wrote in message
...
"Harold and Susan Vordos" wrote in
:

The feedrate is determind by pressure, same as flat
lapping.

That sends up a red flag. I'm sure you've not talking about lots of
pressure, but I can't help but wonder if it's more than the matrix of the
wheel can withstand (as you alluded, maybe a bad wheel).. How are the CBN
wheels bonded? I've never seen one.


The one job we had trouble with we were single side grinding. The
material is 52100 low 60's Hrc. I can't remember exactly and don't have
the drawing here at home. CBN is the only way to do this type of
grinding.

I'd still be inclined to go with a 38A Norton wheel, but that may not work
with that type of machinery. It sure would be my choice for the level of
technology with which I'm familiar. Years ago I made three sets of
supercharger planetary components for Auburn and Cord, each of which used
the same blower guts, but a different housing (Auburn is straight 8, Cord
V8). I recall it ground beautifully, as do the vast majority of hard
materials.


To tell you the truth it's surprisingly easy to achieve these tolerances
on this machine. (When the wheel doesn't fall apart) One of the other
parts we did double disk grinding, we ran for 24 hours and had a total
thickness deviation of 1.6 microns and flatness and parallelism never
exceeded 1 micron. I'm willing to bet that if we re-cleaned and rechecked
the parts that were at the extremes we would find that the deviation was
smaller.

To be perfectly honest, you're way out of my league. While we worked to
close tolerances, I don't recall anything tighter than .0001" (for
flatness). We used to grind a thin cover for the bearing housings of the
guidance system of the missile. They were made of A286 stainless, drilled
and countersunk, then hardened. We'd rough them on a surface grinder, but
to get them flat, we'd spin them in a fixture that, for all practical
purposes, emulated the machine you are using, but very crude and old. It
was an old B&S grinder with drip oilers, if that helps put things in
perspective. We relieved the side of the wheel, using only the outside
1/4" or so, then, with the work head and grinding heat perfectly parallel,
we'd float the part in a pocket fixture, driven by a loose fitting pin in
one of the holes. We could get the parts flat (less than .0001") by
grinding both sides. It's an excellent way to grind, because there's
nothing distorting the part, which was actually held in place by the wheel.


About the chipping. I can't help but wonder if it's not being caused
by your parts chattering slightly.

That's our current thought. The parts that the customer has supplied have
way too much variation, so the tall ones are under pressure and the short
ones might be jumping around as they pass beyond the edge of the wheel.
Either that or we have a bad wheel.

While it may not be what you're hoping for, it might be a good idea to hit
them on a surface grinder to make them uniform in size before using the
double disk machine. Sort of a rough grinding operation, leaving only
enough stock to bring them flat and to size. Dunno. Might be too much
handling.

Your operation being a total
stranger to me, could it be that your coolant plays into the problem?

You might not be familiar with what we are doing but you're thinking is
dead on. The wheel manufacurer was certain it was the coolant. We were
using an equivelant to the one they sell. We then switched to their own
brand and the wheel still chips. They were claiming that the damage was
already done by the coolant we were using.

Then I'd suggest to them that they change the matrix in their wheels!
That's absurd.

Then I pointed out that the
lower wheel didn't chip and its flooded in the coolant. Hmmmm. Well then
you must have crashed the wheel. I'm telling you, that never happened. If
it did I would just get another wheel and get on with my life.

Sounds like the old "pass the buck" thing to me. These wheels must be
fairly expensive, or they'd pony up another, at least to see if it, too,
chipped. I have a philosophy when it comes to such matters. If, in the
end, I find they're the problem, I make certain to use their competitors
for all future transactions.


Like I said the feed rate is controlled by pressure. We are starting out
at low pressure until we get to a point where we are certain that the
wheel is contacting all of the work. Then it shifts to a higher pressure
and then back to low as it finishes.

Do you have any idea when the wheel fractures? It might not be when the
piece finally dislodges. I'm still wrestling with the pressure.

The lubricity idea is interesting.
I'm going to look into that some more. When we are single side grinding
we are using hardened fixtures that ride on a hardened plate. The part we
are grinding locates on a shoulder in the fixture. So there is
opportunity for something to stick. The speeds are fairly slow though and
the flood of coolant is immense. I am thinking that we could re make the
fixture so that the workpiece doesn't come out from under the wheel as
the fixture rotates around. The problem then becomes we would have to
desin a dummy part for the in process gage. (this part is very small) The
double disk ground workpieces use a dummy part mounted on the periphery
of each fixture for gaging. These dummy parts are larger in diameter than
the part being ground.

So the gage part acts like a stop, but electronically? You'll have to
forgive me, for any machine I've ever run, everything was determined by my
hand. I've never used so much as a DRO in my entire machining career.
Everything was done the hard way.

I like the idea that the part never leaves the wheel. It is likely where
the chipping occurs. By its nature, there's not really a need for the parts
to go outside the wheel boundary, so it might be an excellent thing to
pursue, especially if coolant can lift a part occasionally.

Curious. How much of the wheel face is being used? Is it like a Blanchard?

Thanks for your candor on the manual machines. I'll certainly keep your
kind offer in mind.

Anyway thanks for bouncing this around with me. I've got a couple more
ideas as a result.

Not sure I did you any good, but I'd sure enjoy hearing what you conclude.
Why don't you keep us all posted? These are the kinds of problems that are
interesting, and often very difficult to solve. In the end, you'll wonder
how you missed it, assuming it's not a bad wheel, anyway.

Harold

What kind of dust mask are you using? Are you sure it will block the
particle sizes created by grinding?

I use a half face resperator with 3M cartridges and prefilters.
I also use this setup when cleaning up model engine castings with
a grinding stones or cratex (using a foredom).

The rockwell toolmakers grinder is not capable of flood coolent but
does have a mist coolent system. Sound like I sould install an exhaust
fan and try it out.

cs

Now its time to find some other wheels and experiment.

I highly recommend buying Norton 5SG wheels. I pretty much leave
my 5SG46 on all the time.

"Harold and Susan Vordos" wrote in
:


"D Murphy" wrote in message
...
"Harold and Susan Vordos" wrote in
:

The feedrate is determind by pressure, same as flat
lapping.

That sends up a red flag. I'm sure you've not talking about lots of
pressure, but I can't help but wonder if it's more than the matrix of
the wheel can withstand (as you alluded, maybe a bad wheel).. How
are the CBN wheels bonded? I've never seen one.

They are resin bonded. The one we are using is designed for low pressure
double disk grinding. The main advantage is you can go a long time
between dressing. So they pay for themselves in high volume applications.
We were able to go about an hour between dressing with the CBN. We were
doing 140 pcs. per load. The cycle time starts out under 30 seconds. In
an hours time the cycle time gets to be about a minute and we dress the
wheel which takes about five minutes. If the blanks were off of a cnc
rather than a multi spindle we could do better. The amount being ground
was excessive IMO.



The one job we had trouble with we were single side grinding. The
material is 52100 low 60's Hrc. I can't remember exactly and don't
have the drawing here at home. CBN is the only way to do this type of
grinding.

I'd still be inclined to go with a 38A Norton wheel, but that may not
work with that type of machinery. It sure would be my choice for the
level of technology with which I'm familiar. Years ago I made three
sets of supercharger planetary components for Auburn and Cord, each of
which used the same blower guts, but a different housing (Auburn is
straight 8, Cord V8). I recall it ground beautifully, as do the vast
majority of hard materials.

I've got a bit of an update. A customer has comitted to the machine
today, and for his application I'll be using conventional wheels and
double disk grinding. Funny you should mention turbos...



To tell you the truth it's surprisingly easy to achieve these
tolerances on this machine. (When the wheel doesn't fall apart) One
of the other parts we did double disk grinding, we ran for 24 hours
and had a total thickness deviation of 1.6 microns and flatness and
parallelism never exceeded 1 micron. I'm willing to bet that if we
re-cleaned and rechecked the parts that were at the extremes we would
find that the deviation was smaller.

To be perfectly honest, you're way out of my league. While we worked
to close tolerances, I don't recall anything tighter than .0001" (for
flatness). We used to grind a thin cover for the bearing housings of
the guidance system of the missile. They were made of A286
stainless, drilled and countersunk, then hardened. We'd rough them
on a surface grinder, but to get them flat, we'd spin them in a
fixture that, for all practical purposes, emulated the machine you are
using, but very crude and old. It was an old B&S grinder with drip
oilers, if that helps put things in perspective. We relieved the
side of the wheel, using only the outside 1/4" or so, then, with the
work head and grinding heat perfectly parallel, we'd float the part in
a pocket fixture, driven by a loose fitting pin in one of the holes.
We could get the parts flat (less than .0001") by grinding both sides.
It's an excellent way to grind, because there's nothing distorting
the part, which was actually held in place by the wheel.

A-286. Ick. Ive cut a bit of that. I worked on an interesting turnkey
once on a Y-axis sub spindle twin turret lathe. We rough and finish
milled then rough and finish ground an A-286 part. We were running parts
and I heard something heavy fall into the chip pan. I looked into the
machine and couldn't see anything wrong so I went around and looked in
the chip pan. There was half of a 3/4" end mill in there. Never stopped
the machine and didn't damage the part. The end mill just got dull and
broke. Tough stuff that A-286.
I'm amazed at how guys like you made parts back in the day. If you were
to watch us grind on this machine you wouldn't believe how easy it is.
That is once you get the fixture right, get a good wheel, and dial in the
program. On manual grinders you pretty much have to be on your game all
day. Now-a-days all the development is up front (my favorite part) then
once it's dialed in and proven capable there is not a lot of skill
required in running the machine.



About the chipping. I can't help but wonder if it's not being
caused by your parts chattering slightly.

That's our current thought. The parts that the customer has supplied
have way too much variation, so the tall ones are under pressure and
the short ones might be jumping around as they pass beyond the edge
of the wheel. Either that or we have a bad wheel.

While it may not be what you're hoping for, it might be a good idea to
hit them on a surface grinder to make them uniform in size before
using the double disk machine. Sort of a rough grinding operation,
leaving only enough stock to bring them flat and to size. Dunno.
Might be too much handling.

Yeah it would be too many ops. That customer is surface grinding now.
Productivity and quality is not nearly as good as what we are doing.


Your operation being a total
stranger to me, could it be that your coolant plays into the
problem?

You might not be familiar with what we are doing but you're thinking
is dead on. The wheel manufacurer was certain it was the coolant. We
were using an equivelant to the one they sell. We then switched to
their own brand and the wheel still chips. They were claiming that
the damage was already done by the coolant we were using.

Then I'd suggest to them that they change the matrix in their wheels!
That's absurd.

Then I pointed out that the
lower wheel didn't chip and its flooded in the coolant. Hmmmm. Well
then you must have crashed the wheel. I'm telling you, that never
happened. If it did I would just get another wheel and get on with my
life.

Sounds like the old "pass the buck" thing to me. These wheels must
be fairly expensive, or they'd pony up another, at least to see if it,
too, chipped. I have a philosophy when it comes to such matters.
If, in the end, I find they're the problem, I make certain to use
their competitors for all future transactions.

They were passing the buck without a doubt. That's what prompted me to
ask you about double disk grinding. I was hoping to find another supplier
and maybe get some advice. Anyway I don't have a lot of faith in these
guys anymore. I'm going to give Norton a call for this new deal.



Like I said the feed rate is controlled by pressure. We are starting
out at low pressure until we get to a point where we are certain that
the wheel is contacting all of the work. Then it shifts to a higher
pressure and then back to low as it finishes.

Do you have any idea when the wheel fractures? It might not be when
the piece finally dislodges. I'm still wrestling with the pressure.

The lubricity idea is interesting.
I'm going to look into that some more. When we are single side
grinding we are using hardened fixtures that ride on a hardened
plate. The part we are grinding locates on a shoulder in the fixture.
So there is opportunity for something to stick. The speeds are fairly
slow though and the flood of coolant is immense. I am thinking that
we could re make the fixture so that the workpiece doesn't come out
from under the wheel as the fixture rotates around. The problem then
becomes we would have to desin a dummy part for the in process gage.
(this part is very small) The double disk ground workpieces use a
dummy part mounted on the periphery of each fixture for gaging. These
dummy parts are larger in diameter than the part being ground.

So the gage part acts like a stop, but electronically? You'll have
to forgive me, for any machine I've ever run, everything was
determined by my hand. I've never used so much as a DRO in my entire
machining career. Everything was done the hard way.

I'm telling you that you would find no joy in operating this machine.
Setting it up and wringing it out is where the fun is. The way the gage
works is that you set it with gage blocks and zero it out. During the
cycle the gage advances and measures the part or dummy part in process.
As the machine gets close to size it reduces the pressure (and therefor
the feed rate), then when the gage measures zero it pulls the wheel up,
then stops.


I like the idea that the part never leaves the wheel. It is likely
where the chipping occurs. By its nature, there's not really a need
for the parts to go outside the wheel boundary, so it might be an
excellent thing to pursue, especially if coolant can lift a part
occasionally.

Thats our current theory. If that customer wants to carry on, I'm
thinking we either change the wheel or use a fixture where the part stays
under the wheel and we use a dummy for gaging.


Curious. How much of the wheel face is being used? Is it like a
Blanchard?

Sort of except the wheel is not segmented. The whole face of the wheel is
used.

snip


Not sure I did you any good, but I'd sure enjoy hearing what you
conclude. Why don't you keep us all posted? These are the kinds of
problems that are interesting, and often very difficult to solve. In
the end, you'll wonder how you missed it, assuming it's not a bad
wheel, anyway.

That's why talking things out is always good. It gets your mind out of
the rut it's in and suddenly you see the problem. Unfortunately I wasn't
involved in this project until recently, so I'm trying to get up to speed
fast. I'll let you know how the new deal goes, and if we ever get back to
the other jobs I'll let you know what we figure out.

--

Dan