We lose 10 points each time we restart a part, but I'm taking the
class to learn--not necessarily to fluff my GPA. I may very well do
another wheel simply for the hell of it.
Either that or when I get to make my own project up after finishing
this one I'll do something with a wheel on it.
So what does the C2/C5 rating refer to? Grain size? Carbide vs.
"other" content? Is there some sort of system to choose which grade
where, or is it just down to C2 for some stuff, C5 for others, all other
grades not made anymore?
Searching on google got me a whole lot of marketing, but not much
Sounds like bicycle parts: cheap, durable, light--pick two.
These inserts get used on any damn thing that finds its way onto the
lathes. Poor things probably had to cut stone at some point. In fact,
I had to put a steel center into the chuck and take a light cut off of
it so the mandrel would run true immediately before I machined the
wheel. So, yeah, it got "steeled" first.
Would the steel or aluminum--not both rule also apply to HSS bits, or
are they OK with it since they can be sharpened?
I wound up leaving the outside of my flywheel .003" oversize (we have
a tolerance of .005" over/under) so I could file/sand off the uglyness.
Alas, there is no lubricant. I did try painting my wheel with a film
of oil for one cut, but it didn't appear to help any, so I didn't mess
with it any more. Got a bit stinky anyhow.
My lathe actually had two carbides sitting at it. One was undamaged,
but the other had an impressive little heap of metal welded firmly to
the cutting edge.
But that's really nothing compared to the guy who took a .050" pass
using a carbide insert cutter in the mill, but ran it backwards and way
too fast. It took off .050, but as a smear instead of as chips. Ah,
B.B. --I am not a goat! thegoat4 at airmail dot net
I've been out of the shop so long that I am no longer knowledgeable where
carbides are concerned. It's particularly bad considering they've made
great strides with carbide, too, so I can only assume that it may not be as
critical as it once was. I'm not convinced you'd find many machinists
that really understood the differences in how they're put together, though.
When you go back to my time in the shop (primarily brazed carbides),
constituents of the carbide were altered to accomplish the performance
required. Carbide went from hard to strong, and from edge wear resistant
to crater resistant. As you moved from one feature towards another, you
gained certain qualities, but lost others. It could be that today it's
just not as important. Dunno.
Your chance of accomplishing good cuts is way down. It would be especially
true if the carbide is intended for machining steel, which I would imagine
HSS is not as critical as to how it's applied, but when it is a concern, one
selects tool steel high in cobalt, which offers tougher conditions at
elevated temperatures. Any HSS will work for aluminum, especially if you
understand chip breakers and rake angles. You can create tools that will
peel it off faster than you can imagine. Lubrication is very important,
however. It doesn't take much, something as simple as brush application
works fine. Kerosene is the lubricant of choice for aluminum, but almost
anything is better than nothing. I've used Stoddard solvent that isn't real
clean with great success, but if you'd like things to smell nice, consider a
small can of WD-40. It appears to be nothing more than solvent with a
little wax dissolved in it, along with a perfume. It works fine for
It was common practice to have a small can on the machine with an acid brush
in it. To keep the can from getting blown about by the air hose (they're
use extensively in production shops, believe it or not) you'd place a piece
of stock in the bottom. I've always had a can of kerosene and sulfur based
oil at my lathe and mill.
With the inserts you described, it's no wonder. Once you find chip
welding on an insert, for all practical purposes, it's no longer a good
insert. The welding generally occurs because of tip flaking or cratering,
with the chips welding into the rough edge or surface. There's usually no
way in hell it will cut well once that happens.
Carbide is so weak in tensile that a tool that backs up ever so slightly is
usually ruined. Running a cutter backwards is a sure recipe for
destruction. You must have witnessed a hell of a lot of sparking unless he
was machining aluminum.
You'll come to realize that not everyone in your class will have the same
dedication to learning as you may have. I took a welding class several
years ago. One of the students was a druggie, and wasn't interested in the
least in learning anything. He took advantage of circumstances for reasons
best known to him. Didn't make sense to me, but it apparently did to him.
Sigh! He finally quit showing up-----
I'll do some more digging on carbides and grades. If I find anything
juicy I'll post it in RCM. Seems like something that would be nice to
I'm sure it is too. Would an aluminum-cutting setup involve only a
different insert, or also a different insert holder. IIRC, the holders
out there have a negative rake (angles down towards the work, which I
believe is called negative) and a negative side-rake. (down towards the
headstock) Are the rake angles a function of the holders, or are all
holders angles this way, expecting the lip on the edge of the carbide to
determine back/side rake?
Rake angles I think I've got a handle on. At least enough to get
started. As I understand it a chip breaker is just a little groove some
ways back from the cutting edge, correct?
Is diesel close enough to kerosene to work? I can get a little
container of diesel easy, but kerosene will be a hassle. I'm in texas,
so our diesel is as sulphury as law allows. (:
Good to know. Thanks.
It was aluminum. Now I can't wait for someone to do it with a steel
piece so I can watch the sparks! (: Before I ever use a cutter out of
the "studentized" cabinet I always check it first. I think I know which
one he used because it's covered in rubbing marks and two of the three
inserts are missing the tips. The teacher says he's going to leave it
in the cabinet for the rest of the semester so people will learn to look
at their tools before using them.
Heh, over in my welding class two weeks back some guy showed up for
the first time since the beginning of the semester. The teacher simply
told him up-front that he hasn't been there, his excuse (broke down
truck) was bullshit, and he would do nothing more than waste his and the
teacher's time and a whole bunch of electricity. Kicked him out on the
spot. I like that teacher!
In my machining class we've gone from 12 down to seven or six
students. Probably going to be five by the end of the semester.
Welding is worse, started with 11, down to six who show up at all, and
it'll likely be three of us by the end. OTOH, my other classes are
grad-level and our flaky guys are the ones who've missed as many as
three days. (:
B.B. --I am not a goat! thegoat4 at airmail dot net
In article <DoNotSpamthegoat4-87661B.09280206032005
Diesel will work, or you can buy a jug of lamp oil at Wally World for a
few bucks. It's just deodorized kerosene, which is the major component
of WD-40. You can even get it with a pleasant floral scent (yuk).
Agreed. Very few seem to grasp the significance of choosing the proper
grade. I'd welcome anything you can uncover.
There are holders that determine rake angle, such as the negative rake types
you're apparently using, but there are inserts with grinds that can alter
the rake angle to some degree. It's conceivable to have negative rake
holders that have positive rake inserts, but they're usually somewhat timid
in performance. The edges are relatively fragile and easily chipped, so
they're usually used for light cuts only.
I'm shaking my head in disbelief as I read you're being taught to use a
negative rake holder with aluminum, however. You couldn't come up with
any worse combination than you have. Even for roughing, positive rake is a
better choice in aluminum. It requires far less horse power. The material,
being quite soft and low in tensile, machines very easily. There is little
benefit in using negative rake, and it goes from a bad idea to a horrible
one for finishing. Negative rake tools don't cut at the tip, but rely
instead on what is known as a false cutting edge. The cut occurs back of
the tip, where cratering is generated. When you try to take light cuts,
the tip comes into play and isn't up to the task. Long ago, it was
recommended that a slight chamfer (.005") be stoned on the tip to discourage
chipping, prolonging the useful life of the insert. You can imagine how
poorly it would perform when taking a light cut. It's not a good idea to
use negative rake for finishing, not even in steel, although if the cuts are
heavy enough, it works fine. You really should be using positive rake,
and a sharp tool, with no chip welding of any kind.
Positive rake tools generally have a cutting edge on one side of the insert
only, so a triangular insert has only three cutting tips, not six.
Yes, that's correct, but it's a good idea to incorporate a chip breaker as
your rake angle. It takes a little grinding experience to get good at it,
but it really pays benefits. A simple rake angle improves machining
ability, but creates horrible chip problems. When you couple the chip
breaker with the rake angle, all that goes away. If nothing else, you gain
considerable safety, not generating long strings that can wrap around your
I own a couple Dodge diesels, and hate the smell of the fuel. I've never
tried it, but I can't imagine it wouldn't work. I used Stoddard in place
of kerosene to get away from the smell, which is similar to diesel. If
you have a (Stoddard) solvent container for cleaning parts, just dip a
little out as needed. I've done that for years. Sulfur is very much a part
of lubricating when machining. One of the best oils for machining steel is
sulfur based cutting oil. The stinky stuff.
By now you grasp the importance of not using negative rake, hopefully. You
have enough material left to make one good pass and end up with a beautiful
surface. Don't blow it screwing around with the negative rake inserts.
If, by chance, you do, chalk it up to learning. You'll remember the screw up
far better than you would good success. Making mistakes is very much a
part of the learning process, especially on machines. You'll come to realize
that not everything is as it appears. Often you'll dial a cut and the
machine takes more or less than the amount you "requested". A good
machinist knows how to get around that problem. A loser rarely ever
figures it out.
By the time we're old enough to attend such classes, we're expected to
behave as adults. People like him (and the druggie that was in my class)
have a way of disrupting the learning of those that are serious. I like
that teacher, too.
That one would work fine. You don't really need a chipbreaker for
what you are doing. I respect harold a lot but he's pretty
compulsive about doing things the 100% right way. For small depths
of cut you won't see any real detriment to not having a chipbreaker
except maybe the chip coming off will mark the finish to some
Try grinding a turning tool that is similar to the sherline one,
but don't put any back rake on it - use only three grinds to form
1) front clearance, 2) side rake, and 3) side clearance. It
will look like the one on the far right side of this photo:
and in that shot the tool would be cutting *away* from the viewer.
Another view of the same tool, where it would be cutting towards the
viewer and slightly to the right:
And the final view from underneath:
From the photos you can see it's pretty similar to your sherline
diagram, but the grind for the top surface is parallel to the long
axis of the tool, there's no 'back' angle. The edge thus formed
between the top surface and the side grind is nearly exactly along
the original edge of the side and top of the square cross-section
tool. What this means is you can resharpen this kind of tool
by simply grinding its *front* face, and the height of the
cutting edge does not change.
It's only three grinds on the HSS tool blank - if you do the
front, and side, but no top grind to form side rake, you've
made a brass turning tool.
I've found that back rake has never been essential for the stuff
I do, at work or at home. So I just leave it out.
If you *wanted* to form a chipbreaker in that kind of tool,
the idea would be to run a narrow groove alongside the cutting
edge, on the top surface. This allows the chips to flow off
at a larger angle than the real rake angle, and they eventually
strike the grooves far edge and snap.
When I took a shop class for the first time, there was an entire
four hour class period devoted to trying to get HSS tools ground
properly. Apparently in some classes the instructor simply
hands out 1/4 CRS blanks for the students to practice on.
One final caveat for you: pedestal grinders look pretty innocuous.
They're not. While you are grinding tool blanks by hand, the
blank will become hot, and your hand will become tired. You will
be applying a fair amount of pressure to the tool blank to force it
against the wheel.
The wheel will remove flesh faster than you can imagine - I personally
ground a pretty good-sized divot out of my thumb when I slipped
while grinding a lathe tool. Didn't bleed much at first but that
thing throbbed for weeks afterwards. Take your time and think
of the wheel surface the same way you would if you were grinding
your tool on the roadway, out of an open car door. I bet it's
about the same SFPM.
please reply to:
Good point. But somewhere along the line I'm going to try to force
the issue and find a cut that'll require a chip breaker, just so I have
a chance to play with the idea. I think perhaps steel would do it. So
far even with the carbides it's been more prone to looooong curls of
If you know a way to force long chips that would mandate a breaker
I'd like to know it too.
While I'm thinking of it...
As I understand things, if I do change the height of the cutting edge
the only real drawback is that I need to compensate and move the tool up
until it's level with the centerline. Correct? The lathe I've been
using has a quick-change post that lets me set the height, and I have a
feeler gauge set that's unreadable now, but would make dandy shims if
I'm ever using a non-adjustable tool holder.
Cool! I'll grind the other end of my tool that way and see how it
works out since I have to redo a brass bushing.
Why a flat top on a brass tool? To keep it from pulling itself in?
Are there other materials that would want zero side rake? Is there
perhaps a list somewhere of common materials and appropriate cutter
Is there a standard distance back I should go, or just look and see
where the chips are hitting the top of the tool and put it there?
I've had my share of grinder mishaps. My personal best--or worst--is
getting a bolt I was grinding a flat onto get pulled between the
grinding wheel and rest, taking my finger with it. It finally took
enough flesh off the side of one finger that I could slide my hand out
sideways without getting snagged again. Imagination be damned! I have
first-hand (heh) experience! Whole thing took maybe two seconds. Since
then I've had lots and lots of respect for even wee little grinders. If
the rest has a gap big enough for my finger I either adjust the rest,
remove it entirely, or find another grinder.
Seems that accident only took skin--healed up fine and really doesn't
stand out above the other 5 billion scars my hands sport.
My second-best experience was grinding something, shutting off the
wheel, and having it explode after I got about five feet away. That one
had a vibration somewhere below operating speed, so my guess is that the
wheel popped when it hit that speed/vibration/harmonic while winding
down. So now I also stand clear while the wheels are spinning up and
spinning down and won't touch (or walk past) a machine that shakes while
running. While I grind I tend to keep my head to the side a bit--just
B.B. --I am not a goat! thegoat4 at airmail dot net
True on all accounts. The problem here is if you wait until you actually
need a proper chip breaker, you've missed a golden opportunity to get it
straight, from the start.
Chip breakers, once again, are load sensitive. Jim is right on the money.
A chip breaker that works beautifully for a roughing cut is likely to fall
flat on its face when taking finish cuts. At best, you'd profit by the
positive rake, but not much else. That's not a problem when you're running
parts in volume, because you generally go through a roughing sequence before
any of the parts get finished. That, too, is a part of learning to machine
properly. Your tools are ground and setup appropriately. My point in
getting you to try chip breakers is to learn about them and have them firmly
entrenched in your mind, so when the need arises you don't have to go
through the learning curve.
Simple. Proper positive rake. Light feed. No chip breaker. You can
generate all the strings you desire. That's the point of my information.
The use of chip breakers is a package deal. Lots of things have to come
Understand that some aluminums cut without making strings. It's the nature
of the material. Amongst them are 2024 and 7075, each of which will gladly
cut string free under the right conditions, including the absence of a
proper chip breaker. 6061 is another story, and is generally more than
happy to generate strings, although generally very easy to control.
Regardless of the holding system, that's an ongoing problem. I use a
square tool block (my choice) so I shim all my tools. You get used to
having a small box of shims handy and it takes almost no time to set up your
tools. You get to the point where you can pick up a tool and know what shim
is required to hit center. I use anything for shims, including strapping
material, which comes in a myriad of thicknesses. Old feeler gages are
fine, too, just expensive. And then there's always shim stock!
You can go full circle on this issue and stick to making finishing cuts with
chip welded negative rake inserts. I strongly recommend you *don't* avoid
the learning curve. Learn to do it right, even when it takes more time.
You can always back off when it's not important, but without the experience,
you'll have nothing to use as a reference when you're facing problems.
The real benefit of learning the little things is when a tough job comes
along, you may be the only one equipped to deal with it. I gained the
respect of my peers because of my anal approach to machining. No one
wanted to emulate what I did, but they sure as hell understood why I had
success when they did not. Remember, often the difference between one who
can and one who can't is nothing more than how they apply what they know.
You see that on a daily basis in a commercial shop.
That's too simplified, and may or may not work. If you look at chip
breakers that are formed on negative rake inserts, you'll notice they are a
shallow radius which begins at the theoretical false cutting edge of the
insert. It's assumed you're going to take a particular depth of cut and a
given amount of feed, so they factor that in when creating the inserts.
The whole idea is to encourage the chip to start rolling, not to stub into a
wall. That raises cutting pressure, often breaking your tool from chip
A chip breaker that doesn't function has no value. Be certain to learn to
incorporate rake when you attempt chip breakers. It's particularly
important when using HSS, so you can keep temperatures low at the cut, and
reduce cutting pressure as well.
There's no shortcut, you have to start at the bottom and experiment with
each material, slowly accumulating enough information in your head that it
will become useful. You'll know when you've hit a winner. The chips curl
and break nicely, and the tool cuts without much noise. Watch the chip
color (when machining steel) so you don't produce anything above the
slightest hint of yellow. That usually spells an early death for your tool
unless you have very high cobalt, or are lucky enough to be using Stellite.
Tools of this nature generally respond very well to lubrication, too. Helps
keep the temperature down and prolong the tool's life.
My policy is to grind the breaker and take a trial cut. Again, the cut
required determines everything. Maybe start short and shallow and see how
it behaves. You can always go wider and deeper, but can't reverse the
process without wasting a good amount of tool. Once you see what the chip's
doing, you can make the appropriate adjustment. This process can really
pay benefits when you're boring deep holes. With the proper tool
configuration, you can go deep and not generate any strings, which generally
spell tool death when they wrap around the bar. If your bar has enough
clearance, your chips will come out as short crumbles and drop neatly at the
mouth of your part. Lots depends on bar clearance, but I think you get
To start, that's not a bad idea. The only real problem is the CRS doesn't
grind worth a damn. The concept remains unchanged, though.
One thing I don't use is a tool rest. Never. Not for grinding tool bits.
They get in the way and restrict your ability. You likely won't be able to
do that at school, but keep it in mind for home use. Have a special grinder
that you use exclusively for sharpening toolbits, and have it mounted such
that you can stand erect and grind at a comfortable level. It takes some
getting used to, but once you master it, you'll never go back to a
conventional pedestal grinder for grinding toolbits. Knowing how to
properly dress the wheel becomes quite important when you grind this way.
It must run smooth and true, for it becomes your reference point.
Something I never did. LOL. Might be time to investigate, eh?
I seem to recall teenut saying something about the chipbreaker
groove on a HSS tool could be done with a tiny cutoff wheel
and a die grinder.
6061 is like turning silly putty. 2024T6 is more like steel than
aluminum. I love that stuff. Too bad you can't weld it.
This is one reason I avoid back rake - because it means that sharpening
the tool requires resetting center height.
Toolrests are OK for roughing stuff out, but I agree that 90 percent
of the lathe tool grinding I do is offhand, no rest. You have to be
able to get the angles right. Good lighting is vital. My grinder
is tucked away in a far corner of my shop, to keep grit off the machines.
The lighting sucks there, it's one more of those roundtuit items.
please reply to:
It's one of those things that you can go a life time without and swear it
makes no difference.. Bottom line is how much you expect from your machine,
your setup, your ability. I've always carried a definite edge over others
because I cared enough to learn early on. You're likely to find someone
that has the opinion that it doesn't matter. I think it does. I may
sound like an ass, but I can tell you all I need to know about a guy's
ability on a machine by looking at his lathe tools. When they look like
they've been gnawed out by a gopher, I rarely expect anything of substance
to come from the person, and I'm rarely disappointed.
I don't claim to be teenut, but I sure agree with him in this instance.
However, I don't limit myself to that. I can hand grind the vast majority
of my chip breakers using the corner of the wheel. Only when I get involved
with tricky form tools do I usually turn to anything else.
It is a pleasure. During the period that we built the missile, and shortly
thereafter, it was the only choice of aircraft quality material we used. My
first introduction to 7075 was when I had already started my business and
had bid on some helmet gun sights for helicopters. Needless to say, I was
impressed. While you claim 2024 machines like steel, 7075 really does,
and emulates it in tensile strength. I liken it to leaded steel in how it
One of my favorite memories of being self employed was building a wave guide
for Univac. They never came in large quantities, sometimes as many as four
or five, but more often than not, one at a time. They were made from 2024
T351, a real pleasure to machine. Inside the guide a double ended plastic
component that came to a .005" flat end (wedge shaped) was installed, held
in place by four pins, also made of the same plastic. The job brought out
the best of my ability, with it's tight tolerance and exacting demands for
generating the proper configuration of the plastic insert.
Not a very good reason, Jim. I'm the first to step forward and suggest
that you can machine with or without rake, with or without a chip breaker,
but the best work comes from the proper combination of each. It really
jumps out at you when you have more than a couple parts to make. You've
done yourself a disservice, something you'll slowly come to understand. I
guarantee you, your tools don't cut nearly as well as they can. Chip
control is as important as chip generating.
Chuckle! All in good time, eh Jim? Just don't let your entire life time
slip away, putting up with the bad setup as it is. It's almost impossible
for me to properly sharpen tools right now, what with our living in the
shop. My (rough) grinding section , roughly 30 feet from my precision
machines, happens to be the cloths drying station while we're living here,
so my grinder isn't properly set up. Of all the things I can't use as
desired, I miss it more than any of them. Especially the diamond wheel,
for touching up brazed carbide tools. I'm still a strong believer in them.
Old habits die hard.
Actually, I do use them, Jim. A lot more than I admit to. My favorite is
the RB negative rake holder that cuts positive. The inserts are a modified
triangle and have chip breakers diamond ground such that the tool cuts
positive. I also have heads for boring bars that use the same type, but
smaller, insert. They are likely the finest insert tools I've ever owned.
They were particularly valuable to me when I used to run the metering pumps
for a blood analyzing machine for the pharmaceutical industry, where I ran
hundreds of components with a half thou tolerance. I also have
insert tooling for my tracer, which, just like running a CNC, really demands
One thing that turns me off is anyone that turns to insert tooling and
refuses to learn to grind either HSS or brazed tools. Until such time one
knows and understands cutting geometry and how it applies to success,
they're kidding themselves. Any damned hack can load parts in a machine
and apply a tool provided by others. It takes skill and talent to do it the
hard way, and it's all very much a part of becoming a machinist in the true
sense of the word. To substitute the learning curve with insert tools is a
huge disservice to the operator.
I realize that my philosophy may not fit today's circumstances, what with
CNC machines having replaced manual machines almost entirely, but for the
most part, we home shop types don't have the luxury of CNC's, so
shortcutting the learning process becomes a huge stumbling block.
But the flip side of this is that one can be skilled and adept at
grinding tools by hand, and still have *zero* experience or skills
at NC programming. I had pretty much zero there when I first went
to work at that night production job.
Most of the guys there didn't even know you *could* make cutting
tools by hand! But they knew G-code stuff inside and out. I learned
enough in my couple of years there to keep me from being a menace
please reply to:
OK. Maybe you guys can tell me how to dress a new 10 inch grinding wheel!
I have a baldor 10 inch grinder and I installed new name brand wheels
from MSC. I have two different wheel dressors (0-10) (10+) and I still
cannot get the wheels round. I even tried using a diamond point and ruined it.
So, How do you dress a new 10 inch grinding wheel ??
Nothing you're saying makes a lot of sense, Chuck. Can you fill us in on
what you're doing, and how? The very notion that you ruined a diamond
point tells me something is woefully wrong.
Please clarify your wheel dressers, too. I have no clue what the
designations mean. (0-10) and (10+). I can only assume you're making a
reference to the size of the dresser as it applies to the wheel size.
If you are trying to shape and true your wheels with star type dressers,
you're likely to not like what I have to say about them. Before
expounding, I'd like to comment that there is no better way to prepare a
wheel to cut than with such a dresser, but they present some serious
problems in their application. For one, they're difficult to apply such
that you can get a wheel running smoothly. A bouncing wheel is pretty much
useless for sharpening tools. There are better ways to true wheels, which
we'll discuss as quickly as I understand more about your problem.
For sharpening your tool bits it is important that you have aluminum oxide
wheels, *never* silicon carbide, be it green or black.
Tell us more about your setup and lets talk. (Sorry I didn't get back to
your email last weekend. I came down with a killer cold and spent two days
in bed. Life sucks!)
I have a baldor 10 inch grinder with new norton grinding wheels.
(one course and one fine) purchased from MSC.
I have two Enco grinding wheel dressers. One is a #0 and is
rated for wheels 0-10 inchs. The other is a #1 and is rated
for wheels 10-16 inchs. They are not called star dressers
in the catalog but I think they are star dressers.
I also have a 1 inch square Silicon carbide wheel dresser.
I cannot make the grinding wheels round using any of the above
tools. I can remove grit from the wheel but it still does not
make it round. At low speed I can see noticable runout.
I even tried to use a diamond point intended for the surface
grinder to make them concentric and it didn't seem to work very well.
I was holding it by hand.
How do I dress the wheels to make them round?
Since the wheels are not round, they are difficult to use
for anything except rough grinding.
hope this is clearer?
If they have segmented pieces that spin, that's what they are. Jim likes
'em, and even ol' teenut used to extol their virtues, but I'll put my
grinding experience up against their opinions any time anyone wants to have
a discussion. As I said, there is no better way to prepare a wheel for
cutting. By their nature, they leave very sharp grain when properly applied.
Problem is, it's hard to get a wheel running true. In order for them to
function properly, they require a given load, otherwise all you do is grind
away the components. They dress by hammering the wheel, breaking it into
fine particles. Assuming you can get the wheel running dead true, you
can then bear down adequately for the dresser to do a good job, but you can
waste a lot of wheel getting there, and it's not all that hard to get the
wheel to start bouncing again while you're using it. As I said, I avoid
them totally. Don't even own one, nor do I care to. If I had a large 3
phase grinder for grinding on weldments, I'd likely have a different
attitude. They're great for that application.
That's the tool I thought I'd have to explain to you.
You can't bear down with them if you want a wheel to come true. If you
have a work rest, this is one place where it can pay benefits. You place
the dressing stick on the rest, picking a sharp corner, lightly touching the
grinding wheel, which should be at operating speed. The highs only will
make contact with the stick and slowly be lowered until you finally have
full contact all around. If you crowd the dressing, you tend to encourage
the wheel to shrink, but not get corrected. From this you should understand
that it takes a light hand. You can't horse getting the wheel running true.
Once it is running true you can aggressively remove more wheel with
reasonable results, though. Remember: A light touch.
Assuming your wheel is out a considerable amount, and you'd like to true it
up with a diamond first, that works fine, too, but you have to use the same
principle, lightly applying the diamond so only the highs get removed. As
quickly as you have the wheel running true, you should change to your
dressing stick. Diamond dressed wheels don't lend themselves well at all to
offhand grinding because the surface is way too smooth. Exactly the opposite
from what a star dresser does. A light touchup with a dressing stick will
usually prepare the wheel for quite good grinding performance. Avoid the
use of the little dressing sticks that are 1/4" x 1/2" x 3" in size, and are
one solid piece. They are boron carbide, and while they're even harder than
the silicon carbide dressing sticks, unless they are very sharp, they tend
to dull the grain excessively, so your wheel cuts quite hot----very similar
to a wheel prepared with a diamond, in fact.
You may see some real strange conditions as wheels spin up and down. Don't
worry too much about that, just make sure that when your wheel is up to
speed, it runs true. Often the imbalance of larger wheels will cause some
vibration that makes them look like they're running out a lot more than they
really are. If you find your wheels vibrate excessively, it's not
impossible to have ended up with wheels that are not well balanced.
Precision grinders have provisions for balancing the wheels, but pedestal
grinders usually do not.
I trust you know to use the proper flanges, and to always run the blotters.
You risk fracturing wheels when you mount them without. Hopefully you
also understand how to "ring" a wheel to insure it's not cracked when you
As I said, there's nothing wrong with the concept, but it requires a light
touch to be effective. Assuming you still have the diamond at your
disposal, you might try again, making sure the nuts on the spindles are well
snugged. I failed to mention the possibility of your wheels moving about on
the arbor. You want the nuts tight, but not excessively. It's desirable
to learn to use a little less pressure when tightening fasteners on grinding
equipment. Unless something goes very wrong, there's usually not all that
much pressure involved in grinding.
Hopefully something I've said will be useful. Why don't you give it a go,
then let us know.
You don't have to say anything to convince me. I'm the first to say that a
grinding wheel that doesn't run true is worthless.
I think so, although I'm really surprised that you aren't experiencing
success. Are the bearings good in the motor?
I hope you realize that what the problem could be might jump right out at
me, or others, but you may not recognize it, so you could have overlooked
something that might be important. That's why I asked for you to describe
what you're doing, and how you're going about doing it.
Yep, that sounds like a star dresser to me.
I've never had a wheel that ran out, right from the box, so I can't
say how poorly they would true one. They are pretty good for getting
the wheel opened up again, and they're pretty good at getting a flat
surface once it gets grooved or marked.
I've tried the SiC dresser stick that you suggested. I may have
been using too hard a touch on it, given your comments above.
As I said, I've never had a wheel that did not serve for at least
reasonable grinding, right out of the box. What are the chances
that there's just something wrong with the wheel(s) he mounted?
please reply to:
New wheels come with cheap plastic centers so its difficult to get
them mounted concentric in the first place. Might not be a problem
with small wheels but it doesn't take much on a 10 inch wheel to make
the whole grinder vibrate. I think that lead use to be the prefered
material for adapting the large hole in the grinding wheel to the
smaller grinder shaft. Should I replace the cheap plastic spacers
with something better?
I am using the standard flanges and blotters supplied with the wheels.
I did not tighten the wheels very hard because they ususally tighten
themselves up pretty tight. A 1.5HP motor accelerates pretty rapidly
and the 10 inch wheels have a lot of mass so I suspect the motor
tightened them up very tight by now.
I suspect I'm using too much pressure on the dressers and not the
light touch that harold recommends.
This grinder was purchased used and the original 10 inch wheels were
worn down to about 7 inchs. It ran fine with the old wheels.
Perhaps I should remove one wheel to reduce the vibration and dress
the remaining wheel. After I get it running smoothly I can then
add the second wheel and dress it.
If you find the plastic permits the wheel to move about too much, that
wouldn't be a bad idea, but use good sense. There are issues with the
spacers that are critical, which explains why they're sloppy. They may not
work perfectly that way, but they're safe. If you make your spacers too
tight, and the bore of the wheel isn't at a perfect right angle to the wheel
face, it's possible to fracture the wheel when you tighten the nuts. The
snug fit would limit the wheel's ability to square with the flanges, which
it will do, either by cracking the wheel, or compressing what ever is in the
On the outside chance that isn't happening, check how tightly they are
held. If the nut had crud in the threads, it's possible it's not turning
freely, so it feels tight but it isn't. Long shot, yes, but worth a look.
Be certain that the nut runs freely, all the way until it hits the flange,
otherwise you have no clue if you're tightening the wheel, or fighting the
dirty thread. Your flanges should be imprinting the blotters. If you
see signs of the wheel sliding about, with smudges on the blotters instead
of imprints, you're not tight enough. The blotter should appear clean, but
It has been my experience that once a wheel starts bouncing, it encourages
itself. Especially if you have no fixed reference, when you try to reduce
the runout, all you do is make the wheel smaller. If you think you can
simply hold the dresser of choice against the wheel and improve it, you'll
be disappointed endlessly. You have to work smart at reducing the runout,
which means to take it off a little at a time, such that the bounce of the
wheel isn't transmitted into the dressing device. A light touch usually
solves that riddle, along with taking a narrow approach. Don't use the flat
face of a dressing stick, but a corner instead, where the amount in contact
is minimized. Once you get a spot running true, you can usually move out
and improve the immediate areas. It's not rocket science, but it does
require a little thought. Surely you've already noticed how the bouncing
wheel sets up a pattern that tends to repeat. You have to break the cycle.
Unless you ended up with some very poor quality wheels, there's no reason to
not expect new wheels to run smoothly once dressed. If that's what it
takes, then that's what you should do. Just be certain that all your
efforts are when the wheels are at operating speed, and don't discount the
possibility that the wheel sides may not be parallel. That would certainly
yield a heavy side, and would be corrected only by dressing the sides of the
wheel. I often dress the sides with a diamond, strictly for balance, right
down to the blotter. It often improves how a wheel runs.
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