Newsgroups: rec.crafts.metalworking
Subject: Re: Old technology
From: jmorton@euler.Berkeley.EDU (John Morton)
Date: 18 Oct 1994 15:50:07 GMT

In article <1994Oct18.035312.27014@bbxrbk.basis.com>,
Russ Kepler <russ@bbxrbk.basis.com> wrote:
>I've been puzzling over something a bit strange: why does virtually
>every metalworking reference book I have (and I spend a *lot* on
>books) not contain any "recent" lathe tool shaping?  Virtually all of
>the references completely neglect chip breaking grooves, and focus on
>grinding single point insert tools, this when virtually every tool I
>see make for normal diameter reduction is just a couple of grinds from
>a 3/8" or 1/2" square M2 blank?

You bring up some interesting points.  On the one hand, books on "old
technology" are the only ones I find interesting, because they feed
my machinist-need to maintain an ability to make things from scratch.
That is what the trade is all about.

On the other hand, certain important things have never made it into
books; I don't know why.  Neither old nor new books give a satisfactory
treatment of tool grinding, unless you extrapolate the world of lathe
tools just from first principles.  As far as I know, tool grinding is
learned from other machinists, and that's the way it's always been.
I have over a hundred toolbits in my toolbox drawer, and _none_ of them
look like the ones in a book :-).

Conclusion:  machinists don't use reference books.

John Morton			     Mechanical Engineering Machine Shop
jmorton@euler.me.berkeley.edu	     University of California at Berkeley

Newsgroups: rec.crafts.metalworking
Subject: Re: Old technology
From: jmorton@euler.Berkeley.EDU (John Morton)
Date: 19 Oct 1994 21:47:01 GMT

In article <383mo9$42h@crl10.crl.com>, Tala Brandeis <tala@crl.com> wrote:

>Well, it helps to have a desire to know everything about metalworking
>as a prerequisite to *finding* the info.  When I started it was
>impossible to get informtion out of the older machinists, even when
>they knew something.  

Unfortunately this is often the case.  All of my important learning
experiences were isolated occasions when I had somehow established enough 
of a relationship to an expert to get some advice out of him.

>>On the other hand, certain important things have never made it into
>>books; I don't know why.  
>
>When I learned something, not everyone *wanted* to know what I'd 
>learned.  Few of them wanted to take the time to learn it.  Most
>of them had work to do on their own.  In training others most were
>afraid of trying something new.  Many of the techniques with respect

Yes, production is the operative principle.  For this reason it is often
the foreman who is in a position to troubleshoot your setups, if you
are so lucky that the guy knows what he's talking about :-).  "Trying
something new" often means pushing some limitation until you break
something, then backing off a bit - all because the boss is on your case.

>>tools just from first principles.  As far as I know, tool grinding is
>>learned from other machinists, 
>...
>>Conclusion:  machinists don't use reference books.
>
>Some do and some have.  The world is full of different experiences
>and different people.  We all have our ways of finding the information
>we want and need.  

Each one of us knows only a small part of the trade as it is practiced.
I'll retract my pompous conclusion and assume that you and others have
actually come across a machinist consulting a tool-grinding book :-).  

BTW I do use a shop library, but it consists mainly of subjects peripheral
to what I do, e.g. die design, non-conventional machine processes,
codes and specifications, mechanical motions, properties of materials,
catalogs.  A good jigs and fixtures book can come in handy.  

John Morton			     Mechanical Engineering Machine Shop
jmorton@euler.me.berkeley.edu	     University of California at Berkeley

Newsgroups: rec.crafts.metalworking
Subject: Re: still seeking grinder wisdom, please
From: jmorton@euler.Berkeley.EDU (John Morton)
Date: 8 Jan 1995 19:30:50 GMT

You mentioned having a diamond-on-steel wheel.  That is the
proper thing for finishing off and touching up carbide lathe
tools, but it will become useless if you use it on the mild steel
shank of the tool.  The advantage of a green wheel is that not
only does it cut much faster than the diamond, it is not bothered
by grinding steel.  Use it to rough out the carbide, then to
excavate the steel from around where the diamond will touch the
carbide portion of the tool.

The drawbacks of the green wheel are that it doesn't do a very
nice job on either material:  it heats the steel very quickly,
and it wears very fast on either steel or carbide.  But that is
why you must also have a finishing wheel.  The heating is a bit
problematic because a water quench can chill the carbide and
cause it to fracture.  My practice is to quench the tool by
immersing the steel shank in water, not the carbide chip.


The ends of endmills can be done freehand, more or less; that is
really all you can do to them without a fixture.  For a better
job, start by studying a standard universal tool and cutter grinder, 
such as you find in a machine shop.  They are "universal" because
they adopt to tool geometry in many different ways.  However, the
flexibility is in the tool-holding fixture as well as in the machine
itself.  My suggestion would be to concentrate on building one of
these, and using your mill or lathe to hold the grinder.

The cutter grinder uses a basic spin fixture, which accepts various
stock sizes of tool shanks, and may have arbor adapters for the
shell mill arbor sizes.  Adjacent to the free-turning tool holder
(which often uses an air bearing) there is a system of clamping 
rods which support a thin spring-steel finger.  You must be able to
position the finger anywhere around the tool, because it must
register on the flute of the cutter, whatever size it may be, and
either on the end or the side.  

To grind the end, you need an axial stop for the tool arbor; the
finger supports a flute, and then whatever operation you do 
(whether you move the fixture past a stone, or vice versa) will
be repeated on whichever flute faces the stone.

To grind the spiral surfaces, you remove the axial stop, so that
the finger supports the flute as the tool arbor moves axially
in a spiral motion.

This is impossible to explain, but it's pretty simple.  Go to a
machine shop, ask to photocopy the manual for their tool and
cutter grinder.  That will have lots of pictures.  The spin
fixtures are featured in all the ordinary catalogues, I think.

For a grinder, I think the most worthwhile would be a die grinder.
Don't bother with a Dremel; start with at least a Makita or 
something, or one of the regular shop brands like DuMore, which
have a decent duty cycle.  These things use small, cheap stones
which turn really fast.  They can be used as toolpost grinders
in the lathe, but for your purpose it may be best to fasten it
to the milling machine head somehow, so you can move your
spin fixture with the 3-axis table.  

Cover everything very carefully to prevent the intrusion of 
grinder dust.

John

John Morton			     Mechanical Engineering Machine Shop
jmorton@euler.me.berkeley.edu	     University of California at Berkeley

Newsgroups: rec.crafts.metalworking
Subject: Re: still seeking grinder wisdom, please
From: jmorton@euler.Berkeley.EDU (John Morton)
Date: 9 Jan 1995 20:37:27 GMT

In article <3erhrl$n2k@oak.oakland.edu>,
Paul Amaranth <amaranth@saturn.acs.oakland.edu> wrote:
>In article <3eq7qs$lk6@newsbf02.news.aol.com> madmat9@aol.com (MadMat9) writes:
>>John:
>>
>>sharpening service who can do the job right.  I can't imagine trying to
>>get a 4-flute end mill just right so that all four flutes cut equally. 

Sorry, I meant to refer to the 2-flute variety only.  Of course you
can attempt the ones with more complex geometry, but usually one tooth
ends up doing all the work :-).

>nifty tool grinder article.  Accurately grind lathe tools, end mills,
>you name it.  A neat project in precision machining (the air cylinder
>has a running clearance of .0015").  Probably all of the capability

Another good basis for a spin fixture would be a pair of linear
bearings, the Thomson recirculating ball type.

John Morton			     Mechanical Engineering Machine Shop
jmorton@euler.me.berkeley.edu	     University of California at Berkeley