# Recommend some indexable lathe tooling



## G1K (Jan 1, 2009)

I'm looking for a boring bar, internal threading, external threading, and general turning. I'd like indexable/insert vs. brazed carbide. 

I have access to all the HSS I could ever want.

Will be used on 12" swing lathe, 3hp, 3000 lbs. 

I've been using crappy HF tools on my mini lathe, and high quality tools at the shop, but I don't recall exactly what we use there.

Time to pony up the $$ and get some good tooling.

I know J&L is having a sale through tomorrow, and I think Enco is also. There's just too many choices.

Will be working Al primarily, Ti and steel on a less frequent basis. 

TIA
Ryan


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## precisionworks (Jan 1, 2009)

Like dogs, every machinist has their favorite breed of insert

With 3 hp, you have more than enough power to run negative rake inserts. Look at those that hold CNMG, WNMG, TNMG, etc. The inserts are dirt cheap, often as low as $1.00 each on eBay for big names like Valenite, Iscar, Tungalloy, et al.

You can save money using the 'house brand' holders from J&L (like Hertel). I can't remember the alphabet soup for these, but you'll want one that cuts to the left, one that cuts to the right, etc. You'll eventually end up with a dozen or more, adding those as your needs change.

FWIW, CNMG-432, WNMG-432, TNMG-432, are a nice sized insert. Not too huge, not too small & fragile, pretty good for general facing & turning.

Another good brand is the Polish Pafana (imported by Bison/TMX). Penn Tool carries a bunch, and prices are decent. Very high quality, comparable to the best USA brands at about half the cost, sometimes less. Here's a nice kit of boring bars: https://www.penntoolco.com/catalog/products/products.cfm?categoryID=433

Here's a general purpose holder: http://www.penntoolco.com/catalog/products/products.cfm?categoryID=4859


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## SafetyBob (Jan 1, 2009)

Precisionworks, thanks for the info on the tooling. Do you use Penn very much?

My source for tooling is drying up in a year so I have started to look at tooling from the normal MSC, Enco, and have had really good luck with Rutland Tool out of Houston also. 

Since pretty much everything in through the mail, I really don't care who I get it from, I just need good to high quality tooling at a reasonable to cheap price. 

Bob E.


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## precisionworks (Jan 1, 2009)

> Do you use Penn very much?


Quite a bit ... good selection, great prices on items in their sale flyers, 30 day lowest price guarantee. They are really strong on Bison (SetTru chucks, 5C collet chuck, ER collet sets) as well as Pafana, Dolfa, and other Polish tooling.

I purchased my ER-40 collet set from Penn, who had it listed in a sale catalog at $325 (R-8 mount). Back then, Terry was the phone order manager, and could do magic on some pricing

Another good source for Bison/Pafana/Dolfa is Ajax: http://www.ajaxjaws.com/ Like Penn, they have a really nice catalog, and also have an eBay store: http://stores.ebay.com/Ajax-Industries



> good to high quality tooling at a reasonable to cheap price.


EBay is a treasure trove for machinists. Our postman says his back is permanently injured from carrying heavy boxes to my shop If you have patience, the prices are often unbeatable.


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## wquiles (Jan 1, 2009)

I tend to buy the kits on special from either Enco or MSC, but this recent post by a member of the 12x36 Yahoo email group was awesome, and talks a lot more about the different aspects, so I am just copying it here on its entirety:

******************************************************************************
FWIW, my personal experience has been with a 50(?) year Logan 11" or
12" with old belt drive and a 20+ year old Birmingham 12x36 with gear
drive. I sold the belt drive, and love the gear drive, and wouldn't go
back.

With regard to your question about HSS vs carbide, I hope nobody minds
if I submit here my posting from earlier this year in the MWHINTS
(metalworking hints) Yahoo group. As it is now, I can't remember the
last time I used a HSS bit on my lathe, and my tolerances and surface
finishes have never been better. My comments at the time addressed
comments made by others in that group regarding tungsten carbide and
the manufacturers and sales people, but I think it best to post it here
in its entirety. I probably wouldn't be happy with carbide on a belt
driven lathe like my old Logan. My comments are about tungsten carbide
INSERTS. I have thrown away all the brazed carbide tools that I once
had. Keep in mind that these are just my opinions. As the saying goes,
everybody has one! I'm going to expose you to mine. I use my lathe
primarily as a hobby, aspiring to make gasoline and hot air engines.

From Feb, 2008:
" I agree that most tungsten carbide inserts are not suitable for small
lathes. But some of them are. I'd like to contribute some of my
experience to those who DO want to use tungsten carbide inserts on
small lathes. They have become an integral tool in my workshop, but
as others have said, they are not right for everybody or for every
situation. But I didn't realize until the recent thread that my
success with tungsten carbide has not been widely shared. Allow me
to share what I have learned, and what works for me. If you are
happy with HSS, don't waste your time reading this, for changing to
carbide would be a waste of money for you. Personally, changing to
carbide made my hobby a lot more fun and productive. Your mileage
will vary. Being a jack-of-all- trades kind of guy, I'm not an expert
in any one field, and can only claim amateur abilities in my home
shop. But I do know more than most about tungsten carbide
applications. Almost my entire career involved some aspect of using
tungsten carbide. I began my career with 11 years as a product
evaluation engineer for a major manufacturer of oil field rock
drilling bits using tungsten carbide teeth, and finished it with 11
years as a tungsten carbide tooling sales rep for Iscar, Valenite,
and Mitsubishi Carbide. I sold tungsten carbide inserts to
manufacturers and machine shops in Washington, Oregon, Idaho,
Montana, Wyoming, Colorado, and Utah. The most common materials used
in these states are steel, stainless, aluminum and high temperature
alloys, but I have very little experience with cast iron. This was
the great job for a home shop machinist, for many days I couldn't
tell when the hobby stopped and the work began. I always took a
problem solving, applications approach to my customers, and most of
them appreciated that I machined for a hobby. When I faced
particularly difficult or unfamiliar materials, I commonly took scrap
samples home to learn how to machine it on my own lathe. I couldn't
duplicate what their CNC machines could do, and I do all of my
machining dry, but what I learned with my 1.5 HP lathe could often be
scaled up to their 20 HP machines. I retired about 15 months ago. I
have no ties with, and receive no retirement benefits from any of my
former employers. It puzzles me that some think that tungsten
carbide is a sham. The products of the major manufacturers are not
shams. The problems I faced were that there were so many product
choices (grades, chipformers, shape, coating, etc), but the best
combination of them could not always be made in every configuration.
And what worked well in one shop might flop in the same application
in the shop across the street due to some subtle difference in
programming, coolant, etc. As a factory rep, I always offered to "no-
charge" any test tools when the customer wasn't convinced that they
reduced his TOTAL manufacturing costs for that operation. This is
common industry practice. Just ask for a "GTO" - a "guaranteed test
order" - when you try something new. If your distributor or factory
rep won't offer this, go to someone who will. Factory reps have a
lot more authority to do this than distributors do, but good reps
with good rapport with good distributors will back them up.
Admittedly, I couldn't offer this for specially designed tooling, nor
for home shop machinists. None of my bosses ever questioned my
efforts to ensure customer satisfaction with any of our tools, even
without a GTO, or when used as a replacement tool, or when they
bought tools that weren't optimum for their needs. Mitsubishi
Carbide even offers new milling cutters for any reason - even
operator error ! Unfortunately, not all factory reps took care of
their customers, and when I changed jobs, I frequently had to
retroactively correct their negligence. In contrast to the
experience of others, mine has been that tool room lathes and Swiss-
type automatics can be good applications for indexable carbide
tooling. Mechanical screw machines are not.

First, my experience with HSS. My exposure to sharpening and using
HSS bits is far from professional level, but probably more than most
of today's hobbyists. My grandfather was a tool room machinist, and
I have inherited hundreds of HSS bit that he had ground to a wide
assortment of configurations. My dad taught me to run a lathe and to
sharpen HSS bits. And, believe it or not, sharpening and using HSS
bits was a requirement for my BS Mechanical Engineering degree at Cal
Poly, San Luis Obispo, CA, whose motto is "Learn by Doing". However,
since I've learned to use tungsten carbide inserts, my enjoyment
level has soared while my frustration level has dropped. I now use
HSS for less than 5% of my lathe work. (I choose to use carbide
indexable inserts for about 20% of my milling work, but I have only a
one horsepower motor, and won't be discussing milling in this
posting.) Chip control is much better. Surface finishes are much
improved. Dimensions are more predictable. I don't have to use
coolant no matter what SFM I choose to run. And I no longer wrestle
when I pick up a piece of material of unknown alloy. I primarily
machine steel, stainless, aluminum, brass, wood and plastic, but I've
successfully machined on my lathe the toughest materials that my
customers encountered: cast stainlesses, titanium, nitronic, inconel,
hastelloy. Indexable carbide inserts are my first choice for
turning, facing, boring, grooving, threading and partoff in all of
these materials - even plastic.

Some thoughts on using tungsten carbide in a home shop- (I refer to
the products of Iscar, Valenite, and Mitsubishi due to my familiarity
with them - most of the other major manufacturers offer comparable
products. Ask them for details.)

- Lathe Horsepower, Drive, and Rigidity
If you have less than 1 HP, you are in unfamiliar waters for me.
You'd probably be better off with HSS, or positive, single-sided
insert holders. I agree with most of what is said in the website
http://www.thegallo s.com/carbide. htm referred to by another group
member. But I prefer not to use the TiN coatings or utility grade
inserts on a small lathe because they don't have what I feel is a
sharp enough edge. I have a Taiwanese 12" gear-driven Birmingham
lathe that I inherited from my dad. It replaced an old belt-driven
12" Logan. I couldn't recommend carbide tool for the Logan since it
was worn and sloppy, and I don't think the belt would have
transmitted the required power. The Taiwanese lathe came with a
motor rating of 1.5 HP, but the starting windings burned out one day
as I made repeated partoffs with a carbide insert partoff tool. The
replacement US-made motor also has a rating of 1.5 HP, but appears to
have twice the power of the original, so my experiences are based
upon this new motor, and this is probably a good lower horsepower
limit to my recommendations here. [[ It will repeatedly partoff with
a 3mm (.118") wide partoff insert. I've thrown away all of my HSS
partoff blades after learning how to use Iscar's tools, but this is
tricky for any manual lathe, and if you overlook any parameter,
they'll break. (A common industry term is "grenade".) So I don't
suggest these to most amateurs.]] I commonly limit my maximum DOC
to .040" , but if I recall correctly, I've pushed it to .070" DOC in
steel without a problem. Carbide doesn't like flexible setups, or
chatter, so if your machine is old and sloppy, you might as well stop
reading this. And, as a rule of thumb, if your lathe is too small to
hold at least 3/4" shank tooling, stick with HSS or single-sided
inserts. The sharp carbide I'm recommending doesn't tolerate
chatter, or dragging backwards out of the cut.

- Brazed Carbide
My comments here relate to indexable tungsten carbide inserts.
Brazed tungsten carbide stick tools have their place, but they don't
have any place in my shop. Inserts offer repeatablity, accurate
indexability, positive geometries, chip control, coating options,
accurate corner radii, no grinding, and they are not subjected to
the heat from brazing - features I've never enjoyed from brazed
carbide. If you want to use brazed carbide, maybe someone else here
can give some pointers.

- Costs
I use 3/4" and 1" shank OD turning tools. A holder will cost about
$80. The insert styles I prefer cost about $14 to $18 apiece when
bought in boxes of ten. Most distributors don't sell partial boxes
of inserts, but some do, so ask. MSC sells single inserts at a
higher individual cost. You'll have to evaluate for yourself if you
can justify the expense. In my case, if I feel that if can't afford
the inserts, I can't afford the lathe. I'd avoid the no-name carbide
sold by the lower echelon suppliers mentioned in other postings .
This is sometimes reground material, unpredictable, and unlikely to
come with the top-face geometries and sharp cutting edges that a
small lathe needs.

- Carbide Grades
Wow - how to summarize such a broad topic in few words. In general
terms, carbide grades are a compromise between toughness and
heat/wear resistance. Most inserts are optimized for use in high
production CNC environments, where cost savings are often found in
higher feeds and speeds, which result in higher temperature. Like
most materials, tungsten carbide is sensitive to high temperatures,
so most industry research is in the direction of increasing heat
resistance. That's not a factor for most hobbyists. When my face
is 18 inches or less from a spinning chuck, I tend to keep the feeds
and speeds down. I'm looking for toughness in an insert because my
manual lathe doesn't have the rigidity of a CNC, and my boneheaded
handle-cranking is by no means repeatable, or predictable. I prefer
to have an insert wear rather than chip. The demands of industry
have led to grades specific to certain materials, but where I may be
turning steel, stainless and brass all on the same day, or same hour,
I want a general purpose grade. A C2 grade is a good compromise
for most metals, or a C5 if you turn mostly steels. Coatings help
primarily by protecting the inserts from the heat of cutting , but by
nature the act of applying the coatings in hot furnaces degrades the
toughness of the base carbide. In many cases the home shop machinist
would be better off with an uncoated insert in order to optimize
toughness and edge sharpness, and you also save a couple of bucks per
insert. I'd change to a coated grade if I were experiencing built-up
edge (where the material adheres to the insert), or if I did a lot of
stainless steel. If I were to suggest a coating for general home
use, it would be one that uses a PVD, rather than a CVD, process, due
to the lower furnace temperatures, and the typically thinner, more
lubricious coatings. The PVD process can also coat up to a sharp
edge, where the CVD process requires a rounded honed edge. My
favorite coating materials are TiCN (titanium carbo-nitride) , and
TiAlN (titanium aluminum nitride). Counter-intuitively , TiAlN is a
wonderfully temperature resistant coating initially designed for use
without coolant, but it also offers a high lubricity factor, which
helps prevent built-up edge. To the best of my knowledge, the
toughest coated insert in the industry is Iscar's IC3028 (IC328 for
milling). I can't verify it, but I have been told that it's
toughness, while not equal to HSS, is at least comparable to HSS.
This has a PVD TiCN coating. The TiAlN coating version is called
IC9028. The uncoated version of this is IC28 grade. This is
classified as a non-ferrous grade, and is not optimized for steel but
will work in steel, too. All major manufacturers offer something
competitive with this, and what they have on their conversion chart
that's equivalent to Iscar's grades are what you want. ( Grade
numbers are added and deleted constantly. I left Iscar 7 years ago,
so specifics may have changed since then, but IC 28/IC328/IC3028 have
been benchmark grades for them.) Unfortunately, the toughest
grades generally aren't available with the chipformers designed for
light depths of cut. Even though I call it roughing on my
lathe, .040" DOC is generally considered a finishing application, so
these inserts tend to come with wear resistant grades to handle the
higher SFM's commonly used in industry. So when I choose a finishing
chipformer, I have to compromise and select the toughest grade
available in that configuration.

- Insert Shape
The most commonly used insert shape and size is the double-sided 80
degree diamond, such as the CNMG432. With its 80 degree included
angle, it can cut up to a 90 shoulder. It's popularity ensures that
it is available in the most configurations and grades that are of
interest to me, and at the most competitive costs. EVERYBODY makes
CNMG's. There is valid ground to argue for a narrower angle, like
a DNMG , if needed, but these will cost more, and offer fewer
choices. There is also a very valid argument for using single-
side "positive " inserts. They are freer cutting, and if you need
the freest cut, they are the way to go. But the cost per edge is
higher than a double sided insert with the same features, and there
are fewer options available if you need to address a specific
application problem in the future. I can't remember any instance
where the "upsharp" double-sided/ "negative" inserts didn't provide a
free enough cut, but cutting a long, slender shaft might be more of a
challenge. Since I'm an amateur and more likely to chip an insert
than wear it away, the double-sided, four-cornered CNMG-style is my
choice if I could only have one. The third letter of the ANSI/ISO
nomenclature (M in this case) denotes the tolerance class. The two
most common options are "M" and "G". A home shop machinist needs to
equate the "M" with "as molded", and the "G" with "as ground". As an
insert comes out of its molding process, the cutting edge has
a "hone" of .005" or more. This is well illustrated in Mitsubishi's
product bulletin #B036A
(http://www.mitsubis hicarbide. com/mmus/ catalog/pdf/ b/b036a_fj_ mj_gj_ms
_01-04.pdf), where their photos distinguish between a "M class"
and "G class" insert. This is advantageous in most applications in
order to keep the cutting edge from chipping. To get an "up sharp"
edge or tighter tolerance, the insert must be peripherally ground.
Most manufacturers call these CNGG's or CNGP's. This adds several
dollars to the cost of each insert, but this is a necessity for most
aluminums, titanium, plastics, or wood. I also use them for taking
off a few thousandths, even is steel, which normally requires a honed
insert edge. For aluminum and plastic, I prefer inserts that are
both ground and polished. The top faces of these are polished to
practically a mirror finish, which greatly helps to prevent builtup
edge from forming. When dragged by hand across the top of your
thumbnail, a proper CNGG or CNGP will easily shave off some
material. A CNMG will not. The third digit designates the cutting
tip corner radius. In this example it is "2", indicating a 1/32"
radius. A "1" indicates a 1/64" radius. CNMG's are available with
corner radii down to 1/64", but most inserts below 1/64" must be
ground, so can only be made in a CNGG or CNGP style. It isn't a hard
and fast rule, but it is generally recommended that the tip corner
radius is the minimum depth of cut for that insert, in order to
ensure that the radius is full engaged in the work. Thus, the
minimum DOC for a CNMG432 would be .031". Where I generally don't
cut more than .040" DOC due to horsepower limitation, a CNMG431 is a
much better choice for me. I won't explain the nomenclature here,
but for manual turning (and facing) TOWARD the chuck, the proper
insert holder for a CNMG or CNGP or CNGG431 is MCLNR12-4 (for 3/4"
shank tooling) or MCLNR16-4 (for 1" shank tooling). These holders
hold the insert at a 9 degree negative angle toward the work piece,
thus giving a 9 degree front relief angle.

- Chipformers

Ahhh - the blessings of chipformers! To be able to make little chips
in the shapes of "6"s and "9"s instead of a rats nest of entangled
razors! But keep in mind that if you are machining a tenacious
material like some aluminums or stainlesses, it may still be a
challenge to always break the chips. Subtle differences in
chipformer shape can make a big difference, and proper chipformer
selection was often the hardest part of selecting the right insert
for a customer. Chipformers also can give you a POSITIVE cutting
edge at the material even when the insert itself is held at a
negative angle by the MCLNR holder. Chipformers are not
standardized between manufacturers like the insert sizes and shapes
are, so every manufacturer has their own nomenclature. For the
depths of cut that I use, I need a chipformer designed for finishing
or super-finishing, even when I consider .040" DOC to be roughing.
And even the super-finishing chipformers aren't expected to control
the chips at DOC below .020". Chipformers usually have a two letter
designation, and it is common for finishing chipformers to include
the letter "F". I prefer to use what are known in the industry
as "high positive" chipformers. For DOC below about .005-.010", I
use a ground insert like a CNGG or CNGP with a finishing chipformer
like Mitsubishi's "FJ" (with a positive top rake that varies from
+12 to +20 degrees) or Valenite's "SR" (with a positive top rake of
+12 degrees). When held in a 9 degree negative holder, a 20 degree
positive top rake will enter the work with an 11 degree positive
angle. Since these inserts have an "upsharp" edge, they may chip if
used too aggressively in interrupted cuts. They are not recommended
for heavy cuts in steel, but they have worked well for me up to .040"
passes in steel, and everything I do in aluminum. Since these
inserts are commonly used for high temperature alloys like titanium,
the grade choices are limited to the higher hardness end of the
spectrum, but tend to be PVD coated or uncoated. I pick the toughest
grade available. These are designed to work at about .002" to .010"
feed, and .004"-.050" DOC. From .010"-.040" DOC roughing, I feel
more secure about not chipping the insert by using an "as molded"
insert. Examples are the Valenite CNMP 431-C5 (+12 degrees top
rake), the Mitsubishi CNMG 431-MJ (+12 to 20 degrees), and the Iscar
CNMG 431-PP (+13 degrees). The honed edges can handle steels very
well, and can even handle moderate interrupted cuts. These are
available in more grades than the CNGP or CNGG, and once again I'll
select the toughest PVD or uncoated grade.

I hope this helps."

Bob G
Salt Lake City
******************************************************************************


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## precisionworks (Jan 2, 2009)

Just got this email info from Penn Tool :

You can browse our on-line "Industrial Tooling Buyers Guide" @ www.penntoolco.co and DEDUCT 10% from current pricing and also search for all of your tooling requirements on sale.

Please contact our sales department for any inquiries you may have 
@ 800-526-4956, Fax: 973-761-1494, Email: [email protected]


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## Torque1st (Jan 3, 2009)

wquiles, Thanks for the excellent information. 

I have had the same experience with the tooling you mentioned. I have used HSS, Brazed Carbide, and Carbide Inserts, on many of the materials you mention along with a LOT of cast iron. I used a lot of HSS for specific form tools, parts that are made on CNC equipment nowadays. On a manual lathe HSS works for that application. I usually ground all of my own HSS and brazed carbide tooling. I much prefer inserts but my experience with them is back from the 70's, interestingly some from Valenite. Inserts worked great on cast iron back then. Personally For manual machines there is still a place for HSS but I don't have any use for brazed carbide. High quality holders are required for inserts. Watch out for sprung or damaged insert holders.

Chip breakers would have helped a lot with some nasty SS I had to make parts from once. I experimented with various options but had to get the job done. One of those nasty stringers almost cost me my right index finger. I never could get those chips to break with the tooling available at the time.  Cast stainless made great chips but inclusions could destroy an insert or a part if it happened on the finish cut.


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## cmacclel (Jan 4, 2009)

Your best bet is Ebay.

I bought 2 5/8's right hand 35 Degree diamond holders that where $100+ at Enco or MSC with 20 inserts around $70 shipped. I also bought a button tool with 20 inserts for $35. Keep in mind these are $15 each insert through the retailers!

3x Carbide through collant drills for $12 each. Ebay can't be beat!

Mac


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## Torque1st (Jan 4, 2009)

Watch the Ebay stuff tho. A holder that is out of spec or worn/damaged can eat $$ inserts like candy.


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## wquiles (Jan 4, 2009)

cmacclel said:


> Your best bet is Ebay.
> 
> I bought 2 5/8's right hand 35 Degree diamond holders that where $100+ at Enco or MSC with 20 inserts around $70 shipped. I also bought a button tool with 20 inserts for $35. Keep in mind these are $15 each insert through the retailers!
> 
> ...



+1. I only buy stuff from Enco/MSC when in kit form (with inserts included) and only if on special/coupon, but on Ebay is normally even cheaper. I recently bought a brand new, solid carbide 1/2" dia, 8" long, coolant through, SECO boring bar with 10 inserts, key, all in original packaging, for $129 - a solid carbide bar like that is at least $200-300+, plus another $50-100 for the inserts, so you can see how relatively "cheap" it was 

Following *Torque1st*'s advice, I prefer to only buy new tooling from Ebay 

Will


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## precisionworks (Jan 4, 2009)

> I prefer to only buy new tooling from Ebay


Even when buying new, you still have to watch closely what you're buying. 

Some time ago, I won the auction for a NIB Seco face mill with four inserts ... but additional inserts were available from Seco only, at $20 each, so that tool got sold quickly

There are many tool holders, brand new Iscar, Valenite, etc., that have a shank size too large to fit a BXA slot. Not a problem, as long as you have a mill with solid carbide tooling to reshape the shank to fit. Don't even think about doing this with HSS or cobalt end mills, as the shank on any decent tool is between 45 - 50 HRc.

Speaking of milling cutters, I finally found a Polish face mill that uses the same CNMG-432 inserts used on the lathe -- but the face mill run the "unused" corners. Which means that there are 4 corners for the lathe + 4 more for the mill, which makes the cost per edge almost zero. Mine came from Stegman Tool, who are very nice to deal with (they have many others also):

http://stegmantoolcompany.thomasnet...er-rh-cut-with-r8-and-weldon-shank?&forward=1







In mild steel, this tool easily runs at 1500 rpm (785 sfpm):devil:

I mention this tool because if your lathe & your mill can share inserts, it means that many fewer inserts that you have to keep on the shelf. My larger boring bars also use the same insert:






That bar came from Penn Tool, made by Bison/TMX Pafana, and is 1.75" diameter. The boring bar holder is welded steel plate.


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## SafetyBob (Jan 6, 2009)

OK Precisionworks, I just spent the better part of 3 hours looking and getting more and more disappointed at the fact there are so many CNMG 431 or CNMG 432 inserts out there that my head is starting to explode. 

There are miles and miles of numbers.......any more hints? (the 4 year old child next to me isn't helping either).

Why can't they just say, use this for aluminum? 

Oh, I know, that Seco-Carboloy insert that you referenced on the other thread "Lathe advice" specifically for aluminum......I couldn't find that to save my life....gotta model number?

Bob E.


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## wquiles (Jan 7, 2009)

precisionworks said:


> There are many tool holders, brand new Iscar, Valenite, etc., that have a shank size too large to fit a BXA slot. Not a problem, as long as you have a mill with solid carbide tooling to reshape the shank to fit. Don't even think about doing this with HSS or cobalt end mills, as the shank on any decent tool is between 45 - 50 HRc.



Question: For my old 8x machine, to fit the 5/8" tool into the AXA holders, I actually cut some of the inside of the AXA holder for the tool to fit. What I take from your statement above is that I am better off leaving the holder alone, and cutting down the shank of the actual tool, right? 

Will


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## cmacclel (Jan 7, 2009)

wquiles said:


> Question: For my old 8x machine, to fit the 5/8" tool into the AXA holders, I actually cut some of the inside of the AXA holder for the tool to fit. What I take from your statement above is that I am better off leaving the holder alone, and cutting down the shank of the actual tool, right?
> 
> Will



I myself would cut the tool itself rather than the holder but I doubt it would really make a difference. Then again I would probably cut the cheaper part of the 2 which would most likely be the holder 

Mac


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## wquiles (Jan 7, 2009)

cmacclel said:


> Then again I would probably cut the cheaper part of the 2 which would most likely be the holder



That was exactly why I was cutting the holder - much cheaper at about $12-14 each, but then I was wondering how much flex would it add to the holder by taking metal away from what is basically a "C" structure or "C clamp" which is weak by design - I guess it depends on how much metal is being removed :devil:

What got me thinking was all this talk about having the stiffest platform for carbide tools. From looking at both options (tool vs. tool holder), it is probably better to leave the "C" alone and take metal away from the tool's shank - I guess 

Will


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## cmacclel (Jan 7, 2009)

Will I agree with you but realize unless your going to be doing some serious machining with Huge Depths of cuts I doubt you will have any problems going either way. 

Mac


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## precisionworks (Jan 7, 2009)

> there are so many CNMG 431 or CNMG 432 inserts


There are lots to choose from, but much like vanilla ice cream, most are similar. I buy mine on eBay, and look for a CNMG-432 that's *coated*, as opposed to a bare or uncoated insert. Some coatings work better than others, and you'll develop a preference over time, but a general purpose TiN (gold color) to a TiAlN (black color) usually works well in mild steel. For aluminum, there are specific inserts that work dramatically better because of a highly polished rake face & no-hone edge treatment - they look like a mirror finish, or a chrome plated finish. Expect to pay nearly $10 each for these, versus $1 or $2 for general purpose mild steel inserts. Here are some (not all manufacturers offer the CNMG shape) that show what to look for:

http://www.iscar.com/ProductLines/Pdf/VCGT_CCGT.pdf

https://www.widia.com/images/pdf/techRef/turning/kennametalChipCntrl.pdf


Here's a high quality, American made insert & the price is right:
http://cgi.ebay.com/10PIC-VALENITE-CNMA432-SV310-CNMG432-INSERTS-126-NEW_W0QQitemZ360103797460QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item360103797460&_trksid=p3286.c0.m14&_trkparms=72%3A1240|66%3A2|65%3A12|39%3A1|240%3A1318|301%3A1|293%3A1|294%3A50



> I am better off leaving the holder alone, and cutting down the shank


Either one will work, but I always mill material from the bottom of the shank (you could mill the lower pocket of the holder). By taking material off the low side, the tip of the insert will still be adjustable to centerline.


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## precisionworks (Jan 7, 2009)

FWIW, the 432 has a relatively large corner (nose) radius, where the 431 is 'sharper' or tighter in radius. The 432 acts somewhat as a wiper, where the 431 leave right angle corner without a transition.


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## KowShak (Jan 7, 2009)

precisionworks said:


> FWIW, the 432 has a relatively large corner (nose) radius, where the 431 is 'sharper' or tighter in radius. The 432 acts somewhat as a wiper, where the 431 leave right angle corner without a transition.


 
I'd be careful about using the term "Wiper", it describes a very specific type of insert designed to give better surface finish at high feed rates, or to give better finish at the same feed rate as a non-wiper insert.

http://en.wikipedia.org/wiki/Wiper_insert

Larger corner radii are more robust than tighter corner radii and are used roughing, i.e. heavy cuts and fast feeds for material removal, where as an insert with a much smaller corner radius will be used for finishing, i.e. doing the final light cut that will give the object its size and surface finish.


This will explain everything about turning in more detail than you care to read.

http://www2.coromant.sandvik.com/coromant/catalogue2007/tech_a.pdf

There is a section about insert geometry, one about insert grade etc. It is Sanvik sales literature but there is a lot of general machining information in there, I found it quite informative. 

Aluminium is soft, so its easy to machine, but if you use the wrong insert you can get "built up edge" problems, where the metal you're cutting sticks to the carbide and in blunting it. You can remove the aluminium (often it scrapes off the insert with a fingernail) but you will have to stop cutting to do that, so it'll slow you down. I've seen single sided positive rake inserts with quite an aggressive cutting edge recommended for aluminium to avoid BUE.


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## precisionworks (Jan 7, 2009)

> be careful about using the term "Wiper", it describes a very specific type


You are technically correct, as there are many specialized wiper inserts available. The 432 *can *act as a wiper if the tool post is swiveled so that the edge of the insert is almost parallel to the part being turned ... "follower" is probably a more correct term than wiper. Whichever term is used, the effect is the same, which is to produce a low micron surface finish (which normally requires a finishing insert) with a general purpose or roughing insert. We ran that insert (but the next bigger size - CNMG-532) as our most used rougher & finisher, routinely using it for bearing fits where the tolerance was +/- .0002 ... which is normal for those types of fits. The insert brand was Iscar, and we purchased a few hundred at a time, because the rep gave us any Iscar tool we wanted or needed - free of charge.



> an insert with a much smaller corner radius will be used for finishing


As a rule, that's correct. And a 431 will sometimes leave a finer finish than a 432. But corner radius is only one part of the equation. Is the edge honed (slightly rounded over) or is it no hone? What is the substrate? What type of coating is used. Is the insert run wet or dry? Add another half dozen variables (SFM, DOC, IPR, type of machine, etc.) and it's easy to see why some broad nosed shapes, like a 432, will give a better finish than a small radius 431.



> if you use the wrong insert you can get "built up edge" problems


BUE (Built Up Edge) is a problem in any gummy material. Titanium alloys & most aluminum alloys are both prone to cause BUE. In aluminum, the best way to avoid that problem is to use an aluminum specific insert like those from Iscar or Kenna (referenced in links in post #17). They all share the common features of a high positive cutting edge, no hone, & highly polished rake face. By using these special inserts, a negative shape like CNMG can outperform most positive inserts.



> Your best bet is eBay.


I've managed to snag a few high positive CNMG's on eBay. If there's a good close up photo, you can easily see what you're getting. No photo or a bad photo means it isn't worth taking a chance.

I landed a contract job some time ago, and needed a hard turning insert (most shops define hard turning as any part with a hardness over 42-45 HRc. Conventional coated carbide inserts work well up to that hardness, but have very short life above that level). Of the available choices, cermets seemed to give the best value, but were nearly $20 per insert. Found a company on eBay selling new, old stock, American made cermets, and bought 100 for $50. Used part of those on the contract job, and still have a lifetime supply


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## SafetyBob (Jan 8, 2009)

Precisionworks and Mac, thank you once again. I will have the time tomorrow to dig into this info. 

Last night I stayed up very, very late on Seco's site and really studied their turning material. I came very, very close several times to actually "getting it", but now with more practical words of wisdom coming out, I am getting a very good understanding of what I need to do or should I say get. 

Thanks for the links, they will be priceless. 

I know I may never come close to what Mac (yes, I am pointing you out specifically) does on the lathe, I will build a flashlight from scratch at some time in the future, but for now, the grooving and modifying that I am doing and need to do in the future need to be up to YOUR guy's standards, so that I can truly take pride in being able to do what most people can't or won't do. 

So far, this hobby has become challenging and as rewarding as just about anything I have done in a long time.....

Bob E.


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