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  1. #1
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    Default Just a home hobbyist looking for carbides.

    I'm struggling a little bit in finding several carbide inserts for my machines. Application is just general purpose around the shop.
    I have been looking the carbide charts up and down, and have a handle on the shapes and angles, but the size and other variables escape me.


    Anyway, 1st on the list is my set of import lathe tools - 5/8 shanks. They all use the same inserts which look to be TCMT. Well, not knowing much, I quickly ordered a 10 pack from Amazon - TCMT 21.51 3/32 thick. They looked great in the picture, but they are about half the size I need.
    What I have are 4.1mm thick and about 15mm on the side length. The hole is 4.5 mm and countersunk. And there is clearance angle. Are the 32.52 the ones I need? What does the 32.52 and 21.51 signify?


    Next I have an EM150-34 3 flute fly cutter for my mill. It looks like they need a pretty good clearance angle and no center hole - so TPG32? TPF32? Searching for TPG shows inserts without a center hole, but my ID sheet says N, R, or F are without hole. G is double sided cylindrical hole. So, what gives? Also, do I need a chip breaker style? The 15mm insert from my lathe tools do fit the fly cutter, but there is clearly no need for the center hole.


    Then my small boring bar - SIR 0375 K11. The triangle insert in it now has bulges on the sides. And those sides are only about 8mm long - so smaller than the TCMT 21.51 inserts. Internet says Size 11.

    My bigger boring bar S-SCLCR12-3 says inserts CCGX, CCMT. Which should I use?

    Anybody help with some recommended inserts for me?

    Thanks

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    This has been a mine firld for me for years. Thank you for this

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    This is a great little book. It has many pages on inserts with pretty pictures, definitely worth the money

    Engineers Black Book: Machinist and Manufacturing Reference Book




    Sent from my iPhone using Tapatalk Pro

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    Quote Originally Posted by carlherrnstein View Post
    You can decipher the ISO designation with this chart. Insert Designation Chart - provides ANSI and ISO designation code definitions for carbide insert shapes, relief angles, tolerances, chipbreaker codes, hole types, size values, thickness values, radius values, wiper lead angle, wiper clearance angle,

    That is the same one I have bookmarked. It is indeed a great resource!

    For general purpose turning I like Iscar IC 800 series.
    Quote Originally Posted by steve-l View Post
    This has been a mine firld for me for years. Thank you for this
    Uhh.. have you not had internet for the past 20 years or so? LoL
    I agree, insert designations and numbers are certainly not my forte`, but, Google is!

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    Thanks for that link. That's one of the ones I looked over. But now, giving it a 2nd look, it makes more sense that it did initially.

    I just might pick up that book - looks great. Lots better than flipping pages in the MSC book.

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    Quote Originally Posted by acrosteve View Post
    Thanks for that link. That's one of the ones I looked over. But now, giving it a 2nd look, it makes more sense that it did initially.

    I just might pick up that book - looks great. Lots better than flipping pages in the MSC book.
    Are the pages laminated with a plastic coating? That would be handy in the sense that I hate washing my hands every time I need to look in the big book.

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    Check out Lathe inserts .com

    He's done the work for you so you don't have to. Very knowledgeable and sells what works with hobby-size and lower powered machines.

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    I think I have them all figured out except my small boring bar.

    It's a trigon with 8mm sides, but the thickness is 2.61mm or .102. That seems to make it a WCMT 4" " Blank.

    But that size doesn't seem to be very common, or commonly available.

    Am I on the right track?

    Thanks

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    That's the chart that I've been using for years. It just works.

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    Insert Designation Chart - provides ANSI and ISO designation code definitions for carbide insert shapes, relief angles, tolerances, chipbreaker codes, hole types, size values, thickness values, radius values, wiper lead angle, wiper clearance angle,

    I've used this reference for years as well. Today I went to it and the character set is messed up in the charts. Weird! May just be this browser though. It was a good resource for me. Hope this helps.

    Best Regards,
    Bob

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    Inserts are made to inch numbers with a few rare exceptions.
    So a 3,2.5, 2 is 3 8ths ic, 2.5 16ths thick and a 2 64ths radius.

    The IC is the size of a circle that touches all sides or the tool.
    A way to check the IC is to stand the shank end of and endmill on the insert. In this case of a "3" a .375 endmill touches all sides be it a square, triangle or diamond.
    On a number 2 insert a .250 endmill fits.

    Thickness on molded chipbreaker inserts is checked over the chipbreaker at the cutting edge not in the center of the insert which will be higher
    I suspect your "W" trigon is .094 thick which is a 1.5 as the middle number.
    Try a 3/8 and 1/4 endmill on your triangles so you can tell what I mean about just touching the sides.
    Then find what size endmill fits the same way on your trigon. This will give you the first number in the inch description.

    Once you know the inch number you can find the ISO number and search for it also.

    More confusing is that a SIR 0375 K11 is normally an internal threading bar but you could fit a triangle or a trigon in the pocket.
    Bob
    Attached Thumbnails Attached Thumbnails ic.jpg  

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    Thanks for those tips. Yea, this little bar is something I picked up 2nd hand with the insert already in it, so who knows.

    Glad you clarified the IC designation. I might have thought that the circle would have to cover the whole insert. However... the Insert Designation Chart linked above says "cutting edge length" for the size. And if you compare the W to the T, they are very different, which is strange to me because of the similarities of the shapes.

    Is there an advantage to the T or W in certain applications? I may just as well be suited with a triangle instead of the trigon.

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    Quote Originally Posted by acrosteve View Post
    Thanks for those tips. Yea, this little bar is something I picked up 2nd hand with the insert already in it, so who knows.

    Glad you clarified the IC designation. I might have thought that the circle would have to cover the whole insert. However... the Insert Designation Chart linked above says "cutting edge length" for the size. And if you compare the W to the T, they are very different, which is strange to me because of the similarities of the shapes.

    Is there an advantage to the T or W in certain applications? I may just as well be suited with a triangle instead of the trigon.
    ANSI or inch based system is I.C.
    ISO /metric is gludge to approximate cutting edge lenght but it’s not perfect match because the underlying dimensions are in inches and corner radius fools you in measurements.

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    Quote Originally Posted by acrosteve View Post
    ....

    Is there an advantage to the T or W in certain applications? I may just as well be suited with a triangle instead of the trigon.
    The lead angle changes. A trigon is two twisted triangles to give you the 80 degree included tip.
    Mostly it is a replacement for a C insert but has three or six corners so economy over a 2 or 4 corner C insert.
    For sure a T locates and stays in the holder much better than any W can.
    I do not like designing around or using trigons but sometime you have to.

    Are the pockets in your small bar straight 90 up and down or on an angle?
    One can use positive (angled side) inserts in a negative (90 degree wall) pocket but it won't last long.
    Yes I know it's all so confusing with all the possibilities, numbers and letters.

    You have inspired me to build some web pages, carbide insert calculators and cross references.
    To me it is easy peasy after 40 plus years of making such, to others I can see where it is a minefield of confusion.
    If I have a simple square, diamond or triangle in my hand how do I know the corner radius size using only my calipers over the rads or flat to rad?
    Turns out that the solution is easy.
    Bob

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    The sides of the pocket do look square. The leading angle is achieved by the orientation of the flats on the main part of the bar. So you are right, I would probably be better served with a "N" lead angle. Thanks for pointing that out.

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    Looks like I might have to settle for a TCMT, as the TNMT seems to be pretty hard to find.

    And the 1.5 size is even more rare, I think. But perhaps the 1.8 (9mm) would fit? I know the tcmt 21.51 will not.

    You mentioned it is an internal threading bar. Wonder what insert is intended for it?

  23. #19
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    acrosteve, or can I just use Steve,
    DO NOT put "home hobbyist "in your titles or posts here. Instant rejection, a maybe not even read by some or many.

    Goggle your bar number for insert types.
    The 11 on the end is supposed to mean a 1/4 inch (2) or metric 11 insert but you say the TCMT 21.51 will not fit.
    That is strange indeed. Is the insert hole too far out or the insert way loose and does not seat? Is the insert anywhere near the top of the pocket walls?

    Measure your screw hole with some calipers. Write it down and divide by 2.
    Put the calipers against and straight or 90 to one wall and measure to the far side of the screw hole. (you are after the smallest number here)
    Subtract the 1/2 the screw hole number you got in step one.
    On a .250 insert design you will get .125 minus a tad as the screw hole is biased against the walls so it will pull in.
    Under 1/4 inch the inch number system changes gears but the next steps down are .1875 and .156.

    Doubtful a "N" insert if you could find one would work for boring in this bar geometry. C or P.

    I get the what the heck and why so hard to figure out.
    It's because people make hundreds (maybe thousands) of styles of insert and holder configurations. Each with a reason.
    Gets worse when you get into carbide grades .........all carbide is not created equal even if the same color or coating.
    As a fab I once added it up and I can offer over 2000 variations of carbide insert grades to a customer in a single insert. Each a touch different in how it works.
    Now add ten different chip-breaker designs on this and enter the rabbit hole to my crazy land of solving customer problems.
    Bob


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