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Thread: TPG insert questions

  1. #1
    Join Date
    Mar 2004
    Location
    Upper Penninsula of MI
    Posts
    54

    Post

    Hey,

    I've been using the Aloris 16 "turning/facing" tool holder for some time now (3 yrs.). Mine is the CA series, in a big Monarch 18.5" lathe. I use that tool holder everyday and I love it. The TPG is a positive side clearance insert! That's what the "P" stands for. With the Aloris 16 holder, the insert retainer (hold down cap) serves as the chipbreaker. That is, if you have original equipment from Aloris! The insert retainer cap has a piece of carbide sweated into it to serve as the chipbreaker. And what's more it is adjustible! Because the hold down cap has a slot through which the retainer screw fits, it allows you to slide the "chipbreaker/retainer cap/hold down" towards the insert cutting edge. The chipbreaker on mine extends the full length of the cutting surface so that it will function with whatever depth of cut I take. I can also control the chip curl size by moving the chipbreaker towards or away from the cutting edge, depending upon the material, and feedrate (I like to pull #9 shaped chips off consistently). It's a great piece of equipment! I wouldn't think of using anything else for quick heavy material removal on the lathe!

    Howard

  2. #2
    Join Date
    Jun 2002
    Location
    Northern New England
    Posts
    2,704

    Post TPG insert questions

    I've been working with ccmt, dcmt and tcmt inserts for a while but recently got hold of an Aloris BXA with several toolholders, including the number 16 turning/facing insert holder. It uses TPG inserts which raise several questions.

    TPG has no chipbreaker and zero side rake angle and depends on the chipbreaker in the holder. Are newer inserts with varying geometries better than the TPG (chip forming, breaking)?

    Is anyone using other TP-- insert types as long as they are the proper thickness and no center hole? Any with chipbreakers and what type(s)?

    Den

  3. #3
    Join Date
    May 2001
    Location
    Utah
    Posts
    175

    Post

    I use TPGs all the time. They do work better with a chipbreaker on top. I use size 3XX inserts (3/8" included circle) with CBT-3 chipbreakers. They can be found on page 270 of the KBC catalog. Or page 286 of the ENCO catalog (not listed as CBT-3, just ENCO part number 379-2951.
    Jim

  4. #4
    Join Date
    Nov 2002
    Location
    Kenosha, not the pass the other one
    Posts
    2,448

    Post

    I've tried the TPG holder for the Aloris and frankly I find it wanting. True the inserts are about as cheap as one can go with carbide inserts and are about as common as flies on a sugar pie. The Aloris holder I feel is far superior is the D80. Uses CNXX4XX seies inserts. Four cutting edges versus the TPGs three. But one does not have to spend the money for the Aloris. If you can pick up a used 4XX series CN-16/20 style tool holder it can be modified to fit an Aloris (or any of the other knock-offs or competetors on the market). If you really need the clearance the TPG can give think about modifying a DN-16/20 series tool holder
    The optimist says the glass is half full, the pessimist says it's half empty. The paranoid in me says somebody put a hole in it.

    Remember pessimists are at heart opptomists. They know things can and will get worse.

  5. #5
    Join Date
    Jun 2002
    Location
    Northern New England
    Posts
    2,704

    Post

    Spin: Are you using inserts without chipbreakers to get 4 edges ... ok, I see, 4xx is negative and "flippable", right ?

    The D80 appears similar to the BXA-16 I've got except the 16 is double ended for turning and facing. Are you talking about clearance for the cutting end of the tool or maybe thinking about the Aloris TPG turning tool holder ?


  6. #6

    Post

    rheng
    The "P" in TPG means there is a 11* angle around the periphery of the insert. This also means you cant flip it over . If the second letter is a "N", that means there is a 90* around the insert. You can flip it over to use the other side.
    When you refer to the chipbreaker in the holder I'm assuming you are using a clamp on chipbreaker? These dont really change the cutting angle, they just curl the chip back towords the work.
    Mike

  7. #7
    Join Date
    Jun 2002
    Location
    Northern New England
    Posts
    2,704

    Post

    Mike: When I mentioned negative I had just finished looking at CNMG 432 inserts at carbide depot and still had them on my mind.

    The Aloris #16 has a clamp on, adjustable, carbide chipbreaker.

    I guess what I wondered about the most was the lack of a back or side rake on the TPGs. Maybe I'd better take a better look at the holder and see if the insert sits back at a slight angle. The Aloris catalog makes it look like the insert sits level. Doesn't this, combined with the flat top on the TPG insert, make for less than ideal chip forming?

    Den

  8. #8

    Post

    Den
    You are correct. It would really help if the insert is tilted back. Some holders actually tilt the insert left or right at a slight angle. The problem with that is the holder becomes a left or right tool.
    Another solution is to grind your own chipbreaker on the insert. Dress a wheel to a sharp corner and CAREFULLY touch the top against the sharp corner. Most ground in chipbreakers are 10* .090 wide. Dont go right to the edge, leave about .005/.010 land between the cutting edge and where the chipbreaker starts.(Boy its hard to explain this by typing). If the insert is coated your going to grind through it affecting the life of the insert. Practice on used ones.
    Mike

  9. #9
    Join Date
    Jan 2003
    Location
    On the Oil Coast,USA
    Posts
    16,871

    Post

    Chip breakers,I make my own,just take a piece of O-1 and make yourself a triangle about 1/16"smaller than the insert and about .100" thick,file the edges with about a 15*back relief then heat treat and leave as hardened,clamp this on top of your insert and try it,if it wants to bail up the chip grind the angle a little lower say 15*.I never have any problems with them wearing out,just amke sure the back/bottom is honed flat.

    Also you might have a look at milling inserts,some of the tpg milling inserts have chip breakers formed in ,I have used these in a pinch on soft steel and aluminum with excellent results.

    Oddly enough a TPG 322 is the best at turning bronze and brass,so long as its set with the top neutral.
    I just need one more tool,just one!

  10. #10
    Join Date
    Nov 2002
    Location
    Kenosha, not the pass the other one
    Posts
    2,448

    Post

    I'll link in some photobucket shots tommorow of the Aloris D80 and the similiar ones I modified out of 1" square insert holders.
    The optimist says the glass is half full, the pessimist says it's half empty. The paranoid in me says somebody put a hole in it.

    Remember pessimists are at heart opptomists. They know things can and will get worse.

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