I was talking to a real machinist about carbide inserts and he said to get started just buy a cnmg with a negative rake. that way you can 8 pieces out of a single insert. well when i do a search i can't seem to find a square one that can be flipped. could any one help me figure out what insert and holder he was suggesting ? thanks
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Carbide insert and holder help needed.
- Thread starter sundown57
- Start date
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- Nov 25, 2015
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what kind of lathe do you have?
Before I answer that.
Before I answer that.
- Joined
- Nov 25, 2015
- Messages
- 9,995
ok, those will do it.
So to get 8 cutting edges out of a cnmg, you need 2 holders, a normal one and one to hold it 90 from the normal so it can do chamfers and what not.
The cnmg is not square. It's a rohmbus
So therefore the need for a 2nd holder to use the side that's not normally used.
So for normal cutting you'll get 4 edges, then with the 2nd holder 4 more.
I think the machinist means a SNMG insert. That has 8 identical cutting edges. Because these inserts are targeting larger lathe's you have to take heavy cuts to get the chip breaker working. Not an insert for making small stuff. Also when you chip an edge, the bottom edge could also be ruined. To safe money, you have to calculate the price per cutting edge.
Because of the 90° cutting edge (no clearance), this insert is nut suitable to cut up to a shoulder. A WNMG insert has 6 identical cutting edges and a °5 degrees clearance.
- Joined
- Jun 12, 2014
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Number of cutting edges is more of a factor in production machining, otherwise I would stick with CNMG, WNMG, DNMG type inserts. CNMG type there are alternate holders to use additional edges, but is it really worth it.
i cant understand why NO company that sells inserts put the number to the holder that goes with it. I picked up about 100 inserts at a flea market and have yet to find any holder to fit any one of them. I just ordered this set off amazon. looks like a good starter set.
https://www.amazon.com/ASZLBYM-Inde...8-7-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9tdGY&th=1
https://www.amazon.com/ASZLBYM-Inde...8-7-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9tdGY&th=1
Most inserts can be used with different holders. If you google the insert type, you will find suitable holders.
If you have a mill, you could make the holder your self. It takes time to do so but it is not a difficult project. If you have a CNC mill, than it even isn't time consuming.
I make most holders my self so they fit my needs and tool post.
