Advice on choosing inserts.

[John_Dennis]

I have used up my inventory of randomly acquired inserts for my randomly acquired tool holders and must now choose and purchase some more.

I have two boring bars that use TCMT 21.51 and 32.5 inserts some RH turning tools DNMG43 and NPL51 I mostly cut steel and stainless with these. Any advice? especially bargains of course.

My Lathe is a very heavy 11 inch Weiler Tool room Lathe, very stiff high speed and lots of power.

Thanks
JD

 

[benmychree]

I have always advocated for simplicity in insert tooling, mainly suggesting the use of positive rake geometry, best for low powered hobby machines, it is in my opinion fallacious to focus on how many cutting edges might be possible with negative rake tooling, which puts extra strains on light duty machines commonly used by hobbyists, contributing to wear and loss of precision alignments, Besides all that, the use of HSS and the craft of grinding those tools is highly recommended, reliance on insert tools is pure laziness. Learn the craft/trade!

 

[markba633csi]

I agree with John- High positive inserts are my go-to for much of my turning
and HSS for the in-betweens and custom shapes

 

[John_Dennis]

I do use high speed steel for a lot of my work but when I want carbide, these are the holders that seem to work well for me. Since all of my cutters have come loose, they are unlabeled so I do not know what they are. Accuracy of the insert dimensions is my lowest concern while toughness and suitability for tougher steel and stainless alloys are my primary concern. Grinding HHS for small boring bars is also very tedious so I prefer to use carbide. My lathe is not typical for the home shop, it weighs almost as much as my Bridgeport

 

[mksj]

I think most mainstream manufactured inserts would do well in a rigid lathe with Hp. I like the Iscar IC907 as an all around insert coating for steel and stainless, I use them in a CCMT and DCMT and seem to get good life out of them in a range of ferrous materials. I also have a number of Kennametal DCMT with a KC730 coating that are OK. DNMG is a negative rake so requires more rigidity/Hp, usually 5Hp and above. Most of my boring bars are CCMT or CPMT, I have one that is a TCMT that I do not use, so can't advise on those inserts. My lathe is 2500 lbs so quite rigid, and not shortage of Hp.
ISCAR DNMG 432-TF IC907 DNMG150408-TF IC907

ISCAR DNMG 432-TF IC907 DNMG150408-TF IC907 Carbide Inserts 10 PCS Free Shipping | eBay

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[G-ManBart]

I have a mixture of expensive, brand name inserts for some things, and inexpensive imports for other things. I have been absolutely floored by the durability and results I get with the imported "blue nano" inserts from a couple of eBay vendors in China. I read a few posts by folks who had good luck with them, so I grabbed a couple of packs to try and now I'm going to buy something like ten packs of each size I use because they're that good and that inexpensive. I have them in CCMT, DCMT, CNMG and maybe one other...all seem to work equally well. For the price it's not much of a risk to try.

I actually had a project boring a hardened end-mill holder that chewed up normal carbide inserts quickly and the blue nano inserts were a lot better...probably lasted three or four times longer. It still wasn't ideal so I switched to CBN to finish the job.

Nano blue TCMT110204 TCMT110208 TCMT16T304 TCMT16T308 ZM1135 Carbide Turn Insert | eBay

Model: TCMT110204 / TCMT110208 / TCMT16T304 /. Color: Color.

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Nano blue HRC65 Carbide Insert DNMG150404-MA DNMG150408-MA ZM1135 Cutting Tools | eBay

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[BWS Arms]

I have switched to using these Mitsubishi inserts. They have been great. My big lathe weighs 5k with 7.5hp and my small one is 2.5k and 5hp. I mostly turn 17-4 and 4140.