inserts and cheap chinese holders

[swatson144]

I just finished adding this to my web site in hopes it would help a few. Since it seems posts are dropping out due to the change over / growing pains. This was cut and past and'll give someone something to do I hope.

It seems that very often people have a little trouble with inserts for cutting tools. Generally each manufacturer will go by either ANSI or ISO standards and sometimes reference both.

If you have name brand holders such as Kennametal, Sandvik, ISCAR, etc. It is really as simple as calling the manufacturer/distributer help desk with the identification of an insert that you are currently using (ie TCMT21505LF), material you want to cut, finish desired, and model # of the holder. They will make recommendations.​

Many of us in the home hobby machining have bought into the 30$ chinese holder set from one of the many import places. I'm going to use that varity as an example but the principle will hold true even if you have something completly different ie CNMP431 Kennametal has a very nice catalog of turning inserts with the 1st several pages being pretty much everything most of us need to know about how the ID/Catalog #s work. You probably should open it and leave it in a window while you continue being bored by me.​

So you bought the set and the seller said "uses TCMT21.51 inserts". That's ANSI description. You bought a 3/8 shank set and each holder came with an insert on it and no spares. Hmmm the inserts are like 5$ each and you aren't really happy with the way they cut and would like to change something such as the tip radius may give a better finish if larger etc. So we need to determine what changes we can make in # TCMT21.51 and still have it fit our holder (later edit changed the highlight color to make it more obvious)
​

TCMT21.51 1st position is the shape. This cannot change round peg triangular hole.
TCMT2.51 Insert clearance angle C=7° This can be changed depending on what your material needs**** add more later.
TCMT21.51 3rd position is tolerance class. M is pretty low. If you see anything else in this position (unlikely) except U or N it would be an improvement with no real effect.
TCMT21.51 Insert features.T, with hole, one countersink, and chip groove on one rake face. Pretty much can't change this and still get the larger screw to fit.
TCMT21.51 Size in qty of 1/8" 2 in this case because the inscribed circle of the 3/8" holders in our example is 1/4" can't change or the insert will be too big/small for the holders.
TCMT21.51 Thickness in qty of 1/16" x 1.5 or 3/32" changing by .5 +- probably would not make much difference except adjusting the height at the tool post.may be no decimal
TCMT21.51 Corner Radius in qty of 1/64" can (should) be changed. 1 = 1/64" which is pointy. changing to somthing rounder can offer an improvement in surface finish.
So that pretty much completes the information included with our example ANSI inserts. If you go to page 108-109 (or whichever has your actual insert) you'll see that it is conviently listed in both ANSI and ISO. TCMT110204 is the ISO # for TCMT21.51. Note that the decimal in size can be left out as is Kennametals want. Each different manufacturer adds to the end some more designations outside the ISO / ANSI standards to catalog specifics. Sorta like auto makers add lariat, rally etc
I have nothing to do with any mentioned brand I just gotta start somewhere!
refinements and more to come (I hope)

Edited to remove lines and adjust the highlighting.
Steve

 

[pdentrem]

Being able to read the catalogue can be very helpful. Tons of info available and use the toll free if you have any questions.
Pierre

 

[Tony Wells]

One note on the 80° inserts is that if you do any roughing, a holder is available to utilize the 100° corner as well, making the negative inserts useable on 8 corners. Of course, no square shoulders, and a longer lead angle is prone to induce chatter on long, slender work. But they have their uses.

 

[FarFar]

Bougth a holder and made a better one myself.
Cheap,fast to put on and take of,always on centre and better than anything comercial.
Uses all corners of CCMT inserts.
Only expense is two screws and four wrecked CCMT inserts upside down.

Kind regards

Niels

 

[Tom Griffin]

Thanks Steve for a very useful explanation of the ANSI insert standards. Perhaps Phil should consider sticking it to the top for future reference.

Tom

 

[swatson144]

The best thing you can do if you bought one of those multiple tool holder starter sets is throw them in the bin and buy a decent tool holder. Those holders do not provide enough support for the insert, allowing it to move. These kits are one of the primary reasons that the use of carbide insert tooling is criticised in home shop machining.

Just my 2c

I think perhaps that is a little harsh. Yep they absolutely suck compared to Sandivik kennametal or any other brand. My little 12x36 Jet with AXA toolpost is limited to 1/2" tooling most of the major brands don't go down that far and if you do find them competition in the bidding is fierce. I'd buy a bigger tool post but I suspect that would just bring out that the machine isn't rigid enough nor powerful enough. It's no Monarch. We won't even squeek about my 9x20 Jet.

You are very correct about

These kits are one of the primary reasons that the use of carbide insert tooling is criticised in home shop machining.

but I have found that getting real inserts is a huge improvement. It is my opinion that the included inserts are like many of the Chinese cutting tools and are made to look like a cutter but not necessarily actually work. If you have a rigid powerful lathe don't waste your money on these sets not even as a step up/stop gap.

My machines are at the low end of being able to effectively use inserts. So tooling is being problematic. I'm tickled to have found inserts that are making blue chips with .020 - .035 DOC, decent finish and reasonable chip control.

Yep still looking for better holders but the hobby $ usually run out before I shop in earnest.:biggrin: My friend actually gave me a good TCGT holder yesterday but I have to give it back as it is too tall even if I widened the slot to fit.

Steve

 

[R.G.]

HSS inserts

I've looked at the HSS inserts a couple of times without actually getting any of them. See http://www.arwarnerco.com/

Any experience or opinions there?

 

[Bobby Bailey]

We use the A R Warner hss inserts and tooling for most of our barrel work. Excellent finish and super easy to resharpen the inserts, all you need is some oil and a good oil stone. ( hard Arkansas ) Lay the insert upside down on the oiled stone and swirl it around with your finger and it will be as sharp as new in a couple minutes. On 4140 and 416 we get a finish that almost looks like a ground finish. The only other tool we use that gives a better finish is a Diamond tool holder and it gives as smooth a finish as ground stock w1 we have on hand.
If you try the Warner tooling/inserts, call Mike Warner instead of ordering off the web site. They have always given me a small discount when I call. Great folks to deal with and a great product.
Bobby

 

[R.G.]

We use the A R Warner hss inserts and tooling for most of our barrel work. Excellent finish and super easy to resharpen the inserts, all you need is some oil and a good oil stone. ( hard Arkansas ) Lay the insert upside down on the oiled stone and swirl it around with your finger and it will be as sharp as new in a couple minutes. On 4140 and 416 we get a finish that almost looks like a ground finish.

Good to know. I think I'm headed for a set of them.

The only other tool we use that gives a better finish is a Diamond tool holder and it gives as smooth a finish as ground stock w1 we have on hand.

This is the Bay-com tangential cutter?

 

[dickr]

I concur with Tom (TLGriff) That's a great idea. Swatson (Steve) really put some good info, on inserts
It's really easy to think they look or are the same but the quality is miles apart. I would try to get away with that on occasion in the shop only to go back to the quality. it's kind of a pain to read it all but it's no different than the serial number on cars, etc. If you know the numbers it tells a lot.
dickr