Gallery, Projects and General > How do I??

Insert Madness.....Help Please!

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mc:
The C grades are for brazed tooling, not inserts.

To give you an idea, I've attached a photo of one brand in one of my regular suppliers catalogue. There is no mention of C grades.
(I did look for a PDF, but the only PDFs I can find are for insert types/sizes/grades with no explanation of the grades)
Every manufacturer will usually have their own grading system, which is why if you want to find the most suitable insert, you need to research what each manufacturer produce.

As well as the grade, there will also be various chip breaker options, although it's more common for the insert grade to also cover the chip breaker option now.

Then there is the option of other insert materials, like PVD (diamond - more suited to softer non-ferrous or non-metallic materials), CBN (Cubic Boron Nitride - more suited for tough/hardened materials and demanding cuts), and ceramic inserts (similar applications to CBN).


But having had a quick look at what options are available in TCMT09 size, the options seem to be very limited.
Personally, I'd suggest getting a SCLCR(or L) (or another style of holder depending on how you'd like to approach work/take cuts) that takes CCMT inserts, as even in the small 06 size, the insert options are far greater. Or if you can fit a bigger holder that takes the bigger 09 inserts, the options seem to increase more.

You do only get two usable corners on the rhombic inserts for any given holder (you can get other holders that allow you to use the larger angle corners - SCBCL/R), but they are a more popular inserts shape than triangular, so more options exist.
For the TCMT inserts, options don't really expand until you reach the size 16 inserts.

vtsteam:

--- Quote from: mc on February 21, 2022, 03:24:50 PM ---The C grades are for brazed tooling, not inserts.

--- End quote ---

mc thanks, I've got fancier insert tools, but I started this thread to try to identify what size inserts my bottom of the barrel el cheapo 1/4" lathe tools took. I think of them as nearly expendable rough cutting tools, and as soon as they get through the scale, sand inclusions, interrupted cuts, and skin chill, I will likely switch to hand ground HSS tools.

I understand that your supplier has an array of carbide coatings sizes configurations and base materials. But I like things simple and basic and traditional. And the projects I produce are the same kind of thing. For me that's the part of the machining hobby I'm attracted to.

To give you an idea how cheap and reactionary I am, for carbide inserts, this is my supplier's catalog, and yup, they do stock indexable C2 inserts, not just brazed C2:

https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313&_nkw=c2+carbide+inserts&_sacat=0&LH_TitleDesc=0&_osacat=0&_odkw=c2+carbide+inserts

Of course I have no objection to brazed C2 tooling -- as mentioned earlier, I just ordered three of them to see what they will do when pitted against one of my home castings.

vtsteam:
Today I received the three $3 Chinese 3/8" C2 carbide brazed lathe tools, so I put one to work right away. It did great, taking off rough surface iron from the sand cast hot piston in an interrupted cut (~ 0.125" eccentric) with no problem. It seemed to have almost no nose radius and I haven't ground it on the green stone yet, but it performed well enough anyway. Last pass looks good and finish consistent with the first. No chipping or breakage and it looks like no wear.

I was cutting .010-015", didn't go deeper mainly because the casting was unsupported by the tailstock. I didn't want to jar it out of the three jaw where I was holding it by the bore. I wanted to reduce bore eccentricity, rather than that of the surface. That just makes boring easier.

I'm very pleased with these inexpensive brazed tools for my particular purpose. A definite bargain.

Below are the roughed out hot piston (taller one) and the cold piston, which was done earlier with a carbide indexable insert tool. The brazed tool was faster to finish the job, even though the casting was longer.

PekkaNF:
Happy to hear of your good results.

My success rate with cast iron with brazed inserts has been high too. Pretty much all brazed inserts russian/chinese orgining seem to work most of the time as long as they are on small shank. I have met some pretty big russian inserts that were like 20 mm square and really thick. They were practically impossible to sharpen to a keen edge. I was told that they are really good on positive angle and DOC over 5 mm....our roughing is industrial finishing. Only systematic problem I had with brazed "hobby" tools of indian origin, markings were good but they would crumble. Two sets of them.

Inserts can be very good too, but there are two problems:
1: Although pretty much all brazed carbide tooling works I have had less than 50% success rate with cheap inserts. Some claim that they had better luck, but for me it does not work out to buy cheap inserts. Some relatively cheap tool shanks work fine.

2: The whole insert business is a jungle. After you have found the correct insert geometry that you actually screw into tool shank you are into a treat. There are different grades of base material, coating, nose geometry, chip breakers and what not. And all that is really really important! Some inserts are optimised for certain task. Remove the hell out of the stainless unobtanium steel, pressurized air as coolant and tip life of 15 min on really rigid machine.

And insert + shank is pretty expensive down payment. You need to know what you are getting. Then it works fine. THis is contary to brazed carbide...you buy wrong or dud and you loose 8 USD. Big deal. Usefull insert shank costs 20-60€ + box of inserts starts at 40 €....it is great when it works, but my income does not allow repeated mistakes.

And then there is skewed scale of how different machines we have. You just can't assume that hobby roughing is industry finishing. True to a certain extent but not exactly. Industry might be able to use much smaller tip radius, because their machine is more rigid, controlled materials and coolants. Hobbyist may need to compromise on pretty much everything else but time. We can't and we don't need to shift 3 kg of swarf in few minutes but some inserts are designed to do that.

Pretty much what I know is that for aluminium you need uncoated and "polished" inserts, some of them work for stainless steel and free cutting steel too. For most iron material I use "general" use insert that is PVD coated. And I stick with them. There are so many insert/shank/grade/chipbreaker combinations that you can get lost to them.

Confession time: I have some GRP500 cast ends...that is pretty high tensile spherical cast iron. I use PVD coated general use inserts after I get under the skin.

https://online.lamina-tech.ch/catalog?item=T0001889

There are shitload of fake inserts floating on the usual sites. I buy these only from the local industrial tool distributor that makes me jump trough hoops to buy them, but original works for me. I have seen copies and they are hard to recocnize by looks, but all effort is used for looks, not for function.

vtsteam:
I agree totally, Pekka, re inserts for home shop use. Good to hear specifics of what you find useful on a practical scale for the materials we generally use.  :beer:

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