Carbide insert question

[Megar arc 5040dd]

I am wondering what the difference is, other than the shape itself, between the different shapes of lathe inserts? For examaple is there an advantage or disadvantage to any of the following shape of inserts? CCMT, DCMT, TCMT, WCGT. Please correct me if I have the abbreviations/codes wrong I am asking about 80* rhombic, 55* rhombic, triangle, and trigon. I have been using HSS 99% of the time over the last 15 years but would like to pick up some more insert tools. Both for convenience as well as the times where the material just messes up the HSS. I have a couple tools that use CCMT that I have had mixed results with. I believe this could just be the busy bee tools inserts I bought about 15 years ago that I only just used the last one I had the other day. I am going to pick up different nose radius to try as well as some sharper edged ones for aluminum. That got me thinking that I don't seem to notice people in youtube using CCMT as much as TCMT or DCMT. I was wondering if there is a reason and if one shape it better than another for generalt use.

A bit more information on my specific use case. My lathe is a babit bearing 10 inch atlas. Most of what I turn is mystery steel as well as some 1018 and aluminum. I ran into a situation the other day when turning down a craftsman socket into thin wall cheaper than snap on socket. HSS went dull really fast and gave a poor finish but carbide worked really nice and gave a nice finish. I figured since I am ordering inserts if there were other types that work better I would give them a try.

 

[TorontoBuilder]

I am wondering what the difference is, other than the shape itself, between the different shapes of lathe inserts? For examaple is there an advantage or disadvantage to any of the following shape of inserts? CCMT, DCMT, TCMT, WCGT. Please correct me if I have the abbreviations/codes wrong I am asking about 80* rhombic, 55* rhombic, triangle, and trigon. I have been using HSS 99% of the time over the last 15 years but would like to pick up some more insert tools. Both for convenience as well as the times where the material just messes up the HSS. I have a couple tools that use CCMT that I have had mixed results with. I believe this could just be the busy bee tools inserts I bought about 15 years ago that I only just used the last one I had the other day. I am going to pick up different nose radius to try as well as some sharper edged ones for aluminum. That got me thinking that I don't seem to notice people in youtube using CCMT as much as TCMT or DCMT. I was wondering if there is a reason and if one shape it better than another for generalt use.

A bit more information on my specific use case. My lathe is a babit bearing 10 inch atlas. Most of what I turn is mystery steel as well as some 1018 and aluminum. I ran into a situation the other day when turning down a craftsman socket into thin wall cheaper than snap on socket. HSS went dull really fast and gave a poor finish but carbide worked really nice and gave a nice finish. I figured since I am ordering inserts if there were other types that work better I would give them a try.

I too would like to know what the benefit of pointier angle is, say a 55 degree D over an 80 degree C... Oh and why a C over a W trigon for that matter?

 

[lucsimoneau]

Quick answer would be the following: strength and versatility.
Let me explain:
V shaped insert 35 degrees allows you to get into tight corners and make small shallow grooves at the same time. Mostly used as a finishing insert with a 1/64 or 1/32 corner radius. The shape vs body allows 2 corners/insert. In some instances, the insert can be rotated making 4 edges/insert.

D shape insert would be used more as a versatile finishing/roughing insert, allowing more strength then a V insert. The increase in angle will require added machine power due to the angle. Still 2 edges/insert.

C shape is a very strong insert used for roughing and good for face machining.

T shape is versatile, strong and has 3 edges/insert. Makes for a more economical solution

W trigon shape yields 3 edges/insert and is stronger than the C shape.

At school we use almost exclusively the V (1/64 and 1/32 radius), D (roughing/facing 1/32 radius) and W (roughing/facing 1/32 radois) shapes on our CNC lathes and the T shape on our manual lathes (right, left and neutral tool holders).

This is a vast subject and everyone has their own preference on the subject. For my small manual lathe, I use a kit purchased from Accusize with basically C, D, W, threading and cut-off inserts.

Ouf!

 

[thestelster]

Post in thread 'What inserts do you like and why?'

Jul 2, 2022

When deciding on going carbide inserts, there are many factors that come into play.
-insert shape
-material being machined
-hardness of material
-coatings
-finish i.e light finish to roughing

And machine ability:
-ridgidity
-horsepower
-speed

That is why it is imperative to search out all the information you can about a particular insert you want to use. Companies like Sandvik, Kennametal, Mitsubishi and other top manufacturers, spend so much money on research and development. Go into the website and get that information. Without that knowledge, you're doing yourself a disfavor...

• thestelster

• 

 

[thestelster]

Thread 'What inserts do you like and why?' https://canadianhobbymetalworkers.com/threads/what-inserts-do-you-like-and-why.5495/

 

[Susquatch]

My personal favorite is Trigon (W) with an anvil. Won't do everything but does most things. 6 edges. Widely available. Very economical.

 

[Megar arc 5040dd]

My personal favorite is Trigon (W) with an anvil. Won't do everything but does most things. 6 edges. Widely available. Very economical.

With 6 edges would mean that it is a negative rake tool right? My understanding, and I could be very wrong, is that negative rake tools don't work on small light duty machines like mine. I don't recall exactly why, might be tool pressure or something like that. What size lathe do you have?

 

[Megar arc 5040dd]

Thread 'What inserts do you like and why?' https://canadianhobbymetalworkers.com/threads/what-inserts-do-you-like-and-why.5495/

That was an interesting thread and a long read. I saw a lot of people saying what types of inserts they use. But it seems the reasons for using them were mostly because that was the style that they tried and so they stuck with it. I didn't see much as far as comparing the different styles to one another. I am hoping to avoid buying them all over time and trying them only to end up not using most of them. If there are advantages that make one style stand out as better than I will go that route first. Even buying inserts from ali express can add up when you when there are so many combinations of styles and nose radi and if it is for steel or aluminum.

 

[thestelster]

That was an interesting thread and a long read. I saw a lot of people saying what types of inserts they use. But it seems the reasons for using them were mostly because that was the style that they tried and so they stuck with it. I didn't see much as far as comparing the different styles to one another. I am hoping to avoid buying them all over time and trying them only to end up not using most of them. If there are advantages that make one style stand out as better than I will go that route first. Even buying inserts from ali express can add up when you when there are so many combinations of styles and nose radi and if it is for steel or aluminum.

Go to post #50 in that long thread. Have a look at the attachments. Lots of information from the Sandvik catalogue.

 

[PeterT]

CCMT has the advantage of use in both lathe shanks & boring bars. They come in a crazy range of types, nose radii, coating... And very reasonably priced on AliExpress, Ebay etc. Youcan get them at tool stores but I have found no difference. Its what I use 60% of the time.

The other say 40% is DCMT for reasons above. But they can get into nooks & profiles CCMT can't using toolholder layouts you don't see in other holders. Boring bars also available but only to a certain min diameter (CCMT can be smaller) so depends on your work, They are a bit bigger, so typically bigger 16mm shank on my tool post, also my primary cutter. I just bought some 'stainless' inserts for the heck of it that were cheap & came along with a particular tool. They are just amazing in what was a tougher mystery 304 alloy I rarely use because cutting was up till now PITA. At ordinary 500 rpm the finish was very nice & I did consecutive whisker passes in 0.001 diametric range which was not really possible before. I'll snap a pic next time. Turns out they cut regular 1018 better too. So inserts are evolving which is why well intended advice may be dated or even not as applicable on your machine or work.

They make inserts for the industrial world & we benefit from their accessibility. They don't make them for the hobby world. We get the table scraps, but they are still pretty tasty LOL. What I would suggest is just make note of the physical parts people are making in real life mode on machine like yours. Pictures or mags or YouTube. What alloys & what kinds of machines. Chances are high its an insert somewhat like these. Likely driven by a combination of cost & cross toolholder utility & end result quality on hobby type machines. If those parts look like what you would be happy with, then its really that simple presuming the other (lathe/material/operator) factors are comparable. One buddy, very experienced machinist, is a HSS evangelist but he commented to me the other day he ran out of his 'good stuff' & bought a replacement size from one of the common suppliers. After much grinding & adjusting & futzing he concluded it was just not like what he had been using for years (now unobtanium), so was starting to change his tune. So there's that.

 

[Don Sipes]

In general terms smaller less powerful lathes work better with inserts that have a positive rake. Carbide works better at higher spindle speeds so older lathes may not have the speeds to get the best performance from carbide. My lathe came with 80 degree rhombic, positive rake tooling so I have stuck with that and it works well. Recently I have been using more brazed carbide, since I lucked out on finding a grinder to properly sharpen them. They work well too.

 

[KeeponDragon]

the other factor worth mentioning when ordering inserts, is the grade.
VP15TF vs UE6020 vs US735
I have learned each of these has properties making one more suitable then the other for different materials.
I was more or less ordering based off of price...cuz I'm cheap like Mower is...
But after having sub-optimal results, I chose to educate myself better...

I'll also put in my 2 bits for the trigon inserts. I ordered them by mistake. From Ali of course.
So rather than them collect dust, I decided to deepen the investment and I ordered a boring bar and insert holder that uses them.
The 6 cutting edges is a great feature.
And now I have a boring bar capable of hogging out heavier cuts

 

[Megar arc 5040dd]

Go to post #50 in that long thread. Have a look at the attachments. Lots of information from the Sandvik catalogue.

I read the attachments and found they have the same problem as most manufacturer supplied documentation half of it is far more technical than what applies to the home hobbyist. Most of us aren't interested in where making sure to always use the exact right tool or insert for the best return on investment of time and money like a business is. especially one running cnc or one that can bill tool costs to customers. The other half of the information is typically a sales pitch. Notice that in the attachments you refer to they talk about using the shape of insert that is best for that particular situation and using a different shape for a different situation. Read between the lines and they simply want you to buy everything they sell. No where do they say for most of your situations tool X will work so just buy that and the odd specialty one as you need it. When selling to large businesses it works because that is what it's intended for. But when selling to the home hobby guy most of that info is just over complicated and not helpful. It is the same in many industries. In welding the average farmer or guy in his garadge doesn't need 20 different types and sizes of welding rods but a shop welding lots of different alloys and a variety of exotic metals does need that as well as all the information on the data sheets.

Sorry to rant but for anyone new and only learning and doing something as a hobby manufacturers information is often not a good starting point. It often makes people become overwhelmed with information and can turn them off of a hobby. Better to start with general information and as a person learns that then get into more specific information if it is needed.

All that being said there was still some iinteresting information in the Sandvik catalogue and I thank you for pointing me to it

 

[thestelster]

I read the attachments and found they have the same problem as most manufacturer supplied documentation half of it is far more technical than what applies to the home hobbyist. Most of us aren't interested in where making sure to always use the exact right tool or insert for the best return on investment of time and money like a business is. especially one running cnc or one that can bill tool costs to customers. The other half of the information is typically a sales pitch. Notice that in the attachments you refer to they talk about using the shape of insert that is best for that particular situation and using a different shape for a different situation. Read between the lines and they simply want you to buy everything they sell. No where do they say for most of your situations tool X will work so just buy that and the odd specialty one as you need it. When selling to large businesses it works because that is what it's intended for. But when selling to the home hobby guy most of that info is just over complicated and not helpful. It is the same in many industries. In welding the average farmer or guy in his garadge doesn't need 20 different types and sizes of welding rods but a shop welding lots of different alloys and a variety of exotic metals does need that as well as all the information on the data sheets.

Sorry to rant but for anyone new and only learning and doing something as a hobby manufacturers information is often not a good starting point. It often makes people become overwhelmed with information and can turn them off of a hobby. Better to start with general information and as a person learns that then get into more specific information if it is needed.

All that being said there was still some iinteresting information in the Sandvik catalogue and I thank you for pointing me to it

Trust me, we feel your pain. We've all been through this ourselves.

So, here is an example of deciding which insert to use.
The bar in the stock is 3/8" and we need reduce it's diameter. And let's say it's fairly long and we need to use a center in the tailstock.

Well, you can see the the triangle (T) insert won't go anywhere close to the end of the rod. The 80° rhombic (C) gets closer but we still can't use it. But the 55° rhombic (D) works perfectly well, and this situation I can turn that rod down to 0.200". And if we had the 35° Rhombic (V), we can gt even closer.

 

[thestelster]

Choosing positive vs negative inserts.

Negative inserts are stronger and have double the cutting edges since you can flip them over. They can also take deeper cuts. But they work best with very rigid, higher powered machines. If you use negative inserts in a light machine, you have a greater propensity for chatter.

Positive inserts have half cutting edges since they're only single sided, the cut provides more of a shearing slice, and therefore uses less power. They work well with a lighter lathe.

I have a relatively stiff and robust lathe, 16x54 and I exclusively use positive inserts. I have found for the type of work I do, which is generally under 1" in diameter they give me the best finish. I use C and D inserts almost exclusively.

 

[Susquatch]

With 6 edges would mean that it is a negative rake tool right? My understanding, and I could be very wrong, is that negative rake tools don't work on small light duty machines like mine. I don't recall exactly why, might be tool pressure or something like that. What size lathe do you have?

Basically, the insert has zero rake. Instead, the tool holder and shim/anvil provides the rake.

I use two sizes of WNMG - 1/4 that I got in a set. It's the only tool I use from that set. DON'T BUY FANCY SETS. But that one tool does work great. So I a way, the set did help me choose which insert was the most versatile for me - maybe that was even worth the cost..... I also have boring bars and a left hand tool that take that same W insert. The smallest tools I have are a 1/2 inch shank. But they cannot be flipped so they only have 3 corners. That's still 50% better than just two. I also use a 1/4 round insert. You just rotate it as it gets dull. But round inserts can provide a great finish when nothing else works.

My lathe had a 13" swing and a BXA Aloris Style Toolpost. The standard tool holders are 5/8 so that's the tool size I prefer. You can get or make 3/4" Tall tool holders for it too. It's easy to find WNMG inserts and tools that fit 5/8 and 3/4" tool holders.

As I said before, my goto carbide is a Trigon with an anvil. This is probably the strongest insert shape that there is that can do tight corners. Combine that with 6 working corners and common tool holders in most shapes - including boring bars and both R & L tools and it's very hard to beat. Like you, I don't want a big huge collection of inserts. It's bad enough that you need different tip radiuses, but you also have to get them for different materials. So I decided to standardize on Trigon. I have no regrets. Although I do have a small collection of the smaller size that I got with that first stupid set...

I didn't expand my carbide tools to include other shapes like T (triangle) or S (square) or R (rhombic) because you never know what else you need. And most of these are not really that different from the Trigon. You can do a light undercut with trigon so that covers off most Rhobic and Triangle. The only one that you can't really do is the sharper diamond shaped tools. But I find them fragile. They also only have 2 tips. So when I need something special, I usually just grind some HSS. That's a lot easier that buying a variety of inserts for a specialty use. I'm not a job shop. I'm a hobbiest.

What size is your lathe and what size is your tool holder?

 

[Megar arc 5040dd]

Basically, the insert has zero rake. Instead, the tool holder and shim/anvil provides the rake.

I use two sizes of WNMG - 1/4 that I got in a set. It's the only tool I use from that set. DON'T BUY FANCY SETS. But that one tool does work great. So I a way, the set did help me choose which insert was the most versatile for me - maybe that was even worth the cost..... I also have boring bars and a left hand tool that take that same W insert. The smallest tools I have are a 1/2 inch shank. But they cannot be flipped so they only have 3 corners. That's still 50% better than just two. I also use a 1/4 round insert. You just rotate it as it gets dull. But round inserts can provide a great finish when nothing else works.

My lathe had a 13" swing and a BXA Aloris Style Toolpost. The standard tool holders are 5/8 so that's the tool size I prefer. You can get or make 3/4" Tall tool holders for it too. It's easy to find WNMG inserts and tools that fit 5/8 and 3/4" tool holders.

As I said before, my goto carbide is a Trigon with an anvil. This is probably the strongest insert shape that there is that can do tight corners. Combine that with 6 working corners and common tool holders in most shapes - including boring bars and both R & L tools and it's very hard to beat. Like you, I don't want a big huge collection of inserts. It's bad enough that you need different tip radiuses, but you also have to get them for different materials. So I decided to standardize on Trigon. I have no regrets. Although I do have a small collection of the smaller size that I got with that first stupid set...

I didn't expand my carbide tools to include other shapes like T (triangle) or S (square) or R (rhombic) because you never know what else you need. And most of these are not really that different from the Trigon. You can do a light undercut with trigon so that covers off most Rhobic and Triangle. The only one that you can't really do is the sharper diamond shaped tools. But I find them fragile. They also only have 2 tips. So when I need something special, I usually just grind some HSS. That's a lot easier that buying a variety of inserts for a specialty use. I'm not a job shop. I'm a hobbiest.

What size is your lathe and what size is your tool holder?

My lathe is 10" plain bearing lathe with axa qctp. It's a really old atlas with the short bed. My speed ranges without going into back gears range from about 250rpm to 985rmp.