What inserts do you like and why?

[Susquatch]

He states there between the 51 and 54 min marks that there is no longer any need for HSS. "Carbide is it".

Gotteswinter just crapped in his own porridge in my books. Although I agree with the value of Carbide inserts and also in the merits of reworking them, I cannot even remotely subscribe to the idea of dumping HSS completely.

Lost my appetite for porridge too.

 

[Dabbler]

I cannot even remotely subscribe to the idea of dumping HSS completely.

His context is that of a commercial user. Even his home shop is now primarily a job shop, and more than half his income derives from it. He has gone to part time a Bosh Electronics, where he works.

For a hobby shop there's nothing like HSS, especially in those sub-1-hp lathes and mills. Somewhere around 3HP, carbide seems to gain the upper hand. Even on my 7HP lathe HSS has a role.

 

[Canadium]

I've been resharpenng inserts for years - it works very well. The edge the you make with hand grinding is more fragile and breaks down quicker than a factory edge, but it is sure worth it!

When you have a 15$ Kennemetal insert, it is a nice bonus to get twice the cutting time on it.

I think he's doing more than just getting twice the cutter time. As I understand it the common criticism of carbide inserts is that they are designed for high speed mass removal of material and don't provide the fine finish or accuracy that can be achieved with HSS at lower speeds and lesser depth of cuts. However this is largely dependant on the nose radius of the carbide insert. By grinding a little off the nose, the nose radius can be reduced to give the carbide insert a different capability.

 

[little ol' e]

It would be interesting to see a head-to-head test between these KBC Korloy inserts and the same (?) "Korloy" inserts from AliExpress, since there's a 10x difference in price between the two.

Thinking about the Gotteswinter statement about (modified) carbide inserts: it has been mentioned before that using the 'for aluminum' carbide inserts can work quite well for small lathe/hobby users. The cost (from AliExpress,not KBC!) is not much, so perhaps worth an experiment.

Why the 10x price difference...
Since I never purchased anything from Aliexpress in the past, Let me see if I can explain. Some if not many here probably already know but here goes.....,

Carbide is about 80% cobalt and 20% tungsten across all the competitive tooling companies. Sandvik, Iscar, Die-jet, Mitsubishi, Ingersol and even Kennametal has become very good over the past several years on the milling side of things.

I doubt you will see those percentages in anything Aliexpress has to offer on the cheap side. I could be wrong, but, I have tried many different grade inserts and coatings over the years. I learned to stay away from many.. Seco is another under the umbrella of on the cheap side along side Korloy, Kyocera and several others which I won't comment on...

On a side note,
Do yourself 1 favor, Don't try to re-sharpen a " Carbide Insert " for more life after the coating has worn off and the carbide is clearly full of wear lines and worn... If you know why I say that... That's great, because you already know.

Good luck to all here in the forum, have fun, enjoy the journey with your machines and try to keep an open mind when it comes to tooling, inserts and coatings. @ Degen!

Over and out

 

[Susquatch]

As I understand it the common criticism of carbide inserts is that they are designed for high speed mass removal of material and don't provide the fine finish or accuracy that can be achieved with HSS at lower speeds and lesser depth of cuts. However this is largely dependant on the nose radius of the carbide insert. By grinding a little off the nose, the nose radius can be reduced to give the carbide insert a different capability.

That's a valid criticism by many. And I agree with you about that debate.

My own criticisms are a bit different. As you read my "opinions", keep in mind that I have lots of Carbide tooling and I generally like it. However,

1. Carbide inserts are expensive. No way around that. It seems that the better they are the more they cost. They cost a lot. Even the cheap ones.

2. It seems to me in my uses that they break too easily. You cannot sharpen an insert that is missing its whole nose.

3. They generally require too high a speed for my liking. I don't like high speed except for roughing and I generally do rough with Carbide.

4. I am a low volume hobbiest/farmer. I don't give a rats butt about volume or production or the value of time. I'm gunna take my time enjoying the task and whether it's carbide or HSS doesn't matter one iota to me.

5. I feel like you need lots of them both in terms of volume, different styles, and different materials, and different profiles. The complexity and variety is ridiculous. Plus you need a half dozen holders.

6. For many of my convenience needs, I can get hss inserts. I've never broken one of those yet.

7. Can't do profiles with inserts unless you have CNC. Must use HSS to grind profiles.

8. My memory sucks. I can't remember all that insert terminology. Nothing to remember with HSS.

9. Somethings just don't work with Carbide Inserts and if they do, I don't know how. Eg Shear tools, tight chamfers, trepanning, tiny boring bars......

10. Lead time - when I have a repair to do, I cannot be waiting for a Carbide Order to arrive. I grab a chunk of hss, grind what I want, and go!

OK, my flak jacket is on! Bring on the debate!

 

[Former Member]

Why the 10x price difference...
Since I never purchased anything from Aliexpress in the past, Let me see if I can explain. Some if not many here probably already know but here goes.....,

Carbide is about 80% cobalt and 20% tungsten across all the competitive tooling companies. Sandvik, Iscar, Die-jet, Mitsubishi, Ingersol and even Kennametal has become very good over the past several years on the milling side of things.

I doubt you will see those percentages in anything Aliexpress has to offer on the cheap side. I could be wrong, but, I have tried many different grade inserts and coatings over the years. I learned to stay away from many.. Seco is another under the umbrella of on the cheap side along side Korloy, Kyocera and several others which I won't comment on...

On a side note,
Do yourself 1 favor, Don't try to re-sharpen a " Carbide Insert " for more life after the coating has worn off and the carbide is clearly full of wear lines and worn... If you know why I say that... That's great, because you already know.

Good luck to all here in the forum, have fun, enjoy the journey with your machines and try to keep an open mind when it comes to tooling, inserts and coatings. @ Degen!

Over and out

I understand coatings more than you think. Use my lathe and mill commercially. I have had my carbide end mills resharpened. Some recoat, some don't.

Again understand your metallurgy and chemical compositions before mentioned coatings are the best point blank.

I am working up my skill level to sharpen in house on the HSS and Carbide end mills. Unfortunately for carbide you need diamond wheels to do anywhere near a good job.

As to sharpening inserts again there are specialised jigs and fixtures (which I have some) to be used but considering the low cost of the insert and time involved I wouldn't unless a specific application requires it.

 

[Former Member]

That's a valid criticism by many. And I agree with you about that debate.

My own criticisms are a bit different. As you read my "opinions", keep in mind that I have lots of Carbide tooling and I generally like it. However,

1. Carbide inserts are expensive. No way around that. It seems that the better they are the more they cost. They cost a lot. Even the cheap ones.

2. It seems to me in my uses that they break too easily. You cannot sharpen an insert that is missing its whole nose.

3. They generally require too high a speed for my liking. I don't like high speed except for roughing and I generally do rough with Carbide.

4. I am a low volume hobbiest/farmer. I don't give a rats butt about volume or production or the value of time. I'm gunna take my time enjoying the task and whether it's carbide or HSS doesn't matter one iota to me.

5. I feel like you need lots of them both in terms of volume, different styles, and different materials, and different profiles. The complexity and variety is ridiculous. Plus you need a half dozen holders.

6. For many of my convenience needs, I can get hss inserts. I've never broken one of those yet.

7. Can't do profiles with inserts unless you have CNC. Must use HSS to grind profiles.

8. My memory sucks. I can't remember all that insert terminology. Nothing to remember with HSS.

9. Somethings just don't work with Carbide Inserts and if they do, I don't know how. Eg Shear tools, tight chamfers, trepanning, tiny boring bars......

10. Lead time - when I have a repair to do, I cannot be waiting for a Carbide Order to arrive. I grab a chunk of hss, grind what I want, and go!

OK, my flak jacket is on! Bring on the debate!

If you are you are going to try one for general turning I might suggest these, I love them since I started using them.

 

[Former Member]

His context is that of a commercial user. Even his home shop is now primarily a job shop, and more than half his income derives from it. He has gone to part time a Bosh Electronics, where he works.

For a hobby shop there's nothing like HSS, especially in those sub-1-hp lathes and mills. Somewhere around 3HP, carbide seems to gain the upper hand. Even on my 7HP lathe HSS has a role.

I started using brazed Carbide and later Carbide Inserts on my old Logan with a 1/4HP motor. Loved it. Still used HSS on special cutters for the reasons @Susquatch lists.

When I did my mill riser on that lathe cutting 4041 it was inserts that got the finish and could do the cut. All done at slow speeds as this was a 70lbs chuck.

 

[Susquatch]

you are you are going to try one for general turning I might suggest these, I love them since I started using them.

Couldn't agree more. I like them too. Here are mine.



Note the damage on the small one. But to be fair, it has a lot of miles on it.

Not visible in the photo is the grinding I had to do on the big holder to get decent clearance. The original could not be used for face cuts without turning the tool post.

There are two things I especially like about these inserts.

1. They can be simply turned 15 degrees or so for a whole new edge. One insert lasts forever. That small one is about 5 years old and has never been replaced - just turned it a bit to get a fresh edge. This has a huge affect on ROI.

2. They produce a very good finish even at lower speeds than specified. The only thing more reliable is a HSS Shear Tool.

As I said right off the bat, I am not Anti Carbide. Just not anti HSS Either! I think Gotteswinter is crazy despite @Dabbler's explanation.

I'm glad you posted these. I would highly recommend them for other hobbiests too.

 

[Susquatch]

Having just discussed the advantages of round inserts, I confess that I'm quite surprised that nobody has brought up triangular vs rectangular vs diamond vs Trigon etc. Surely all these shapes have their place.....

I confess I like Trigon inserts. They have three working points, and are generally great for hogging off metal at high speeds and feeds.

I'm not fond of triangular inserts. But I can't explain why. I guess I just don't trust the reliefs.

I am ok with rectangular but don't like having just two edges. Why use rectangular when Trigon will do everything rectangular will do with 50% more edges for the money?

I do not like diamond inserts. In my opinion, long points like that are more suited to HSS.

Flack Jacket On......

 

[Canadium]

I started using brazed Carbide and later Carbide Inserts on my old Logan with a 1/4HP motor. Loved it. Still used HSS on special cutters for the reasons @Susquatch lists.

When I did my mill riser on that lathe cutting 4041 it was inserts that got the finish and could do the cut. All done at slow speeds as this was a 70lbs chuck.

What speeds (approximate range) do you typically use when using inserts?

 

[Former Member]

What speeds (approximate range) do you typically use when using inserts?

I find that the speed as a lot more flexible. I do a trial cut or two and adjust accordingly. Depth of cut depends on two things HP and lathe (or mill) rigidity. Again trial cuts give you a feel for your machine.

A starting point is the old recommended standard's generally speaking speed can be increased and depth of cut as well. Some materials will require slower speeds (hardness) with increased depth.

Again all of these adjustments are to achieve finish, accuracy and tool life.

I do strongly recommend cutting or cooling fluids be used as all of these changes increases heat generated and this should be avoided and this should be avoided at all costs.

An longtime old machinist (master machinist) friend put me on to higher speeds over 20 years ago. His advice was as fast as you can go and get the results you want, book be damned. Carbide has changed the tables.

 

[little ol' e]

What speeds (approximate range) do you typically use when using inserts?

I figure most here are machining more mild steels, so I will start with that.

I generally run most inserts in the 400-1800RPM range on a manual lathe. Simply because we can't feed it consistently like a CNC lathe could, therefore, you generate more heat and wear on the inserts. Having said that, it will work really well with the proper grade inserts for both roughing and finishing.

You want to keep the heat in the chips... The tool needs to stay as cool as you can keep it ( not hot to the touch, warm is where your tool will be most of the time cutting) as well as the bar stock. Use air or coolant, I prefer air.
Why air manually? Carbide does not like heat or inconsistencies (chip load-feed) Therefore, carbide inserts want to crack and wear quickly when you apply coolants to them. If your semi finishing or finishing coolant will be ok since your not generating much heat at that point and your only taking .02 semi and .012-.015 for finishing.

When choosing inserts, you want a decent radius for roughing ( At least .03r on any insert you choose) . I use triangular inserts 85% of the time I would say.
Now, Shell mill inserts as shown above by @Susquach. They are amazing for ruffing in all types of steels. They will eat A2, D2, PH4140, P20, H13 , 01... that tool will take it no problem. Nice dish for chip breaking and flat top inserts work really well too in that style of insert. Keep the RPMS around 900 unless you can really feed it. Don't go heavy, just take .03 DOC's and the insets will last.

Lets try machining something in airplane mode here,

We will begin with a 2" diameter bar of HRS with a stick-out of no more than 6"- no tail stock hole since we will face only.
Lets take DavidR8's tool, inserts and go at it.
Thanks David, we will pay it forward, I promise!

Since we are starting out with only 1 style insert with a .015r, we need to keep the RPMS up a bit for roughing with it, kinda backwards to what we should do, but, I don't have the keys to David's tool box just yet to see if we could use something else.

Now because of the .015r, that tells us this is a semi finishing/finishing grade carbide insert (we won't get into the coating this time. Why, because it will heat up so quick the coating will be gone in minutes manually machining). Having said that, we know now, this insert and coating does not like heat at anytime, it will turn its nose up and down with heat until it wears down quickly. Using air or coolant, those inserts will wear rather quickly. Too much heat then add coolant, they will just crack. Carbide inserts need consistency for the most part. The more expensive inserts can withstand much more abuse in manual machining, they have much better coating and tougher grades of carbide.

Lets start roughing...
We will set the RPMS to 750 for our first pass in the 2" diameter HRS bar stock with a stickout of 6" Take .025 feeding slowly with air ( Coolant up to you I would stick with air until finishing )
The insert will now have some wear due to the radius and coating. It will be black around the nose and all around its face. Nothing we can do about it, keep it for skimming the next 1.
Now since that insert has been " heat cycled " and their are other good corners, lets keep that 1 aside for just skimming HRS and the like going forward.

@DavidR8.. We need the keys to your tool box soon lol...

Lets put another insert in since the scale and first .025 depth was a bugger to get through with that insert.

On a side note, for the hobby guys.
A nice HSS cutter, nicely ground with relief would have done just a good a job at 80-110 rpm with 2 passes at .015
Unfortunately, for new guys, grinding cutters and adding reliefs is not something you can learn so quickly.
Insert changes are quick and make results instantly. That's the trade off.


Lets try bumping it up to 1200RPM for semi finishing only taking light passes of .015-.02 max doc with this insert feeding it rather quickly for a nice chip color, Lets take it down to 1.890 leaving us with about .015 give or take. We will finish the last .015 in 2 passes, I mic and split the difference here.
After semi, pull the insert out, put it aside... This will be your semi finishing insert for some time now (hopefully)
Throw in another insert. Don't turn it, put another 1 in, Keep it for finishing.
Lets go to 1800RPM, for the finishing pass, add coolant or WD-40 or what ever flavor oil you like. Amsoil synthetic works too.
A little bit of emery paper to clean up the insert marks if you left any, although it should be a nice finish since we swapped out inserts.

Final note,
When you buy cheaper inserts etc, try to keep track of the lots numbers, this will help when you find yourself stuck as to why the new box of inserts isn't cutting as well as the last 1's did.

I have never done a write up like this in my lifetime, so, it certainly isn't perfect, but will get you pretty darn close guys.
Time to make twin paper rocket, my brain hurts now.
Hope this helps a bit!

 

[Canadium]

...........

An longtime old machinist (master machinist) friend put me on to higher speeds over 20 years ago. His advice was as fast as you can go and get the results you want, book be damned. Carbide has changed the tables.

Typical recommended speeds for carbide inserts I've seen bandied about the net are around 2,000 rpm. Considering my old lathe maxs out at 1200 I'm not sure why I'm even considering trying carbide inserts. If as @Susquatch points out the majority like myself are just hobbyists taking our time with limited resources why am I investing big bucks in a brand name QCTP that requires dozens of expensive tool holders, expensive carbide inserts and is better suited to inserts than HSS!? Why not just stick with the freeby old lantern toolpost which may be best suited to the HSS which my lathe is best suited and designed for? I'm afraid that if I were honest I might admit that it's just because QCTP's and carbide inserts are sexier and nothing else!

 

[little ol' e]

I'm not sure why I'm even considering trying carbide inserts.

From a hobby standpoint.
The key to carbide inserts is about getting instant results rather than grinding HSS or carbide blanks depending on 1's skill level when it comes to grinding.

HSS and carbide blanks will always have its place in manual lathe machining, regardless.
Milling, not so much...

 

[little ol' e]

If you are you are going to try one for general turning I might suggest these, I love them since I started using them.

View attachment 27910

Would you say the chips shown on those cutters above ^^^ were produced with a good speed and feed for that type of insert?

I understand coatings more than you think. Use my lathe and mill commercially. I have had my carbide end mills resharpened. Some recoat, some don't.

Again understand your metallurgy and chemical compositions before mentioned coatings are the best point blank.

I am working up my skill level to sharpen in house on the HSS and Carbide end mills. Unfortunately for carbide you need diamond wheels to do anywhere near a good job.

As to sharpening inserts again there are specialised jigs and fixtures (which I have some) to be used but considering the low cost of the insert and time involved I wouldn't unless a specific application requires it.

I understand your experience. You KISS approach is obviously working for you looking at the chips that came off the inserts your learning to love .
Give em' a Kiss point blank.

 

[Former Member]

Would you say the chips shown on those cutters above ^^^ were produced with a good speed and feed for that type of insert?


I understand your experience. You KISS approach is obviously working for you looking at the chips that came off the inserts your learning to love .
Give em' a Kiss point blank.

Actually the chips on the larger one are from Chinese mystery casting, hard, but powders when you cut it.

The other is scarf from mill running hard fast cuts.

Its not about KISS but biggest bang for the buck.

 

[thestelster]

Typical recommended speeds for carbide inserts I've seen bandied about the net are around 2,000 rpm. Considering my old lathe maxs out at 1200 I'm not sure why I'm even considering trying carbide inserts. If as @Susquatch points out the majority like myself are just hobbyists taking our time with limited resources why am I investing big bucks in a brand name QCTP that requires dozens of expensive tool holders, expensive carbide inserts and is better suited to inserts than HSS!? Why not just stick with the freeby old lantern toolpost which may be best suited to the HSS which my lathe is best suited and designed for? I'm afraid that if I were honest I might admit that it's just because QCTP's and carbide inserts are sexier and nothing else!

Well, 2000rpm might be suggested for some materials and certain diameter work. My lathes max speed is 1000rpm, and I use carbide inserts almost exclusively, but I do have HSS bits for certain applications or scenarios. I think having both systems in your arsenal is advantageous. But there are certain situations where HSS will not work, ie turning hardened parts. Or inefficient ie, turning a large diameter part, where the suggested speed would be so low that you risk falling asleep. I will extend an invitation to you or anyone for that matter, to come over to my shop, and we can try several cutters, and you can make an honest opinion. I know you're in Hamilton, but if you come up to the Keswick area feel free to drop by.

 

[Former Member]

Typical recommended speeds for carbide inserts I've seen bandied about the net are around 2,000 rpm. Considering my old lathe maxs out at 1200 I'm not sure why I'm even considering trying carbide inserts. If as @Susquatch points out the majority like myself are just hobbyists taking our time with limited resources why am I investing big bucks in a brand name QCTP that requires dozens of expensive tool holders, expensive carbide inserts and is better suited to inserts than HSS!? Why not just stick with the freeby old lantern toolpost which may be best suited to the HSS which my lathe is best suited and designed for? I'm afraid that if I were honest I might admit that it's just because QCTP's and carbide inserts are sexier and nothing else!

Start with one insert holder and see how you like it, forget the QCTP, make yourself a 4 position holder, no you don't need a mill, this is the first thing I made for my Logan with the Logan. Teaches you a lot about lathe work and set up.

No need to dive in with Big Bucks, go slow and easy.

As to speed, use what you have play a little to maximize performance this is what makes you better then the rest.

One other thing learning how to hand grind is a skill you should learn even if you abandon it later, again teaches you a lot about metals/tooling and edges.

 

[little ol' e]

Actually the chips on the larger one are from Chinese mystery casting, hard, but powders when you cut it.

Ok... I will give you that 1. Hard Chinese mystery casting that turns into powder while machining it.

The other is scarf from mill running hard fast cuts.

I think they call it swarf/turnings or chips but it any case,
What were your speeds and feeds during your hard fast cuts producing those chips on tool #2 ? Also in what material... to help other members understand what the chip loads and chips will look like if they were to try this.
Thanks