Best Cutting Tools for Lathe Beginner

[Susquatch]

I mostly turn aluminum (6061) and plastic (Delrin and some UHMW) with occasional items of 12L14 or 1144 steels. I often need short but accurate internal bores for bearings and long bores for housings and such. Also, internal threads.

That's quite a wide range of applications...... Cutting aluminium and plastic is not difficult and I can definitely see the advantages of using proper inserts that don't suffer from edge buildup.

But I think mystery steel is what gets most of us all tied up in knots. It certainly is my nemesis.

For my projects, polished positive rake inserts such a DCGT and CCGT work well.

What do you mean by polished?

I've had excellent results from the cheap eBay Chinese inserts labled as "Iscar" but almost certainly not. Prices have recently greatly increased but most of my inventory (probably sufficient for my lifetime) was purchased for less than $20/box of 10 and each insert has 4 edges so $0.50 per edge. Prices on eBay are now double or so ($1/edge). I don't think that it is reasonable to save a dollar by using HSS but then to waste 15 minutes sharpening plus having to reset tool height; your mileage may vary!

I often find this number of edges thing to be a false promise. Often the edge breaks or wears in a way that the other edges can't be used. I know I'm hard on inserts because of my mystery metal work and the frequency of interrupted cuts to clean up stock. Resetting tool height is a zero problem with a good standard. It's easy to justify using inserts on the basis of the ease of work continuation after a failure alone, and price per edge does come down fast. My favorite Trigons have 6 usable edges, but if only they really had 6 usable edges.

If you cannot tell, I have learned to use inserts, I do use inserts, and I like using inserts. I just don't recommend them as a starting point for a new machinist, and I also think this whole debate of cost is a red herring PROVIDED what you have works for what you are doing. If it doesn't work the whole cost discussion is meaningless.

It's getting there that gets you out of range cost wise. Tooling up for carbide inserts is NOT a trivial expense despite the logic that says otherwise! All these sizes, tool holders, edges, designs, point radius, coatings, anvil or shim, material targets (steel, CI, Al, hard steel, etc etc quickly add up. Multiply by the intent (RH turning, LH turning, tight corners, facing, chamfering, grooving). Plus you normally have to buy 10 of each for each. Worse, when it doesn't work, a newbie has no idea why. Getting help is NOT trivial.

As I said, I am getting there myself. But it wasn't an easy trip and I'm still not fully there yet. As I write this, I'm still mud wrestling with insert threading. It's sooooo confusing. I've been single point threading with HSS for 40 years. I'm darn good at it. I can only begin to imagine what it would have been like if I had started with Carbide Inserts.

For boring I use Chinese solid carbide boring bars with CCGT inserts. The carbide boring bars are more rigid than steel ones and that is essential for a 1/2-inch bore 3 inches long. I'm uncertain how one would substitute HSS.

Most of my boring bars are steel with inserts too.

But I'm not above using solid carbide, or steel bars with small 1/4 or 1/8 HSS Bits.

I'm also not above drilling and reaming.

But my goto is steel with inserts.

Things get more and more interesting as the hole diameter gets smaller and the depth gets deeper.

IMHO, boring small deep holes is NOT beginner territory. Better to drill and ream if you can. If you can't, ANUSOL helps.

I agree that a bump knurler is not really suitable for a light lathe such as a Myford. Hemingway Kits have a rather nice scissor type that is specifically Myford sized.

Right on.

Or maybe a cut knurler would be a good project.

A cut knurler is on my ToDo list. Not sure making one is a good newbie project though. I don't know how well they work on smaller lathes. @Mcgyver @gerritv?

 

[trevj]

What do you mean by polished?

Once you see a xxGT insert, you will know exactly what he means.

Smooth and shiny, like they are chromed, except they are not!

The xxGT edge is SHARP!

 

[Susquatch]

Once you see a xxGT insert, you will know exactly what he means.

Smooth and shiny, like they are chromed, except they are not!

The xxGT edge is SHARP!

I have 4 different xxgt inserts that are neither polished nor sharp.

The only ones that are sharp, are the ones specifically made for aluminium.

 

[thestelster]

I have 4 different xxgt inserts that are neither polished nor sharp.

The only ones that are sharp, are the ones specifically made for aluminium.

I bet those aluminium ones are xxGX. Those are often the shiny ones. Mirror like finish.

 

[kstrauss]

High positive rake inserts for aluminum (DCGT for example) have a polished, almost mirror, finish and are extremely sharp (I have the cuts to prove it!).

Mystery metal is certainly a problem and I avoid such. Most of the things that I make are probably smaller than 1 cubic inch so splurging on the "good stuff" like 1144 typically costs less than $1. It isn't worth trashing an insert or getting a awful finish by using an unknown material.

Interrupted cuts are definitely an issue with carbide. My solution is to use CCMW inserts. Same holder and tool height as a normal CCMT insert but almost indestructable of HSS. Note that these are zero-rake and give a great finish on brass like 360. See https://littlemachineshop.com/products/product_view.php?ProductID=3696&category= for the only source that I know -- local suggestion appreciated!

Yes, if the size matters I generally drill, bore and ream.

 

[Susquatch]

High positive rake inserts for aluminum (DCGT for example) have a polished, almost mirror, finish and are extremely sharp (I have the cuts to prove it!).

Ah yes, the key isn't xxgt, it is "for aluminium". I have those too and I use them for steel per discoveries by @Dabbler & @RobinHood. Game changer. But again prolly too much diversity and simultaneous specialization for someone with their first lathe.

Mystery metal is certainly a problem and I avoid such. Most of the things that I make are probably smaller than 1 cubic inch so splurging on the "good stuff" like 1144 typically costs less than $1. It isn't worth trashing an insert or getting a awful finish by using an unknown material.

I am a farmer. I use what I can get my hands on. Rarely do I ever have the luxury of specialized metal. Even a small piece requires a road trip to a supplier so it doesn't happen cuz I have the perfect size chunk of metal right here hidden in this here cultivator frame bracket. Most of what I make is relatively big.

Interrupted cuts are definitely an issue with carbide. My solution is to use CCMW inserts. Same holder and tool height as a normal CCMT insert but almost indestructable of HSS. Note that these are zero-rake and give a great finish on brass like 360. See https://littlemachineshop.com/products/product_view.php?ProductID=3696&category= for the only source that I know -- local suggestion appreciated!

WOAH! That's a HSS insert! I use something similar from ARWarner. Love it too. Hard to beat a nice HSS INSERT!!!


See, the problem growing? You use this for that, and that for this. And so the variety and number of tools in the carbide tool kit grows. I'm ok with that at my point in the curve - or perhaps I should say that after 40 years of HSS, I was ready for that. But it will cast an ominous shadow over the path of a fellow with a new lathe. If everyone was exactly like you or exactly like me, we could prolly tell them exactly what to get and how to use it. But the chances of that are slim.

This is yet another reason why I prefer to recommend starting with HSS. A newbie can do almost anything with it once they learn to grind their own. You are WAAAAY beyond that. I'm just now getting there.

Once they find their way, there is lots of time to find and buy the right insert tooling. In the meantime, they will never get caught short on a job they cannot finish without another tooling order. And more importantly, they will learn something that will serve them well in the future.

 

[gerritv]

@Susquatch way too much overthinking. I can't recall the last time I used HSS except as a graver on my Sherline. I get good results with my 'whatever I bought' inserts from AliExpress. On al, steel, brass, bronze, O1/A2. Only problem that comes up is with mystery metal but switching to a new insert and playing with RPM usually solves that.

 

[Susquatch]

@Susquatch way too much overthinking. I can't recall the last time I used HSS except as a graver on my Sherline. I get good results with my 'whatever I bought' inserts from AliExpress. On al, steel, brass, bronze, O1/A2. Only problem that comes up is with mystery metal but switching to a new insert and playing with RPM usually solves that.

You love your new avatar so much that you are passing it on to me now? LMAO!

I do tend to overthink things. But after careful overthinking of how much overthinking got applied, I think not this time!

Even though I am already mostly there, embracing carbide insert tooling has been very painful, very time-consuming, and very expensive for me. I don't wish that on anyone. Especially not someone with their first lathe.

 

[kstrauss]

Congrats on your first cut!

A minor point to further muddy the HSS/carbide insert discussion:

With inserts you only need one insert holder of each flavour. You can very quickly change between inserts for aluminum, inserts for steel, inserts for interrupted cuts and... This doesn't seem a big deal until one realizes that each QCTP holder is likely $20-$30 and for convenience you will want a QCTP holder for each HSS tool. Ten Chinese inserts (4 or more cutting edges each so 40 perfectly ground and honed edges ready for play) are frequently about the same price as a single QCTP holder.

 

[Susquatch]

With inserts you only need one insert holder of each flavour. You can very quickly change between inserts for aluminum, inserts for steel, inserts for interrupted cuts and... This doesn't seem a big deal until one realizes that each QCTP holder is likely $20-$30 and for convenience you will want a QCTP holder for each HSS tool.

This is a VERY VALID POINT. I'd only add that the list of different inserts to fit each tool includes different nose sizes, different coatings, different target materials, different chip breakers,...... box of 10 for each. So being able to use one holder and tool for all those is a REALLY BIG DEAL!

 

[trevj]

I have 4 different xxgt inserts that are neither polished nor sharp.

The only ones that are sharp, are the ones specifically made for aluminium.

I have yet to buy a xxGT insert that was not looking like it was chromed by a shop that cared!

Maybe MY experience, but they have all been smooth and shiny, in my experience. And sharp!

 

[Susquatch]

I have yet to buy a xxGT insert that was not looking like it was chromed by a shop that cared!

Maybe MY experience, but they have all been smooth and shiny, in my experience. And sharp!

I've only been at this insert thing for a few years now, so I know I could be all wet. It wouldn't take much. My understanding is that ABCD inserts mean:

A - is the insert Shape (trigon, rhomboid, triangle etc)

B - Relief Angle at Nose

C - Dimensional Tolerance

D - Chipbreaker & Clamping

For xxGT inserts
G = length 0.001 / thick 0.005
T = one sided chip breaker

There is nothing in any of that which specifies coating, polish, or edge sharpness. Basically, you could get anything.

Oddly, the application target material isn't part of the insert designation. Instead it is listed in the insert specifications for a given Part Number (sometimes.... LOL).

My experience is that inserts designed for cutting aluminium (N) are almost always both sharp and polished. Rarely otherwise. The insert lettering is not relevant.

Here are two of my inserts. Both are WCGT. The right one is for Steel (P) the left one is for Aluminum (N).



For reference,
P is for Steel
M is for Stainless
K is for Cast Iron
N is for Non Ferrous like Alum
S is for High Temp Alloys
H is for Hard Metals

In case anyone is wondering, things like nose radius, size, etc are all given by a set of numbers after the 4 letters above. The format and meaning of these numbers are different for metric and ANSI.

The above info is not intended to be comprehensive. It is only meant to point out that xxGT is relatively meaningness in terms of polish and edge sharpness.

As a new insert user I found all this stuff to be mostly Greek and VERY confusing. For that reason, I created the following thread to get usage info from more experienced members.

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

This thread by @Ironman provides more comprehensive insert terminology and information as well as some entertainment!

Tips/Techniques - Carbide Turning Inserts - Tutorial

If you are puzzled by the Greek jumble of letters and numbers on a carbide insert, or want to start using carbide, here is a bit of info

canadianhobbymetalworkers.com

Here is a link to the complexity of insert shims/anvils

Thread 'Carbide shims/anvils' https://canadianhobbymetalworkers.com/threads/carbide-shims-anvils.9842/

Lastly, here is an index to OEM insert info that I created a while back.

Links to carbide insert reference documents

Hi all, many members have generously provided links to their favorite insert websites carbide insert catalogs, insert information and reference documents. I've been trying to create a list of those links from all the threads I have run across. It's a very painful search process and I'm not doing...

canadianhobbymetalworkers.com

If nothing else, all this info underlines the complexity of the subject.

With all due respect to those who think it's simple, I disagree. In my view, it's complicated, complex, misleading, and often ambiguous. Even after you think you are starting to understand, curveballs are rampant.

Here is a challenge for those who think they know such things. (@thestelster is not allowed to answer..... LOL)

My right hand external threading tool is an SER1616H16. My left hand external threading tool is an SEL1616H16. No biggie on its own. They came with 16ERAG60 inserts for the RH Tool, but 16IRAG60 internal inserts for the left hand tool! What the Fk is with the internal inserts for the Left Hand External Threading Tool!!! Why not 16EL (Left Hand External) inserts?

In other words, why is the insert called an internal RH insert when it is meant to be used in an external LH tool?

 

[Dabbler]

In other words, why is the insert called an internal RH insert when it is meant to be used in an external LH tool?

Never having used one, I'd say because both situations cut on the same side of the cutter...

 

[Susquatch]

Never having used one, I'd say because both situations cut on the same side of the cutter...

That's a good point. I believe they are indeed the same.

But what about the difference in the nose relief between internal and external? Or is that built into the insert holder?

And how come I can buy External Left Hand Inserts? Shouldn't they be labelled IR/EL?

 

[kstrauss]

Agreed that some things are complicated! Threading inserts aside, selecting the inserts for turning on small lathes is reasonably simple.

There is a great deal of useful info at https://www.carbidedepot.com/resources

The chart at https://www.carbidedepot.com/formulas-insert-d.htm is particularly useful. Click on any of the items to get more details of the possible values.

 

[Susquatch]

There is a great deal of useful info at https://www.carbidedepot.com/resources

The chart at https://www.carbidedepot.com/formulas-insert-d.htm is particularly useful.

I'll add this to my carbide info thread.

Thanks Ken.

 

[Susquatch]

Here is a challenge for those who think they know such things. (@thestelster is not allowed to answer..... LOL)

My right hand external threading tool is an SER1616H16. My left hand external threading tool is an SEL1616H16. No biggie on its own. They came with 16ERAG60 inserts for the RH Tool, but 16IRAG60 internal inserts for the left hand tool! What the Fk is with the internal inserts for the Left Hand External Threading Tool!!! Why not 16EL (Left Hand External) inserts?

In other words, why is the insert called an internal RH insert when it is meant to be used in an external LH tool?

I think I have Sussed out the answer to this question. It's a bit complicated (LMAO), but here goes. @thestelster - ok for you to chime in now.

First off, the insert recommendation to use an IR for external left threading is ok as it will work for most thread pitches using the AG pitch range, but it's technically wrong to do so. It's basically bad advice from the OEM.

The nose relief will be more than needed and the thread profile will only work properly in the middle of the AG thread range.

It's easier to see the issue when using a topping insert like say a 20N thread pitch. In this case, you do need to use an EL insert. The easiest way to see this is to recognize that an internal thread depth of a 20TPI thread is less than the external 20tpi thread. So an IR 20UN insert cannot cut the proper depth for a 20tpi external thread. It will not be deep enough. You must use an EL 20UN insert. That's only one aspect of the issues.

Basically, the seller cheaped out by providing an IR insert with the EL holder. In so doing, they confused the rat shit out of an old man.

I've put a month into this issue only to discover I was misled.

I'd love to hear opinions to the contrary.

 

[Dan Dubeau]

If all you want to do is make stuff then carbide inserts are the easiest and best go-to option to start with.

I still hold onto the notion that every machinist should know how, and be able to grind a HSS toolbit suitable to complete the machining task at hand in whatever material they're machining (if HSS is suitable for it.....). They should also know how to grind a HSS drill too. It's foundational knowledge that absolutely should be something everyone should learn. You need to know what kind of cutting edge to present to the workpiece to achieve the desired results you're after, not just guess at it and throw money at the problem. Another foundational skill is learning to calculate speeds and feed properly. All of those are so glossed over by beginners and IMO are so vital to the success of a project and longevity of tooling. The information and calculations are not that difficult (and very well documented), and once you do them a few times for your tooling and frequently used materials you will develop a better understanding of what they mean, and how to problem solve finish and tool life problems as you encounter them.

That said, I'm a big fan and user of carbide inserts, and even the cheap import ones have earned a place in my shop. I used to not be a fan of import abrasives or cutting tools, considering them a false economy, but I can't find fault in any of the inserts I've received from bang good or amazon. Have yet to order anything from Ali, but they all come from the same well anyway.

Edit: I would skip the brazed carbide stuff unless you find a screaming deal on a bunch of it. Insert offer so much more utility IMO. The extra hassle of sharpening carbide tooling isn't worth the measly cost saving behing brazed toolbits. That's my take, for a beginner there are bigger fish to fry.

 

[MrWhoopee]

Hmm, if I had to buy carbide inserts for every thing I did, I would be much poorer and would not get much done. As some inserts are over 10 buckos each, and 1 misdead may destroy the insert, verses a HSS bit that can be reground many times cause it could be 4 inches long, generly less then 10 buckos, and the fact 75% and more of my work is in unhardened metals, HSS is the go to.

You're obviously looking at the name brand inserts. I have purchased 2 or 3 dozen packs of inserts off Aliexpress, never paid more than $1.25 (U.S.) per insert. The threading inserts I'm currently using are $.58 each. Just ordered 2 more packs.

https://www.aliexpress.us/item/3256805935771680.html

I don't claim they are as good as the name brands, but they are not junk and at $.20/edge I don't care.
I am one of those who prefers to spend his time making parts rather than grinding tools, though I certainly know how.

 

[MrWhoopee]

For those considering purchasing some inserted tooling, a set like these is definitely a good start.

https://www.aliexpress.us/item/3256805344533110.html

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I have purchase a LOT of this type of tooling, both off eBay and Aliexpress. They have all been good quality tools, well made with hardened shanks and using standard inserts and fasteners. None of it has been junk.