Hi Jon, CNMG are my goto, best value for money and you can face and turn with them without having to adjust your tool post to get clearance. The negative rake means they generate a lot more cutting force than a sharp positive rake insert, therefore mini lathes usually struggle to drive them well. Forget 0.1mm finish cuts on carbon steel, you will never get a good result. My advice would be minimum 0.5mm depth of cut and feed as fast as your lathe will let you, this way you will get good chip control and surface finish. Cheers, Jon
Ditto on what Jon said. The CNMG's like to eat so they really shine when taking deep cuts and removing alot of material. For light or finishing cuts I found it is better to switch to a different insert.
I will need to grind off too much with the live center that I have. It is not very long so I thing a longer more narrow live center will provide enough clearance. Thanks for watching.
Your video and the comments do a good job of showing the pluses and minuses of these insert tools. CNMG and similar inserts along with their holders are really too big for a small lathe. Tool overhang exacerbates the rigidity problems often seen in small lathes. If you don't have an extended point live center (often called a CNC center) the bulk of the insert holder gets in the way on small work as shown in the video. Small lathes don't have the horsepower to make the inserts perform as intended. Then there is the expense of inserts. If they last, good times, but it you start breaking them right and left it gets to be a costly endeavor. I have holders and inserts for my 12x24 lathe, but I don't bother using them. Non-Chinese cemented carbide tools and a green aluminum oxide wheel for the bench grinder give years of happiness. Choked up in the holder, they cut the distance between the holder and the work by a third or better. These tools may be ground to a sharp corner or a very small radius that reduce a cause of chatter. If and when the corners break down they may be renewed in just a moment with the bench grinder. As always, use what you like the best and gives good results. In machine work there are usually 10 ways to do something. Cheers from NC/USA
It’s good to see you try these out despite the many opinions as to whether or not they should be used with smaller machines. I did the same, and so far so good. It pays to make up your own mind. The only thing I can’t work out is which way the seats are supposed to face. One side has square edges and one side is chamfered. Any idea?
Hi, the inserts that I have are symmetrical with cutting edges on all points. Therefore my ones can be turned upside down and and used in the same way. Maybe your ones are different?
@@thehobbymachinistnz I worked it out. The insert is symmetrical but the seat/shim the insert sits on (at least on my tool) has a chamfered edge. The reason for this is because the pocket for the insert is milled out and the inside corners aren’t perfectly 90° so they chamfer the bottom of the seat so that it can sit perfectly flush. I since did some more research and worked this out.
Matty from Matty's Workshop has been using TNGG inserts and getting some really fabulous finishes. I went looking to see if they were available in a 12mm shank holder, but as you found 16mm is the smallest, so I've been contemplating doing what you did and machining one down, the hang-out being my only real concern on my little homemade lathe. 👍
@@thehobbymachinistnz You and me both, my little homemade lathe is tiny compared to most lathes on UA-cam, including the cheap Chinese versions, but it can do nice things, see my video this Friday for an example of what it is capable of, finish wise that is. 👍
Thanks for the tips and details. Very helpful. I’ve often wondered if buying even larger tool holders (22+mm) and machining the dovetail directly into the tool holder would be an even simpler approach to minimizing the overhang 😉. Of course the tool holders may be too hard to easily machine the dovetail. 😜
I think Abom79 has done this to a couple of his toolholders, as well as some of the long time youtube machinists have done this. The tool becomes more ridged using this method, but makes the tool more of a single purpose tool.
John Mills on his "Doubleboost" channel has done that with some of his bigger tools, tapping into the hard body for the height adjusting screw could be tricky though ?
With regard to the CNMA inserts, because they have that positive relief angle ground in, they are more for light roughing and finishing. That’s because of the less support underneath the cutting edge. Where as the CNMG insert is a negative rake which gives it more support underneath the cutting edge. This allows for much heavier cuts especially if you have interrupted cuts. Now with regard to your holders, you should never take the material off the bottom of the holder when your sizing it to fit your tool block. In your case it doesn’t really because you can adjust the height of your tool block. But let’s say your running them in a CNC machine where the tool blocks are fixed and not adjustable…it would be a problem. There is a specific height dimension that’s held from the bottom of the tool holder and to the nose of the insert. Once you alter that the way you did, you can’t use them in a fixed tool block without shimming them back up. That’s why if you notice in the tool holders you bought, the step is machined in the top of the tool shank.
Kia ora - consider the 250-102 / XL toolholders. about $30NZD/ea from Ali, fits in a standard A size aloris clone, takes 16mm tools and larger boring bars. Also if you're a cheapo like me, the CNMG inserts are incredibly easy to regrind with an inexpensive high grit diamond wheel. Just a narrow slit along the top surface, grinding towards the insert parallel with the long edge, angled down slightly to create top rake and a chipbreaker. Does small DOC much nicer than anything I can find stock, and way easier than starting from scratch.
Hi, thanks for your comments and advise. I think I should have gone for the 250-102 / XL QCTP and toolholders from the beginning. I have invested in around 25 or more 250-001 toolholders so I'm kind of locked into that now.
nice video, I have thought about doing the exact same thing thank you for sharing your experience 👍👍👍 thinking about the finish, .. I think if you make a deeper cut you might get much better finish, because I suspect that you are not quite "reaching" the chip breaker on those inserts with shallow cuts, .. ?? I am no expert by any means so could be totally wrong, but it would be very nice to see a test with faster speed and deeper cuts. thank you very much
@@thehobbymachinistnz deeper cut means more load on the machine. Not a problem at all for the Abom size machines Adam uses, but definitely not ideal if you are running a 1/2 horsepower Southbend running a belt. For that the DCMT/SCMT/TCMT/CCMT inserts are ideal. They are usually recommended for finishing cuts but for small underpowered machines they are a go to tool and they save money because you only need at most 2 of them. I use a SCMT for facing and chamfering and a DCMT for longitudinal cutting right up to 90° shoulders as they are also good at facing. Left hand tools have hardly any use so if on a budget I would not bother spending money on them but rather to invest in better quality holders. Chinese kits often come with negative(neutral) rake insert tooling and they are best avoided on small machines. Besides, some of the cheap inserts do not have more cutting surfaces once turned over or at least they do not come with chip breakers one the underside.
This is proof that UA-cam info can sometimes be misleading. Adam (Abom79) works on large powerful machines which has the torque and power to plow through heavy cuts for which negative(neutral)rake inserts are desirable as they are much stronger to handle the big loads. They do however require more torque and load on the machine and for this reason they are a bad idea for smaller machines where power is limited. The best inserts for small machines is the ones you started with that comes with a positive rake. They are ideal for light cuts and normally provides nicer finishes. Yes, the drawback of these type of inserts is that they come with less cutting edges and will need replacement less often. I small price to pay for being able to work easy and accurately on machines with little power.
Funny you should ask that. I had that exact same question when I watched Jeremy Schmidt make his belt grinder. I brought my set based on his comments. I inherited a set of imperial Mitutoyo mics from my late father, but I needed a set of metric mics. I think these are quite good quality. Well, I have had no issues with them, they work just as good as my imperial mics, and they appear to be accurate. I do recommend them if you cant afford the more expensive mics.
Any chance you could post a link to the ones you got? NZ dealers tend to grab the low end of the quality of cheap tools, I prefer to get the "expensive" cheap tools haha. Looks like they are reasonably good quality. Cheers
Negative rake inserts are good on big rigid lathes, it'd be tricky on smaller bench lathes.
Yes, I will need to see how this goes. Thanks for watching.
Always good to do some experimenting and testing. Go for it.
Thanks Michel.
Hi Jon, CNMG are my goto, best value for money and you can face and turn with them without having to adjust your tool post to get clearance. The negative rake means they generate a lot more cutting force than a sharp positive rake insert, therefore mini lathes usually struggle to drive them well. Forget 0.1mm finish cuts on carbon steel, you will never get a good result. My advice would be minimum 0.5mm depth of cut and feed as fast as your lathe will let you, this way you will get good chip control and surface finish. Cheers, Jon
Thanks for your comments and advise Jon, much appreciated. I will do more testing with depths, speeds and feeds and see how it goes.
Ditto on what Jon said. The CNMG's like to eat so they really shine when taking deep cuts and removing alot of material. For light or finishing cuts I found it is better to switch to a different insert.
Grind some metal off the back of the tool holder so you can get closer to the live centre. Cheers Tony
I will need to grind off too much with the live center that I have. It is not very long so I thing a longer more narrow live center will provide enough clearance. Thanks for watching.
Your video and the comments do a good job of showing the pluses and minuses of these insert tools.
CNMG and similar inserts along with their holders are really too big for a small lathe. Tool overhang exacerbates the rigidity problems often seen in small lathes. If you don't have an extended point live center (often called a CNC center) the bulk of the insert holder gets in the way on small work as shown in the video. Small lathes don't have the horsepower to make the inserts perform as intended. Then there is the expense of inserts. If they last, good times, but it you start breaking them right and left it gets to be a costly endeavor.
I have holders and inserts for my 12x24 lathe, but I don't bother using them. Non-Chinese cemented carbide tools and a green aluminum oxide wheel for the bench grinder give years of happiness. Choked up in the holder, they cut the distance between the holder and the work by a third or better. These tools may be ground to a sharp corner or a very small radius that reduce a cause of chatter. If and when the corners break down they may be renewed in just a moment with the bench grinder.
As always, use what you like the best and gives good results. In machine work there are usually 10 ways to do something.
Cheers from NC/USA
Thank you very much for your comments.
It’s good to see you try these out despite the many opinions as to whether or not they should be used with smaller machines. I did the same, and so far so good. It pays to make up your own mind. The only thing I can’t work out is which way the seats are supposed to face. One side has square edges and one side is chamfered. Any idea?
Hi, the inserts that I have are symmetrical with cutting edges on all points. Therefore my ones can be turned upside down and and used in the same way. Maybe your ones are different?
@@thehobbymachinistnz I worked it out. The insert is symmetrical but the seat/shim the insert sits on (at least on my tool) has a chamfered edge. The reason for this is because the pocket for the insert is milled out and the inside corners aren’t perfectly 90° so they chamfer the bottom of the seat so that it can sit perfectly flush. I since did some more research and worked this out.
Matty from Matty's Workshop has been using TNGG inserts and getting some really fabulous finishes. I went looking to see if they were available in a 12mm shank holder, but as you found 16mm is the smallest, so I've been contemplating doing what you did and machining one down, the hang-out being my only real concern on my little homemade lathe. 👍
Yes. Kurtis was sold on them, when he needed a "Good finish". they are good. My normak go too is WNMG
Thanks for your comments. Let me know if you do try one. It would be interesting to see how they work.
I think Matty has a much larger lathe than me.
@@thehobbymachinistnz You and me both, my little homemade lathe is tiny compared to most lathes on UA-cam, including the cheap Chinese versions, but it can do nice things, see my video this Friday for an example of what it is capable of, finish wise that is. 👍
Thanks for the review / info...good stuff !
Thanks for watching.
Thanks for the tips and details. Very helpful. I’ve often wondered if buying even larger tool holders (22+mm) and machining the dovetail directly into the tool holder would be an even simpler approach to minimizing the overhang 😉. Of course the tool holders may be too hard to easily machine the dovetail. 😜
I think Abom79 has done this to a couple of his toolholders, as well as some of the long time youtube machinists have done this. The tool becomes more ridged using this method, but makes the tool more of a single purpose tool.
I was quite surprised that these shanks were very hard coming from China. Maybe with the right cutters you could cut a dove tail. Thanks for watching.
John Mills on his "Doubleboost" channel has done that with some of his bigger tools, tapping into the hard body for the height adjusting screw could be tricky though ?
With regard to the CNMA inserts, because they have that positive relief angle ground in, they are more for light roughing and finishing. That’s because of the less support underneath the cutting edge. Where as the CNMG insert is a negative rake which gives it more support underneath the cutting edge. This allows for much heavier cuts especially if you have interrupted cuts.
Now with regard to your holders, you should never take the material off the bottom of the holder when your sizing it to fit your tool block. In your case it doesn’t really because you can adjust the height of your tool block. But let’s say your running them in a CNC machine where the tool blocks are fixed and not adjustable…it would be a problem.
There is a specific height dimension that’s held from the bottom of the tool holder and to the nose of the insert. Once you alter that the way you did, you can’t use them in a fixed tool block without shimming them back up.
That’s why if you notice in the tool holders you bought, the step is machined in the top of the tool shank.
Thank you for the info.
Thanks for sharing 👍
No problem. Thanks for watching.
Kia ora - consider the 250-102 / XL toolholders. about $30NZD/ea from Ali, fits in a standard A size aloris clone, takes 16mm tools and larger boring bars. Also if you're a cheapo like me, the CNMG inserts are incredibly easy to regrind with an inexpensive high grit diamond wheel. Just a narrow slit along the top surface, grinding towards the insert parallel with the long edge, angled down slightly to create top rake and a chipbreaker. Does small DOC much nicer than anything I can find stock, and way easier than starting from scratch.
Hi, thanks for your comments and advise. I think I should have gone for the 250-102 / XL QCTP and toolholders from the beginning. I have invested in around 25 or more 250-001 toolholders so I'm kind of locked into that now.
@@thehobbymachinistnz nothing like running head first into the consequences of our own actions haha, I'm quite the expert at that too! All the best :)
nice video, I have thought about doing the exact same thing thank you for sharing your experience 👍👍👍
thinking about the finish, .. I think if you make a deeper cut you might get much better finish, because I suspect that you are not quite "reaching" the chip breaker on those inserts with shallow cuts, .. ??
I am no expert by any means so could be totally wrong, but it would be very nice to see a test with faster speed and deeper cuts.
thank you very much
Thanks for watching and your comments. Yes, I have used the tool a bit more after this video and a deeper cut does produce a better finish.
@@thehobbymachinistnz deeper cut means more load on the machine. Not a problem at all for the Abom size machines Adam uses, but definitely not ideal if you are running a 1/2 horsepower Southbend running a belt.
For that the DCMT/SCMT/TCMT/CCMT inserts are ideal.
They are usually recommended for finishing cuts but for small underpowered machines they are a go to tool and they save money because you only need at most 2 of them.
I use a SCMT for facing and chamfering and a DCMT for longitudinal cutting right up to 90° shoulders as they are also good at facing.
Left hand tools have hardly any use so if on a budget I would not bother spending money on them but rather to invest in better quality holders.
Chinese kits often come with negative(neutral) rake insert tooling and they are best avoided on small machines.
Besides, some of the cheap inserts do not have more cutting surfaces once turned over or at least they do not come with chip breakers one the underside.
This is proof that UA-cam info can sometimes be misleading.
Adam (Abom79) works on large powerful machines which has the torque and power to plow through heavy cuts for which negative(neutral)rake inserts are desirable as they are much stronger to handle the big loads.
They do however require more torque and load on the machine and for this reason they are a bad idea for smaller machines where power is limited.
The best inserts for small machines is the ones you started with that comes with a positive rake.
They are ideal for light cuts and normally provides nicer finishes.
Yes, the drawback of these type of inserts is that they come with less cutting edges and will need replacement less often. I small price to pay for being able to work easy and accurately on machines with little power.
Thanks for watching. I also use these inserts on my larger lathe.
Half dead center might be useful
Yes, I may work. But it will probably need to be longer than the center that I am using as the bearing casing hits the tool.
Hey :D I have already watched like 5 vids 👍and I see that you seem to use those INSIZE mics I was wondering what is your opinion on them?
Funny you should ask that. I had that exact same question when I watched Jeremy Schmidt make his belt grinder. I brought my set based on his comments. I inherited a set of imperial Mitutoyo mics from my late father, but I needed a set of metric mics. I think these are quite good quality. Well, I have had no issues with them, they work just as good as my imperial mics, and they appear to be accurate. I do recommend them if you cant afford the more expensive mics.
@@thehobbymachinistnz Tnx👍
Any chance you could post a link to the ones you got? NZ dealers tend to grab the low end of the quality of cheap tools, I prefer to get the "expensive" cheap tools haha. Looks like they are reasonably good quality. Cheers
Hi, I have just posted the links to the tools I purchased in the description.
Interesting.
Thanks for watching.