Brand new lathe owner here, this was super-useful, thanks! (I had no idea, and was amazed by the improvement in surface finish, just by changing the tool angle slightly!)
Thank you for sharing your knowledge with us. Great video and results using carbide inserts. I have an old South Bend 13"x72" lathe from 1960. Engine lathe with a 3-step pulley and 2-1/4" wide belt. It has been used hard and lied about when I bought it. My first lathe that I bought in 2019, I just turned 70 years old in April. You have made it clear that you need to know what you are working with and compensate to keep it on the mark. Old lathes can still turn out good work. Learn what's best for yourself and for the lathe to get the best results. I use carbide inserts and HSS in combination and I understand what you were trying to express with the speed and diameter, at least I have learned that little bit while using my lathe. Again, thank you.
Thank You! Yes - old machines can produce high quality work, some people seem to think there are hard and fast rules for speeds, feeds etc, but there's usually a "work around" once you get to know your machines well.
@@framavia2201 It does seem that with inserts for my lathe the best results are in the 400+RPMs and at 900+RPMs. Every once in a while I get good results at slower speeds. Still a long ways to go and a race against the clock. lol
If you look at all the specs that manufacturers of carbide inserts make for their tooling, it will show you a "minimum depth of cut". There are roughing, finishing, and in betweeners as far as inserts go. The manufacturers make their spec sheets based off of getting polished surface finishes with a cut. Has to do with "sharpness" of an insert. Nose radii basically. But yeah they go through a lot of effort to give us all the information we could ask for to basically know exactly what the insert is gonna do and how it will perform before it even touched material. Talk to any rep from insert suppliers and they should know all this info. If you have a particular job coming up get with a supplier and give him your needs and measurements and they can pull up the tooling that will get the job done. That being said, absolutely worth it to get accustomed to using HSS especially for us home gamers as its super versatile, far cheaper, and can still do anything we need it to. On the rare cases we are working with tool steel alloys, thats really when carbide is a must.
The problem isn’t the carbide, it’s that you’re not supposed to do the finishing cut with a roughing tool, you need an insert with a small nose angle and decrease the feed, there might also be some vibrations that are causing the poor surface so make sure that the part isn’t sticking out too far from the chuck, otherwise you might need a tailstock.
This is the BEST video I have ever seen on explaining surface finish problems with carbide! Now I can see where I am going wrong. I have an old Colchester Triumph lathe - very similar to your Student just a lot bigger. Also with a top speed of 1000rpm. I am very lucky - although it looks tatty the lathe is in mint condition. I have been getting terrible surface finish with my carbide tooling. Obviously taking much too light a cut. They really need to be worked hard. I didn't see the point in a DRO on a lathe - until I saw yours. It works very well indeed.
I was much the same about the DRO. Then I did a job at work on the mill (unusual, I'm a stainless fabricator) using the DRO. After that I just HAD to put one on my lathe at home. Now I'd never go back.
I have noticed the differences in finish when taking light cuts, but I tend to not switch to high speed steel. I guess I need to get better at grinding the HSS tool bits. This is good information!
You can get good finish with carbide tips, you run the machine extremely slow and use a really slow feed, takes a long time but you get a perfect mirror finish (although this isn't really practical in a working machine shop as it takes too long)
I mostly use carbide inserts except when cutting Polyurathene as the HSS tool need a very steep positive rake angle and sharp point the 2nd is when cutting coarse pitch multi-start acme / Trap. threads as carbide doesn’t have enough clearance and it rubs where as HSS can be ground with clearance then It doesn’t rub . 3rd is making tiny HSS boring bars .
Really great video showing plusses and minuses. I have been having to do a lot of post-polishing, trying to get passes with either HSS or Carbide Inserts on a minimal 10" Atlas 10F lathe. I gen'ed up an excel spreadsheet of surface speeds versus pulleys versus stock diameter. That's where the reality of the limits of these classic lathes showed up. Even trying to get surface speeds for Aluminium is hard to do at small diameters.
It's just the nature of the beast...plus carbide inserts are generally designed for production runs and reaching target dimensions quicker and in less passes on huge machine tools rather than fiddling with spring passes on bench top lathes!
That's the problem running indexable carbide insert tooling on the older lathes built when HSS was still the norm. At 1"diameter 1100 RPM would give you about 300 SFM, which is about minimum.
Most machinists think that carbide is the be all and end all of cutting tools but they couldn't be more wrong, personally i never use carbide for plastics or soft metals because they're completely unsuitable and there were many times when I've had to use HSS on steels because the carbides just didn't suit the job/ circumstances.
I am guessing the spindle bearings in that lathe are as old as the machine itself? Some of your problems may lay there I think. Harmonic waves in the finish usually are adjustment or worn spindle bearings more than anything else...
Harder materials you always want to run a little under the center line. Soft materials you stay center. Unless facing thats the only time you always want to stay on centerline.
Retired machinist/toolmaker here (40+ years). This is painful to watch…. If you need to polish anything to size, you’re NOT a machinist. If you can’t maintain a surface finish (as specified by a blueprint) without polishing, you’re NOT a machinist. You should be able to maintain size and surface finish with either carbide or HSS if you know what you’re doing.
The video's dynamic range is way out there. Can barely hear the talking so need to turn the volume up, then as soon as the lathe starts the speaker blows up. Some editing would be really helpful here, or at least speak louder or use some kind of a mike. As for finish you really need inserts with the right geometry for finish cuts... I've never gotten a shiny finish off of HSS, no idea why. Best I can get is a brushed steel finish.
the insert has a proper angel thers no point in tilting the slide. And those marks come from wrong feed and speed ans vibrations. you should only leave 2 times the diameter hanging out.
Granted the marks come from cutting at the wrong speed, but thats kind of my point, the top speed of this lathe is 1000 RPM, which becomes too slow to get really good results with carbide inserts at diameters much under 2 inches. Lots of people in this situation will get better results with a well honed very sharp HSS tool with a small nose radius.
Get to the point already. Didn't need to waste time showing off the DRO just to prove carbide can't cut small. One big cut, cuts good. One small cut, cuts like crap. Put the HSS in and do the same. Two videos scaled down to 4 minutes or less.
Brand new lathe owner here, this was super-useful, thanks! (I had no idea, and was amazed by the improvement in surface finish, just by changing the tool angle slightly!)
Glad it was helpful!
Thank you for sharing your knowledge with us. Great video and results using carbide inserts. I have an old South Bend 13"x72" lathe from 1960. Engine lathe with a 3-step pulley and 2-1/4" wide belt. It has been used hard and lied about when I bought it. My first lathe that I bought in 2019, I just turned 70 years old in April. You have made it clear that you need to know what you are working with and compensate to keep it on the mark. Old lathes can still turn out good work. Learn what's best for yourself and for the lathe to get the best results. I use carbide inserts and HSS in combination and I understand what you were trying to express with the speed and diameter, at least I have learned that little bit while using my lathe. Again, thank you.
Thank You! Yes - old machines can produce high quality work, some people seem to think there are hard and fast rules for speeds, feeds etc, but there's usually a "work around" once you get to know your machines well.
@@framavia2201 It does seem that with inserts for my lathe the best results are in the 400+RPMs and at 900+RPMs. Every once in a while I get good results at slower speeds. Still a long ways to go and a race against the clock. lol
If you look at all the specs that manufacturers of carbide inserts make for their tooling, it will show you a "minimum depth of cut". There are roughing, finishing, and in betweeners as far as inserts go.
The manufacturers make their spec sheets based off of getting polished surface finishes with a cut. Has to do with "sharpness" of an insert. Nose radii basically. But yeah they go through a lot of effort to give us all the information we could ask for to basically know exactly what the insert is gonna do and how it will perform before it even touched material. Talk to any rep from insert suppliers and they should know all this info.
If you have a particular job coming up get with a supplier and give him your needs and measurements and they can pull up the tooling that will get the job done.
That being said, absolutely worth it to get accustomed to using HSS especially for us home gamers as its super versatile, far cheaper, and can still do anything we need it to. On the rare cases we are working with tool steel alloys, thats really when carbide is a must.
The problem isn’t the carbide, it’s that you’re not supposed to do the finishing cut with a roughing tool, you need an insert with a small nose angle and decrease the feed, there might also be some vibrations that are causing the poor surface so make sure that the part isn’t sticking out too far from the chuck, otherwise you might need a tailstock.
U might have solved my problem🙌🏽
Just discovered your channel. Really like these turning experiments.
Glad you like them!
Doesn't it figure? You try to show the problems and come up with excellent results. Nice video.
This is the BEST video I have ever seen on explaining surface finish problems with carbide! Now I can see where I am going wrong. I have an old Colchester Triumph lathe - very similar to your Student just a lot bigger. Also with a top speed of 1000rpm. I am very lucky - although it looks tatty the lathe is in mint condition.
I have been getting terrible surface finish with my carbide tooling. Obviously taking much too light a cut. They really need to be worked hard.
I didn't see the point in a DRO on a lathe - until I saw yours. It works very well indeed.
I was much the same about the DRO.
Then I did a job at work on the mill (unusual, I'm a stainless fabricator) using the DRO.
After that I just HAD to put one on my lathe at home.
Now I'd never go back.
learned alot on using hss and tungston thanks.
I like your understated style. The information is very helpful for a musician like me who also likes other stuff. Don't listen to the haters!
Thanks, think I have to accept a few haters doing something so public! Far more motivated by positive comments though!
I have noticed the differences in finish when taking light cuts, but I tend to not switch to high speed steel. I guess I need to get better at grinding the HSS tool bits. This is good information!
Thanks for this info. Will have an experiment of my own now.
You can get good finish with carbide tips, you run the machine extremely slow and use a really slow feed, takes a long time but you get a perfect mirror finish (although this isn't really practical in a working machine shop as it takes too long)
Thanks for the tips!
I mostly use carbide inserts except when cutting Polyurathene as the HSS tool need a very steep positive rake angle and sharp point the 2nd is when cutting coarse pitch multi-start acme / Trap. threads as carbide doesn’t have enough clearance and it rubs where as HSS can be ground with clearance then It doesn’t rub . 3rd is making tiny HSS boring bars .
Really great video showing plusses and minuses. I have been having to do a lot of post-polishing, trying to get passes with either HSS or Carbide Inserts on a minimal 10" Atlas 10F lathe. I gen'ed up an excel spreadsheet of surface speeds versus pulleys versus stock diameter. That's where the reality of the limits of these classic lathes showed up. Even trying to get surface speeds for Aluminium is hard to do at small diameters.
spider runs across the table at first few seconds of video lol
1st thing I saw, 4yrs later 😂
It's just the nature of the beast...plus carbide inserts are generally designed for production runs and reaching target dimensions quicker and in less passes on huge machine tools rather than fiddling with spring passes on bench top lathes!
Yup, couldn't have put it better - I have an idea for a whole new video now.
That's the problem running indexable carbide insert tooling on the older lathes built when HSS was still the norm. At 1"diameter 1100 RPM would give you about 300 SFM, which is about minimum.
Most machinists think that carbide is the be all and end all of cutting tools but they couldn't be more wrong, personally i never use carbide for plastics or soft metals because they're completely unsuitable and there were many times when I've had to use HSS on steels because the carbides just didn't suit the job/ circumstances.
Don’t drag back with your carbide insert they are prone to chipping the tip wind back out it will help as well
Thanks for that information. Very helpful.
You're welcome!
nice work
Thank you! Cheers!
0:00 there's a spider in the background on the machine
Fantastic video, thank you!
Thank you! (good comments will encourage me to make more I hope)
I am guessing the spindle bearings in that lathe are as old as the machine itself? Some of your problems may lay there I think. Harmonic waves in the finish usually are adjustment or worn spindle bearings more than anything else...
Yeah, I want to investigate the headstock and bearing preload at some point, almost certainly original
16:30 ? are you at the center with the insert ? First thing to check..
Harder materials you always want to run a little under the center line. Soft materials you stay center. Unless facing thats the only time you always want to stay on centerline.
Retired machinist/toolmaker here (40+ years).
This is painful to watch….
If you need to polish anything to size, you’re NOT a machinist.
If you can’t maintain a surface finish (as specified by a blueprint) without polishing, you’re NOT a machinist.
You should be able to maintain size and surface finish with either carbide or HSS if you know what you’re doing.
Try all that on a clapped out worn machine, then come back and tell us.
The video's dynamic range is way out there. Can barely hear the talking so need to turn the volume up, then as soon as the lathe starts the speaker blows up. Some editing would be really helpful here, or at least speak louder or use some kind of a mike.
As for finish you really need inserts with the right geometry for finish cuts... I've never gotten a shiny finish off of HSS, no idea why. Best I can get is a brushed steel finish.
About what spindle speed were you running in the video? 13-1500? Just wondering. Great video
The highest speed on this lathe is 1000, thats another reason I have to resort to HSS sometimes.
@@framavia2201 ah. I completely understand with the hss. Carbide can be real picky. You ever considered converting it to run a little faster?
I don't like to use that tool for finish cuts... they pull into the bar.
Yeah same, V and D style inserts can get much higher surface finish
what kind of steel is that?
It's just some bright mild steel - like EN1A or 12L14, its one of those which will machine very easily, but give you finish problems from time to time
Great info but please give a sound warning. I near blew my drums out.
Noted!
7:44 .. u drive to many RPM :D ,,, but your inserts are 2 cuts on each right? so you have lots of money for new ?
That was not even close to minimal recommended RPM, those inserts can easily work up to 800 sfpm. Just look at some CNC lathes using same inserts.
great vid!!
Thxs Sir!
Buen Video
Where did you buy this first pellet from the video?
I Cant remember where I got it, its a CNMG431
What model?
the insert has a proper angel thers no point in tilting the slide. And those marks come from wrong feed and speed ans vibrations. you should only leave 2 times the diameter hanging out.
Granted the marks come from cutting at the wrong speed, but thats kind of my point, the top speed of this lathe is 1000 RPM, which becomes too slow to get really good results with carbide inserts at diameters much under 2 inches. Lots of people in this situation will get better results with a well honed very sharp HSS tool with a small nose radius.
Are they BLUE ? ? it's good .. if not .. to much rotation and too little feed me friend (y)
Get to the point already. Didn't need to waste time showing off the DRO just to prove carbide can't cut small. One big cut, cuts good. One small cut, cuts like crap. Put the HSS in and do the same. Two videos scaled down to 4 minutes or less.
ur voice could be lower ?! your voice so low and the machine so loud :|
carbide need more cutting pressure the HSS, and a good depth of cut and chip load, That will fix your crap finish.
Next video : carbide vs nails
very poorly titled. wast of my time