first cut problem

[andyp123Participant @andyp123]

Hi, at last i have got my Myford lathe running and this evening took the first cut, however, as you will see in the photos, it wasn’t a great success. Couldn’t get a smooth finish and it just seemed to push the metal along and created a big burr. And facing left it scuffed.

By-the-way, not sure what the metal is, it was just some scrap someone gave me for exactly this sort of thing!

any clues on what I’m doing wrong?

thanks, Andy

[Paul KempParticipant @paulkemp46892]

Difficult to tell from a photo but as a start I would weigh that bit of metal in and buy a piece of known steel.  Looks like a copper or high copper alloy both of which are not particularly nice to turn and probably not the best material to learn on.  Weighing that in will pay for a reasonable bit of known steel and then you can play around with tool types hss self ground, replaceable tips or even brazed carbide – the latter will get howls of derision on here but they have served me very well in the past and are cheaper than tips!

Paul.

[mark costello 1Participant @markcostello1]

Could We see a picture of the tool edge?

[not done it yetParticipant @notdoneityet]

I started with some aluminium round bar (supplied from where I worked). 30, 40 and 50mm diameter, I think, but likely still Imperial back then…

No problems with that unless tool/operator/machine.  It will be one of the three!

Cutting aluminium bar was an easy starter.  The only real operator error was allowing the tip to get too hot!

Brazed carbide sets were cheap – and therefore nasty.  Green grit needed to get the cutting angles ground better.  Or buy from known suppliers (not chinese/ebay).

[Speedy Builder5Participant @speedybuilder5]

Looks like Phos Bronze to me – lucky boy!

Bob

[JasonBModerator @jasonb]

A photo of the tool in the machine and a closeup of the cutting edge would be useful and also to see if it is HSS or carbide. Most likely blunt or not set on centre height.

Keep the expensive bronze for something later like the boiler for your oscillator, the larger more copper coloured one is not so easy to turn but the smaller looks to have less copper as it is yellower and will be more useful.

[Andrew CrowParticipant @andrewcrow91475]

It looks like you have the tool on centre as you have faced to the centre on one of the pieces so as Jason has stated above it’s down to tool geometry and condition, some photos of the tool being used would also help.

Looking at the material, you have two different types which probably require different geometry to produce a good finish. It may help for you to obtain a couple of books on basic turning from authors like Tubal Cain or Martin Cleeve which give all the basic shapes, clearance and rake angles.

Andy

[JasonBModerator @jasonb]

Or just settle on CCGT inserts and they will cut both of the different bronzes without issue as well as a lot of other materails. It will then take that worry out of getting a decent finish.

[SillyOldDufferModerator @sillyoldduffer]

I diagnose these problems by looking at the three main causes:

• Machine: wrong RPM, feed-rate, insufficient rigidity to wear or poor work-holding, wrong cutter shape, not at centre height, or blunt.
• Material: may not be machinable!  Or difficult.  Too soft, too hard, many metals work-harden during cutting.  Choose carefully, and know what it is.
• Man:   operator doesn’t know, yet, what he has to do.   Doesn’t recognise symptoms.  May be clumsy or poorly coordinated.  Practice required, plus some good books, or a mentor. Lots of practice: turning, facing, boring, threading, trepanning, tapering, finish, and accuracy all have to be mastered.

In this case maybe all three, but mainly learner driver and scrap metal.  Made a terrible start myself due to collecting scrap to learn on, and it all turned out to be horrible.  I was convinced that Mini-lathes don’t work – complete rubbish.   By chance, a friend asked me to turn a steel rod to size, and provided the metal.  It was wonderful – EN1A.  Now I advise beginners not to pratt about with scrap – buy known metal, where the specification says “free-cutting” or “good machinability”.  After learning on them, try scrap.   It can usually be machined by an experienced man.

Hard to tell from the picture, but Andy’s rod looks like Bronze – a difficult metal.  Might be a soft Brass.   Be aware that ‘Bronze’, ‘Brass’, ‘Aluminium’ and ‘Steel’ are alloy families, not one metal.   There are thousands of alloys, each race-tuned to meet a manufacturing need, and very often not machinable.  (The Aluminium alloy used to make extruded greenhouse frames is too soft to machine well in a lathe.  The steel alloy used to make cutters is much too hard.  etc etc.  Beware scrap.  DIY store metal is mostly nasty too.)

The cutter might be wrong toom a machine shortcoming.  For example, those brazed carbide tip cutters are often supplied unsharpened!  I found out the hard way.   HSS and carbide inserts are safer.  Bear in mind that sharpening HSS is an acquired skill.  Some lucky so-and-sos have no bother learning it.  Others struggle – after a lot of practice I manage, not very well.   Watch out for well-meaning chaps who assume that because they are good at grinding HSS, it must be easy.  They are misguided!  A man problem.

Persist.  Starting out, I made many small  mistakes.  Practice, reading the books and taking forum advice slowly eliminated them.  Then something ‘clicked’ and I was away.   The man had learned enough about materials and his machine to get reliable results, unconsciously!  Part of the learning is recognising what’s going wrong.

Andy is doing the right thing: try it, and ask here if it goes wrong.  Lot’s of good suggestions already.   Consider them all, even if they seem contradictory, for example:

• I say avoid Bronze, a difficult material
• Jason says, correctly, Bronzes are cut well by CCGT inserts.

Mine is ‘get you started’ beginner advice; train on easy materials.  Jason’s advice is gold in the next stage –  how to machine Bronze on a real job.  But there’s no learning objection to Andy trying CCGT immediately; inserts are a ‘good thing’.  One caveat: Andy’s Myford was designed when HSS was king, and the machine is a bit slow and underpowered for carbide.   Jason and I have Chinese WM280’s; they’re heavier, faster and more powerful than a Super 7, making it easier for us to get good results from inserts.  Carbide performs best when driven hard and deep with gusto!  Something else to explore.

Dave

 

[SillyOldDuffer]

On SillyOldDuffer Said:

…  One caveat: Andy’s Myford was designed when HSS was king, and the machine is a bit slow and underpowered for carbide.   Jason and I have Chinese WM280’s; they’re heavier, faster and more powerful than a Super 7, making it easier for us to get good results from inserts.  Carbide performs best when driven hard and deep with gusto!  Something else to explore.

Dave

 

Really Dave!  You spoilt a good reply by tacking on some outdated generic drivel about Myfords and carbide tooling.  Myford 7 series lathes are perfectly happy with carbide insert tools.  I never go above 700 rpm for general turning and am very happy with the results I get on all metals.  CCGT tips are excellent for a good finish.  They do not need to be driven hard and deep, that will break the very sharp cutting edge.

all the best😊

Rod

[JasonBModerator @jasonb]

Rod beat me to it, you have totally missed the advantages of the **G* inserts ober **M* on hobby machines.

My 280 seldom goes into the faster speed range so 1100rpm tops.

As for under powered and less rigid the inserts work well on my little Unimat 3 too.

Also does not need to be driven hard or drrp, here is a 0.001″ cut which I don’t consider deep

Now I might consider this deep but at 100rpm hadrly what I call fast

 

[Andrew CrowParticipant @andrewcrow91475]

The only thing I would add to the above is that if you’re on a tight budget which many new starters are then you have to consider that a carbide tool holder and a pack of tips is around £60 you can buy several HSS tools for a lot less than that and they will last for a lot longer than 10 carbide tips.

I do use carbide insert tools hence the reason I know the cost but they are only another useful addition to the tool box.

Learning to grind your own tools is a useful skill and only practice makes perfect.

Andy.

[JasonBModerator @jasonb]

You would also need to factor in a bench grinder and possibly a diamond stone to shape and sharpen those HSS blanks. Plus hope the grinder has a half decent rest.

The main advantage for a beginner is they remove the question of geometry and tool shape from the equation. HSS can come later once the setting of the tool, material and speeds & feeds have been grasped.

[JasonB]

On JasonB Said:

You would also need to factor in a bench grinder and possibly a diamond stone to shape and sharpen those HSS blanks. Plus hope the grinder has a half decent rest.

The main advantage for a beginner is they remove the question of geometry and tool shape from the equation. HSS can come later once the setting of the tool, material and speeds & feeds have been grasped.

I wouldn’t disagree with anything there Jason, but an off hand grinder is a useful tool to have anyway likewise diamond laps. Incidentally I generally use India or Carberundum slip stones for finishing HSS tools and probably touch up the tools several times before requiring a major re-grind.

As for the tool rest some good practice for a beginner to make one ie Harold Hall’s from MEW a few years ago.

Andy

[JasonBModerator @jasonb]

I’m not against a small belt sander/linisher as another option for sharpening HSS. Usually have a good sized flat table. Flat abrasive area makes it easy to set the table angle. Also does for knocking off burrs whan a bit of bar comes out the hacksaw, fettling castings and shaping sheet metal. I have a small 25x50mm size diamond on a handle that I touch up the HSS with.

Best not get into the tool making debate, Andy wants to build the engine for his son’s boat not his future grandson🤐

Anyway here is a quick video for Dave. One of the redder bronzes, a leaded bronze and a bit of copper tube for good measure. Running at 700rpm Myphord speed and knocking it down to 80rpm with no visible change in surface finish. Light 0.1mm (0.004″) Depth of cut.

[larry phelan 1Participant @larryphelan1]

Far be it from me to blunder in where angles fear to tread, but here goes !

God only knows what that “free material” is, could be anything. To my inexperienced eye, it looks like bronze of some kind, not the easiest material to start with, I would think.  Try a piece of common-or-garden mild steel, much more forgiving along with no problem a piece of HSS. This mix has served me well to date and HSS is not too difficult to grind to shape [you will need a bench grinder anyway ]

What happens when you break your turning tool ? no problem, just regrind it !  I do it all the time, but then, I,m a cheapskate.

From what I have heard/read ,bronze of any kind is not easy to work.

I bought a piece of it years ago, when I was young and foolish, it,s still in the drawer, unused.

The lesson seems to be—-KNOW WHAT YOU ARE PLAYING WITH !

[old martParticipant @oldmart]

There are several very good books on the subject of using a lathe, somebody will know the titles.

[cedric 1Participant @cedric]

<p style=”text-align: left;”>Yes it’s  better to pay the money and buy known mild steel stock to practice on so you know what you are dealing with. Unknown offcuts can be all sorts of difficult to machine materials that cause more frustration  than its worth.</p>
Like Roderick above, I too use carbide insert tooling on my ancient Myford at full speed of 800rpm or so. CCMT for roughing and CCGT for finishing and light roughing .

Being of the generation where every schoolboy was taught in metalwork class to grind a lathe tool bit, I have no problem grinding HSS if required. Like any skill, it can be learned and developed with practice,  but the carbide is just easier. And it seems to cut all materials without the sort of problems pictured.

 

[FulmenParticipant @fulmen]

My preferred approach is to start with HSS to learn how to set up a cutter. This gives valuable insight in cutter geometry that will be useful for using carbide as well, and it saves you from breaking too many costly inserts while figuring out how to run the lathe. Of course I use carbide 99% of the time now, but I’m never lost if I need to make a specialty cutter.

[larry phelan 1Participant @larryphelan1]

As Old Mart said, there are plenty of good books on the subject.

Sparey, Stan Bray, and others well worth a read, no nonsense there.

Also, when you break a cutter at 8pm on a Saturday night, it,s much easier to grind up a piece of HSS than a carbide tip !

Just saying !

Remember, it,s all part of the learning curve.

[FulmenParticipant @fulmen]

I had to do that just the other day at work. I was waiting for a tap to finish a project, turns out that it was on back order for 4 weeks. And I didn’t have full profile inserts for that pitch. So what do you do? Grind a small cutter and get it finished now.

But I still maintain that the biggest value is understanding cutter geometry. Carbide isn’t just carbide, inserts come in every geometry imaginable. And choosing a high rake insert for interrupted cuts in hard steel will become very expensive very quickly.

[Roderick Jenkins]

On Roderick Jenkins Said:

On SillyOldDuffer Said:

…  One caveat: Andy’s Myford was designed when HSS was king, and the machine is a bit slow and underpowered for carbide.   Jason and I have Chinese WM280’s; they’re heavier, faster and more powerful than a Super 7, making it easier for us to get good results from inserts.  Carbide performs best when driven hard and deep with gusto!  Something else to explore.

Dave

 

Really Dave!  You spoilt a good reply by tacking on some outdated generic drivel about Myfords and carbide tooling.  Myford 7 series lathes are perfectly happy with carbide insert tools.  I never go above 700 rpm for general turning and am very happy with the results I get on all metals.  CCGT tips are excellent for a good finish.  They do not need to be driven hard and deep, that will break the very sharp cutting edge.

all the best😊

Rod

Sorry Rod, not true.  Well known that carbide inserts perform best when driven hard and deep at high-speed: read the specs. That one hobbyist with a slow lathe doesn’t go above 700rpm isn’t best practice.

If it softens the blow, whilst a WM280 is faster and more powerful than a Myford, it too is slow and weak by carbide insert standards.  Nonetheless I get good results from them.  I didn’t rubbish Myfords, I said carbide is easier on my machine.

Point is it’s easier to get good results from carbide with a fast lathe than a slow one, and that a beginner might be disappointed by inserts on a slow machine.

Plenty of lathes inferior to Myfords: pre-war machines designed for HSS don’t work well with inserts because they’re too slow.  Chaps occasionally pop up claiming HSS works better than carbide: one explanation is their lathe isn’t fast enough.

To me lathes are just tools, and I shine a cold hard light on them.  No emotion.  Myfords have many good features, but they are far from perfect.  May be shocking to be told they have shortcomings, but it is obviously so.  So do all the others!

Ever thought loyalty to the Myford brand might be “outdated generic drivel”?  In 2025 there are many better alternatives.   Chinese hobby lathes offer more choice and are cheaper.  Second-hand industrial lathes are better specified and affordable due to CNC and industry moving abroad.  Myford sit between.  Though they have technical issues, I’d say their main fault is “too expensive for what you get”.

🙂

Dave

 

[JasonBModerator @jasonb]

Dave it whas nothing to do with Myfords. They also work well on things like my Unimat 3, Cowells lathes and Shelines

 

Yes the **M* type inserts are “blunt” and work best when pushed hard on rigid machines where they deform the metal and literally push it off the bar.

But Me and Rod are talking about the much sharper **G* inserts which tend to cut the metal off not push it off. This has many benifits for the home user where the lathe may be slower, have less power or be less rigid, or a combination of all three.

Try watching the videos I posted of perfectly acceptable surfaces with light cuts at slow speeds. You may also want to read my articles in the”workshop” section of the site where the same applies to using inserts intended for non ferrous on all materials.

Not forgetting that cutting speed is not based on spindle rpm alone. Stick a 9″ flywheel casting in a Myford or other “slow” lathe and the cutting speed in m/min won’t be slow

[BazyleParticipant @bazyle]

Are cooking forums full of people saying “Just buy prepacked sandwiches. Buttering bread is so difficult and opening a tin of sardines requires years of training and specialist equipment”.

[Dave SParticipant @daves59043]

In days of yore the only carbide you could buy was somewhat large grains in a binder. This is not “sharp” in the world of sharp things. Sharp edges in this material “crumble” as the bits of hard wear resistant carbide are pulled from the matrix. This type of carbide is ideal for “moulded” tools, where the edge is thicker. These tools *need* rigidity and power to force the metal off, as they operate by fracture rather than sheer IIRC.

fast forward to today and carbide formulation has changed. The carbide particles are much smaller and the matrix is able to hold them better. Carbide is now available with edges as sharp as HSS. Look at a reasonable quality carbide endmill and you’ll see 5nm particle size as quite normal.

I run old school moulded carbide in my lathe for OD turning, but it’s a 2 ton machine. I generally don’t run it “fast enough” but I do get good surface finish and the inserts last for ages.
I run ground sharp inserts on boring bars because they reduce the cut pressure and make in size bores easier.

In the new mill I am running carbide, not because it needs it for the speed, but because it’s easier to have 1 tooling material – I don’t have to remember which mills are which when setting up the tool paths or loading the machine.

Modern carbide tools are not the same as old ones and as long as you pay attention to what you use they are very suitable for light machines. Unfortunately the internet will not let the facts get in the way of old skool wisdom.

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