Newbie needs advice about a lathe

[Old Guy]

This diagram may help?
https://www.theengineerspost.com/wp...1524889401899-min.jpg?ezimgfmt=ng:webp/ngcb19
And on a small lathe like this (similar to mine) I find it best to always use SHARP tools, - e.g. HSS tools or Carbide inserts for ALUMINIUM (Not cheaper ones for steel!).
The Carbide inserts for steel that I have experienced always need to be "honed to sharp for best work. The small lathe just does not have the torque and STIFFNESS to handle the loads that are required to make the carbide inserts for steel work properly.
So, I use the HSS tools and keep them sharp.
I rarely take more than a 0.020" cut - as the swarf can be too strong to break into chips - but usually many cuts of ~0.010 are good for this size of lathe. HEAVY cuts can be made, but the whole thing starts to twist under heavier loads, so you lose PRECISION.
This is a hobby, so "manufacturing production" speeds and feeds are not suited to "Hobby" lathes. If you need big speeds and feeds then spend 10 times more on a heavy industrial machine that is designed to do the work.
But if making precision models, take it slowly, carefully, and enjoy the whole experience. - It works for me. Life is not a race: the only race is "the Human race"! Relax and feel good about your work, and you'll enjoy it.
Centre tools with a rule - as above - then cut across an end of bar and the cutting centre will show you how accurately you have set the tool. - A centre "pip" means the tool is a fraction too low, but a pip that gets "pushed-off" by the tool means the tool is too high. - High is worse than low for anything as the tool will not cut properly but need "HIGH LOADS" to make it work. Too low, and there is a chance of the tool digging-in... but keep the tool end close to the tool post (a long whange hanging out is just bad practice! - It needs to be short and stiff for good work). - I never extend the cutting end of the tool more than 2 x tool-bar thicknesses from the tool post. - except where there is no other way, such as when boring. I.E. a 1/2" square tool MUST NOT extend more than 1" from the tool post support. But a 1/4" base beneath a carbide tip at the end of a 1/2" bar really needs more support, for the heavy cuts it is designed for. Which is one reason a 1/2" of HSS works so much better.
The STIFFNESS of a 1/4" bar is 1/8th of the STIFFNESS of a 1/2" bar. So, the tool is just poorly supported and will vibrate under cutting loads, at the natural frequency of the stiffness of the bar. When I use a Carbide tipped tool, there is only the MINIMUM of tool extending from the tool-post - and I sharpen with a diamond hone to give it the best chance of doing the cutting (shearing of metal) that I want it to do.
Enjoy making precision parts - not swarf and scrap!
K2

Great advise Ken I will take it all onboard
John

 

[Old Guy]

Hi John,

The 'grooves' on the top of the HSS tools are there to provide a 'rake angle' which varies according to the material being cut. for example the proper top rake for Brass is zero while for free cutting mild steel it would be around 7° (I admit that I also use these to cut brass). Softer material such as copper or pure aluminium need even greater top rake angles. If you have a look in the Boxford book I sent there is a good explanation of the tool geometry on page 20. The tool holders discussed in this chapter of the book is now really out of date as QC toolposts have become more into the hobby market. I think that your guesses about the carbide tools are correct. I do actually have a set but very rarely use them.

By the way, if possible you should get to one of the larger model engineering exhibitions in the UK. I usually get to a couple every year but of course with restrictions in force these have not been run for a while. The Midlands model Engineering exhibition is a good one attended by people from all over the UKand is on Thursday, Friday and Satuday in the middle of October and is well worth attending if you get a chance allowing for the cost of fuel these days, although it is improving at the moment, but it would be at least a couple of hours drive for you (but mainly motorway).I'm not sure about any exhibitions in your area but I would expect there to be at least on big one. At these larger ones there are usually many main suppliers such as Chester, Chronos, rdg etc as well as private exhibitors ranging from small schoolboy example to 1/4 scale traction engine , loco from small to huge as well as clocks, homemade workshop equipment and many other types of model engineering including some very quirky ones. they usually have workshops which are free to attend such as metal casting, turning etc., and a great opportuinity to talk to others and buy materials - if you pre order you can collect on the day without sometimes extortionate postal costs.
Now I'm off to greet the builders!

TerryD

Hi Terry
Thanks for the advise I will look into getting to the show
John

 

[Old Guy]

Hi John,
as others have mentioned you need to know what you are turning.
Don’t buy material with just a description but buy specific types.
I’d get some EN1A to start with.
That can be turned to a lovely finish.
Practice with that until you get it right.
As for your Starting and Stopping issues.
Your lathe is designed to start using the button. It’s known as a “No volt release.” If you open the guard or hit the reverse switch, you will need a reset.
It is done to prevent the machine starting accidentally. If the power goes off the lathe won’t restart or if you close the guard it won’t restart, until you press the reset.
Good luck and have fun.
Julian

Thanks Julian
At the moment I am having trouble finding suppliers that are quoting the actual type of steel or at least ones that would sell you shorter lengths, the ones I have found on line seem to have a 3metre minimum, the search goes on for suitable supplier

John

 

[Dalboy]

Just for interest take a look at THIS which shows the HSS Set look at the photos. As I said I have this set which was given to me along with a insert set when I brought
my lathe and mill (well if you don't ask you don't get)

And looking at the carbide insert tools I think I got the one on the left wrong it indeed does look like a boring bar as pointed out earlier

 

[Dalboy]

Thanks Julian
At the moment I am having trouble finding suppliers that are quoting the actual type of steel or at least ones that would sell you shorter lengths, the ones I have found on line seem to have a 3metre minimum, the search goes on for suitable supplier

John

Try somewhere like Metals4U at the bottom of each item there is a custom length box I buy by 300mm or 1ft. I am Just a satisfied customer

 

[terryd]

This diagram may help?
https://www.theengineerspost.com/wp...1524889401899-min.jpg?ezimgfmt=ng:webp/ngcb19
And on a small lathe like this (similar to mine) I find it best to always use SHARP tools, - e.g. HSS tools or Carbide inserts for ALUMINIUM (Not cheaper ones for steel!).
The Carbide inserts for steel that I have experienced always need to be "honed to sharp for best work. The small lathe just does not have the torque and STIFFNESS to handle the loads that are required to make the carbide inserts for steel work properly.
So, I use the HSS tools and keep them sharp.
I rarely take more than a 0.020" cut - as the swarf can be too strong to break into chips - but usually many cuts of ~0.010 are good for this size of lathe. HEAVY cuts can be made, but the whole thing starts to twist under heavier loads, so you lose PRECISION.
This is a hobby, so "manufacturing production" speeds and feeds are not suited to "Hobby" lathes. If you need big speeds and feeds then spend 10 times more on a heavy industrial machine that is designed to do the work.
But if making precision models, take it slowly, carefully, and enjoy the whole experience. - It works for me. Life is not a race: the only race is "the Human race"! Relax and feel good about your work, and you'll enjoy it.
Centre tools with a rule - as above - then cut across an end of bar and the cutting centre will show you how accurately you have set the tool. - A centre "pip" means the tool is a fraction too low, but a pip that gets "pushed-off" by the tool means the tool is too high. - High is worse than low for anything as the tool will not cut properly but need "HIGH LOADS" to make it work. Too low, and there is a chance of the tool digging-in... but keep the tool end close to the tool post (a long whange hanging out is just bad practice! - It needs to be short and stiff for good work). - I never extend the cutting end of the tool more than 2 x tool-bar thicknesses from the tool post. - except where there is no other way, such as when boring. I.E. a 1/2" square tool MUST NOT extend more than 1" from the tool post support. But a 1/4" base beneath a carbide tip at the end of a 1/2" bar really needs more support, for the heavy cuts it is designed for. Which is one reason a 1/2" of HSS works so much better.
The STIFFNESS of a 1/4" bar is 1/8th of the STIFFNESS of a 1/2" bar. So, the tool is just poorly supported and will vibrate under cutting loads, at the natural frequency of the stiffness of the bar. When I use a Carbide tipped tool, there is only the MINIMUM of tool extending from the tool-post - and I sharpen with a diamond hone to give it the best chance of doing the cutting (shearing of metal) that I want it to do.
Enjoy making precision parts - not swarf and scrap!
K2

Hi K2,

The 'roughing' tool on the diagram (Middle row LH end) you linked to is my preferred basic shape and I use it for most of my turning as well as the LH cutting tool of the same profile for LH turning (which I rarely need to do. I find that geometry very robust. I even use the tool for most finishing but keep it well sharp and polished with diamond 'slip stones'. For the facing off step diameters usually I use my parting blade, extended a little, into the internal corner. I only use a special facing tool when facing across a completely flat surface and Often I find that I can produce an very acceptable face with my 'roughing' tool. Of course for special jobs I may grind up a certain shape. but that is rarely needed. Also tyro users may not know about the 'built up edge' of a tool which occurs when turning some materials, and how to combat the problem.

I should also like to point out here that the tool should be set a little above the centre to allow for the spring in the tool and the job, the larger the diameter the higher the tool needs to be. South Bend, in their 1934 edition of 'How To Run a Lathe' suggest 5° above centre or 1/64th per inch of of the job diameter as do Boxford. the tool should not be set on perfect centre, except to very small light turning.

Regards
TerryD

 

[Old Guy]

@Old Guy The HSS tool you attempted to use looks dull to me. See the bright line along the cutting lip:

View attachment 140006

The leading corner of the tool does all the cutting. It should be very sharp and you should expect to hone it periodically to keep it from rounding over. I like to use diamond paddles for honing. Done regularly, you only need to use the fine and superfine. The three surfaces that meet at the cutting edge should be very smooth and highly polished.

Honestly, the pre-ground HSS tools don't look well-sharpened and the geometry is questionable on several of them. A zoomable picture is at the following link:

https://www.chronos.ltd.uk/product/set-of-8-sct-solid-hss-lathe-turning-tools-12-mm-square/
Since they are only charging 38 pounds for a set of eight, it makes me wonder if the HSS is really up to snuff, as well.

Craig

Hi Craig
That's a bit of a bummer then I was thinking that if I bought a set from a good supplier like Chronos they would be good to go but it would seem not and those grooves to me look they make the cutting angle too great but what do I know it's back to you tube and see what the guys that have site are doing I think

John

 

[terryd]

Thanks Julian
At the moment I am having trouble finding suppliers that are quoting the actual type of steel or at least ones that would sell you shorter lengths, the ones I have found on line seem to have a 3metre minimum, the search goes on for suitable supplier

John

Hi john,

Try 'Noggin Ends' (click link), they used to based in the West midlands not far from where I was born, but are now in Stoke- on- Trent. For future refernce they have stalls at most major exhibition for purchase or collection of online orders. Macc Models in Macclesfield is also a good source for small quantities and of course there is the old standby eBay

TerryD

 

[Old Guy]

Hi K2,

The 'roughing' tool on the diagram (Middle row LH end) you linked to is my preferred basic shape and I use it for most of my turning as well as the LH cutting tool of the same profile for LH turning (which I rarely need to do. I find that geometry very robust. I even use the tool for most finishing but keep it well sharp and polished with diamond 'slip stones'. For the facing off step diameters usually I use my parting blade, extended a little, into the internal corner. I only use a special facing tool when facing across a completely flat surface and Often I find that I can produce an very acceptable face with my 'roughing' tool. Of course for special jobs I may grind up a certain shape. but that is rarely needed. Also tyro users may not know about the 'built up edge' of a tool which occurs when turning some materials, and how to combat the problem.

I should also like to point out here that the tool should be set a little above the centre to allow for the spring in the tool and the job, the larger the diameter the higher the tool needs to be. South Bend, in their 1934 edition of 'How To Run a Lathe' suggest 5° above centre or 1/64th per inch of of the job diameter as do Boxford. the tool should not be set on perfect centre, except to very small light turning.

Regards
TerryD

Hi Terry
I was hoping that the set bought would be more like the ones in the diagram but I haven't found any with those profiles so far.
John

 

[Old Guy]

Hi john,

Try 'Noggin Ends' (click link), they used to based in the West midlands not far from where I was born, but are now in Stoke- on- Trent. For future refernce they have stalls at most major exhibition for purchase or collection of online orders. Macc Models in Macclesfield is also a good source for small quantities and of course there is the old standby eBay

TerryD

Thanks for the link looks very interesting
john

 

[Old Guy]

Hi John,

I think from left to right:

1). Facing tool - to turn a face on a step change in dia. and get a sharp internal corner where it meets the smaller dia.
2). boring bar - internal dia.
3). 60° external threading tool;
4). 60° internal threading tool;
5). Unsure, looks upside down in box;
6). Parting off tool; (I use parting blades in a holder);
7). Right Hand plain turning;
8). Left Hand plain turning tool.

I don't care for tools with such sharp points, I much prefer a round ended tool, especially for a finishing cut but keep a pointed one for sharp internal corners (or to cheat if I need to get a sharp corner at a step I'll finish off with a parting tool). Having said that you can always re model some of them when you have experience and you can grind new shapes on the back end of others and use them flipped over. Another alternative of course is to learn to grind your own tools using HSS blanks and sell the Chronos ones at some time in the future. As far as the carbide indexable tools are concerned it looks as though the used tip has a problem.

I haven't commented on the finish you showed us earlier but looking again it seems as though it is a shaft of some kind as the unturned portion in the middle picture looks as if it is ground. In that case it could be a high carbon alloy steel which would be difficult to turn. The HSS blanks are arriving this a.m. but as I have the builders starting some work on the house it may be a day or two before I can come back to you. I'll send another message by 'conversations'.

Regards

TerryD

Hi Terry
The whole of the bar has been turned by me except the bit in the chuck and basically show different finishes achieved its probably just a poor photo that might give it the ground appearance that would be something wouldn't it
John

 

[Dalboy]

@Old Guy I have just been out to the workshop and using the HSS one that you say you used I produced these two finishes both turned at 250RPM the left hand side next to the dark area was at a faster feed than the end one(The black is only done with a sharpie to show the unturned section) The steel used is EN1

I also used cutting oil

 

[Old Guy]

Hello Dalboy
There's a bit of a difference there isn't there's the bad finish was too fast a feed rate you reckon the smaller diameter on the end looks pretty good to me, but looks like even with EN1 you still need to watch what your doing.
I had a bit of a practice this afternoon I decided to part the end off the bar shown in the pics and supported the far end with a steady because it is too large to go through the spindle, I used the parting tool in the HSS set and everything went according to plan just, shows parting can be a sweet delight.
If you use an MT2 centre to steady a long bar what size centre drill should you use and how deep should you go.
I also found another set of smaller HSS tools that must have come with the Lathe they are 10mm on measuring them but for some reason look a lot smaller than the 12mm I bought
John

 

[Dalboy]

If you use an MT2 centre to steady a long bar what size centre drill should you use and how deep should you go.
I also found another set of smaller HSS tools that must have come with the Lathe they are 10mm on measuring them but for some reason look a lot smaller than the 12mm I bought
John

I normally go in about half to 2/3rd up the taper then put in a live centre to support. Others may do it different that also depend on what centre drill size you use

 

[william_b_noble]

just a note - HSS is only expensive if you buy it new, not surplus. I have sold off probably 100 pounds or more of HSS from an estate for $2 to $5 per pound (depending on what and how nice). old broken end mills and saw blades are often HSS and make good tooling.

for the queston about what size center drill - it's best to use an actual center drill, and size it so the tailstock has a chance of staying engaged with the hole.

 

[Old Guy]

I normally go in about half to 2/3rd up the taper then put in a live centre to support. Others may do it different that also depend on what centre drill size you use

Hi Dalboy
I am asking the question because I have destroyed the standard mt2 centre that came with the lathe despite lubricating with oil before use maybe I put too much pressure on it or maybe the hole was too shallow not sure about this. I have bought a love centre but have found that it is too short and doesn't hit the pin to release it when you draw it back and it was a pain to get it out so I haven't used it again I'm thinking I might glue a small disc to the bottom to hit the pin
I think I bought it from Chronos so I might speak to them Maybe I bought the wrong one but I will have to check on that.
John

 

[Old Guy]

just a note - HSS is only expensive if you buy it new, not surplus. I have sold off probably 100 pounds or more of HSS from an estate for $2 to $5 per pound (depending on what and how nice). old broken end mills and saw blades are often HSS and make good tooling.

for the queston about what size center drill - it's best to use an actual center drill, and size it so the tailstock has a chance of staying engaged with the hole.

Hi will
I think that everything to do with metal and machining is much more readily available in the USA than it seems to be here.
I do have a set of proper centre drills but as they are all the same angle all you are doing using the different sizes is drilling a deeper wider hole and was wondering if certain drills were intended for various sizes of MT centres.
John

 

[Dalboy]

Hi Dalboy
I am asking the question because I have destroyed the standard mt2 centre that came with the lathe despite lubricating with oil before use maybe I put too much pressure on it or maybe the hole was too shallow not sure about this. I have bought a love centre but have found that it is too short and doesn't hit the pin to release it when you draw it back and it was a pain to get it out so I haven't used it again I'm thinking I might glue a small disc to the bottom to hit the pin
I think I bought it from Chronos so I might speak to them Maybe I bought the wrong one but I will have to check on that.
John

It just needs enough pressure to support the piece too tight may damage it as you work the piece it can warm up and expand making the centre even tighter.
Keep checking that it has not become too tight during the turning.
Remember that Chronos sell at the lower end of the market and may not be as good quality as some of the more expensive places that sell the same type of products.

Keep it lubricated through out the turning operation. Even though I am relatively new to metal turning I have learnt a lot from those that have been doing it for years.
Keep asking questions I did when I first started
I am however reasonably good when it comes too woodturning and a few of the problems I can relate back to that.

 

[terryd]

Hi Dalboy
I am asking the question because I have destroyed the standard mt2 centre that came with the lathe despite lubricating with oil before use maybe I put too much pressure on it or maybe the hole was too shallow not sure about this. I have bought a love centre but have found that it is too short and doesn't hit the pin to release it when you draw it back and it was a pain to get it out so I haven't used it again I'm thinking I might glue a small disc to the bottom to hit the pin
I think I bought it from Chronos so I might speak to them Maybe I bought the wrong one but I will have to check on that.
John

Hi John,

The original machine suppliers (Chester?) will be able to provide extras such as live centres.

Remember there are 2 types of dead centre. Hardened ones which are intended for the tailstock and 'soft'(unhardened) ones intended for use in the lathe spindle you can test this with a light stroke of a file, if hardened the file will skid. Using a 'soft' centre in the tailstock can 'destroy' it by simple friction but they can be turned when mounted directly in the lathe spindle. The reason for the use of such a centre in the spindle is for turning between centres when absolute accuracy and concentricity is required, it is spinning with the work so the headstock is effectively a live centre with no friction involved at the workpiece unlike at the tailstock end and can be itself machined in situ to eliminate any faults and ensure that it is exactly concentric with the lathe's axis. It would be most unusual for a hardened centre to be as badly damaged as you describe as it would have to get to red hot in order to anneal the hardness.

Here is some advice from the Southbend Manual of 1934 explaining turning between centres, note the statement -" ...the tail centre is hardened..." - implying a soft centre in the lathe spindle which doesn't need to be hardened. And by the way to remove a stubborn device from a morse taper such as is in the tailstock make yourself a forked wedge when possible when, unlike the main spindle there is no rear access, also useful for removing stubborn chucks from a bench drill or milling machine spindle, without damaging the drawbar in the latter case.

Also for fun

Best Regards

TerryD

 

[terryd]

It just needs enough pressure to support the piece too tight may damage it as you work the piece it can warm up and expand making the centre even tighter.
Keep checking that it has not become too tight during the turning.
Remember that Chronos sell at the lower end of the market and may not be as good quality as some of the more expensive places that sell the same type of products.

Keep it lubricated through out the turning operation. Even though I am relatively new to metal turning I have learnt a lot from those that have been doing it for years.
Keep asking questions I did when I first started
I am however reasonably good when it comes too woodturning and a few of the problems I can relate back to that.

Hi John, Dalboy,

Just for your information, after my last post I came across this in the same Southbend 1934 Manual regarding centres:

Not sure if the ' "...groove around..." is still relevant here in the UK at least, I must check mine but the comment about the "...always hardened..." certainly is.

Regards
TerryD