Newbie needs advice about a lathe

[willray]

No offence taken about my turning skills as this is the first time I have attempted to turn a piece of bar.

Everyone starts somewhere!

I started with the carbide tool because this happened to be mounted in the tool holder when I purchased the lathe, I tried a light cut to start but I believe that carbide tools prefer a more aggressive cut to give a better finish

This (carbide needs deeper cuts) is partially an old-wives tale. It's closer to the truth to say that the vast majority of carbide tooling, and especially replaceable-insert tooling, is designed for machines that can take a deeper cut, and therefore the geometry is optimized to produce a better finish with a deeper cut. Brazed-carbide tooling does not have exactly the same problem, and there are actual sharp carbide inserts - look for inserts designed for aluminum cutting if you want sharp - they last just fine in steel for hobby use.

That being said, your surface finish doesn't look like "not a deep enough cut". It looks like bad tip geometry for the material.

An insert that's designed for a vastly deeper cut is one source of bad tip geometry, but your lathe is not designed for taking "carbide deep" cuts, so if the carbide tool you're using came with the lathe, I'm going to bet against it being intended for super-deep cuts.

Incorrect tool height turns good tip geometry into bad tip geometry, so I'd say that stays on the list of possibilities, but, if you describe how you're setting the tool height, that would help us rule that out.

Tip damage also does exactly what you see in that section where you've got short little bright lines followed by tearouts going around and around your part. It also does that "mush metal over the edge" like you see at the shoulder between your different turning depths.

I bought a set of ready ground HSS tools but had no joy with these either they do seem to have a very sharp pointed cutting edge and I believe a very slightly rounded cutting edge can give a better finish.

It's definitely true that a more broad cutting edge can make for better surface finish, but unless you bought pre-ground tools from someone who's just being an ***, the problem is more likely that you're either choosing the wrong tool, or presenting it to the work incorrectly. (Or, the steel your turning is inappropriate for HSS) Many ground HSS tools have a rather sharp corner, but except for the threading tool, and sometimes roughing, few are presented to the work "sharp corner facing in". It might help for you to track down something like South Bend's "How to Run a Lathe"

http://www.vintagemachinery.org/pubs/1617/3789.pdf
And look at their section on tool geometry.

... it's also entirely possible that you've just chosen to try to start your turning journey with a piece of completely snotty scrap steel. I've a couple chunks of mystery metal lying around that just won't cut nicely for love nor money. They're out there. If you want to dial in your turning approach using a known quantity, buy a chunk of 12L14. Machines like a dream, and it'll let you focus on learning to do your end of the job of turning, and not spend time getting confused by mystery-metal weirdness.

Good luck!
Will

 

[terryd]

Well here's a numpty attempt at uploading a few pics I don't know if its still going to be there when I post it the problem has been that some pics go but others get the too big message even though when you get the info on them they are all the same size ie 1.7mb and the vids not having it at all

Hi OG,
First, I'd just like to say that a proper name and sign off would be nice. Looking at your pictures I would say that it is the cutting tool you are using, I hardly ever use carbide, it's really meant for production machines and high removal rates. I much prefer HSS tools, once you know how to grind (lots of information online and in books) and set them they are excellent and easy to touch up on the go with a diamond slip 'stone' rarely needing regrinding. I've attached some examples turned with hss on my battered old Boxford lathe using HSS tooling. Two are are examples of plain and taper turning one is faced and the last one is of a lathe mounted threading device for small threads, the steel, especially that of the faced piece is of unknown origin from a scrap pile.




TerryD

 

[terryd]

Hi again Craig
About the iCloud thing, we bought a new laptop a few yrs back and there may have been a free iCloud usage deal with it or maybe it was included in the price that we were charged but we don't really need or want to use it, but that might be how the pics I take on my iPhone transfer on to the Mac automatically.
My wife recently got an Email saying that our iCloud contract had Expired and it would be £50 to renew it so she cancelled it
John

Hi OG,

If you join the Boxford lathe Users forum on io.com, there's loads of helpful stuff on general machining for all turning not specifically for Boxfords and in the files section is a copy of 'Know Your Lathe' a book produced by Boxford which members cab download and which gives a lot of information about grinding and setting HSS tooling which is universally applicable. The members may be able to point you to a forum specially for your lathe.

In my almost 60 years of turning both as a toolmaker and hobbyist of late I've not really come across a material which HSS won't cut well if ground to a suitable angle for that material. I've used freecutting, cast, silver steel(drillrod in the US), high carbon, stainless and 'mongrel' scrap steels as well as most non ferrous and plastic materials. The only material I find difficut are some bronzes but even they respond to HSS eventually when turned with care. I've attached a picture showing a length of old hot rolled steam pipe from France made from goodness knows what, (note the many layers of paint and whitewash on the section in the chuck) that I turned up to make a 'round square' - a favourite of 'Bogstandard' who will be remembered as a founding member of HMEM by long term users, unfortunately John is no longer with us, he didn't take fools gladly and was not afraid of saying so. Even the weld seam of the pipe didn't faze the HSS and parted with an HSS blade in a home made parting tool holder



And yes indexible carbide tooling is specifically produced for fast stock removal on production machines. Also sintered tips like indexible carbide don't like intermittent cutting and can chip. A length of HSS 10 mm square by 100 mm long will cost a fraction of carbide tips (e.g. £3.50 at RDG), can be ground differently at both ends and will last the average hobbyist a lifetime if treated properly.

TerryD

 

[Old Guy]

Everyone starts somewhere!



This (carbide needs deeper cuts) is partially an old-wives tale. It's closer to the truth to say that the vast majority of carbide tooling, and especially replaceable-insert tooling, is designed for machines that can take a deeper cut, and therefore the geometry is optimized to produce a better finish with a deeper cut. Brazed-carbide tooling does not have exactly the same problem, and there are actual sharp carbide inserts - look for inserts designed for aluminum cutting if you want sharp - they last just fine in steel for hobby use.

That being said, your surface finish doesn't look like "not a deep enough cut". It looks like bad tip geometry for the material.

An insert that's designed for a vastly deeper cut is one source of bad tip geometry, but your lathe is not designed for taking "carbide deep" cuts, so if the carbide tool you're using came with the lathe, I'm going to bet against it being intended for super-deep cuts.

Incorrect tool height turns good tip geometry into bad tip geometry, so I'd say that stays on the list of possibilities, but, if you describe how you're setting the tool height, that would help us rule that out.

Tip damage also does exactly what you see in that section where you've got short little bright lines followed by tearouts going around and around your part. It also does that "mush metal over the edge" like you see at the shoulder between your different turning depths.



It's definitely true that a more broad cutting edge can make for better surface finish, but unless you bought pre-ground tools from someone who's just being an ***, the problem is more likely that you're either choosing the wrong tool, or presenting it to the work incorrectly. (Or, the steel your turning is inappropriate for HSS) Many ground HSS tools have a rather sharp corner, but except for the threading tool, and sometimes roughing, few are presented to the work "sharp corner facing in". It might help for you to track down something like South Bend's "How to Run a Lathe"

http://www.vintagemachinery.org/pubs/1617/3789.pdf
And look at their section on tool geometry.

... it's also entirely possible that you've just chosen to try to start your turning journey with a piece of completely snotty scrap steel. I've a couple chunks of mystery metal lying around that just won't cut nicely for love nor money. They're out there. If you want to dial in your turning approach using a known quantity, buy a chunk of 12L14. Machines like a dream, and it'll let you focus on learning to do your end of the job of turning, and not spend time getting confused by mystery-metal weirdness.

Good luck!
Will

Hi Will
Thanks for all the great info as in your first paragraph I was actually wondering about this carbide thing as a lot of the vids I watch they are using carbide for pretty much anything they do from deep starting cuts to fine finishing cuts.I suspect the carbide I have was purchased by the previous owner at the time of his purchasing the machine I'm not sure if it comes with a selection of tools supplied with it. when I bought it there were three carbide tip tools but no HSS tools at all, the set I bought were from a well known engineering supply company on eBay called CHRONOS and would hope they are of a good quality I will post a vid of them and the wooden box they come in, they look very similar to a set sold by SOBA which I believe are a very good make.
I will definitely have a look at the South bend vid you mentioned and I know I have come across this web site before and could well be subscribed to it I will be going back to the various vids that go into using tools correctly.
I am hoping that the main cause of the abortion I produced is the snotty scrap steel syndrome I have ordered to short lengths of Black mild steel round bar and bright steel round bar but the they don't actually quote the number, I went to my local engineering steel stockholder to try to buy some 230MO steel bar but they only wanted to sell 3 metre length to me which was very puzzling as they had millions of off cuts of the various types of steel bar sitting sitting outside in wooden pallet boxes when I enquired about the offcuts they said they were all of specialised steel and their mild steel offcuts go straight into a ship in the yard that a scrap metal dealer buys of them and they are not allowed to go skip diving on fear of the sack.
I have been trying to aquire a piece of steel or cast iron to make a mount for QCTP to fit to directly to the cross slide it is approx 5" x 3" x 2" but its turning into an impossible task as no one seems to stock even 3"x3" square bar they all seem to top out at 60mm square I never expected to have this kind of trouble buying material
But what doesn't kill you makes you stronger you can only hope
John

 

[djc]

The reason for that is because reversing single-phase motors isn't as easy as reversing three-phase motors

Please could you look at part number 28 on page 24 of the manual and advise why you believe the manufacturer's description as 'DC motor' is incorrect. Would you also write a few words on what magic the control box might contain that allows variable speed from a single phase motor. Thanks.

 

[Old Guy]

Hello Terry D
I'm not sure what you mean by the signing of with a proper name as I always sign off as John in all my posts,
I have never said that I thought that HSS tools were in any way inferior to carbide and I am sure they are excellent if not better than carbide for certain applications I only started with the carbide tool because it was the only type of tool that came with the lathe when I bought it and have since bought a set of HSS tools as advised by many of the web sites I have been watching before getting in to the dark art of grinding you own tools which I would imagine takes a fair amount of skill and practice to do properly.
As a self confessed newbie to machining I am obviously groping in the dark at the moment for many things, the last time I had anything to do with engineering was when I was 16 years old when did an introductory training course at a large engineering company in Oldham I am now 73 the only thing I can remember of that course was some training on a milling machine but even that is a blur.
Thanks for all your advise which I will be taking on board and some great pics there as well...John

 

[terryd]

Hello Terry D
I'm not sure what you mean by the signing of with a proper name as I always sign off as John in all my posts,
I have never said that I thought that HSS tools were in any way inferior to carbide and I am sure they are excellent if not better than carbide for certain applications I only started with the carbide tool because it was the only type of tool that came with the lathe when I bought it and have since bought a set of HSS tools as advised by many of the web sites I have been watching before getting in to the dark art of grinding you own tools which I would imagine takes a fair amount of skill and practice to do properly.
As a self confessed newbie to machining I am obviously groping in the dark at the moment for many things, the last time I had anything to do with engineering was when I was 16 years old when did an introductory training course at a large engineering company in Oldham I am now 73 the only thing I can remember of that course was some training on a milling machine but even that is a blur.
Thanks for all your advise which I will be taking on board and some great pics there as well...John

Hi John,

Sorry I missed your name , I think that it's better to seperate the name from the text, it just makes it easier to spot. As you are in the UK, I'll scan the relevant parts from 'Know Your Lathe' Boxford Book and send them via the 'conversations' which is part of this forum, it is accessed via the envelope icon next to your username, however I will need your full name for that - the one you registered her with. I also have a copy of the South Bend book mentioned by someone else, I too a rather rough scan from the internet and spent a long time tidying it up to make it very legible and readable, I'll also send a copy of that.

If you need it I can grind up a couple of HSS tools for you to try with instructions on setting tool height etc if you woulld like you can message me via conversations, I'll see if I can message you using your username 'Old Guy'.

I'm 76 myself and served my apprenticeship with BMC (British Motor Corp, aka British Leyland, aka Rover group). worked in engineering for some years before qualifying as a teacher and taught Mechanical Engineering for many years with experience on lots of machine tools and industrial practices such as metal casting as well as machining.

Best regards, get in touch,

TerryD

 

[terryd]

Hello Terry D
I'm not sure what you mean by the signing of with a proper name as I always sign off as John in all my posts,
I have never said that I thought that HSS tools were in any way inferior to carbide and I am sure they are excellent if not better than carbide for certain applications I only started with the carbide tool because it was the only type of tool that came with the lathe when I bought it and have since bought a set of HSS tools as advised by many of the web sites I have been watching before getting in to the dark art of grinding you own tools which I would imagine takes a fair amount of skill and practice to do properly.
As a self confessed newbie to machining I am obviously groping in the dark at the moment for many things, the last time I had anything to do with engineering was when I was 16 years old when did an introductory training course at a large engineering company in Oldham I am now 73 the only thing I can remember of that course was some training on a milling machine but even that is a blur.
Thanks for all your advise which I will be taking on board and some great pics there as well...John

Hi John,

I just started a 'convesation' using your username and it seems to have been successful, send a reply to confirm and then I can send you useful stuff,

Regards

TerryD

 

[terryd]

Please could you look at part number 28 on page 24 of the manual and advise why you believe the manufacturer's description as 'DC motor' is incorrect. Would you also write a few words on what magic the control box might contain that allows variable speed from a single phase motor. Thanks.

Hi,
Sorry to butt in to the conversation, DC motors are usually controlled for speed by using the DC current in conjunction with a PWM controller rather than using variable resistors which is another possibility.

For ac motors an example of speed controller is a VFD circuit, there are other methods. it's not magic, just electronics.

Regards

TerryD

 

[ShopShoe]

Old Guy,

I think you're on the right track to practice on known materials. My learning began with ordering and turning many different materials, but making sure a lot of those were "known" materials. If you want to experience what many say is the "nicest" turning, try some brass. It's probably a good idea to have some around for making small things that are softer than steel: I suggest making a brass-headed hammer as a project: You'll love having that tool available in your shop.

For learning about toolbits, get some preground HSS tools sized for your lathe and some unground ones to practice "matching" to the stock ones. (In the USA, Little Machine Shop sells a kit with the preground and blanks for practicing and learning, perhaps a supplier closer to you does the same -- Does Anyone Know?)

Otherwise, online information on grinding HSS toolbits is all over.

--ShopShoe

 

[terryd]

Old Guy,

I think you're on the right track to practice on known materials. My learning began with ordering and turning many different materials, but making sure a lot of those were "known" materials. If you want to experience what many say is the "nicest" turning, try some brass. It's probably a good idea to have some around for making small things that are softer than steel: I suggest making a brass-headed hammer as a project: You'll love having that tool available in your shop.

For learning about toolbits, get some preground HSS tools sized for your lathe and some unground ones to practice "matching" to the stock ones. (In the USA, Little Machine Shop sells a kit with the preground and blanks for practicing and learning, perhaps a supplier closer to you does the same -- Does Anyone Know?)

Otherwise, online information on grinding HSS toolbits is all over.

--ShopShoe

Hi S.S.,

There are several excellent suppliers here in the UK, RDG engineering supplies and Chronos are a couple of the best, but most of the machine tool suppliers such as Chester and ArcEurotrade are tool suppliers and of course there is always eBay. I have however offered to grind up a couple of tools for John as example to try. As for materials I find that I can turn just about anything given the right cutting geometry with HSS, mind you I've not done much lead or uranium etc so I can't speak for those . It is such a useful, forgiving and versatile material unlike sintered carbide tools which are generally specialised (there's an oxymoron for you) and there is a need to buy many types of tips to get the best from them.

Anyway that's just an opinion and others will have different ones, it's the way of the world, I just accept the differences.

Best regards

TerryD

 

[terryd]

Hello Terry D
,,,,,,,,,,, before getting in to the dark art of grinding you own tools which I would imagine takes a fair amount of skill and practice to do properly.,,,,,,,,,,
l...John

Hi again John,

Grinding toolbits in HSS is not so difficult. To begin I use a cheap small double ended bench grinder monted on a board with a home made adjustable support, nothing complicated. This is complemented with a simple set of card templates cut at various angles according to whichever tool I'm grinding, these are used to set the angle of the support rest. Not my idea, it was one suggestion of Harold Hall.

IA few years ago I built an adjustable cutter and tool grinding table with accessories and modified a small grinder to accept diamond coated cup or saucer wheels at one end. This was to the design by Harold Hall, a one time editor of Model Engineers Workshop magazine, but this is for much more complicated grinding but worth it once you have experience. The basic grinding rest is here and is designed to be made using only a lathe. Below is a picture of my version of the more advanced one, but the basic one is just as capable. The rest was badly damaged by water during a garage/workshop fire (I was well insured thank goodness) and I refurbished it after rescueing it a few days afte the fire was extinguished and the building made safe. Here are a couple of pictures.

1) Damaged grinding rest rescued following garage fire:



The rust was not as bad as it looks, it was mostly just surface rust without much surface penetration.

2) The same rest after refurbishment, the accessories were likewise damaged and refurbished:



Just shows what can be achieved with a selection of emery abrasive cloth and elbow grease. You can just about see a little of the modified bench grinder in the background, which is raised on a block of wood with a cup wheel fitted (the grinder not the wood!) .

Best regards

TerryD

 

[djc]

For ac motors an example of speed controller is a VFD circuit, there are other methods. it's not magic, just electronics.

I wonder if you could show me a VFD that works on the single phase AC motor that willray thinks is powering the machine in question.

 

[willray]

Please could you look at part number 28 on page 24 of the manual and advise why you believe the manufacturer's description as 'DC motor' is incorrect. Would you also write a few words on what magic the control box might contain that allows variable speed from a single phase motor. Thanks.

Ah, never mind - you're absolutely right, I missed that it was a DC drive! Thanks for pointing that out.

I think if you look closely at the motor used in the Chester DB10 and similar lathes, you'll see the magic that enables it to be speed controlled when used on either DC or AC...

Will

 

[willray]

I am hoping that the main cause of the abortion I produced is the snotty scrap steel syndrome I have ordered to short lengths of Black mild steel round bar and bright steel round bar but the they don't actually quote the number

Do be aware that 1018, one of the more common steels you'll find as what I think you'd call "black mild steel" ("hot rolled" over here), can be a bit of a challenge to get a good finish on. It likes sharp tooling and, at least on my lighter lathes, cutting oil makes a big difference.

Good luck!
Will

 

[william_b_noble]

With all due respect, no.

Unless you are using some kind of servo (or I suppose stepper) drive system, "zero RPM" to the controller means "put out zero power". It does nothing to lock or restrict rotation of the rotor. There undoubtedly are servo-drive lathe spindles, but I suspect very, very few of us are using them.

The real origin of the confusion is that in these (and similar) lathes, the "speed knob" (potentiometer, whatever) is a speed knob, it's not an off switch. You want "off", you turn the motor off. You want slow, you turn the speed knob to slow.




Again I beg to differ. On all the real lathes I've met, when you want the lathe to start, you engage the clutch, and when you want it to stop, you disengage the clutch and engage the brake. The push button "start" switch only spools up the motor, and it won't activate if the clutch is engaged.

Low RPM with the knob at minimum speed is because you presumably want the lathe to turn at minimum speed when you have the knob at minimum speed... It would be kind of silly to have it do otherwise

I will respectfully disagree, we are both right in some way. The lathe in question is driven by an electronic drive, probably a 3hr33 phase AC drive. Every variable frequency AC drive I fave used attempts to drive the motor to the commanded speed. Zero rpm means just that, the machine is commanded to resist rotation of the spindle, the motor is not uncovered until the drive is commanded to depower the motor. On the drives I set up, I do this using 3-wire control and pushbuttons. The drive remains energized so it can accept new commands, but when STOP is selected and the deceleration profile, if any, has completed, the drive removes power from the motor. This is not what happens when the frequency is adjusted to a low, even 0 value.


Similarly, with a DC drive, with either a tach or back EMF feedback, the drive will provide current into the motor to achieve the commanded RPM. Only when commanded to do so will the drive remove power.

 

[Jules]

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

 

[Dalboy]

Hi again John,

Grinding toolbits in HSS is not so difficult. To begin I use a cheap small double ended bench grinder monted on a board with a home made adjustable support, nothing complicated. This is complemented with a simple set of card templates cut at various angles according to whichever tool I'm grinding, these are used to set the angle of the support rest. Not my idea, it was one suggestion of Harold Hall.

IA few years ago I built an adjustable cutter and tool grinding table with accessories and modified a small grinder to accept diamond coated cup or saucer wheels at one end. This was to the design by Harold Hall, a one time editor of Model Engineers Workshop magazine, but this is for much more complicated grinding but worth it once you have experience. The basic grinding rest is here and is designed to be made using only a lathe. Below is a picture of my version of the more advanced one, but the basic one is just as capable. The rest was badly damaged by water during a garage/workshop fire (I was well insured thank goodness) and I refurbished it after rescueing it a few days afte the fire was extinguished and the building made safe. Here are a couple of pictures.

1) Damaged grinding rest rescued following garage fire:

View attachment 139989

The rust was not as bad as it looks, it was mostly just surface rust without much surface penetration.

2) The same rest after refurbishment, the accessories were likewise damaged and refurbished:

View attachment 139990

Just shows what can be achieved with a selection of emery abrasive cloth and elbow grease. You can just about see a little of the modified bench grinder in the background, which is raised on a block of wood with a cup wheel fitted (the grinder not the wood!) .

Best regards

TerryD

Sorry Old Guy for going off topic.

TerryD can I ask was this made from plans or your own design if from plans where can they be obtained thank you

Derek.

I am also a new metal turner/worker as normally I am found woodworking and woodturning. Started my first project in January

 

[terryd]

Hi again Craig
About the iCloud thing, we bought a new laptop a few yrs back and there may have been a free iCloud usage deal with it or maybe it was included in the price that we were charged but we don't really need or want to use it, but that might be how the pics I take on my iPhone transfer on to the Mac automatically.
My wife recently got an Email saying that our iCloud contract had Expired and it would be £50 to renew it so she cancelled it
John

Hi John,

I use a Macbook, iPad and iPhone as well as a PC. The basic iCloud is free with no setup charges for Mac owners up to 5gb storage. When you exceed the basic limit it is possible to increase the strage limit , I upped mine to 50gb for a relatively small monthly payment. There never is a setup fee, there are two possible explanations for you experience, yo have exceeded the 5gb nasic limit and need to increase your storage limit, but it wouldn't cost £50.00 to 'set up' or it was a scam and was attempting to get your bank details. As a Mac owner you still have 5gb of free storage - it doesn't lapse. Check out the iCloud link on your Mac.
At least that's how I understand the situation.

Best regards

TerryD

 

[terryd]

Sorry Old Guy for going off topic.

TerryD can I ask was this made from plans or your own design if from plans where can they be obtained thank you

Derek.

I am also a new metal turner/worker as normally I am found woodworking and woodturning. Started my first project in January

Hi Derek,

It is in Harold Hall's books available on Amazon, often 2nd hand relatively cheaply, these have both plans and extensive instructions (once you get to know his system!). The one for the basic rest which is excellent and all of the instructions for additional devices to go with it is in Workshop Practice Series No 38. Here is an Amazon link (click text). There is more information on Harold's site which I linked to in the previous message but here it is again, (click text).

Regards

TerryD