Best type of material to use for beginners

[Guy RobinsonParticipant @guyrobinson27287]

What’s the best type of material to use in a mini metal lathe for a beginner?

[Guy RobinsonParticipant @guyrobinson27287]

Beginner

[Jeff DaymanParticipant @jeffdayman43397]

Round?

[SteambuffParticipant @steambuff]

What do you want to make?

[Thor 🇳🇴Participant @thor]

Hi Guy,

It depends on what you want to make. If you just want to learn/practice turning, free-cutting steel is cheap and easy to turn, also free-cutting brass. You may also find free-cutting light alloys.

Thor

[JohnFParticipant @johnf59703]

Guy, the real answer is the correct material for the job in hand, however if you want something thats easy to use and can be used for many items/components is free cutting mild steel EN1a

If you have any questions regarding the suitability of a material for a particular component post your question on here and you will for sure get an answer. Take care if the part is to be used in a high stress situation you need special steels in this situation !

John

[Ady1Participant @ady1]

Scrap metal

Then you can make a mess and learn at the same time

[Dennis DParticipant @dennisd]

I would agree with JohnF get a piece of metal of known type from one of the many suppliers who advertise on here. Then you can experiment with different speeds and feeds ,tool types (Carbide / HSS ), coolant to see what finishes you can get. With an unknown piece from the leftover box it can be discouraging when you can’t get a decent finish . I now use a bit of masking tape around any decent lengths of stub bar and write on it the material type. Telling the difference between Silver Steel and Stainless when it’s got a bit grubby in the box under the bench is one example where I have come unstuck.

[SillyOldDufferModerator @sillyoldduffer]

NOT scrap metal, at least to start with. An absolute beginner has a lot to learn about rpm, tool shape, depth of cut and feed-rate and it's easier to start with known materials. I wasted a lot of time on my mini-lathe discovering that odd bits of metal found in the average home are poo. (Different story if you have access to workshop scrap or someone who knows.)

Problem with scrap recovered from manufactured items is that many alloys do not machine well while some are utterly vile, or need to be softened by heat treatment first. Likewise DIY store metals – their aluminium is sticky and the steel gritty. DIY store brass rod is OK, but not the best. Plastics are often difficult to turn and although the lathe will do it, wood is not ideal on a metal lathe. Cast Iron varies between wonderful and horrible and is always dirty. Some stainless steels machine well, but most are difficult because they work harden. Copper and Lead are too soft to machine well. I'm told Magnesium alloys machine best of all, but are an exciting fire hazard. Avoid steel pipes used for gas and electrical conduit until you have more experience – they come with hard welded seams.

In a mini-lathe, I preferred machining shop bought brass (CZ121), Aluminium (2014), free-cutting mild steel (EN3B) and mild-steel (EN1A) in that order. When actually making things, the other way round! My all-time favourite metal is brass because it cuts easily with a good finish and doesn't need lubrication. The swarf comes off in clean flakes, just don't get it in your eyes. My least favourite is cast iron, it often has a very hard skin and, because it's full of carbon, a black mess goes everywhere. You end up dirtier than a black goat playing with printers ink in a coal mine.

Dave

[not done it yetParticipant @notdoneityet]

If just ‘playing around’ – not actually trying to make something, I would suggest a short larger diameter disc (for facing cuts) and a longer thinner round bar that might pass through the spindle. You can then simply start practising facing cuts and cylindrical cuts. I would suggest to start on a free cutting aluminium and then progress to harder (or softer) materials.

Maybe it is high time you introduced yourself to the local model engineering society/club? Likely some suitable offcuts available from helpful members.

[Former MemberParticipant @formermember19781]

[This posting has been removed]

[Kevin MurrellParticipant @kevinmurrell62078]

Fairly new to this myself… I called into Chronos on Friday and bought two lengths of 1/2" BMS free cutting. Quite whether that is the right term I am not sure, but nobody laughed. It mills OK, but drilling into it is very very hard work. The centre-drill was OK, but then a 3mm drill wouldn't touch it. First I assumed the drill was blunt and tried another, then somehow thought the mill was going backwards (it can't BTW), but persevered. Eventually I broke through the surface and the rest was what I would expect. Is this surface-hardened? Is that a thing? Should I have been more precise in what I asked for?

Kevin

[Mick B1Participant @mickb1]

Posted by Kevin Murrell on 03/09/2018 16:56:35:

…

Eventually I broke through the surface and the rest was what I would expect. Is this surface-hardened? Is that a thing? Should I have been more precise in what I asked for?

Kevin

BDMS is bright drawn mild steel. Theoretically it should be homogeneous, but does frequently have a sort of skin on it that is more resistant than the material inside. All the metallurgy I can remember reading says that mild steel can't work harden, but I don't think I really believe that. So I think the skin's either from work hardening, or scale that been driven into the surface by the drawing process, or both. It's usually present to some degree, but is not very conspicuous in the best material.

[Anonymous]

Posted by Kevin Murrell on 03/09/2018 16:56:35:

……….. two lengths of 1/2" BMS free cutting. Quite whether that is the right term I am not sure, but nobody laughed. It mills OK, but drilling into it is very very hard work. The centre-drill was OK, but then a 3mm drill wouldn't touch it. First I assumed the drill was blunt and tried another, then somehow thought the mill was going backwards (it can't BTW), but persevered. Eventually I broke through the surface and the rest was what I would expect. Is this surface-hardened?

If it's proper free cutting steel it will most likely have a small proportion of lead in it. It's a low carbon steel so there's no way it's going to work harden. Should be easy peasy to drill. So either it isn't what it purports to be, or there's something wrong with the drill. Given it milled ok I'd suspect the drill. What is the provenance of the drill?

Andrew

[John Paton 1Participant @johnpaton1]

My advice would be to look around local industrial estates and see if you can find a firm who machines round bar.

Then explain what you are doing and ask nicely if they 'scrap bar ends' of free cutting mild steel in their scrap bin.

I find some firms really helpful and let you fetch out what you want from the skip. One firm gave me a goodly bundle of lovely10mm dia bar ends about 200mm long which get used for all sorts of things – machines a dream!

Alloy and plastics can be a bit more difficult to find and are very variable in how they machine so are not so good for a complete beginner. Same approach however will often produce the goods.

[MWParticipant @mw27036]

As a fiend for scrap i am, i would have to suggest using a known material to begin with. I guarantee you'll be spoiling less of those tools you spent your hard earned on.

Michael W

[Kevin MurrellParticipant @kevinmurrell62078]

Just following up my posting about difficulty in drilling certain spots in EN1A:

I have found this problem twice now – 1/2" square stock EN1A – drilling through to 6mm fine generally, but then on the next hole I hit a very hard spot. Latest occurrence: Centre-punched, centre-drill to a couple of mm, then a 3mm drill bit – worked fine down to about 10mm then stopped! And I really mean I couldn't get any further in. So I flipped the part over and tried from the other side – I could barely mark the surface and the drill just wandered about.

This is really frustrating – particularly when you have a few hours work already into a part.

In something I read, there was talk about normalising stock like this: heating to 800C, then letting the stock air cool.

Is this something one should do as a matter of course?

Edited By Kevin Murrell on 15/09/2018 07:01:36

[Anonymous]

Posted by Kevin Murrell on 15/09/2018 07:00:18:

In something I read, there was talk about normalising stock like this: heating to 800C, then letting the stock air cool.

Is this something one should do as a matter of course?

Generally no. Bright drawn steels are stressed, particularly the outer layers, during manufacture. If you machine away parts of the surface the stresses can become asymmetric and cause the part to bend like a banana. For turning I never anneal as the machining is symmetric to the part and so the problems don't arise. Milling is different. If I need to machine BDMS then I normalise first. It's one reason I use a lot of hot rolled steel for milled parts, as it's a lot less prone to looking like a banana.

Going back to the original problem, it's the same old questions. I'm not sure I'd trust the material to be EN1A. What lathe are you using? What drills; manufacturer, old or new, where did they come from? Speeds and feeds? A picture of the setup may help to determine the issue.

I've never seen this problem when turning and dilling on the lathe. I've only seen it once when milling EN3B flats, where I broke two carbide cutters on the same part. Actually I didn't break the cutter, but the material took all the teeth off, converting an endmill to a ballnose mill. All the other parts from the same length of material were fine. Since I was milling spokes for my traction engine models these parts were normalised in an electric furnace before machining.

Andrew

[Chris Evans 6Participant @chrisevans6]

I have a good relationship with a local steel stockholder who will let me go in and look at the offcuts rack. All steel is correctly marked and of traceable provenance. Just picked up over 4 foot of 1" round EN1A for £10 as a cash sale. OK not as cheap as buying the whole bar but good for home use.

[Ian S CParticipant @iansc]

If you go looking through scrap bin for unknown steel, it's handy to have a small file with you to test if the metal will at least cut on the lathe, no use getting home with a great looking lump of steel that is just about hard enough to make lathe tools! Early in my days on the lathe I did make a few things using old car axles, such as this tool holder, turned on the bottom and sides with the bar across the jaws of the 3 jaw lathe chuck, and the area where the tool fits milled in the vertical milling machine.

Ian S C

Edited By Ian S C on 15/09/2018 14:06:09

Edited By Ian S C on 15/09/2018 14:07:23

[JasonBModerator @jasonb]

I had the same issue with a bit of 1/2 x 1 EN3 the other day took the edge straight off a brand spanking new 10mm sq HSS with 8% cobalt flycutter bit I had been sent to try out and when I say took the edge off I mean turning it into a round nosed tool not just dulling the edge. 1/4" further along the steel cut perfectly well. I have had it happen about 3 times now and am sure it is the material not the tool bit, machine or methods.

This tool did gave a 90deg corner

[Nick HulmeParticipant @nickhulme30114]

Posted by Kevin Murrell on 15/09/2018 07:00:18:

Is this something one should do as a matter of course?

No, ask your supplier to check the batch number with their supplier.

[Author]

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