You're looking at this backwards.

Buy material suitable for the things you're going to make. For instance, I don't keep leaded steel as many of my parts get welded.

Lots to learn about about materials, lesson one being they don't all machine well. In fact some are obnoxious! Beware unknown scrap, some of it is very nasty indeed!

Best thing is to check specifications for what's its says about 'machinability'. Look for at least 'good machinability', or 'free-cutting' in the blurb.

Are you in North America? 12L14 is equivalent to Leaded EN1A, which is a mild-steel alloy specifically formulated to machine well. EN1A-Pb is excellent – much better than ordinary mild-steel, which is 'OK' rather than 'good', because it tends to tear causing poor finish . Black mild-steel machines slightly better than Bright Mild Steel in my experience, and although bright comes with good surfaces, the way it's made can cause it to warp badly when cut. Don't let that put you off!

Cutting fluid is generally a good thing apart from Brass and Cast Iron, which both cut dry. Steels prefer a heavier oil or emulsion, but try without first, especially if using Carbide cutters. Aluminium and alloys benefit from a light oil like paraffin.

Most Brasses machine well. Cast iron often has a hard difficult outer skin that has to be penetrated, but is good once that's been done. Be warned though – cast-iron is filthy and the mess goes everywhere. Brasses produce sharp swarf that can't be removed from flesh with a magnet. Don't get it in your eyes!!!

Pure Aluminium and many of the alloys made to be extruded into window frames etc are nasty soft sticky stuff. They don't machine well. However, many Aluminium Alloys are 'good' – check the specification. Most online metal vendors describe what they're selling well enough. If buying from a local shop, tell them you will be machining the metal.

Some metals work harden, that is start soft and go hard and tough under pressure. Stainless steels are notorious, but Bronzes and other metals do it too. The trick is to cut and keep cutting, well lubricated, never allowing the tool to rub. If the cut fails, the metal hardens, perhaps harder than HSS, blunts the tool, causing more rubbing, and then complete failure. The metal can be hard enough to defeat resharpened HSS. I avoid stainless – too many bad experiences.

Most metals can be machined once a certain level of skill is achieved, but I didn't make progress until I'd practised on friendly metals. Once you know what to expect, trouble is more obvious, as it what to do about it. Balancing feed rate, depth of cut, rpm, cutter type and lubrication to suit awkward metals is the answer, but not easy to describe how to do it in words.

Dave

Edited By SillyOldDuffer on 15/08/2021 13:16:55

You can look up the specifications for steel and aluminium on line and amongst the info should be the machining qualities. Aluminium should be cut with a little lubrication as if turned dry it can stick to the tool edge.

I started with Aluminium round stock. More forgiving than steel.🙂

It has a low melting point and the cutting/shearing of the metal can be sufficiently high (at the cutting surface) to stick it to the cutter. WD40 as lubricant avoids the problem.

If you're just "Practicing" ie. just making swarf , doesn't really matter what you use.

Regards Ian.

Agree, don't get too hung up on the technicalities at the early stages. Get you hands on an assortment of bits (many metal merchants sell assorted 'short ends'  and see how you get on – you'll learn as you go. But, just turning for its own sake will soon get pointless and you risk losing interest.

Get a couple of books about lathe work that include simple projects – doesn't matter much what those are – but you will learn a huge amount much quicker by having a specific job to complete where you will need to work to tolerences and with differents materials / finishes etc.

Either way, enjoy yourself and don't stress. In many years time as an experienced model engineer then you will need in depth knowledge of the 'right' materials.

Take care. Mike

Edited By Mike Hurley on 16/08/2021 09:56:34

That's completely contrary to any teaching program! There's a huge difference in the value of random DIY 'practice' and focused learning with expert help.

Advice from one beginner to another : try and make something. Buy a kit with plans and the proper materials and have a go. If you muck it up then you can easily replace that piece of material and you will have learned something in the process.

One of the first things I made was a simple pen. Find a suitable insert (like a parker refill), draw up a basic drawing (a good skill in itself), then source a bit of nicely cutting brass stock. You get to practise knurling, thread cutting (with taps and dies), taper cutting (just using the compound slide), and at the end of it you have something you are proud of. It can be as simple or as complex as you like, my first was over simple. I might make another just to see how far I've come on (not as far as I would hope I reckon!).

"A second hand lathe" with a QCTP and the ability to grind "Old school" tools, Did you really need to ask the questions John????

Regards Ian.