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choices of material to turn

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john mostyn15/08/2021 09:37:47
7 forum posts
5 photos

Hi All,

I have just purchased a second hand lathe and am a beginner to machining.

What are good grades of metal to purchase to turn.

is 12L14 steel good or is there better

what is a good stainless to try, same with alloys.

I know that bright bar is better than black bar, but what grades are good?

thanks guys

cheers

John

Nicholas Wheeler 115/08/2021 10:34:06
771 forum posts
52 photos

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.

John Haine15/08/2021 10:35:11
4270 forum posts
251 photos

Looking that steel up it is leaded free cutting so should be pretty good. Don't even think about stainless until you have some experience with ordinary steel, but when you do, 316 is a reasonably machinable grade.

SillyOldDuffer15/08/2021 13:14:33
Moderator
7681 forum posts
1694 photos

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

Emgee15/08/2021 14:43:18
2193 forum posts
272 photos
Posted by John Haine on 15/08/2021 10:35:11:

Looking that steel up it is leaded free cutting so should be pretty good. Don't even think about stainless until you have some experience with ordinary steel, but when you do, 316 is a reasonably machinable grade.

I have always found Stainless 303 is the easiest to machine but with any grade you need to keep the tool cutting or it quickly work hardens.

Emgee

old mart15/08/2021 15:39:34
3397 forum posts
210 photos

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.

Howard Lewis15/08/2021 18:03:00
5533 forum posts
13 photos

If you are newbie to machining, make your mistakes on free cutting steel, such as leaded.

Stainless, can come later, when you have more experience.

Scrapping some 12 mm free cutting steel, if you get something wrong, will be cheaper than stainless, and less likely..

You learn to walk, before trying to sprint. Channel swimming comes after you have learned swim.

You are at the bottom of a learning curve.

Very few of us ever reach the peak! It's a LONG way off for me!

Get some books and read up on using a lathe, it will save you frustration and puzzlement.

You can gain experience by making simple accessories for the lathe, which will be useful after you have made them.

When you are familiar with the machine and using it, then you can try different materials. Then you will start to learn about feeds and speeds, depth of cut and tool shapes for best effect..

Howard

not done it yet15/08/2021 21:24:49
6433 forum posts
20 photos

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.

larry phelan 116/08/2021 07:55:23
1114 forum posts
14 photos

First thing you need to get is a big scrap box, believe me, you will need it !cheeky

Circlip16/08/2021 08:11:20
1382 forum posts

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

Regards Ian.

old Al16/08/2021 08:53:11
184 forum posts

their is a lot to learn about lathe work, machining in general and the materials we use. Its a very hard way to learn if all you are doing is playing on the lathe and reading books on it.
Go join a club and get a few lessons from someone with experience

Mike Hurley16/08/2021 09:47:16
207 forum posts
70 photos
Posted by Nicholas Wheeler 1 on 15/08/2021 10:34:06:

You're looking at this backwards.

Buy material suitable for the things you're going to make.

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

SillyOldDuffer16/08/2021 10:05:50
Moderator
7681 forum posts
1694 photos
Posted by Circlip on 16/08/2021 08:11:20:

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

Regards Ian.

With respect, I disagree!

Early on I nearly abandoned the hobby because, by chance, my collection of scrap supplemented by DIY store metal was all rubbish. A nasty mix of stainless, squishy aluminium, hardened steel, dead-mild steel, odd bits of welded pipe and special purpose alloys. Nothing worked as expected. I wrongly assumed it was my equipment, only later twigging the need to develop operator skills and that my materials were awkward b*ggers.

Depends where you live maybe: my part of England does very little manufacturing, so most of my scrap is domestic. These days makers prefer stamping, extrusion, rolling, and grinding to traditionally machined metal, so the machinability of domestic scrap is random. All the ground rods I've taken out of printers and scanners machine well, except for one. Identical except carbide and files won't touch it; I've no idea what it's made of.

With experience most metals can be machined more-or-less successfully, but learning on random scrap is asking for trouble. When things go wrong, it's either the tooling, the operator, or the material. To me it makes sense for beginners to eliminate material problems so they can concentrate on their own shortcomings and learning to drive the machine. Practising on weird scrap is highly educational too, but I feel is best saved for later.

Dave

Nicholas Wheeler 116/08/2021 10:20:29
771 forum posts
52 photos
Posted by Circlip on 16/08/2021 08:11:20:

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

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.

Jim Nic16/08/2021 10:22:59
avatar
358 forum posts
202 photos

I'm with Dave on this. There have been numerous threads on here over the years initiated by newbies wandering why they can't get a decent finish on a piece of metal when it turned out they had no idea what the spec of the metal was. The advice has always been the same: don't attempt to work with material of unknown spec until you are familiar with your machine, cutters and techniques.

After 10 years learning I still buy most of my materials from Macc Models, one of this sites Shopping Partners, who supplies metals which are largely easily machineable on our hobby machines.

Jim

Brian John16/08/2021 13:18:51
1484 forum posts
582 photos

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.

Nicholas Wheeler 117/08/2021 02:51:50
771 forum posts
52 photos
Posted by Brian John on 16/08/2021 13:18:51:

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.

That's excellent advice, but it doesn't have to be a kit. I'm sure a look around the house/workshop/car/etc will soon find something to repair. The second thing I made with my first lathe was a replacement handle for the freezer, about 15 years after I broke it.....

Jon Lawes17/08/2021 05:06:24
avatar
689 forum posts

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!).

Circlip17/08/2021 10:24:21
1382 forum posts

Yes, the expected s***storm, and yes SOD, you might reply with respect but then go on to say in your first paragraph of your reply you NEARLY gave up. If the will is there, you'll find a way. Problem with T'internet is that it's so easy to load basic problems onto the "exspurts" and watch the rings of drivel generated. Surprised that no one has replied with "Get whatever material you want, there's a CARBIDE insert to machine it" Transient hobbies abound, depends on what you want to achieve, life is a constant learning curve, jump in and get yer boots wet. "You can't machine hardened steels!", my generation used "Specialist" Wimmet tipped tools, VERY exotic (at the time) but old hat nowadays. As a turning "Luddite", my tooling is Carbon and HSS based with the infrequent smattering of brazed/welded tip carbides, "But if you want to cleave quickly, you should use - - - ". I'm NOT in industry any more so regard my efforts NOW as a hobby. Averse to modern methods? Nearly four decades ago, introduced one of our (at the time) national transport system manufacturers to the advantages of Waterjet cutting rather than Turret press operations.

"Practice" on anything, it's called LEARNING.

Regards Ian.

john mostyn17/08/2021 12:12:22
7 forum posts
5 photos

Thanks All,

im in australia, we are in lockdown from this virus. I found a steel supplier that has 1214, 1137, 1045.

originally I went to a steelyard that sold me some round 'black bar' which i found out later was a amateur welders pack of steel. Since then, thanks to you guys i have some 1214 in different sizes. My first project, and getting to know my lathe was some bolts. M10 x 1.5 so i could bolt my bench grinder down and grind some HSS. The bolts didn't have a hex head, so i just knurled some round bar and they did the job. Then I ground up a couple of tools with the grinder now.

thanks for your help guys.

cheers

John

Edited By john mostyn on 17/08/2021 12:17:30

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