What steel to use for Kozo’s Shay

[papflynnParticipant @papflynn]

Hi,

I've recently bought Kozo Hirako's excellent books 'Building the Shay' and 'Building the Heisler'.

I'm itching to start building the Shay but I have absolutely no stock material to work with. I plan to get a few 3 metre lengths of steel of different diameters as well as some flat sections.

Whenever I ask people as to what type of steel to get I get many conflicting answers, such as:

"EN1A Pb as its so easy to machine."

"Get EN3B which is cheaper than EN1A ."

"Get EN8A steel which is better than EN1A."

Because I want to get a selection of profiles, I don't want ot end up with steel that is not versatile.

So, what do you all think I should get? I assume that there's not one type that fits all but which is the most versatile for locomotive building?

Paul

[papflynnParticipant @papflynn]

[JasonBModerator @jasonb]

This recent thread may throw some light on the subject

Edited By JasonB on 03/10/2016 20:14:38

[papflynnParticipant @papflynn]

thanks Jason, just read through that article twice. I think I might go for EN8M as it's harder than EN1A. But what exactly does 'free machining' mean. I presume it means easy to machine, is that correct?

[loco manParticipant @locoman67579]

For general machining details – and providing that no arc-welding is involved- I would much prefer En1A Pb. With sharp tools and plenty of cutting fluid it can give a surface finish approaching that available from cylindrical grinding. As I remember from my time 'on the tools' in the late '60's / early 70's the lead content of En1A could cause porosity in welds.

No problem, though with either silver soldering or 'sifbronzing' .

En8 is the next – readily available – higher tensile steel. After that, En16T – but possibly an 'over-kill' for the Shay.

Ian

[JasonBModerator @jasonb]

I would also go for EN1A for the majority of the round stock, square and flat bar is more likely to be available as EN3, keep the EN8 for axles, cranks etc.

You will find the free machining steels do what it says on the tin, they are easier to machine and you will have less problems getting a nice finish, the leaded EN1A Pb is even nicer to machine but would come out a bit pricy if you used it for everything.

[MWParticipant @mw27036]

Would be interesting to hear why EN1A pb is more expensive, i also thought EN1A was leaded already?

Oh, and for the reasons stated above, i also agree EN1A is probably going to be the versatility winner for bar stock,

unless you go out of your way to get it EN1A, alot of flat and block mild is going to be EN3, this can be good if you're intending to case harden, not sure if thats a given with what your making but just letting you know it's doable on that but not the leaded..so i've heard at least. 

there is also a futher distinction to muddy the waters, between bright drawn and black, the latter being the least processed. 

All material can be rated by it's "machinability" it was a scale meant to make things like this easier to solve but seldom seems referred to. 

Michael W

Edited By Michael Walters on 03/10/2016 21:29:07

[Mark CParticipant @markc]

An interesting point for anyone who does not already know, the major difference between bright drawn/rolled and black (apart from the scale) involves skin tension in the bright materials – you will get significantly more distortion from bright bar than black particularly when milling. It is a result of machining the skin away leaving the manufacturing stresses in an un-even condition. If you take a bit of bright bar and mill the top off it, the chances are it will be bent (hogging on the cut side) when you put it on a refference plane.

Mark

[John Stevenson 1Participant @johnstevenson1]

I buy a lot of steel bar, usually in full lengths unless we are talking 4" plus. Most unless specially ordered is what is know in the trade as GCQ which stands for General Commercial Quality is is generally EN3B.

Black steel or hot rolled is also EN3 or EN3B, never been sure of the difference. I never use EN1 leaded as a lot of my work is shafts and because the lead gives it very good machining qualities it also makes it very soft so pressing a shaft in for an interference fit will invariable bell the shaft or bend it.

The next statement is something I have found over time and have no proof as to whether my interpretation of it is right or not just that it works for me.

Many people say black steel doesn't machine well and is gummy which I fully agree with up to a point. And that point is size.

I have some black steel here 16mm round, bought in for some window bar jobs. It saws well, welds well which is ideal for the job but turns like crap. HSS, tipped, new tip, doesn't matter, looks like wrought iron.

Now the next size I carry which is 25mm, [ pity I don't have any 20mm as a test ] turns fine and when you get up to 50mm if you belt the speeds and feeds right up you can get a mirror finish on it far better than bright drawn and more like EN8.

Now the unproven statement.

I put it down to how fast the bar cools when it comes off the rollers. The thicker the bar, the slower and the better finish. That's why I say I'd like to test some 19mm or 20mm to find this cut off point.

For me and my supplier who I presume buys off the same major stock holders as everyone else 16mm is rubbish at turning but 25 is OK, 30 is even far better.

I can save a serious amount of cash using black. Bright comes in nominal 3 metre lengths and black is roughly the same price but comes in nominal 7 metre lengths.

[Mark CParticipant @markc]

John, are you using positive or negative inserts? You may find a negative with wiper geometry will sort out the problems. I always consider black bar to be fully annealed and hence completely soft with no residual skin – it tears rather than cuts but that does not explain the size/cutting properties you describe.

Mark

[loco manParticipant @locoman67579]

The question has been raised as to whether En1A is lead bearing.

From a copy of 'Macready's Standard stock range of quality steels and specifications' dated October 1975 it would appear that there were a number of 'sub-sets' of En1A. Quoting their descriptions and trade names, 'Usaspeed' classed as 'super freecutting bright steel' was listed as " BS970:1955:En1A" replaced by BS970:Part 1:1972:220M07, colour coded Green. The same catalogue refers to 'Usalead' lead bearing freecutting bright steel. Same BS description but colour coded Magenta.

In the same catalogue there is reference to 'Usatel' – 'Tellurium bearing freecutting bright steel' colour coded gold' and noted as being one of the fastest machining of all steels. However I cannot find any trace of a BS970 'En number'

The lead-containing En1A I knew in my time in the 'shops' as 'Leadloy' (sic) and was used widely for the production of such items as hydraulic fittings – where the very good surface finish straight from the tool (NO emery cloth!) was a help in sealing against up to 4000 lb/sq.in. oil.

Unfortunately – as a direct result of having lost my job last year after 19 years in the drawing office when the steelworks at Redcar closed down – I can only refer to such catalogues {especially the afore-mentioned 'Macready's) etc. that I have managed to retain. So it is quite likely that there are others who have more up-to-date information and I look forward to their knowledge / input / information

I am following this thread with interest. I would stress that I have, and have not, had any connection whatsoever with Macreadys — other than referring regularly to their (by now long-outdated) catalogue

Ian

[John Stevenson 1Participant @johnstevenson1]

Mark.

I have standardised on one tip for turning and boring, the only difference I use a plain one for turning and one with a hole in for boring as that what my tooling expects.

These are 16mm TPUN and all have a negative rake.

Main reason is cost. A triangular tip gives you 3 bites of the cherry whereas the CMG ? type only give you two.

I never use double sided inserts as often the lower one gets damaged before it's been used and standardising on only two main turning tips means i can buy bulk and get real good prices.

I see some of these tips advertised from a 'cheap' £3 up to £7 and I have never yet paid a £1.00 a tip but i do buy a 'lot'

Now having said this by using the same machine, same tool, same tip, the only variable is the material and for me 16mm black is crap, anything over 25 is good and as you go bigger it gets better.

[papflynnParticipant @papflynn]

Ok, thanks everybody for your input but to be honest I'm getting more confused.

I think I'll opt for Jason's suggestion…

"I would also go for EN1A for the majority of the round stock, square and flat bar is more likely to be available as EN3, keep the EN8 for axles, cranks etc.

Many thanks

Paul

[Mark CParticipant @markc]

John, the TPUN is a positive plain insert (the inserts with holes in would have a different letter in place of the N) and negative would be TN**. If you are happy with them then all well and good but you have some bigger machines I belive from reading other comments on here (repairs to motors etc). If that is the case, you can easily cope with the "trigon" type in a true negative arrangement along with the "wiper" geometry which would give you good finish with substantial stock removal etc. I would get in contact with one of the insert reps and get some samples to try.

The subject of inserts has been up on here before so I will not comment further to prevent dragging the discussion too far off on a tangent….

Mark

[JasonBModerator @jasonb]

Posted by Michael Walters on 03/10/2016 21:18:39:

Would be interesting to hear why EN1A pb is more expensive, i also thought EN1A was leaded already?

If you start replacing some of the cheaper constituents with more expensive lead then the price will go up.

No lead in EN1A, it is just free cutting, small percentage of lead in EN1A Pb makes it even more free machining and easier to get a good finish on it.

[Roderick JenkinsParticipant @roderickjenkins93242]

Free cutting is effected by reducing the tendency to form a built up edge on the tooltip and ensuring that the swarf comes away in chips. In EN1A this is achieved by the addition of a small amount of sulpher. As Neil says, the addition of lead is even more effective. I seem to remember that selenium has also been used.

Rod

[MWParticipant @mw27036]

Thanks, i always thought that EN1A was effectively EN1A pb but clearly it's not. So without the lead i guess you can surface harden EN1A?

Michael W

[richardandtracyParticipant @richardandtracy]

I tend to use Magenta (leaded EN1A) which is also called 11SMn30Pb, Steel No. 1.7018, 230M07Pb depending on the standard used. (Standards are good, lets have lots of them!)

Why? Well, as bright bar it comes in 3m lengths, which fit in my van without cutting, so I don't pay a cutting charge and the stockist won't allow cutting in their yard. I use little enough, and the extra cost is much less than the cutting charge.

Regards,

Richard

[Author]

Posts