Horses for Courses

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Wolfie, and any other beginners. I think Terry’s concise and general explanations are very well put. I’ve been in engineering all my life and I am still learning about different metals and which are best for what, in general terms I am aware of most of it. A lot of choices for materials are for the “designers” to decide upon, and for the “doers” to use, so don’t think you are being ripped off or being taking for a ride having to use many different or higher priced metals in one project. Untill you have gained a little knowledge and experence, you have to trust the plans that you have somewhat. If you want to design, then yes you will have to read widely and be prepared to experiment with many failures ensuing. But if something does not work the first time or two don’t give up just persivere, you are bound to learn as you go along. This is the way industry has built up over very many years. 

 

Regards Nick.

Edited By Nicholas Farr on 11/12/2010 13:24:32

[Richard ParsonsParticipant @richardparsons61721]

 

Jeff can you explain your statement *”For beginners in general I stand by my “no aluminium in steam models” advice statement for minimum disappointment. Just my opinion, your mileage may vary.”

I know it is your opinion and as my old mate ‘the Animal’ used to say “opinions are like bottoms – we all have one”. But everyone has a reason for their opinion. Can you tell me why you will not use Aluminium should not be used on a steam engine? I am slowly gathering metal to re-visit Mason’s Minnie this is very difficult to do in Hungary since the visit of oriental gents with suitcases full of cash. They cleaned out everything.

I want to use an aluminium cylinder block with (as the numbers’ are right) with PTFE pistons and PTFE piston valves. There are a couple of technical problems which I have yet to solve completely but I have several solutions. 

[Jeff DaymanParticipant @jeffdayman43397]

Hi Richard,

 

I have tried aluminum in several steam models for several parts, on an experimental basis.

 

In contact with steam, especially superheated steam, aluminum can corrode rapidly. If it corrodes under paint it makes a horrible mess. If used as a bedplate it works OK as long as it is kept cool. If it warms up, the stroke and valve timing can change and bind up the engine.

 

If a PTFE piston is used in an aluminum bore it may work OK. A steel or iron or brass piston in aluminum cylinder will wear rapidly and ruin the cylinder fast, unless the cylinder is hard anodized by an industrial coatings shop.

 

For cylinders if a cast iron liner is used in the bore and valve seat it works OK but the differential expansion of cyl to liner must be taken into account. If it is not, the liner will fret in the fit to the aluminum and develop leaks as the engine is warmed and cooled between uses. Again this is worse the hotter the steam is. If elastomeric seals or silicone sealant are used everywhere the aluminum meets the liner this problem can be reduced or eliminated. (but why bother? chunks of cast iron for cylinders are just as easy to machine as alum and have no such problems.) If stainless or mild steel liners are used in aluminum, there can be severe galvanic corrosion problems also, which again can be reduced with silicone barrier films, but risk of corrosion is always present. I don’t think in 100 years people looking at aluminum structures or models will see much intact aluminum, it does corrode rapidly in many circumstances. If you are spending time making beautiful models, I suggest cast iron, brass, bronze and stainless steel for longevity.

 

For bearing surfaces, aluminum is awful. If you use alum for a bearing box you should use a bronze or cast iron bushing. Shafts running in aluminum even at low speed or as control shafts will wear the alum rapidly. If using bushings, a heavy press fit is needed to retain them if they get warm, again due to the high coefficient of thermal expansion of aluminum.

 

Hope this explains my opinion. I just don’t want for beginners to steam models to have to re-learn hard lessons and get discouraged.

 

Now, tell me the circumstances of these oriental gents buying up metal in Hungary. Why are they buying up metal stocks there particularly, and do the metal stores not re-stock after a big sale? What are these gents doing with the metal? I realize it may be expensive, but can you not order specialty metal from McMaster Carr or other US mail order houses? Most places I’ve been, admittedly only North and South America and Western Europe, you can find bars of cast iron and mild steel at metal shops and in toolrooms. Is this not so in Hungary?

 

JD

 

 

[JasonBModerator @jasonb]

I suspect these oriental gents are buying up all scrap and other items that can be put into the melting pot and turned into new lathes & mills for us model engineers. I would not think they are buying virgin metal stock but are likely to be selling back what they don’t use themselves.

 

There are several model engineering suppliers in Germany etc which I would have thought could get the materials to you. or find a friend with a strong arm and large suitcase

 

Jason

[KWILParticipant @kwil]

John Olsen’s answer on Stainless Steel has me puzzled, 303 stainless machines exceptionall well, at present I am screwcutting some 2BA threads on brake rods and there really is no problem at all.

[Keith Wardill 1Participant @keithwardill1]

Some interesting things in this thread –

There are plans around (By Richard Tingey) for a traction engine using duralumin for cylinders – I assume the hardness of dural offsets the wear problems of aluminium.

 

Re obtaining metals (Richard Parsons) – I live in Romania, and have similar problems, so I can understand why he is considering other metals for Minnie. I have a metal dealer in our local city who occasionally seems to have the unobtainable in stock – the problem is that he won’t take orders, so its a case of ‘yer takes yer chance’ with what is on the shelves. I tend to just go browsing occasionally, and if ther eis something that may be useful, I buy it. (prices seem to good – but I haven’t seen and gentlemen with case of money ).

 

The comment by JasonB is a good one – I lived in Germany for over 25 years, and nowadays I sometimes order stuff that way.  The kicker for mail order is cost – from Germany it is not so bad, but anything from Britain is a total ‘no-no’ – the carriage charges are outrageous, often running to two or three times the cost of the material.

I have noted once before in another thread that someone in Britain is making a very high profit out of postage charges – I have experience of suppliers quoting ‘approximately 45 pounds’ to send me a metals order of about 35 pounds (to Romania). I had the parcel sent to a friend in England, which cost about 5 pounds, and he then sent it on ( Post Office) at an additional charge of 5 pounds – so who was trying to rip me off?.

 

 Jeff Dayman asks why it is not possible to buy bars of cast iron and mild steel off the shelf in Hungary – I guess Richard will also reply to this, but my opinion is that model engineering in both these countries is very rare, so the sale of metals in the volume/quantity we need is virtually non-existant – you may be able to buy it in industrial quantities, but I for one don’t know how I can handle several hundred kilograms of cast iron.

 

 

 

 

[Jeff DaymanParticipant @jeffdayman43397]

Please bear in mind I know nothing at all of life and ME activity in Hungary, so if my questions about it are silly please inform me.

 

When I was growing up in rural Ontario Canada there were no metal stockists, no tool shops and no ME colleagues for many miles and so they may as well have been on the moon. I had no car or indeed any money to buy anything. I learned from these circumstances to hang around the back doors of machine shops and garages and welding shops and get to know the guys working there. Often times I earned a scrap length of steel or iron or bronze doing odd jobs or helping out with lifting something heavy, or taking a tray of coffees to the guys there. Maybe this would work in Hungary too, just a thought. (Don’t try it though if there’s a risk of being picked up for spying or something I’m not aware of)

 

JD

[John OlsenParticipant @johnolsen79199]

Kwil, the existance of one reasonably machineable grade does not change the fact that generally stainless is more difficult to machine than other materials. Generally does not mean always. Also the more corrosion resistant it is the more difficult machining it is likely to be. Part of the problem with stainless is the poor heat conductivity, plus many grades will harden when they are rubbing rather than cutting, so drilling deep holes can be a problem.

 

So if the job needs it, it is worth finding out which grade will suit and tracking some down, but just grabbing a random offcut of some sort of stainless may lead to disapointment.

 

Here in the antipodes,  ther are not a lot of what you would regard as model engineering stockists, so we mostly have to go to the importers. For things like mild steel bar, they will usually not cut anything smaller than about an inch diameter, so it is a whole 6 metres or nothing. For specialty steels like ground stock, cast iron bar, and so on, they will cut smaller sizes. In one case they also keep a computer record of what offcuts they have, so you can ask what they have in the way of offcuts of around a desired size. It is better to buy a little more than to pay a cutting fee!

 

The main brass stockist around here will only sell a minimum order of $50, and also has a cutting size limit, so you sometimes end up having to buy 4 meters when you only want a few inches. This is where a club can be useful.

 

regards

John

[Ian S CParticipant @iansc]

John, I may have an answer to the brass problem, last time I visited my supplier I asked about orders from other parts of the country, and that was OK by them. The company is:

Little Metals Co.  22 Stewart st Christchurch, PO Box 33055

            http://www.info@littlemetals.co.nz

  They have brass, bronze, copper, zinc and aluminium. The blokes who run the place, started it because of the way the firm that you proberbly deal with was being run (they are ex staff from it). No minimum order, and they cut to size.

  My frirst dealing with stainless was carving a cup like piece out of a 2″dia x 3″ long bit of 316, its definitely not free cutting! But on the whole I,v not had too much trouble, maybe because I don’t know what I’m doing.

  With one exception with my hot air engines I use cast iron for pistons, and steel for cylinders(cast iron would be better),the exception is a brass cylinder, with a teflon skirted aluminium piston. What gets me is the ones on another site (they proberbly look in here to) that want minimum friction for thier hot air engine, but think that an aluminium piston in a copper (water pipe) cylinder is OK, this combination is one of the highest in the order of friction.

  As corrosion in aluminium goes, I think its the statue of Eros in London that has been repaired after over 100yrs, think it was one of the first major works in aluminium. Ian S C

[JasonBModerator @jasonb]

Jeff with the current price of scrap metal  it is very hard to find anything in a scrap bin as most companies cannot afford to throw away their waste or even swarf and even a scrap dealer will want a high price, thats if HSE will even let you on the premisis.

 

You only have to look here (UK) to see the black market in street signs and CI drain covers to realise that there is not the amount of scrap available.

 

Jason

[Richard ParsonsParticipant @richardparsons61721]

 

Parts of Hungary were much more industrialised than Romania. Hungary was considered, in those days, to be the ‘happiest cell in the whole blooming Jail’. 

Their industries however, in the main, were rundown, the machines knackered, and their quality was dreadful. There was a rapid de-industrialisation. Hungary was full of scrap-iron. In ’04 and ‘05 I could get almost anything by way of steel, but it was mostly only fit for ‘cattle pen fittings’, it is full of ‘shuts’, hard spots and flaws. It is dreadful to machine. There was a local foundry I made patterns and tried to get then to cast them up for me but the bureaucracy involved was huge and the boss was away so nothing could be done. It too went in ’06, the whole blooming lot including the corrugated iron roofs etc.

In ’06 along came some oriental gents with suitcases full of cash. If there is one thing NO Hungarian can resist is a suitcase full of cash, especially if all the paperwork the oriental wants is a name (any name will do) on a paper written in Chinese for the cash. The scrap yards, stock yards, garages, autosbonto, (motor scrap) yards, hedge rows etc were scraped clean. Even good machines, metal framed sheds and fir tree racks were sold cut to pieces and loaded onto freight cars bound for Europort or where ever. Most of the work was done by Romanians and Bulgarians.  Other things just disappeared. These included several pylons which were due to be erected on a new power line.  Children’s playground swings, Street furniture and the like often just vanished. Copper also tends to do the same vanishing trick (including several kilometres of the over head conductors from the Budapest to Szeged railway).

Those local stockholders who continued in business only bought small amounts of structural steel for building. The rest just went out of business and became un-employed (a favourite Hungarian occupation). The cash, well, it too just vanished.

Why it has not yet happened in Romania is probably the general scarcity of metal working.  So the ‘suitcases’ have not yet appeared.

As to postage from the U.K. it is a dead ‘rip-off’. I am trying to arrange ‘Cab freight’ where a driver puts a small package in his cab and gets a good reward on delivery.  At the moment this is on hold because the boss man cannot get his head round the idea of forwarding stuff delivered to his depot in the UK by post.  Any way He only wants full loads.

Jeff – in Hungary people who make things from ‘scratch’ are almost unknown. You can get a small lathe; there is one in the local DIY superstore. It has been there for years! There are model makers who make wonderful dioramas from plastic kits. There is a local 9mm railway club but making their own locos/rolling stock is beyond them. They would rather pay someone else (usually Germans) to do it for them. People are beginning to make things for themselves but it is mostly building work.

As JasonB reports metal is getting as rare as ‘hen’s teeth’ in the UK..

Keith next year, in the late spring, when things warm up a bit, I may well wander over to Arad bu i will have to investigate the busses first.  in Hungary i can travel for free, how is it in Romania?.

 

Edited By Richard Parsons on 12/12/2010 12:35:32

[WolfieParticipant @wolfie]

Interesting and useful discussion chaps. It all helps. How come Hungary hasn’t fallen over then?

[Keith Wardill 1Participant @keithwardill1]

Jeff – No you aren’t asking dumb questions – it is interesting to get the chance to explain that not everyone has the facilities available in Western Europe and America – there is no concept of ‘model engineering’ in Romania, so there is literally no support – a large contributory factor is things like salaries. In the area I live (Romania) typical salaries are between 400 to 1000 Lei (1 Euro = 4.45 Lei) – no-one (apart from the usual black market Mafia) has money for luxuries like modelling, and the Mafia have no interest.

 

Scrap is valuable here, rarely a day goes past without someone banging on our door asking for any scrap metal – copper used to be impossible (electrical cable was all aluminium until recently), but is now appearing in DIY places as cable/pipe.

 

That said, there is quite a steady business investment going on in our area – several large new modern shopping malls have been built which compare with any I have seen in Western Europe. (Tesco has a big presence in Hungary). There are several large (German) DIY supermarkets around  such as Praktiker, OBI, Bauhaus, Dedemann etc all like B & Q, but with a better range of stock – but all aimed at the house /garden renovator. It is all aimed at the consumer, not at the hobbyist.  We have the same DIY supermarket feature as Richard – an OBI store opened in Arad two years ago, and on the shelves was one 7×12 chinese mini lathe (same as Clarke CM300) – its still there!.

 

Best feature is cheap property and land in lovely countryside, and excellent Romanian wine at throw-away prices.

 

Richard – It would be good to meet you if you make it. – No free travel as far as I know – I have just had to buy a new car – the old one was suffering from the effects of bad country roads. Air travel is good/cheap – Arad and Timisoara have good small airports – Google Whizzair, Carpat Airlines, Blue Air. I hope to make a goody-gathering road run via Germany to England and back sometime in Summer, so I could get across to you then (heavy snow at the moment) – I’ll keep in touch.

 

Sorry about going off-thread, everyone – it was just convenient to anwer the questions in this thread.

[Peter G. ShawParticipant @peterg-shaw75338]

Going back to Wolfies original questions, I’m afraid there is only one answer.

 

Now, I’m not a metallurgist (spelling?) or a mechanical engineer, so like you I have had to start from rock bottom, and the way I did it, over 20 or so years, was to buy lots of books and read, read, read and even then read, eg Tubal Cain’s book on Hardening, Tempering & Heat Treatment (WSP 1) is falling apart, partly due to the number of times I’ve read it, and partly, I think, because it probably wasn’t made properly.

 

Having said that, how about Peter Wright’s book,  Model Engineering – A Foundation Course. This book does go into what the various metals are, and what they are used for. Alex Weiss’s book, Workshop Materials, WSP 30, is another which has some advice in it.

 

If you are financially disadvantaged, then perhaps you could try the library service – they may have some or all of them available, and if not, they can go inter-library, or even British Library, but be warned, these latter two will be expensive, possibly more than the book itself.

 

Good Luck, and enjoy the reading,

 

Peter G. Shaw

 

 

 

[Ian S CParticipant @iansc]

Not exactly model engineering, but weren’t The Mafia in Italy caught building counterfeit Ferrari cars. Ian S C

[TerrydParticipant @terryd72465]

Workshop Materials WSP30 only  £4.70 New, delivered – Here

 

Terry

[WolfieParticipant @wolfie]

“We have the same DIY supermarket feature as Richard – an OBI store
opened in Arad two years ago, and on the shelves was one 7×12 chinese
mini lathe (same as Clarke CM300) – its still there!.”

Err how much are they asking for said lathe?

[Keith Wardill 1Participant @keithwardill1]

Ian SC –

I guess the Mafia can find (or create) a bigger market for counterfeit Ferraris than for model locos or TEs.  (Shame) There is one Ferrari here in Arad (its a well-known sight in the city – most cars here are recycled German cars or old Dacias) – must have a close look and see if it is counterfeit, and see if the owner(?) will tell me how much he paid

 

Wolfie –

last time I looked, the lathe no longer had a price on it, but I seem to remember a few months ago it was around  2000 Lei (Say 400 Pounds Sterling) – if you want it, let me know, and I’ll go get it and send it from Romania, if you pay the postage (See earlier posts regarding postage ripoffs)

 

 

[Author]

Posts