Model engineering’s (live steam) big five

[LukerParticipant @luker]

A while ago a few of the builders on a private messaging group (I run for youngsters), had a discussion on how to measure oneself as a model engineering builder. We came up with 5 (arbitrary)’ levels’; each one unique in complexity and requiring a different set of applied knowledge. Simply put they were as follows:

1.       Model engineering basics(basic fitting and turning, limits and fits)

a.       Successfully quartering a set of wheels with no rattle fits on the bearings and connecting rods and of course no binding.

b.      For the traction guys, it was a set of gears that mesh uniformly with a plastic shopping bag that is not loose at any point, or crushed.

c.       Another one was a steam tight but mechanically free piston fit.

2.       Successfully making and testing a boiler. (soldering, fabrication)

3.       Casting your own components. (metallurgy)

4.       Making a live steam injector suitable for your build. The smaller; the greater the skill set. (precision turning and taper turning)

a.       Another one was a leak free clack without smashing the ball onto the seat to get it to seal. (Machining a hole ‘rounder ‘than  a commercial reamer)

5.       Successfully making a pressure gauge. (instrumentation calibration)

Most of the builders here scored an easy 2, very few scored 3 or higher and those that did typically had a number of builds under their belt. Of course the elder low scorers argued the existential nature of model engineering; that it’s only for fun, this is an arbitrary list, these are impossible, I don’t build like that etc. etc. (at which point I had to smile).

This was just for fun to give the youngsters something to aim for (goal driven accomplishment). I did wonder how well the members here would do? BTW this was for live steam (most of the guys either do loco’s or traction engines), but I’m sure similar lists can be made for IC engines etc.

[JasonBModerator @jasonb]

I’d probably add designing your own Loco/TE/ IC Engine/etc from scratch as another notch on the workshop door frame. So many just build to old published designs where there are words and music to guide them but it is another level to reach if you start with an old engraving or photo and work it all out for yourself.

[noel shelleyParticipant @noelshelley55608]

An interesting idea Luke and if I was faced with a candidate with level 3 on your scale I would offer them a job and try to see their practical education was enhanced by the theory that goes with it. Sadly in the UK practical skills are very limited and not valued unlike many places. Apprenticeships are coming back but they don’t seem long enough to teach the tricks of the trade that old tradesmen passed on. A qualified carpenter who was 18 ? It’s a changing world.  Noel.

[Peter Cook 6Participant @petercook6]

Makes me a solid zero – or possibly some negative number!

[BazyleParticipant @bazyle]

You also need to allow for other branches of Model engineering. Clockmaking for instance, model boats, hand tools, machine restoration (not painting lathes), drawing and CAD skills, painting models. 3D printing and electroforming/plating too.

[JasonBModerator @jasonb]

Luke did say “BTW this was for live steam (most of the guys either do loco’s or traction engines), but I’m sure similar lists can be made for IC engines etc.”

 

Although casting is a skill in itself I would not look down on someone who has not cast anything as many model engineers may only have a small shed, part of a garage etc available to them and foundry work needs a reasonable amount of room and judging by Luke’s videos does not bode well for a clean tidy patio. So just because someone can’t try casting does not make them any less an engineer.

Also not everything suits home casting, for a start you may want iron castings and there are not so many who do that just sticking with non ferrous. Those that want crisp detail are often better off cutting from solid, same with those who’s scaled down parts would be too thin to expect metal to flow and they are better with fabrications or cutting from solid.

So maybe that should be another number on the list being able to create a complex part by cutting from solid or fabrication.

[Charles LamontParticipant @charleslamont71117]

An old standard for a ‘masterpiece’, in the sense of completing one’s ME apprenticeship, was making a Quorn T&C grinder.

I would add to Bayzle’s list, and following Jason’s points: traditional wooden patternmaking, including coreboxes and/or oddsides; sharpening; scraping; making and using laps; making special cutters, including hardening & tempering.

[JasonBModerator @jasonb]

If new blood is to be encouraged into the hobby I would probably not want to force them down the traditional wooden path. Yes an understanding of pattern making with all it’s draft angles, loose pieces, cores or self coring, etc is good to learn but these days 3D printing patterns or using a CNC router or desktop CNC should be included.

After all the aim for many  is to make your loco, IC engine etc and enjoy it rather than spend time and money on making something to make something else.

I expect Luke’s “Casting your own componenets” includes the pattern making not just the foundry work.

[LukerParticipant @luker]

The premise was that each of the big five has a clearly defined outcome using a unique (undefined) skill set, easy to test without bias. In practical engineering these are clearly defined workshop professions, but the skill set has changed over the years. For example, some of the mentioned skill sets like pattern making (either traditional or 3D printed) or fabrication from solid is definitely a feather in the cap of any model engineer, but this isn’t particularly challenging, and how would you measure the skill of the pattern or the solid? The end result, like a good casting or an assembly with good limits and fits results in something tangible and testable.  Incidentally the basic machining level outcomes were designed to test machining accuracy and ability to manage tolerance stackup. A similar argument can be made for tool making and tempering. This skill set is useless unless it can be practically used and tested. Making a reamer to make a perfectly round hole for a clack or the taper reamers for the injector is the ultimate test for tool making and tempering. Anyone that’s tried making a tool for machining brass will attest to this.

This was meant to be a proper challenge, easy to test without emotional bias. If these tests were applied in the model engineering shows I wonder what the outcomes would be. A good looking presentation isn’t necessary a good engineering build, and if a great deal of the items were bought then why should that person do better than someone that has scratch built their steam engine (requiring a much larger skill set and engineering knowledge base)?

Jason, I hear you with regards to design but I would leave this out of the big 5, simply because it’s incredibly easy to design a steam engine. If you copy legacy work your design will steam well enough, and the bigger builds will steam just fine on a poor efficiency design. The difficulty comes with the initial hand calculations, then the non-dimensional analysis and finally the FEA simulations; resulting in a very efficient build. How many designers would do this properly? I suppose you could measure the design by the amount of clinker and how the safety valves behave, but that to a large degree depends on the driver.

I would love to see alternative lists for other areas of model engineering, but please make them a challenge; mediocrity is for the non-technical professions!  I’ve designed and build something similar to the corn grinder and trinkets like that only test very basic workshop machining skills (I don’t even bother publishing workshop tooling, it’s too easy 😉   ).

[JasonBModerator @jasonb]

 

The judging criteria and entry forms take care of bought in items to some extent as you have to disclose what may have been bought in be that laser cut frames, commercially cut gears, commercial boiler, boiler fittings, castings etc. Points are divided into catagories such as originallity where a new design will score more than just churning out the same old one, suitability of materials; workmanship, finishing (painting etc)

That won’t cover what the thing runs like but we have things like IMLEC that give a good indication of efficiency .

But not everyone is interested in how many passagers can be pulled around with X amount of coal. There are those that build steam subjects in small scales that are never going to be efficient as you can’t change the physics. Take the likes of Cherry Hill, she tests her engines on steam once just to see that they run and that is is. Does that make her a less accomplished model engineer than someone who can do more laps of a track with a very non scale loco that has been built for practicallity of running rather than scale look?

As for skill of a pattern or casting things like being able to pull it from the sand, complexity of cored passages, surface detail would all be ways to assess how challenging the pattern was to make and obviously a good casting without any of the many defects that can be found in castings would indicate the persons foundry skills. Take a look at the work that goes into say a 6″ scale fully cored traction engine cylinder and compare that to a simple cylinder that may be used on a 3.5g loco which is not much more than a couple of concentric cylinders and a flat face or two, all passages machined.

Boilers would be one form of fabrication as they are predominantly sheet metal work but what about those I see making complex large scale loco cylinders from more solid parts, same would apply to replicating castings on things like stationary steam or IC engines. Working out how to engineer the parts, join them and finish to make them appear as a casting are all skills

[LukerParticipant @luker]

There is no thermodynamic efficiency in the ‘big 5’, these goals were to test a broad skill set range and how close you have come to mastering specific hands-on engineering skill sets. But now that you mention the IMLEC; unless the score card is normalised to the design tractive effort (I don’t know how the loco’s are compared), the later larger loco’s (with added weight) with more coupled wheel sets and an experienced driver will always do very well, when compared to the earlier prototypical designs. This essentially tests design efficiency and driver experience, but a loco can rattle all the way down the track and still do well; not really advocating engineering precision or skill!

Actually Cherry Hill would probably do very well with the big 5 (the big 5 suits her style of model engineering), and I expect she would have scored an easy 3. I wish I had the chance to meet her and discuss the hobby we were clearly very passionate about.

Sorry Jason, but with the pattern and casting you are wrong. A small 3.5g cylinder is technically more difficult to cast than something that seems to be complex just because of cores (like a larger traction engine cylinder). The casting modulus of a smaller cylinder is terrible, typically resulting in poor castings for the inexperienced. Whereas a fully cored larger casting is relatively easy to cast. Those cores, although seemly difficult, are actually quite easy to make with a few simple tricks that most foundrymen pick up quickly. The calculations for the casting modulus and methoding is where most backyard foundrymen battle. Interestingly if those larger cored cylinders are cast-iron in a rigid mould like the phenolic system you don’t even need to worry about risers or feeding from the sprue.

It is very encouraging that judging criteria takes into account the amount of bought in items. Nowadays you could assemble a build from 3D printed metal components, laser cut items and bought in boilers and steam valves adding very little hands-on value to the individual components. Sadly a display like this only highlights, that, the ratio of knowledge to monetary wealth is biased to the wrong side (in my opinion of course!).

[JasonBModerator @jasonb]

I would still say that casting a TE cylinder like this would present most home casters with far more of a challenge than a simple 3.5″ G loco cylinder. Yes you need to get the metal right in both cases but not much good having nice metal with no shrinkage etc if it’s the wrong shape or your cores fail.

Not sure of monetry wealth being in the wrong place. I have found in many cases I can get a part 3D metal printed for less than I can buy a casting for. As the majority of Model Engineers buy in castings then the 3D option is actually the less expensive and more skill needed to do the 3D model in CAD than just buy an off the shelf casting.

Also cutting from solid or fabricating can often work out considerably cheaper than buying in castings, there is certainly more ability needed to do that then simply machining a few surfaces and putting some holes in a casting. You certainly get more workshop time for your money.

Hard to tell what the overall cost of home casting would be as you have to spread the cost of setting up over a number of uses. Fuel, etc for each pour ( more pours if the first casting is not usable) and whatever it may cost to set up for pattern making. Then there is the time “cost” if you are making a pattern does it take any longer to make it from say wood than it does from metal in which case cut out the middle process and fabricate the final part not a pattern

[Martin Johnson 1Participant @martinjohnson1]

Oh well, 67 years in model engineering and I have only scored 1B.  I chased leaks round a copper boiler until it was (very expensive) scrap, the wheels on my first and only loco never did go round smoothly, 1C is impossible.  I have never owned a lathe where I could “just poke a number 80 drill through” as LBSC did, so injectors are a no hoper.  I suppose I limped through 4 by using O rings in clacks.  Pressure gauges???? Life is way too short.

Sadly my design skills in building a unique 7″ scale steam lorry obviously count for now’t.  Scraping machine tool ways has obviously go me nowhere as well and don’t get me started on how many special tools, cutters, jigs and gadgets I have knocked out.

Had plenty of fun along the way though, so who cares?

Did I mention the panel beating for the lorry?  This hobby is way too diverse for such simplistic “test piece awards”.  Save all that carp for the working day.

Martin

 

[JasonB]

On JasonB Said:

I would still say that casting a TE cylinder like this would present most home casters with far more of a challenge than a simple 3.5″ G loco cylinder….

Hard to tell what the overall cost of home casting would be as you have to spread the cost of setting up over a number of uses. Fuel, etc for each pour ( more pours if the first casting is not usable) and whatever it may cost to set up for pattern making. Then there is the time “cost” if you are making a pattern does it take any longer to make it from say wood than it does from metal in which case cut out the middle process and fabricate the final part not a pattern

A beautiful casting to be sure! But with an understanding of the fundamentals of casting I would say this is an average casting, and definitely not more difficult than a smaller casting with an unfavourable casting modulus. I can see how the uninitiated would look at all the additional surface area and think this casting was complex where in fact the converse is closer to the truth. It is more work though, and must have cost a few rand in binder! Still a well earned tick to the big 5!

Costing is an interesting point; as you know my castings are made from sand from my local river and the fuel is used car oil (from my last service). I made the burner and furnace etc. with the only bought items the crucible and refractory. Nearly everything I cast is from scrap picked up from discarded ‘whatever’. So my cost of casting is cents to the kg cast.

You made me reconsider the terms of the big five. I would add that if you can only achieve them with fancy DRO’s CNC or buying the latest phenolic resin binders then you’ve missed the point of acquiring new skills.

You most certainly don’t need to spend ridiculous money to make amazing models, and you don’t need the newest and best tooling, I for one don’t have such luxuries!

[JasonBModerator @jasonb]

Maybe we see things differently. Although I have and still do cut from solid and fabricate using manual machines I looked at the CNC as a new challenge to learn the skills to get the most from it. It gets used now if it is the best tool I have for the job and may only see an hour or two use a month depending on what I’m working on.

But really it comes down to using what tools and methods YOU want to achieve the results YOU want, don’t get hung up on not being a complete model engineer because you can’t tick off all the things on the big 5 on someone elses list just enjoy what you are doing.

[LukerParticipant @luker]

Not at all, there is no argument from me that cutting from solid of fabrication takes skills, having done so myself I understand the effort and skills required. Its not nearly as difficult in terms of fundamental engineering skill when compared to the examples for level 1.

Any tooling or process that is exclusionary based on capital outlay or cost I don’t agree with. Youngsters will not be able to afford the tooling and outlay that CNC requires. A new skill and challenge, absolutely; developing artisanal skills… I’m not so sure. Am I jealous and wish I had nice toys like that… YES!

I like that: ‘Lukers big 5‘. If there’s ever a ME challenge for the experienced ME measuring how many artisanal skills have been mastered you welcome to name the award that 🙂 . Anyone that has experience in the manufacturing sector knows what skills are difficult to master; this was just tied into building a loco or traction engine, and articulated in such a way that you can’t cheat. Everyone that’s actually finished a build would have come across these ‘simplistic test piece awards’.

I agree totally, enjoy the hobby the way you want to. Personally I like to master new skills by spending the bare minimum. This takes time, effort, practice and many a failure, stubborn persistence is probably the greatest skill. If chopping out a finished model, using the same methods, as soon as possible is the goal, that’s fine! Its the way the current world works with instant gratification.

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