Member postings for John Lluch

Thanks Neil. Your points are excellent, and yes you fully got what I intend to be at. My stronger motivation is to try different things even at the risk of some of them not working, and of course I will be sharing all my experiences -good or bad- during the process. And of course my ultimate aim will be to produce a long working, reliable loco. The boiler is the one so far that has spurred the more inflammatory comments, but this is something I leave for a later stage.

Initially, my intention is to build and test some moving parts on compressed air, possibly under stress. This of course does not anticipate how they will work on hot steam but I guess some useful data could be extracted from that.

As you said, implementing popped valves managed by a programmable controller (possibly using a digital rotary encoder on the driving wheel as the input device) you could get the absolute perfection at all times, also considering the actual speed and load of the locomotive to dynamically modify not only cut-off but also lead, and considering as well different timings for intake and outtake events. However, I think that attempting this would be going too far because one objective is to design a loco that actually looks like a steam loco and one that can be made by everyone out of standard commercially available parts if proven successful. This is why I am proposing the Baker valve gear design on this case.

John.

Murray, yes I suppose all 3D CAD programs tend to converge over time in some form or another as users request features only available on one of them. My choice of Solid Edge was merely based on what was being used by a friend of mine. He taught me the basic aspects (mostly conceptual) and then I began to improve by looking at tutorials or youTube videos showing other people's use of it. I definitely will keep posting my progresses

Jason, Oh no!, I didn't mean I won't be running the loco on a track. I definitely do not intend it to be a static piece of work. I will move next year to a location (Fornells de la Selva) that has a medium sized track for 5" and 7.5" locos and a active model club I have already joined. They already own a 2-6-2 live steam loco and a bigger one is currently being build by one of the old members. They also have a bunch of battery powered engines for both the 5" and 7." track. Every two weeks they meet to run their locos for the public, so I will have plenty of occasions to do so as well. It is just that my primary motivation is to design the loco, not particularly riding it.

About aluminium, I just mentioned it for the sake of it. You are right, it should not be used for structural parts and its light weight would affect tractive efficiency if used extensively. I suppose it could be considered if we were talking about rolling stock, just maybe. Or it can be used for example as the boiler skin to keep the isolating material in place. I like very much the look of aluminium, so I guess it can be used that way if I decide not to paint parts of the loco.

A stainless steel boiler is however definitely possible in my opinion. Maybe even one that has *no* or very few soldered parts in it, as bizarre as it may sound. This is something I want to investigate. I've designed industrial heat exchangers for some time in the past, and copper was never an option on that field. So, I think there may be some room for improvement over what it is currently being used on model steam locos. You can call me a fool, but I don't think that cooper is used on a steam powered electric power plants. Said that, I may end to the conclusion that copper is after all the right material to use on the smaller scales, specially given all the advice I am getting against not using it, which I really appreciate. I am not at this stage yet though, so more will come !!

Julian, I would appreciate some more advice or opinion on whether there may be an actual issue or concern on using the Baker valve gear as opposed to the walschaerts. As said, I like the former over the latter because it has no 'sliding' parts and thus it is easier to build and possibly it ends with less overall wear after use. To my understanding the one that produces the most accurate time events is the Stephenson one, possibly followed by the walschaerts.

The Baker produces a somewhat less lineal movement on each side of the piston valve (i.e not fully symmetrical), but this can can be minimised if the levers are relatively long and properly orientated. I was barely there during the steam powered times, as I was just a very small child when steam locos were discontinued, but for what I found on the internet the Baker was only used in the USA, and it seems to me that its significant rate of adoption was more based on aggressive commercial actions by the manufacturer than on real benefits on full sized locos. However, my point is that on the smaller model locomotives the Baker may have its strengths specially if lubricant free polymer based bearings are used. What do you think?

Thanks

Edited By John Lluch on 27/09/2014 09:29:23

Hi Julian, Thanks for your comments.

It is not my motivation to build a scaled down replica or to buy a "kit" and assemble it, but to produce something different. It is not also my motivation to ride the loco. I just seek an opinion on design choices.

Particularly, I dislike the walschaerts valve gear because it inevitably has "sliding" parts. Of course, it works, is easy to understand, and it was the most used in the UK. I am also aware that the walschaerts was recently chosen for the 5AT locomotive.

On the contrary, the Baker valve gear has just "rotating" parts in it, no sliding parts, which I see as a clear advantage both for making and for running it. I can't see anything inherently wrong in it. Also, I have spent a significant amount of time simulating the valve gear until I got a reasonable understanding of how it works and how to optimise it.

About materials, I mentioned aluminium as I mentioned polymers (a.k.a plastic). All these are materials are extensively used in the transport industry (automotive, rail, and so on).

For example, you can find both lineal and rotative bearings made out of a special high strength polymer that will run maintenance free and no wear for a very long period of time even at temperatures above 200ºC.

I also do not see the point on using cast iron except for the sake of mimicking the full size design, which is not what I intend to do. For such relatively small pieces on a model locomotive I think we can just use blocks of extruded or laminated stainless steel and machine or bore them to the appropriate dimensions, no?. Other than that you must be a bit more careful with the tooling and the machining speed, what is the problem with that?, In turn, stainless steel will last forever, no?

John

Edited By John Lluch on 27/09/2014 01:20:18

After reading the book from "The model steam locomotive" by Martin Evans and "Design Procedures for Walschaerts' and Stephensons's valve gears" by Don Ashton, I started to draw my own designed loco in Solid Edge ST6.

That's the first time ever I used a 3D CAD software to draw anything, but I guess my willingness to build a locomotive made me learn how to use the software. My previous skills on (manual) technical drawing were limited to what I learnt during my chemical engineering studies, but I hardly needed them at work. Actually, I never used a professional CAD package before, even a 2D one. So, to be honest I find the Solid Edge software a bit tedious and frustrating at times, though I am sure this is due to my lack of skill than to the software itself.

See below what I achieved so far. My goal is to design a live steam loco that roughly matches the 5" Britannia dimensions but with the following characteristics:

- No importance is attached to the model being an actual replica of a full scale locomotive, but it still should look and be clearly identifiable as a steam locomotive. The loco will have free dimensions.

- Get rid of imperial units in drawings. All dimensions will be in plain millimetres. Parts will have exact measures and will be arranged in ortogonal or horizontal/ vertical planes for as much as possible.

- The assembly will be made of standard industrially available parts where this makes sense and it would deliver an improvement over what is usually used in current designs. For example, I may use lubrication free flat miniature bearings on rods and levers, or lubrication free ceramic bearings on wheel axis. I will use commercially available industrial grade miniature valves, safety valve, regulator, water gauge and so on if possible.

- Stainless steel and aluminium will be extensively and primarily used for all parts, and will be chosen over copper, brass or gunmetal for as much as possible. Technical grade polymer materials will be considered as well. Eventually even the boiler will be evaluated to be built out or AISI 316L steel.

- One objective of the project is that all parts should be carefully 3D drawn in a way that most parts can be automatically build by CNC (computerized numerical control) equipment, or laser/water cut directly out of the drawings, with minimal hand made retooling required if at all.

The video below shows what I came out so far for the valve gear design. I chose a Baker valve gear geometry as opposed to a Walschaerts because it's easier to build and I think it's easier to assemble as well.

In theory getting the correct valve events and timings on a Baker valve gear is a bit tricky, but I guess that after much Solid Edge simulation and the study of the Don Ashton book, I acquired an understanding of the gear so I feel now comfortable with it.

I will come with a ton of questions as my design progresses. So far I would appreciate any comments on what I achieved so far, as well as any visions on my (particular) approach. I hope I am not doing anything totally wrong. I am a total beginner so basically I hope my approach is not totally biased towards the wrong side.

The video shows the loco in forward motion first, then I switch the reverse yoke to backwards, at this time the motion still appears to run forward because the simulator just makes the wheel turn in a specific direction, but in fact the valve events are the correct ones to produce a backward motion. 

Here's the video:

http://youtu.be/hzJr6GkfezY

http://youtu.be/hzJr6GkfezY

Thanks in advance

John

Edited By John Lluch on 26/09/2014 22:35:53

Edited By John Lluch on 26/09/2014 22:44:37

Hi all. Thanks for all your comments and useful information. I am now home so I just attempted to meet a local steam club as suggested earlier, but so far they haven't replied. I have also ordered "Design Procedures For Walschaerts & Stephensons Valve Gears - By D. L. Ashton" and "The Model Steam Locomotive: A Complete Treatise on Design and Construction - by Martin Evans". The later should arrive on Thursday according to Amazon.

After looking further on what can be done and considering my existing background, I figured out that I'd like to make changes to existing designs or even create something from scratch.

As mentioned earlier I have looked at several 4-6-0 or 4-6-2 designs and drawings offered by ajreves and blackgates, however I am still struggling on what to order. The "Britannia" looks nice, but since I would rather *try* to build something from my own design (at least partly) I need to start with some existing drawings that are not over complicated. For example I do not want at this time a 3 or 4 cylinders loco, but just a two cylinders one. Also I noticed that the Britannia has slightly inclined cylinders (I meant not totally horizontal), which also makes things more complicated if I want to change some dimension.

I am aware that I am probably asking too trivial and not very focused questions, but ultimately, my question is: What 4-6-x loco would be easier to build, having less parts, simple design, and clear and clean drawings?

Thanks in advance.

John.

Thanks for all your comments. When I come back home I will contact a steaming club I am aware of near Barcelona. @Russell, the village I am going to move is Fornells de la Selva. This is about 40 or so km south of Figueres.

About stainless steel boilers it is not that I dislike copper, it is just a material I am very used to because of my adquired skills on the chemical industry. Please, can you point me to some miniature loco parts provider in France or Germany? I do speak French and the country is just next door, to say, so approaching them would be easy.

@Julian, I fully understand why steel may be less efficient than coper, but leaving appart official certification issues I would like to understand as well why it would be less durable or valuable. I will go to copper once I understand it, no problem, but its just I worked A LOT with stainless steel in the past, and I used it extensively in heat exchangers.

@John, I will look at your pointers, thank you

Hi @Al, Thanks again. I am not English native, you know. So don't take me wrong, I like the way English natives tend to make use of the language features and richness to alter the meaning of sentences in subtle ways, but it's just impossible for a non-native to catch it all. I use a lot of sarcasm on my own language, but I just do not attempt to do the same on English for obvious reasons (safety, again)

Eventually I will stay in London for several days with my wife and children starting tomorrow, but I am taking a flight and had no previous arrangements to visit a locos provider. I first need to choose which loco to build and start by ordering design drawings. This should give me a closer understanding of what I need to do or order next.

One difficulty I will have is having to deal with Imperial units, I am not used to them so I hardly have a notion of how big or small a part is until I converted into say millimetres. I just computed some measures of a Britannia 5" (or 127mm) locomotive and got impressed about how big the wheels are. I suppose this (my) issue is unavoidable on this field, so ultimately it is just a matter of writing down all measures in millimetres on a copy of the drawings.

Hi @clivel, Yes, I suppose it is always better to stick with original colours. Nice video and loco !! and thanks for the info.

So far i am very pleased of all the warmth I am receiving from you all who have been already in the hobby for possibly years.

John.

Hi @john, thanks for letting me know that at least some of the 4-6-0 locos are no more complicated than an 0-4-0, but just more work. That's good to know. I'd rather be spending more time on a bigger loco than supposedly get a less compelling design finished earlier. I also appreciate your comments on Galatea as from the Blackgates site I got just the opposite feeling. I will then possibly look to build the Britannia or the Black Five as you suggest.

@julian, thanks for you insightful comments. I suppose every one has his motivations, mine is on the operational aspects of the steam locomotive, rather than running or riding the locomotive alone. I've been doing a lot of process automation using logic controllers in the not so distant past. So working on things such as optimising fuel/water consumption, or power, or locomotive speed is what I envision that I will enjoy the most. For instance, a gas fired boiler should allow for a regulation of the applied combustion power depending on locomotive load or boiler pressure in order to minimise steam (i.e. water) loss through the relief valve. Also, I may want to make arrangements on the loco to let this adjust automatically. To my understanding this particular thing is hardly achievable if the engine is coal fired, no?. And Ok, I know everything on the steam technology is already invented, but who cares?

Please, can you clarify what is the issue with stainless steel boilers on non-coal fired engines? I assume one problem is sulphur corrosion caused by coal, another can be the presence of chloride in water, but both can be avoided. Steel has a poorer thermal transfer ratio than coper, but this can be compensated by making it thinner while still maintaining or improving overall strength. Other than that steel is a much stronger, durable and easy to clean material. Virtually everything in the chemical industry is made of stainless steel, so why not use it on miniature locomotives? Has this been tried?

@old al. Yes, I've been thinking on the issues related with carrying a heavy and long locomotive. I assume a 4-6-0 5" loco can weight about 100Kg or so. To be honest I would go for a 2.5" locomotive if it wasn't that I would have no track to run it. But then a smaller 0-4-0 loco isn't as compelling to me. The circuit I eventually will be using the most, specially for testing, will be just at a mere 300 meters from my garage. The track has a special arrangement to load locos on the ground level from a lowered back. Well, I suppose this is common elsewhere, but I mean I should be able to load the loco from my garage to a van using a pulley and then from the van to the track, at least initially.

Hey, just to know. What is the issue with Black Five being black. Can't she be painted on a brighter colour, or was that meant to be sarcastic ?

Thanks.

Thank you all for the useful information. It is very appreciated.. The more I look into and learn about this hobby the more I realise this is serious stuff. This is indeed getting more challenging than what I initially anticipated, but this is not discouraging me but quite the contrary!.

Where I am (Catalonia) is very rare to see a working model steam locomotive, there is however at least one model steaming club I am aware of near Barcelona **LINK**. I guess the first thing I need to do is to contact them. I wonder if someone on this forum have ever met them.

Eventually, next year I will move to a village about 100Km north of Barcelona where a small model rail circuit covering 5" and 7.5" gauges is available, so I can't wait to eventually test a steam loco made by me in the comfort of a very near location.

About my practical skills I must admit that I have no self experience on using tooling machinery, but I have been in the chemical industry designing industrial reactors, heat exchangers and so on -that was at the times when no CAD software was used/available though- so I am confident that I at least understand well all the concepts involved in the building of a steam loco and I also know people on the chemical and mechanical equipment industry who can help me where I do not reach.

My goal would be to build a relatively big loco with tender, such as the "Britannia", "Duchess Of Hamilton", "Galatea" or the "Black Five" from Blackgates, Though I do not understand why Drawings are not supplied for the latter (?).

I do not want to get to a very detailed model but to a nicely working one. Or in other words I am more motivated to get right the functional aspects of it than the visual or aesthetic ones. For example I will be happy to replace allow bearings by small roller bearings if this has sense on some sections, or I may try to design my own boiler in stainless steel and fire it with butane or propane instead of coal to avoid sulphur related problems.

What *big* loco would you recommend (5" gauge) that would not have intrinsic design problems and which design is flexible enough to allow for some custom modifications?

Thanks.

John

Hi,

I am an experienced chemical and automation engineer with a passion for model steam locomotives. After many years working in the chemical industry I have now some spare time and I am willing to build my own 5" gauge loco. It will be my first one !!

I have looked into ajreeves (http://www.ajreeves.com) and blackgates (http://www.blackgates.co.uk) web sites and designs and have send them an email asking for information on specific parts, but so far I have not received a reply of any of them.

I wonder if someone here would share their experiences with these guys or can recommend alternative sources of design drawings or commercial parts for building a locomotive from scratch. I am looking for a 4-6-2 or 4-6-0 locomotive.

Thank you very much for any help.

(sorry for my English)

I am a chemical engineer having worked for 2 decades in the chemical industry. I know this is a one year old thread but I wanted to clarify something about Stainless Steel, which is a very used material in the industry. I mean it is not only for cooking stuff. Stainless steel main weakness is that it is attacked by hydrochloric acid and sulphuric acid. Other that that it will resist virtually any other chemical including very strong acids such as nitric acid. Crevice corrosion may be caused by the lack of oxygen and can happen in very rare conditions, but not on a boiler. It is not definitely caused by lack or 'air' contact. This kind or corrosion also occurs in other alloys such as aluminium, titanium and copper. My take is that what Russell describes was caused by chlorides. Many modern industrial steam boilers are made out of stainless steel and virtually all heat exchangers are made entirely on stainless steel.

John