steam4ian
Elder Statesman
One good turn deserves another
Posts: 2,069
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Post by steam4ian on Dec 7, 2013 9:59:18 GMT
Dianne. Firstly I don't have to direct you to the Australian Code, you appear already aware of it. Also Baggo has sent you the link to some work done by Ausies in relation to sub-miniature boilers. Both of these texts I would have drawn to your attention. Please note that the AMSB sub-miniature code has not recognised the experimental work with but joints reported in the paper.
My concern is how you are going to get approval to operate such a boiler. It is a pressure vessel and I am quite sure that Canada like other civilised countries has Boards of trade, Work Place Safety Directorates or other who certify such vessels. In some jurisdictions, like Australia, certification of certain and well defined types of miniature boilers has been delegated to the clubs and covering associations, hence the AMSB Codes. Who will certify your boiler? How will you get insurance for public liability? How will you NOT be found irresponsible if the boiler does blow and the neighbours child is injured?
BTW, see the AMSB Code for the fire tube design. See same Code for increases to plate thickness when the boiler has mechanical stress other those caused by the containment.
Regards Ian
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Post by wdiannes on Dec 7, 2013 18:19:28 GMT
If someone gets hurt, EVERYBODY even remotely related to the event will be named in the law suit and the court will assess degrees of liability to each individual according to their "due diligence". Even if a Code has the force of law in the area where the incident occurred, following code does not provide blanket immunity. (We went though all of this years ago following a full-size boiler explosion in Ohio so this isn't speculation but FACT.)
For the designer of ANYTHING, the only acceptable defence is "sound engineering practice", even where legal codes exist. Where there are NOT mandatory legal codes, sound engineering is the ONLY justification for a design (not "we have always done it this way"). The existence of a voluntary code may help in one's defence but it will not alleviate one from the practices of sound engineering.
Since this has devolved into "you can't do it that way because it isn't in code and that's not the way we have done it for the last 50 years" I see nothing more to be gained from pursuing this and I am done with it.
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Post by Deleted on Dec 7, 2013 20:40:33 GMT
Hi Dianne
I hope you will continue your venture, it looks an interesting subject that's not often modelled.. as I first stated I'm no boiler builder ( although this will change in due course) or designer but there are others here who are and can give you invaluable advice on your design. stick at it.. I'm sure you'll get the loco finished and running in due course..
Kind regards
Pete
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jma1009
Elder Statesman
Posts: 5,913
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Post by jma1009 on Dec 8, 2013 0:05:43 GMT
hi dianne,
ian's advice and comments are quite correct. this shouldnt put you off - you just need to know the rules and regulations that apply in canada. i am sure most clubs out there will give you all the advice and help you need.
'sound engineering practice' is a misnomer. that is why there are relatively strict regulations and requirements for miniature loco boilers, as 'sound engineering practice' is open to interpretation, and what is someone's 'good practice' is another person's 'bad practice'. especially with new builds of original design.
dont worry at this stage too much about the boiler- you have plenty of time to resolve the issues with same. filing those geared teeth will take you quite awhile! (they werent cut on a machine originally)
like pete, i hope you will persevere and carry on.
cheers, julian
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Post by wdiannes on Dec 8, 2013 3:43:36 GMT
The problem then is that we are speaking two completely different languages because "sound engineering practice" is NOT open to interpretation but is based in science and is provable mathematically and can be verified in a lab. "Sound engineering practice" is what keeps a bridge from falling down on your head or a skyscraper from collapsing into a heap of rubble. "Sound engineering practice" is also the basis for all boiler codes that carry the force of law. It isn't one person's or even the opinion of a committee. Given the choice between "the way we have always done it" or a design that has been analyzed and proven sound mathematically and by "sound engineering practice", I am much more confident being around the one supported by design than the one with tradition behind it. But then that was my life's work and I was always "betting my life on it", often literally.
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Post by Shawki Shlemon on Dec 8, 2013 7:48:55 GMT
"Sound engineering practice" is also the basis for all boiler codes that carry the force of law. It isn't one person's or even the opinion of a committee. Read more: modeleng.proboards.com/thread/8786/coalbrookdale-locomotive-build-log?page=2#ixzz2mrnskFkLIt seems to me we are beating round the bush and coming to the same conclusion , the codes are based on sound engineering and have safety margins more than those required by government organisations . They are designed to help the typical model engineer to build a boiler without getting involved in deep scintefic calculations safely . So far they have served the hobby well and kept us operating safely . I personally can't see any better alternatives to the codes , that is my opinion , others may see it differently .
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steam4ian
Elder Statesman
One good turn deserves another
Posts: 2,069
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Post by steam4ian on Dec 9, 2013 4:54:39 GMT
This could become a very interesting debate about what is "sound engineering practice". Of course every project, no matter what, can be engineered from scratch but that would mean a repeating of the entire history of mistakes and experiments that have preceded the design. Codes give the engineer a hedge on both sides of the solution, what is the minimum and what is too much.
Dianne, if you have a full suite of finite element analysis software and full experimental details supporting weld/solder joint strengths and rigidities then by all means start the design from scratch using "sound engineering practice". Most of us do not have access to this and neither do those third parties which certify our boilers, hence the codes.
As a professional engineer of 42 years experience I have both used and bent the Codes in my sphere of practice as much as anybody and that has not stopped me developing and adopting "novel" cost effective outcomes.
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springbok
Statesman
Building a Thompson Class B1 in 5"g Plus restoring a 3" Fowler steam road Engine "The Wanderer".
Posts: 570
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Post by springbok on Dec 9, 2013 10:36:17 GMT
I am sure that the Canadians have a Boiler guide like here in the UK and Oz. Have you a club nearby that you can ask! Should the front and rear of the boiler be flanged... I confess it looks a facinating project and look forward to see how you make the gears. Q. What scale will it be in. Good luck Bob
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Post by wdiannes on Dec 9, 2013 13:25:41 GMT
There is no Canadian "boiler code" for model locomotives - there isn't even an American 'code' for models. Like many places, the vast majority of modellers aren't interested in doing all the analysis and calculations for a unique design and simply build what has been done before (on the assumption that if 50 have been built and none have blown up, it must be a solid design). Club inspections are also based pretty much around existing designs so with this one they are in unfamiliar territory and it falls to me, as the designer, to prove the design. When I have completed the design and fabrication of the prototype, I will run all my figures through a Mechanical Engineer to verify and certify the design. (A Professional Engineer's stamp is accepted by legal authorities as proof of a safe design.)
The model is being done in 1" to the foot, 4.75" gauge.
Now it is back to making chips.....
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Post by ejparrott on Dec 10, 2013 12:47:20 GMT
in the UK for club approval and a club boiler certificate (and hence insurance) for a totally new design of boiler you will need to produce the calculations that jack alludes to, and full drawings. Or proven example
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Post by Deleted on Dec 10, 2013 16:38:52 GMT
That's right----------- During the design stage of my "BEAR" boiler I used -- and archived --- the calculations and general formulae from Martin Evans "Manual of model steam locomotive construction".... At the same time I liased with John Ellis who is both one of our club's boiler examiners and a commercial model boiler manufacturer as well....Between us we have arrived at a 5" design that externally is very close to the original, but internally makes use of modern updates such as a short combustion chamber...( Which also helped by bringing the tube lengths down to that of a 5" Castle).........John has seen and approved my theoretical calculations and is happy with their source....OK, it's not that much different from a Britannia or Duchess overall but I felt that as it was "New" to the hobby then I best follow that route....Incidentally there is also a 7.25"g No.111 based near Chinnor, Oxfordshire... but I hear on the grapevine that the builder has since passed away, so don't know if the loco was finished or steamed ?? ............... I think DIANNE is taking the right approach ie}-- Acknowledging her local rules and regs and using them accordingly.....It's that "Horses for courses" time again, I would say......
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Post by wdiannes on Dec 10, 2013 17:17:30 GMT
It may 'different' from model boiler code but it is certainly accepted practice in full-size boiler code and complies with the design criteria of accepted engineering practice anywhere on this continent. I HAVE DONE all the calculations from every conceivable approach and all indicate a more than adequate safety factor. I am perfectly willing to submit my design to a Professional Engineer for certification if that is what my local club (or their insurance company) wants because I have total faith in this being a viable and very conservative design, a design I am more than willing to trust my life to, but I am tired of debating this point. If the conversation continues in this vein, I have no interest in continuing this thread.
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Post by doubletop on Dec 10, 2013 20:49:55 GMT
Dianne Apologies for opening that can of worms but best to get it out of the way early rather than have 'useful' advice being given when you are past the point of no return. You've got all the bases covered and clearly you know what you need to do to meet your local regulations. ================================================================================================================
Lets all now sit back and enjoy the journey Pete
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Post by wdiannes on Dec 10, 2013 21:14:45 GMT
There is only one other model of the Coalbrookdale locomotive that is documented (somewhat) and that is out of Germany. Looking at how he did his end plates gave me a better idea, one more simple to build and even stronger. Rather than a disk silver soldered into each end of the boiler, I decided to make the end plates in one piece and machine a groove 1/2 the plate thickness into which the boiler barrel is silver soldered. It increases the joint strength almost 50% (not that the Safety Factor of 40 needed any improvement) but it also makes the whole thing easier to assemble. Since I screwed up my first plates, it was a good time to start again and this method has far less waste copper than making the ends in two pieces. The layout was done in CAD, plotted 1:1, checked for accuracy, and then glued to a 1/4" copper sheet before transferring all the centres to the copper with a centre punch. Three holes were drilled through both front and back end plates and then the plates were bolted together for pilot drilling all the holes. Then the stacked plates were transferred to the mill to clean up the saw-cut edges. One at a time the end plates were were mounted and centred on a faceplate and bolted firm and a circular groove was cut to match the ID and OD of the boiler shell (with allowance for silver solder thickness) The next step will be to drill the flue and tube holes in each plate before assembling the plates to the boiler shell.
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jma1009
Elder Statesman
Posts: 5,913
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Post by jma1009 on Dec 11, 2013 0:09:59 GMT
hi dianne, dont forget things boiler-wise are obviously a lot stricter and 'codified' here in the UK. we can only comment and offer advice on what prevails here. they are even stricter in Australia! all comments and advice are meant to be helpful and constructive, and we all wish you well on a very interesting project. please dont take suggestions and comment as being negative - it isnt meant that way - but is tempered by our own rules and regulations here! as a keen trevithick fan (and living but a stone's throw of where the original penydarren loco ran in 1804) i wish you every success and will help as much as possible - constructively! cheers, julian
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Post by wdiannes on Dec 11, 2013 18:15:06 GMT
Decided today to drill and ream the holes for the tubes - the point where I screwed up the first end plates - and everything worked fine. I actually measured correctly! (Which is good at the price of copper ) Time to temporarily assemble the boiler barrel to the end plates. And prepare the 4 tubes. Still waiting on material for the boiler dome and main flue AND waiting for my rotary table to arrive so I can round the top of the end plates. I need all that completed before I can silver solder the boiler together! With the temperatures here around -30C I like to have a good day's work on hand before I light up the wood stove and warm up the shop!
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Post by Deleted on Dec 11, 2013 22:01:01 GMT
--------- and have a drop of this for "Central Heating".......On the house !! Attachments:
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jma1009
Elder Statesman
Posts: 5,913
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Post by jma1009 on Dec 11, 2013 22:25:51 GMT
hi dianne, excellent pics! what is that lovely lathe you have? cheers, julian
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Post by wdiannes on Dec 11, 2013 23:41:37 GMT
That's my 1941 Southbend 10". It is worn and sloppy but it is all I could afford 25 years ago.
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Post by wdiannes on Dec 11, 2013 23:42:59 GMT
--------- and have a drop of this for "Central Heating".......On the house !! I am sorry sir but I am not much of a drinker. I have tasted that and would rather I hadn't!
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