jma1009
Elder Statesman
Posts: 5,896
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Post by jma1009 on Jul 9, 2020 21:22:30 GMT
I worked up a design in 5"g for 'Pioneer', the first steam loco on the Isle of Wight of 1861 vintage, based on photos (obtained at some cost from the NRM). I don't envisage any difficulties when I get round to starting construction eventually
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Post by jcsteam on Jul 10, 2020 11:12:31 GMT
Full size locos with backhead mounted injectors/clacks usually deliver the water into the boiler through internal pipes, taking it to the front end, reducing the problem of shock to the much hotter firebox. I would like to fit scale backhead fittings to my Austin 7 project and am currently thinking about how to achieve this. Cheers Don If the backhead is not yet fitted, then this could be done with the tube soldered into a bush on the backhead, solder the pipes to go to go striaght up, and then over the top of the firebox and terminate at the mid point of the barrel, (under the dome for instance for checking there not blocked after fitting the backhead) this would also make soldering the backhead on easier. a normal bush for fitting to backhead, but longer, and blind drilled and tapped for the fitting. A cross drilled hole for a 1/8" thin wall copper pipe, and soldered up and annealed and bent to shape before the backhead is fitted. The tube wouldnt have to be thick walled tube, as it isn't part of the pressure vessel. its inside it so long as the bush is soldered correctly and the pipe joint not blocked then i think this would be a simple solution to get around the backhead fitted clacks introducing cold water to the hottest part of the boiler. So long as the end of the pipe was under waterline, then i dont think theres an issue of steam blowing back.
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jma1009
Elder Statesman
Posts: 5,896
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Post by jma1009 on Jul 10, 2020 21:36:20 GMT
Au contraire!
You have the backhead bush sufficiently high up above to clear the firebox crown, and silver solder the pipe to the check valve, and you take it to within an inch or so of the smokebox tube plate.
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Post by 92220 on Jul 12, 2020 8:17:09 GMT
I was thinking on the dummy well tank, have a removable cover to allow access for oiling the valve gear then replace the cover all looks as it should, There would possibly be space for a cylinder oil tank too, connected to the valve rocker on a shortened arm to limit the travel. it is possible but i'm not decided yet as removal of the tanks will leave very little on board water space available. I think practicality will rule in this area. With regards the boiler, i wont be fastening it to the motion bracket but at the smoke box and rear as you say sliding on the frames, using two pieces of angle and a clip which i have seen in another design, (it escapes me which one though). The motion bracket will just be larger radius, so that it sits one mill further out from the copper barrel. Once under the insulation and cladding, it'll not be noticed, and without the inclusion of the angle to fix to the boiler. Frames will be 1/8" as that seems to be a pretty standard thickness through all the designs i have seen in 5". There is a lot of cross braces on this frame so i wouldn't think rigidity will be an issue. Hard part for me is figuring out what might need to come apart for future maintenance and what can be riveted on the frame and what needs to be secured with screws for removal. Regards Jon Hi Jon. That is the way the full size boiler on 9Fs, is fitted. It works fine. Bob.
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jma1009
Elder Statesman
Posts: 5,896
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Post by jma1009 on Jul 12, 2020 19:52:07 GMT
Hi Bob,
A BR 9F is hardly a comparison with these early locos of the 1850s and early 1860s!
I stand to be corrected on all this by such experts as 'mbrown' of the TR with locos of early/mid 1860s, and those experts of the Ffestiniog Railway with now quite a few locos restored to steam of this vintage (the lovely addition of 'Welsh Pony' restored and running the other weekend for the first time in 80 years), but frames originally of this vintage were strip assembled. Imagine planks of wood to make the frames from, except of wrought iron, as they could not produce wrought iron plates of big enough size, and steel plate frames; except they did manage to do this for boiler plates! (Anyone care to comment?)
Obviously, the first jobs are to work out the boiler and the valve gear and cylinders. I wouldn't worry about the well tanks at this stage. You are going to have to make up a wagon to go behind for water anyway IMHO.
Cheers,
Julian
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Post by jcsteam on Jul 13, 2020 8:06:44 GMT
Hi Julian,
The drawings i have for this loco were actually very detailed, and they show two plates for each side of the frame. With a brace across the frame at the front and rear, then a 4" beam of wood for the buffers, attached with angle to the twin plate frames. Ive not looked for other detail but they appear riveted at the points of the horns and the cross bracing ect. I Wont be scaling this feature, as it could over complicate things and make a frame thats not as ridgid. I'll stick with the tried and tested 1/8" thick frames here and adjust the inside measurements as i go.
The horns are very simple. Much like Sweat Peas horns that can be made from 3/8" Steel square, or thick angle and notched on one side for the frame location. I'll be sticking with working springs on the back of the frames, though this will further reduce working space between the frames i quite like the look of working springing, Will need help on hardening and tempering ect when the time comes.
Regards
Jon
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Post by David on Jul 13, 2020 9:40:47 GMT
Running board cut-outs and splashers need a bit of attention due to over width wheels, over-deep flanges, etc. Your frames might be wider or more narrow over the outside than scale too.
Another thing that will not be a problem on yours is sometimes two axles are so close together that our over-size flanges will foul so the axles need moving apart. Brake gear can also get in the way here.
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Post by jcsteam on Jul 13, 2020 11:18:14 GMT
Thanks David,
All taken note of for later.
Jon
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Post by ettingtonliam on Jul 13, 2020 12:19:36 GMT
Hi Bob, A BR 9F is hardly a comparison with these early locos of the 1850s and early 1860s! I stand to be corrected on all this by such experts as 'mbrown' of the TR with locos of early/mid 1860s, and those experts of the Ffestiniog Railway with now quite a few locos restored to steam of this vintage (the lovely addition of 'Welsh Pony' restored and running the other weekend for the first time in 80 years), but frames originally of this vintage were strip assembled. Imagine planks of wood to make the frames from, except of wrought iron, as they could not produce wrought iron plates of big enough size, and steel plate frames; except they did manage to do this for boiler plates! (Anyone care to comment?) Cheers, Julian Julian I know I don't come into your defined category of 'experts', but here goes. For most of the first half of the 19th century, rolled plates were indeed only available in limited sizes. Rolled bar wasn't so limited, so indeed many early locos had their frames made up from flat bar rivetted or forge welded. 'Rocket' for example. By the 1850s and 1860s, possibly driven by a demand for structural plates for the likes of Brunel's Chepstow and Royal Albert bridges, and Robert Stephenson's Menai Straits tubular bridge, the rolling mills had extended their capacity and were capable of producing quite long plates, although still limited in width to a maximum of 3 or 4 feet. Thus, the plate frame became a practical proposition by 1860, indeed Hunslet were producing 0 6 0 tank engines with plate frames by this time, and so were LNWR at Crewe.
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Post by suctionhose on Jul 13, 2020 12:28:50 GMT
I think the short answer is that you do a design to work in miniature. One the that roughly approximates the proportions of the prototype. If you want super scale - and some people on this forum are doing that - you will sacrifice the strength, weight and functionality of the model. That is really decision number one: display model or hard working miniature?
For your proposed prototype - a lovely old thing she is too - if you want to ride behind it I suggest weight and strength should be added in wherever possible. That is the compromise and the reason you need to DESIGN it as a model. What do you want it to do?
I've done this several times. You layout proportions in a side elevation as per original GA. Then you do a plan view fixed about the wheel standards / track gauge and lay things out with oversize thicknesses and sensible operating clearances. As David said, the frames tend to move inward and the cylinders outward of scale locations. However, by then drawing a front elevation, tweaks are made till the proportions on width look right.
There's an art to it, no doubt about it! Common practice here to build 5"g at 1.125" to 1ft instead of the old 1.062" to 1ft. Preserves the proportions better and ends up a slightly larger loco for the gauge. True scale for standard gauge lies in between at 1.1".
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Post by jcsteam on Jul 13, 2020 15:11:37 GMT
Hi,
I found the drawings for the model id mentioned, LBSC Tich, with the boiler fixing. A piece of angle riveted and soldered to the outer firebox wrapper, and a small clip screwed to the frame, that hooks over the angle to allow for expansion of the copper boiler, but hold it firmly at the back end of the frames. I'm not sure if this is still an allowed practice with boilers, but so long as the rivets are fully soldered and the angle resting on the top of the frame, allows the boiler to sit parralel to the frames this would be an easy way to approach the fixing of the boiler. With a few round head screws to the smokebox to secure it that end. I worked out the boiler will be around 4" dia, plus lagging and outer wrapper. takes it to scale dimensions. Ed Parrot commented that i should look at Lion boiler tube layout and adapt that to suit, as this boiler performs well and uses the same 4" outer dia barrel. So that will be the next job.
With regards to plate frames, once the loco is fully drawn out i will see if there is provision for adding dummy lines of rivets to the frames as an additional nod to the original, however that's more holes and possibly not really required, as i cant see any other than where there's a support brace for the frames.
I have a lot of LBSC designs so will look to pinch dimensions from those to maintain a working miniature, and use the drawings from the book to try and maintain correct wheel spacing, size of wheels, ect, so it is as close as possible to what the original would have been. Quite a number of people have commented to me that it looks a fine little engine, so it will have to be made one way or another as i can see it been quite popular on the track if i can get it to perform as good as it looks.
Regards Jon
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Post by ettingtonliam on Jul 13, 2020 15:38:30 GMT
The boiler fixing you describe has been used for many years, both full size and in models, its simple, robust and easy to do. If the angle is rivetted and silver soldered to the boiler shell, there shouldn't be any problems with it.
Be a little careful about slavishly following LBSC's designs, especially his boilers as many of his designs are no longer acceptable without some modification to suit current boiler regulations. If you haven't already done so, join a local club and talk to the club's boiler inspector. Get his agreement to what you propose to do, before you do it. Its cheaper that way! I'm not sure about this, but do LBSC's recommended wheel profiles and back to back spacings agree with current standards?
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Post by jcsteam on Jul 13, 2020 17:35:27 GMT
Be a little careful about slavishly following LBSC's designs, especially his boilers as many of his designs are no longer acceptable without some modification to suit current boiler regulations. I'm not sure about this, but do LBSC's recommended wheel profiles and back to back spacings agree with current standards? With regards to the boiler my understanding is that bushes are required additional to his boiler design, where he specified just to tap the backhead with the required thread. Also I believe Julian gave some pointers on a stays for a Minx boiler either this forum or another that they needed to be of a different design. Instead of the ones specified by Curly. I do have the calculations required for model boilers, (to current regulations) so I can do the calculations to proove the design. Though pointers will always be noted, and greatfully recieved. As for the wheel profiles Curly only stipulated a tapered tread on the leading and trailing wheels, not the drivers. Where he believed the flat tread gained better traction, especially on flat bar rails, and the leading tapered wheels would help guide the loco around bends and be self centering. So for wheels I'll be using 5" gauge standard profiles. Regards Jon
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Post by jcsteam on Jul 17, 2020 8:55:30 GMT
Feeling pleased with myself last night, i finally worked out how to animate fusion 360 models. Drew out a simple oscillator, and watched Lars tutorials, i got a grasp on the animation side of fusion. Still much to learn but a massive leap in my knowledge base i feel. Now i understand the principles of animating it, these can be transferred to the loco when fully drawn, and valve openings/travel measured.
One thing i've realised when drawing or scaling a model, is to work from the driven wheel when drawing. As all other measurements on full size drawing work away from that, or the rail head. Had to start over to make life easier on myself, as i started as the top of the frames as a reference, possible but the long way around using a calculator more than necessary. Also laid down two lengths of bar rail to use as a guide when building for wheel position, and animations.
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Post by jcsteam on Jul 23, 2020 0:03:08 GMT
Hello all,
Although this is still early stages and a lot more design work to solve before drafting in fusion, this is the rear axle set. Currently for ease of alignment at the moment the crankpins are set at the same setting, once im ready to assemble into a working model these will be quartered. Something new tried today to get the 14 spokes, I made one sketch to what I was happy with made sure the geometry was tied down, (parallel lines, ect). Then copied and rotated the sketch lines for the spokes by the set degrees for each pair seven times. (maybe a quicker way but it worked). The angle was copied and pasted from the scientific calculator on my computer for the correct angle. (360/7=51.428571428571428571428571428571 degrees) far easier copying and pasting each time I copied and rotated the four lines, and accurate too.
Hopefully this link works and you can see the beginings of the horns, wheels, axle bearings, (these are simple at the moment as I need to incorporate springs but need the frames drawing from the motion and wheels, to be able to get the alignment correct. The wheels even have the radius and 3degrees of taper on them. Short video
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Post by coniston on Jul 23, 2020 21:08:13 GMT
Link worked perfect, very interesting, you probably could have copied the spokes by the number of spokes rather than the angular offset, but it worked for you and good result.
Chris D
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Post by jcsteam on Jul 24, 2020 8:17:51 GMT
Link worked perfect, very interesting, you probably could have copied the spokes by the number of spokes rather than the angular offset, but it worked for you and good result. Chris D I tried to do that first, but i couldn't find an input for doing it that way. Im sure there is one and if anyone knows of it let me know as its a bit of a long winded way doing it how i did. Anyhow, while i'm here. I did a little more last night, although i'm fairly confident that the wheels are too big, so will need to revisit them. The cylinders look too small, and i have also had to step them out so they can get clear of the coupling rods. Which will be next, what is the minimum thickness for a connecting rod on a 5" loco? As the thinner they are the more scale i can get the cylinder centreline, however this would be at a cost to strength and alas probably good reliable running. The last issue i noticed when i was doing the video. Is when i've edited the history of assembly, the drawing for the port valves to the bore seem to have moved. It's all still a learning curve, and i'm about ready to start the valve gear on the chassis. Although that part will come later, as i intend on designing from first principles for the loco which involves a fair bit of reading of Don Ashtons book, and i'm not one for books normally. I have been playing with valve gear simulators, and promptly making a complete hash of it. So much more study is required. Here's the update via video.
Kind Regards Jon
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Post by 92220 on Jul 24, 2020 11:35:22 GMT
Hi Bob, A BR 9F is hardly a comparison with these early locos of the 1850s and early 1860s! I stand to be corrected on all this by such experts as 'mbrown' of the TR with locos of early/mid 1860s, and those experts of the Ffestiniog Railway with now quite a few locos restored to steam of this vintage (the lovely addition of 'Welsh Pony' restored and running the other weekend for the first time in 80 years), but frames originally of this vintage were strip assembled. Imagine planks of wood to make the frames from, except of wrought iron, as they could not produce wrought iron plates of big enough size, and steel plate frames; except they did manage to do this for boiler plates! (Anyone care to comment?) Obviously, the first jobs are to work out the boiler and the valve gear and cylinders. I wouldn't worry about the well tanks at this stage. You are going to have to make up a wagon to go behind for water anyway IMHO. Cheers, Julian Hi Julian. You are quite right. There is no comparison between the actual boiler of a 9f and the boiler of a 0-4-0 from the 1800s. However, the engineering principles for mounting the boilers, are the same. The boilers expand when hot and are fixed/located at the front by the smokebox, therefore expansion must be backwards and the rear of the boiler must be supported on sliding brackets. It was the mounting comparison that I was attempting to convey. Maybe I just wasn't clear enough in my wording. Bob.
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