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Post by Roger on Jan 10, 2022 22:42:05 GMT
Enjoyed the first part of the articles on injectors in M.E. Roger. Well Done. Thanks for that, I wasn't aware that it had been printed. I submitted it all about 6 months ago, and began to wonder if it would ever appear. I think they'd already done quite a bit on Injectors, and needed to spread things out a bit. Not everyone is that interested in them. Could you let me know what issue that appears in, I can't see it in the table of contents on Issue 4681, which is the latest on the web site? I hope it demystifies the fundamentals, and explains what the various parts of the Injector need to do to make it work. I'm not a 'numbers' person, I think more in terms of creating a 'mental model' of how it all works in slow motion from start to finish. The really clever folk have already done the hard part with the Thermodynamics and experimental work to determine the critical throat diameters and angles. However, once someone had figured out a way that they could be made to work in our sizes, development largely stopped. There have been a few variations but no root and branch re-imagining of their construction. They certainly can be made in the traditional way, but it's far more difficult to do than it needs to be in my opinion. Anyway, I hope it will be of use and encourage others to have a go at making their own.
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Post by fubar123 on Jan 11, 2022 4:53:47 GMT
Hi Roger, The first article is in issue number 4682 , page 152. Along with the series of articles about constructing injectors has worked in as much as I'll be giving it a go.
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Post by Roger on Jan 11, 2022 9:59:24 GMT
Hi Roger, The first article is in issue number 4682 , page 152. Along with the series of articles about constructing injectors has worked in as much as I'll be giving it a go. Thanks for that. I don't know how many parts this will be broken into, it's fairly long. I don't go into specific manufacturing details, although I do provide a drawing for the One Piece Cone that also appears in this thread
If there's enough interest, I might do an article about a specific build of an injector. There are five videos on my YouTube channel that show my mass production method for the cone bodies, and some experiments in case anyone missed those.
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oldnorton
Statesman
5" gauge LMS enthusiast
Posts: 692
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Post by oldnorton on Jan 11, 2022 10:22:08 GMT
Hi Roger
You perhaps don't subscribe to ME then ? It's the latest magazine copy delivered in the last few days. There are just two pages of your article this time.
If you have only submitted the theory discussions from your postings here, then I do think that you should go on to describe your manufacture; there would be a lot of interest. Four recent articles in ME were from a group of chaps (Australian I think?) who reported their efforts of first timers to injector making using traditional, published techniques. It was good to read and the usual difficulties of concentricity, gaps and especially taper reamer making were features. If you are presenting sometime new in design and, hopefully, simpler for the first timer to try, then that is valuable information. I think that all the manufacture needs to be achievable on a 'simple' lathe and perhaps avoid cylindrical grinding of reamers, which most people do not have. There has been a brief discussion on the other forum regarding 'hack saw blade' reamers which one of the writers successfully used. These were effectively four-edge reamers ground from old blades.
If anyone wants to extend this discussion perhaps it should continue in Roger's injector thread.
Norm
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Post by Roger on Jan 11, 2022 18:04:33 GMT
Hi Roger You perhaps don't subscribe to ME then ? It's the latest magazine copy delivered in the last few days. There are just two pages of your article this time. If you have only submitted the theory discussions from your postings here, then I do think that you should go on to describe your manufacture; there would be a lot of interest. Four recent articles in ME were from a group of chaps (Australian I think?) who reported their efforts of first timers to injector making using traditional, published techniques. It was good to read and the usual difficulties of concentricity, gaps and especially taper reamer making were features. If you are presenting sometime new in design and, hopefully, simpler for the first timer to try, then that is valuable information. I think that all the manufacture needs to be achievable on a 'simple' lathe and perhaps avoid cylindrical grinding of reamers, which most people do not have. There has been a brief discussion on the other forum regarding 'hack saw blade' reamers which one of the writers successfully used. These were effectively four-edge reamers ground from old blades. If anyone wants to extend this discussion perhaps it should continue in Roger's injector thread. Norm Hi Norm, No, I've never taken ME. I've been given a huge pile of old ones, and I've seen half a dozen issues over the past few years. To be honest, I'm only interested in the design and manufacturing of things. Most of the materials and methods used seem outdated to me. The CNC stuff I've seen is equally out of date. I'm sure that people do find it interesting and useful if you want to use traditional methods, it's just not for me. I'm not really interested in all of the different types of Locomotives, Regions etc, they're all much the same to me. I can't really tell one from another, I just don't find it that interesting. I hear what you're saying about making Injectors with the minimum of tools. I'll give that some thought. I don't think there's a satisfactory way to turn small reamers, they're just too slender to make that way. There's no reason why you can't use a toolpost grinder for that, as long as it's set accurately to the desired angle. Machining the cross holes in the One Piece Cone can certainly be done if you're prepared to take the time to make a fixture for indexing it on the centre line.
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Post by Oily Rag on Jan 13, 2022 10:41:13 GMT
G'day Roger, what did you use or intend to use to seal the smoke box piercings in your smoke box , such as around steam pipes etc ? I tried to search your thread but failed. I am thinking that Loctite Si586 might be be good for my little loco build.
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Post by Roger on Jan 13, 2022 13:04:10 GMT
G'day Roger, what did you use or intend to use to seal the smoke box piercings in your smoke box , such as around steam pipes etc ? I tried to search your thread but failed. I am thinking that Loctite Si586 might be be good for my little loco build. Hi Daz, I haven't seen an arrangement for this that I thought was either neat or that satisfactory, so I decided to do my own thing. The basic idea is to have a permanently attached large tube that pierces the Smokebox. I TIG welded those in. I procrastinated over many types of seal to fill the gap between the Steam pipe and the tube, including high temperature plastics and Silicone O-rings. However, I concluded that the extreme temperature would probably be an issue for any of these to be practical. Pipe to cylinders through smokebox by Timothy Froud, on Flickr In the end I opted for a Spherical seal that's a really close sliding fit in the tube. I'm proably going to make some sort of two part dust cover to go on the inside to stop ash from getting into the tube. The idea is to allow the tube to move in and out and be at an angle if necessary. The pipe fittings are small enough to pass through the tube. The flat ended union at the top goes to the Superheater header where it's sealed with a nut and copper washer, not shown. That allows the fitting to slide sideways so that the pipe union at the cylinder end can be unscrewed and the pipe slid in towards the Smokebox. Then it's easy to remove it completely. Pipe to cylinders with spherical seal by Timothy Froud, on Flickr The advantage of this arrangement is that you don't need any unions or permanent seals at the point where it enters the Smokebox. Will it work and be satisfactory? Who knows, but I wouldn't have made it if I didn't think it would!
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Post by steamer5 on Jan 13, 2022 14:19:27 GMT
Hi Roger, JB Weld do a hi temp silicon....looks to be good to about 300C. Wonder if it would be possible to make a thick o-ring out of it? Failing that, a quick google shows theres sealers out there that are good for higher temperatures. The company we use to do lagging on site also does work were I last worked where temps were much higher, if you have a company in your area that does industrial lagging maybe a visit or call could point you in the right direction.
Cheers Kerrin
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Post by Roger on Jan 13, 2022 21:48:20 GMT
Hi Roger, JB Weld do a hi temp silicon....looks to be good to about 300C. Wonder if it would be possible to make a thick o-ring out of it? Failing that, a quick google shows theres sealers out there that are good for higher temperatures. The company we use to do lagging on site also does work were I last worked where temps were much higher, if you have a company in your area that does industrial lagging maybe a visit or call could point you in the right direction. Cheers Kerrin Hi Kerrin, That might work, or it might be possible to make a Silicone bung as a dust cover. I like the idea of a purely mechanical solution using metal parts though, then you don't have to worry about the heat. I'm sure the seal is good enough with just the spherical seal, it's a very close fit, as is the seal on the shaft. A smear of Silicone grease could be added, but that would attract ash. That might actually point to an alternative solution for keeping the ash out of the spherical seal. I could just squeeze a load of Silicone grease all around and above the seal. Silicone grease doesn't melt, it just ablates if you put a blow torch on it for long enough. Ash would stick to the surface of it, and that could be cleaned off if it needs to come apart. I could make a shim washer with a slit so it could be slid over the pipe and rest on top of the grease, to keep the worst of it off. I think something will be required to stop the tube from becoming encrusted with black residue. Time will tell.
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Post by steamer5 on Jan 14, 2022 7:07:48 GMT
Hi Roger, Just had another light bulb moment...the glow wasnt great.......you can buy silicon plugs of different sizes for powder coating they are good for temp used 210C. Should be able to get one the right OD, cutting the hole using thin brass tube that is thinned to a knief edge, lubricate with water, works for rubber not sure for silicon. I'm sure you will crack it!
Cheers Kerrin
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Post by Roger on Jan 14, 2022 15:04:05 GMT
Hi Roger, Just had another light bulb moment...the glow wasnt great.......you can buy silicon plugs of different sizes for powder coating they are good for temp used 210C. Should be able to get one the right OD, cutting the hole using thin brass tube that is thinned to a knief edge, lubricate with water, works for rubber not sure for silicon. I'm sure you will crack it! Cheers Kerrin Hi Kerrin, I think that's an excellent idea actually! I've just ordered these ones on eBay which they claim to be good up to 250C. To be honest, it doesn't matter if they suffer in that enviroment because they're not the seal, they're just a dust cover. It's not a big deal if they go hard, crack or whatever, I'm pretty sure they won't melt. I've ordered 17 and 18mm sizes because the hole is 17.7mm and I don't know which ones will fit the best. They're on the slow boat from China, so that's going to take a month. Cutting the hole would certainly work as you describe, or a punch might do if that part is thin enough. These are hollow types.
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Post by steamer5 on Jan 14, 2022 15:13:54 GMT
Hi Roger, They look like they will be great! The ones i have are solid.
Cheers Kerrin
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Post by Roger on Jan 14, 2022 15:38:23 GMT
Hi Roger, They look like they will be great! The ones i have are solid. Cheers Kerrin Hi kerrin, You're spoiled for choice if you search eBay. These were the first that looked to be the sort of shape that I could see fitting and I liked the large flange that will make them easy to remove. Quite how they will respond to being cut and inserted into the tube is anyone's guess. I suppose if they're flexible enough, they might even survive being stretched over the union nut. That would be the perfect solution. I've got some of those three pronged sleeve expanders we used to have for the Hellerman Sleeves, I can see that being used for this. Anyway, this might turn out to be a genius idea, time will tell!
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Post by 92220 on Jan 14, 2022 19:08:40 GMT
Hi Roger.
Just as a simple idea which may or may not work, could you not make a close fitting aluminium inner to9 fit inside a steel outer ring? The differential of expansion would effectively produce a steam tight joint would it not?
Bob
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Post by Roger on Jan 14, 2022 19:39:00 GMT
Hi Roger. Just as a simple idea which may or may not work, could you not make a close fitting aluminium inner to9 fit inside a steel outer ring? The differential of expansion would effectively produce a steam tight joint would it not? Bob Hi Bob, That's a cunning idea. To be honest, I imagine that any close fitting metal seal is likely to expand more than the tube it fits inside. I think I made my Spherical seal from Leaded Bronze, which is going to conduct heat from the Copper pipe it's in contact with. I'm sure that's going to get hotter than the Smokebox since it's got superheated steam inside it. I've tried to imagine how everything will move as the whole locomotive heats up. The Boiler will move, and the Superheater header the Steam feed pipe is connected to is going to move with it. As it is, the Brass pipe is ridigly bolted to that and the Cylinder, so it seemed like a good idea to let the pipe move a little in the Smokebox seal. I'm sure it would work without, but it also means that disassembly ought to be much easier if the pipe can be moved around to get it out. If you could only move it in or out, that wouldn't be anywhere near as easy. A parallel seal would certainly avoid the issue of Ash getting into it though.
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Post by chris vine on Jan 14, 2022 22:49:34 GMT
I think there may be a bit of overthinking going on with this steam pipe through smokebox joint. In truth it only needs to be a close fit and not truly air tight.
There is a huge volume going through the tubes and up the chimney. Look at the leakage path for the smokebox: There are lots of really large holes (through the boiler tubes) and one even bigger one - the chimney.
I think that a close fit (A rattle fit, or something less than .5 mm gap will be plenty good enough. Any sealant and a bit of oily ash will be plenty good enough... Chris.
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Post by andyhigham on Jan 14, 2022 23:06:03 GMT
We are all guilty of over thinking. Often the simplest/crudest solution is the ideal. If a squeeze of High temp silicone sealant seals the gap, keeps dirt out and remains flexible, why look anywhere else?
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Post by delaplume on Jan 15, 2022 0:44:12 GMT
I think there may be a bit of overthinking going on with this steam pipe through smokebox joint. In truth it only needs to be a close fit and not truly air tight. There is a huge volume going through the tubes and up the chimney. Look at the leakage path for the smokebox: There are lots of really large holes (through the boiler tubes) and one even bigger one - the chimney. I think that a close fit (A rattle fit, or something less than .5 mm gap will be plenty good enough. Any sealant and a bit of oily ash will be plenty good enough... Chris. I don't know about a "rattle" fit but certainly there can be a fairly large clearance between the blast pipe and the smokebox. shell......which in a lot of cases has been filled quite successfully with HT Silicone..... Whatever you use it's important to maintain that vacuum when running..
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Post by Roger on Jan 15, 2022 8:22:12 GMT
The idea is to make this easily serviceable, like the rest of the front end. Silicone sealant is a pain to remove, so I really don't want to go down that route.
I know this shouldn't need to come apart that often, but at the moment the blower ring steam pipe comes off with one union, the two Cylinder feed pipes come off with a union at each end. The Chimney slides off to reveal two cap screws holding the Petticoat pipe. With that out of the way, one Banjo bolt gets the Snifting Valve off. Unscrewing the blast pipe releases the complete Smokebox. I reckon the Smokebox could be removed in about five minutes, ten at the outside.
The seal itself isn't an issue, the gap around the spherical metal seal is tiny. Personally, I do think a good seal is important. Any air coming in through gaps is not drawing the fire, but the Steam used to create that flow is using Steam. That's not to say that it won't work, it's just another source of inefficiency which is already terrible. Adding more blower to keep the fire going is not a good solution in my opinion.
The purpose of the bung is purely to keep Ash out of the tube above the seal. I over think everything, but that usually results in a better outcome. Besides, that's what I enjoy. Shortcuts are much less satisfying, and usually less satisfactory.
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stevep
Elder Statesman
Posts: 1,070
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Post by stevep on Jan 15, 2022 9:36:25 GMT
If I may, I will share my experiences of smokebox sealing. When I built my Stanier, I made the whole front of the smokebox removeable - in fact, I turned the ring and door from a single piece of steel. It made cleaning the smokebox a doddle.
The front of my Rob Roy is a conventional ring and hinged door, and the ring is held in with 4 x 10 BA screws. Thinking I would like to be able to clean the smokebox like I did with the Stanier, I removed the 4 screws. It made cleaning out convenient, but the steaming of the loco was awful. I put the screws back in, and the steaming returned to its former performance.
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