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Post by Roger on Feb 5, 2021 21:49:48 GMT
As for being to "rude" yesterday evening to Roger I apologise to Roger. What other forum members may not appreciate is that Roger and I have met each other on 4 occasions in the last 6 years or so, and for more than 6 years have also had at times considerable email correspondence. Roger knows that I am blunt, and he had to redo the rear bunker. But it is a 2 way process. Anyway, apologies, Roger, for any offence caused by me. Cheers, Julian Hi Julian, No offence taken, it actually raised a smile because I could imagine you saying it! It takes a lot more than that to upset me. In any case, it was a fair point, and something I shouldn't have got wrong. Most things come out so accurately that I often don't measure every detail. If one dimension is right, the rest usually follow suit. I think the issue with reamers is that they are so slender that even with all the care in the world, you won't get the fine point to be perfectly on size without going to extraordinary lengths. I might have to get a finer cup wheel, that might help. I'm pretty sure the taper is ok, it's grinding it in half where the errors creep in. |
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Post by steamer5 on Feb 5, 2021 22:15:22 GMT
Hi Rodger,
Given the gear you have would it be possible to make a rear support for the reamer pre grinding the taper?........knowing that the rest of us likely can’t is a bit of a moot point but just a thought
Cheers Kerrin
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Post by Roger on Feb 5, 2021 22:51:41 GMT
Hi Rodger, Given the gear you have would it be possible to make a rear support for the reamer pre grinding the taper?........knowing that the rest of us likely can’t is a bit of a moot point but just a thought Cheers Kerrin Hi Kerrin, I guess you could support it for grinding in half, to be honest I hadn't thought of doing that. Some kind of fine adjustment would be required such that you could put a clock on the side the wheel would be against, and adjust the rest so it resisted bending but without moving it towards the wheel. I might give that a try on the next one, it shouldn't be too hard to set up. Another thought is to put the clock against the side of the reamer away from the wheel, and see if it moves when it's being ground. It wouldn't support it, but it would tell you if it's deflecting away from the wheel. Anyway, that's a useful idea, so thanks for that suggestion, it might lead to a solution. |
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JonL
Elder Statesman
WWSME (Wiltshire)
Posts: 2,991
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Post by JonL on Feb 5, 2021 22:57:50 GMT
I apologise if I came across blunt. I felt Rogers efforts were being unfairly criticised in something that, no matter how seriously we take it, is still a hobby unless we are earning a living from it. As you have had face to face dialogue in the past you will be more easily able to read each others tone than the other readers of your posts. It is worth noting that the casual readers are far more prevalent than the individual recipient though!
I'm glad this thoroughly interesting subject is capable of raising spirited debate. It rather shows have invested everyone is in this project. I will shut up and prevent further clogging.
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Gary L
Elder Statesman
Posts: 1,208
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Post by Gary L on Feb 5, 2021 23:13:25 GMT
You're on the right track there, Roger...........On the footplate you can definitely hear the feed-water "singing" when the injector is working-- even with the various other sounds of a loco on the move... On a model injector I was of the opinion that the "chirping" noise....and it does indeed sound like a small bird chirping --- was air being draw in via the overflow ..... If it was the ball valve slamming down wouldn't that have more of a staccato quality to it ??........In either case, contrary to the "Wisdom of Ages" that has to be detrimental I would have thought ?? Crack-on matey !!........I might not post much but always read what you do and learn from it ( However, I don't think that IBM will be Head-hunting me as a Chief Programmer anytime soon ---LoL !! )... Is it just me... I’ve often heard about this ‘chirping’, but I’ve never heard it myself. Or I don’t think I have. I hear what Alan describes as ‘singing’ but it is constant and tells me that the injector is working. It is not unlike the sound you hear in the pipes when a domestic tap is running. But I’ve never heard birds in the pipe as well. Does this chirp happen over the top of the singing, or instead of? Or is my ‘singing’ the same as someone else’s ‘chirping?’ Not being funny, I’m genuinely curious. Gary |
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Post by Roger on Feb 5, 2021 23:31:18 GMT
You're on the right track there, Roger...........On the footplate you can definitely hear the feed-water "singing" when the injector is working-- even with the various other sounds of a loco on the move... On a model injector I was of the opinion that the "chirping" noise....and it does indeed sound like a small bird chirping --- was air being draw in via the overflow ..... If it was the ball valve slamming down wouldn't that have more of a staccato quality to it ??........In either case, contrary to the "Wisdom of Ages" that has to be detrimental I would have thought ?? Crack-on matey !!........I might not post much but always read what you do and learn from it ( However, I don't think that IBM will be Head-hunting me as a Chief Programmer anytime soon ---LoL !! )... Is it just me... I’ve often heard about this ‘chirping’, but I’ve never heard it myself. Or I don’t think I have. I hear what Alan describes as ‘singing’ but it is constant and tells me that the injector is working. It is not unlike the sound you hear in the pipes when a domestic tap is running. But I’ve never heard birds in the pipe as well. Does this chirp happen over the top of the singing, or instead of? Or is my ‘singing’ the same as someone else’s ‘chirping?’ Not being funny, I’m genuinely curious. Gary Hi Gary, The sound repeats over and over, usually about once a second. Chirping describes it very well in my opinion. I don't think you could describe it as a singing noise, and it's not a continuous sound. That's why I think it's instability causing the ball to lift and then settle while making the characteristic noise. I haven't heard any noises like that from my injector, and I would have expected to if it was just the sound of air entering the cones. My valve is sprung and with a soft rubber facing, so I'm not surprised it doesn't make any noise. |
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Post by John Baguley on Feb 6, 2021 0:55:52 GMT
Hi Roger,
It may not work with your design but certainly with a conventional injector you can feel the vacuum at the overflow if you put your finger over it when the injector is 'chirping'. Air is defintely being sucked in. It could well be the ball valve not seating properly and allowing air to be drawn into the gap in the combining cone. You wouldn't be able to tell with a conventional injector whether it was being drawn into the combining cone or the delivery cone though with the overflow being common to both chambers.
John
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Post by Roger on Feb 6, 2021 8:23:31 GMT
Hi Roger,
It may not work with your design but certainly with a conventional injector you can feel the vacuum at the overflow if you put your finger over it when the injector is 'chirping'. Air is defintely being sucked in. It could well be the ball valve not seating properly and allowing air to be drawn into the gap in the combining cone. You wouldn't be able to tell with a conventional injector whether it was being drawn into the combining cone or the delivery cone though with the overflow being common to both chambers.
John
Hi John, Air will definitely be drawn into both places where water has to jump the gap. I've got a valve over the combined outlet, and you can see the moment when it picks up because the flow halts. However, on my design, I haven't heard the chirping once. I think you could run a conventional injector without the ball because I've read an account somewhere where the author reported watching the flow through the hole. I find it hard to imagine how a plain orifice drawing in air would sound like that. I'm convinced it has to do with the movement of the ball valve and it seating and unseating. |
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Post by cplmickey on Feb 6, 2021 9:07:50 GMT
I get both chirping and singing with my injector. Water on, then steam, and as I reduce the water flow the injector starts to pick up and the "gulp" of water sounds like a chirp about once a second. Reduce the water slightly more and off she goes singing away (and water has stopped running from the overflow at that point).
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Post by Roger on Feb 6, 2021 9:10:11 GMT
With said injector running/chirping, would not placing one's finger over the over flow pipe end determine if it is air that is going in ? Yeah, I admit I am dim if I am off track. Hi Dazza, Air is definitely trying to be drawn into the two gaps. One is closed with the usual ball valve, the other is open to the atmosphere. So in normal operation, the valve should be closed and air will be drawn into the boiler at the delivery overflow. Putting your finger over the overflow would stop the air getting in, but even if it stops the chirping, how would you know whether it was the valve or something else that had stopped? Although the principle of injectors is simple enough, the devil is in the detail. |
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Post by Roger on Feb 6, 2021 9:13:31 GMT
I get both chirping and singing with my injector. Water on, then steam, and as I reduce the water flow the injector starts to pick up and the "gulp" of water sounds like a chirp about once a second. Reduce the water slightly more and off she goes singing away (and water has stopped running from the overflow at that point). I think the singing noise is just the sound to water flowing rapidly through the tiny orifices when the flow isn't that stable. It goes quiet when the flow stabilises. There's a huge range of flow volume, hence velocity, so it's not surprising that it's not always smooth. I guess it depends on what the Reynolds number is for any given flow. |
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stevep
Elder Statesman
Posts: 1,073
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Post by stevep on Feb 6, 2021 9:25:22 GMT
I get both chirping and singing with my injector. Water on, then steam, and as I reduce the water flow the injector starts to pick up and the "gulp" of water sounds like a chirp about once a second. Reduce the water slightly more and off she goes singing away (and water has stopped running from the overflow at that point). I have always understood that the 'chirping', whilst not necessarily a bad thing, wasn't good. My experiences of the injectors on my Stanier 2-6-4T, built to Laurie Lawrence's design, was exactly the same as above. |
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Post by Roger on Feb 6, 2021 10:01:07 GMT
I get both chirping and singing with my injector. Water on, then steam, and as I reduce the water flow the injector starts to pick up and the "gulp" of water sounds like a chirp about once a second. Reduce the water slightly more and off she goes singing away (and water has stopped running from the overflow at that point). I have always understood that the 'chirping', whilst not necessarily a bad thing, wasn't good. My experiences of the injectors on my Stanier 2-6-4T, built to Laurie Lawrence's design, was exactly the same as above. I think some element of instability is inevitable in a design that has to work over such a wide range of conditions. Trying to balance the overflow and water feed volumes is difficult to say the least. I agree that the chirping isn't a good thing, other than its an indication that it's feeding. |
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Post by delaplume on Feb 6, 2021 13:42:16 GMT
Just by way of clarification.....When I said "on the footplate" I meant that to be on a full-size loco's footplate rather than on a 5 inch gauge ( or similar) one.......It's as Gary says}--- the "singing" sounds just like water passing through your domestic pipe........
I've only driven any larger model locos a few times ( an occasional 7.25 inch gauge over 40 or so years ) so can't really comment on their injector performances... Maybe, given their larger sizes, they Warble rather than chirp ??........LoL !!
Any air going into the boiler means that much volume of water isn't.....ie}--not a desirable situation in any event...
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Post by Roger on Feb 6, 2021 17:43:27 GMT
Just by way of clarification.....When I said "on the footplate" I meant that to be on a full-size loco's footplate rather than on a 5 inch gauge ( or similar) one.......It's as Gary says}--- the "singing" sounds just like water passing through your domestic pipe........ I've only driven any larger model locos a few times ( an occasional 7.25 inch gauge over 40 or so years ) so can't really comment on their injector performances... Maybe, given their larger sizes, they Warble rather than chirp ??........LoL !! Any air going into the boiler means that much volume of water isn't.....ie}--not a desirable situation in any event... Hi Alan, Your last comment is very pertinent, and it surprises me that most Injector designs have settled on ones that doesn't prevent this. I guess it's done for simplicity rather than aiming for the ideal. The Chiverton Injectors I've seen have separate valves for both overflows though. |
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Post by delaplume on Feb 6, 2021 18:44:12 GMT
Hi Roger...
So far we have only been dealing with Live Steam injectors....
There's also the Exhaust Injector to consider.....A look in the Black Book at the "H" and "H/J" types should whet your appetite for further investigations ( Multiple cones---- steam operated water valves, etc)...
Enjoy !!
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Gary L
Elder Statesman
Posts: 1,208
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Post by Gary L on Feb 6, 2021 19:19:22 GMT
Is it just me... I’ve often heard about this ‘chirping’, but I’ve never heard it myself. Or I don’t think I have. I hear what Alan describes as ‘singing’ but it is constant and tells me that the injector is working. It is not unlike the sound you hear in the pipes when a domestic tap is running. But I’ve never heard birds in the pipe as well. Does this chirp happen over the top of the singing, or instead of? Or is my ‘singing’ the same as someone else’s ‘chirping?’ Not being funny, I’m genuinely curious. Gary Hi Gary, The sound repeats over and over, usually about once a second. Chirping describes it very well in my opinion. I don't think you could describe it as a singing noise, and it's not a continuous sound. That's why I think it's instability causing the ball to lift and then settle while making the characteristic noise. I haven't heard any noises like that from my injector, and I would have expected to if it was just the sound of air entering the cones. My valve is sprung and with a soft rubber facing, so I'm not surprised it doesn't make any noise. OK, I see. So I won’t fret about not experiencing it! The ‘air’ theory sounds a bit tentative though, why would this create strange noises? I wonder if cavitation is a better analogy? This is the noise that propellers make in water when pushed beyond their load capacity. Cavitation is ‘bubbles of vacuum’ and it occurs when the propeller is moving too fast for the displaced water to rush in to fill the gaps left behind it. The noise is caused by the bubbles collapsing at supersonic speed I believe. Since we are dealing with incompressible water moving at high speed, it is not impossible this could be a feature of injectors too. It might also explain the erosion of cones that some people experience. The transient vacuum followed by a tiny ‘water hammer’ in each collapsing bubble causes molecules of metal to be detached. Something like that anyway. It can cause serious damage to propellers over time. ?? Gary |
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Post by Roger on Feb 6, 2021 20:42:10 GMT
Hi Gary, The sound repeats over and over, usually about once a second. Chirping describes it very well in my opinion. I don't think you could describe it as a singing noise, and it's not a continuous sound. That's why I think it's instability causing the ball to lift and then settle while making the characteristic noise. I haven't heard any noises like that from my injector, and I would have expected to if it was just the sound of air entering the cones. My valve is sprung and with a soft rubber facing, so I'm not surprised it doesn't make any noise. OK, I see. So I won’t fret about not experiencing it! The ‘air’ theory sounds a bit tentative though, why would this create strange noises? I wonder if cavitation is a better analogy? This is the noise that propellers make in water when pushed beyond their load capacity. Cavitation is ‘bubbles of vacuum’ and it occurs when the propeller is moving too fast for the displaced water to rush in to fill the gaps left behind it. The noise is caused by the bubbles collapsing at supersonic speed I believe. Since we are dealing with incompressible water moving at high speed, it is not impossible this could be a feature of injectors too. It might also explain the erosion of cones that some people experience. The transient vacuum followed by a tiny ‘water hammer’ in each collapsing bubble causes molecules of metal to be detached. Something like that anyway. It can cause serious damage to propellers over time. ?? Gary Hi Gary, It's hard to know whether cavitation plays a part. The noise repeats slowly, over and over, so it seems to me that it's a slowly changing set of conditions that keep repeating. Personally, I think it's instability in the flow that lifts the ball, which then takes time to re-seat, possibly spiralling around until it finally does, with air being sucked past an ever decreasing gap. As soon as it does, I suspect that it makes the flow unstable again, water comes out of the overflow and unseats the ball to restart the process. |
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Post by Roger on Feb 6, 2021 22:19:29 GMT
I've made a few cones today to try out some ideas, but not really any progress. However, I did try the 1.1mm diameter Steam Cone throat in the first one I made, and that was hopeless. So here it is drilled out to 1.8mm and being bonded onto a 1.8mm piece of Brass with Loctite to return it to 1mm. All of the tests this week have been done with the 1.05mm throat, so I thought I'd do some tests with the smaller throat to see if that's any improvement.  20210206_211606 by Georgia Montgomery, on Flickr The challenge for using drilled holes for the overflows appears to be finding the sweet spot between several things. 1. You have to provide enough cross sectional area of holes far enough upstream to create sufficient vacuum for it to pick up under all conditions. 2. Drilling a series of overlapping holes big enough appears to cause too much disturbance in the flow. 3. Staggered rows of smaller holes seem to provide the least disturbance. However, more than two rows can cause instability. 4. The further downstream you put holes, the more effect they have for their size. Unfortunately, there are thousands of permutations that you could try, and most of them won't work. However, there are glimpses that it's possible to get acceptable performance, but I'm yet to find an arrangement that's satisfactory. I'll keep plugging away and hopefully I'll be able to home in on something in the end! Much patience is required. Most of the cones I've made have suffered from insufficient suction which stops them from picking up. If I get enough suction, I can get reasonable stability with some arrangements, but not good enough to run down low enough. Very few arrangement fail to work completely. I've tried to avoid using more than two sizes of holes, preferable only one. However, it might be that it's necessary to use more than two sizes. We'll see. I'm sure this can be done, it's just a matter of picking my way through the problems. |
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dscott
Elder Statesman
Posts: 2,440
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Post by dscott on Feb 7, 2021 0:55:48 GMT
The main thing you have to remember Roger is that we are all behind you on your quest.
This as usual is Nightly reading or in my case Reading!!
It was back in 1988 when I had at last got my first Locomotive all together a Gemma and
lit her up with a freshly steam tested Boiler.
At that point I had not heard about the important Run On Air bit.
I was just keen to get something running.
She moved but not very well...
I had built a line in my Parents Garden with a raised steaming/sorting out area.
As she cooled I was taking the slide valve covers off and organizing new valves to sorted out
Dimensions.
Lucky that at the back of my parents Garage was my workshop where ready for the following day
new valves worked perfectly. So much for some of the drawings.
She pulled 3 adults and the result was one of the best.
I have some beer ready for the day when it all works Roger!
David and Lily.
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