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Post by flyingfox on Dec 1, 2020 12:42:59 GMT
Hi Pete, I have answered you in you "Doncaster" file.
Regards
Brian
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dscott
Elder Statesman
Posts: 2,440
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Post by dscott on Dec 2, 2020 0:18:36 GMT
On a couple of mine I am planning on fitting a thin copper plate level with the top of the flange.
Attached to the regulator body. Then using 2 gaskets fit the upper dome.
Easy to replace if there are any problems.
David and Lily.
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Gary L
Elder Statesman
Posts: 1,208
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Post by Gary L on Dec 2, 2020 0:49:57 GMT
Brian, I’ve never known anyone use ptfe in disc form as you have, I honestly would try it in boiling water first. The other risk you have with the countersink screws is overtime they will wear away the ptfe holes and it will become sloppy. I personally think it’s a bad idea and will be a potential disaster when in steam and you end up with a regulator wide open and nothing you can do about it. Sorry to sound negative I just have doubts on that one. Adam Hi Brian I repaired a Speedy regulator using a PTFE disc. The LBSC disc-in-tube pattern is a noted 'leaker' so I screwed a PTFE face to the old 'disc' (in effect). It worked very well; as far as I know, it still does:  (Interesting reflection effects on the bronze mating face, but be that as it may.) I think the clue is to use PTFE as a facing, but have it supported by something more solid. I had plenty of room inside the disc-in-tube, but I appreciate you are limited in the allowable thickness in your dome regulator. Nevertheless, I think the way forward would be to use a bronze disc (which could be quite thin) to support the PTFE and take the mountings for the linkages and the operating rod. Then you just need a couple of dowel pins to connect it to and drive the PTFE. Put another way, the PTFE is just the jam in a bronze sandwich, and takes no strain. In your photo, connecting the linkage pins direct to the PTFE like that would worry me, as it does Adam. You have no way to be sure they won't let go, and that could be a problem. Hope this helps Gary |
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Post by runner42 on Dec 2, 2020 6:13:25 GMT
Brian, I’ve never known anyone use ptfe in disc form as you have, I honestly would try it in boiling water first. The other risk you have with the countersink screws is overtime they will wear away the ptfe holes and it will become sloppy. I personally think it’s a bad idea and will be a potential disaster when in steam and you end up with a regulator wide open and nothing you can do about it. Sorry to sound negative I just have doubts on that one. Adam Hi Adam, I placed the regulator in boiling water for 20 mins. Afterwards I couldn't see any difference in the PTFE disk, the only visible thing was that it was cleaner all the dirt from handling it was removed. However, if it does distort in practice, boiling water (100 deg C) isn't a representative temperature, since we know that at high pressure the boiling point is much higher. I re-iterate that PTFE has been used in the same application by a number of ME's. One who comes to mind is a colleague at SASMEE who has used it in his Highlander locomotive. Brian  P6131836 by Brian Leach, on Flickr  P6221226 by Brian Leach, on Flickr |
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mbrown
Elder Statesman
Posts: 1,790
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Post by mbrown on Dec 2, 2020 11:35:21 GMT
One thing I have thought about doing is using a PTFE disc between the portface and a bronze disc - and arranging it so that the bronze disc moves separately. If the ports are arranged appropriately in both, and the PTFE disc is "nudged" by lugs on the bronze disc, you could have a first and second regulator arrangement with all working faces being between PTFE and bronze (Hope that makes sense). The first movement of the regulator handle would open a pilot port in the bronze disc which would then start to open the main port in the PTFE disc as its rotation continued.
I haven't tried this in practice, but may do so on 99 3462. The PTFE would be fully supported on both sides, there would be no threads in the PTFE itself and, with the right size ports, you'd get a nice gentle opening at first followed eventually by full bore, which should be very controllable.
It would be interesting to know if anyone has tried this. If not, wait a few years until I can give it a go, and I will report the outcomes!
Malcolm
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Post by Cro on Dec 2, 2020 11:44:33 GMT
Maclolm,
I did very similar on a brake valve in 7 1/4" and it worked well, it leaked a bit when wet/cold as I had a wet steam supply when testing but when warm was lovely. All it needed was a small locating peg to stop it from moving but it was a fiddly to do. The disc was no more the 0.5-0.6" Dia with 1.5mm port holes in.
Brian if you just put it in a kettle boiling water I wouldn't expect too much but actively boiling water may be more of a simulation. I'm still surprised it didn't move at all whilst hot.
Adam
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Post by Cro on Dec 2, 2020 11:47:58 GMT
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Post by runner42 on Dec 15, 2020 5:21:55 GMT
Using a very sick air compressor that leaks and struggles to produce an output, it was nevertheless sufficient to show that running on air was OK. The output was around 2 psi and the volume of air being pushed out wouldn't blow the skin off a rice pudding, so it was a good indicator that most things were set right. I set the timing by judging where the piston valves should be, no precision here at the moment so I can improve matters using measurement. The video shows that the left hand cylinder is getting more oil than the right, the lubrication is from a single centrally mounted mechanical lubricator. The oil path lengths are reasonably the same so I should get equal lubrication to both cylinders. Any suggestions on how to tackle this imbalance? Brian  00004_3MAxYH2a_ujsr by Brian Leach, on Flickr |
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Post by Cro on Dec 15, 2020 6:48:05 GMT
Make a lubricator with 2 pumps.
Any variation between the two pipe runs, that could cause a resistance, will mean the oil will choose path of least resistance and favour the other side. Having 1 feed 2 is always a bad idea for this exact reason. If you can fit two tanks one for each pump even better as you know what each cylinder is getting then.
Adam
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stevep
Elder Statesman
Posts: 1,073
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Post by stevep on Dec 15, 2020 9:41:04 GMT
Very impressive running on that low a pressure. I don't think the lubrication will be a problem Brian. When you are in steam (rather than using compressed air), the oil will emulsify with the steam and get carried to both cylinders. I hadn't thought about it before, but running the loco with the front steam chest covers off is wonderful. Great to see the valve moving. I notice you don't have any support for the valve crosshead on the rear of the cylinder. In 5" gauge, I would think that would wear the cover. This is what I did on my Stanier.  As you can see by the combination rod arrangement, it is slide valves, and I have also off-set the valve connection so that the radius rod is in line with the valve. |
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Post by runner42 on Dec 22, 2020 7:08:18 GMT
Purchased a quarter sheet of 3 mm copper (450 mm x 900 mm) to start the boiler. This is enough to undertake the production of the flanged plates for the smokebox tube plate, the throat plate, the firebox tubeplate, the backhead, the firebox back plate and the barrel. I shall need another quarter sheet for the inner and outer wrapper. It is less painful on the pocket to split the purchase in two halves. I was just in time to obtain the first quarter sheet because the Supplier shuts down today for as always in Australia a long Christmas break. The photo shows the marking for the barrel, which when cut out and rolled will provide a cone with truncation to one side. The small end looses material but the big end requires additional material. Although the use of a Sharpie fine point, due to its line thickness causes loss of precision, it does indicate the overall principle of using a Excel spreadsheet to calculate the end shapes so no further machining is required after rolling. The flanging dies are to the correct footprint and the thickness of the plates are 9 mm thick, which is required by the AMBSC Code 1 requiring a flange depth of 3 X the material thickness.  Copper sheet1 by Brian Leach, on Flickr  Copper sheet2 by Brian Leach, on Flickr |
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Post by runner42 on Dec 23, 2020 5:38:01 GMT
Another thing I have forgotten. How much over should the copper blank be with respect to the flanging die to achieve a 9 mm deep flange? Is it just 9 mm? I have 12 mm which I suspect is too much, because I think having a greater amount to flange would produce problems particularly on tight bends. Brian  backhead blank by Brian Leach, on Flickr |
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Post by Kevin on Dec 23, 2020 13:47:58 GMT
Hi Brian
Who supplies your copper sheet
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Post by runner42 on Dec 23, 2020 21:16:06 GMT
Hi Brian Who supplies your copper sheet Hi Kevin, haven't seen your presence on here for some time, you were producing a 3D version of a Black 5 if I remember correctly? My metal supplier is an Adelaide Company www.surmanmetals.com/Brian |
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Post by Kevin on Dec 26, 2020 10:44:04 GMT
Hi Brian
Happy Christmas Brian and thanks for the info, I am still drawing up my Black 5 but have been off it for a while. Had a new knee installed that didn't want to heal to quickly
suspect my being diabetic slowed it down, but am now on the mend and will be restarting on my drawing again soon. I also picked up a 5" gauge
Victorian railways K Class loco to finish so looking forward to getting back in the shed
Kevin
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Post by runner42 on Dec 30, 2020 6:43:02 GMT
Made progress on flanging the boiler plates. I forgot how more time consuming making the flanged plates for a Belpaire boiler can be. The tight corners particularly on the firebox tubeplate and firebox backplate required a lot of annealing and hammering to get them to follow the required contours. Unlike LBSC's design for a Black 5 boiler which has a parallel inner wrapper, whereas DY's design has a tapered inner wrapper,so the firebox backplate has the tightest corners. The marks on the inside of the smokebox tubeplate are due to screws that had to be inserted into the flanging die to enable the die to be removed after the final flanging operation. Without this is was almost impossible to remove it. The position of the marks are going to disappear on drilling the smokebox tubeplate. Brian  4 flanged plates by Brian Leach, on Flickr  4 flanged plates1 by Brian Leach, on Flickr |
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Post by runner42 on Dec 31, 2020 22:12:05 GMT
Left the easiest flanged plate to last ( joking), not that it required a lot of annealing and hammering, it was thinking of how to set up to produce the opposite flange.  throat plate by Brian Leach, on Flickr  throat plate1 by Brian Leach, on Flickr It is not quite finished as it needs V cuts in the flanges to enable a 20 deg bend to be introduced. At the moment I am unsure where to position the bend. I am often surprised by which professional draughtsmen decide what features to provide measurements for and those they consider unnecessary, which require a measurement to be derived by calculation from other measurements. The position of the bend is a case in point. If a piece part drawing was produced then this dimension should have be provided.  throatplate drg by Brian Leach, on Flickr This is the only drawing of the throat plate so much has to be derived from other parts of the drawing and where the bend is positioned is more esoteric than the rest. Brian |
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Post by runner42 on Jan 1, 2021 4:55:17 GMT
A new year's resolution should be to check measurements twice, well today I didn't check once and assumed the spacing is symmetrical. There I was in the shed and realised that the horizontal spacing of the tubes was not included in the sketch I made for drilling the smokebox tubeplate, the vertical measurement was there, so instead of stopping and going indoors to check the drawing I assumed that the spacing was the same as the vertical. Well it is not the case the horizontal spacing is wider than the vertical. The result is that the ligament distance is 0.070" and the AMBSC Code Part 1 requires that the ligament distance be 3 mm with a tolerance of +/- 0.5 mm. Well 0.070" comes in at 2.75 mm. Some harrowing moments before checking the AMBSC Code Part1.  smokebox tubeplate by Brian Leach, on Flickr This gives me a potential problem, do I make the drilling of the firebox tubeplate the same as the smokebox with shorter horizontal spacing or make it to drawing? This would take the tubes out of parallel by a small amount. Brian |
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stevep
Elder Statesman
Posts: 1,073
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Post by stevep on Jan 1, 2021 10:20:52 GMT
I am no boiler designer, but I am inclined to think that a slightly greater spacing at the firebox end would do no harm. In fact, as this is the hotter end of the boiler, it would actually be beneficial as it would allow better circulation.
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Gary L
Elder Statesman
Posts: 1,208
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Post by Gary L on Jan 1, 2021 15:22:53 GMT
I am no boiler designer, but I am inclined to think that a slightly greater spacing at the firebox end would do no harm. In fact, as this is the hotter end of the boiler, it would actually be beneficial as it would allow better circulation. Stevep is right, but draw it out first. Firebox tubeplates are often smaller than the smokebox end, so you need to check you have enough room. Gary |
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