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Post by Roger on Sept 30, 2018 8:03:54 GMT
Glad you like it Pete, I'm just wondering about how to machine the handles halves and what to make them from. The full sized one has two wooden pieces in a clam shell arrangement, but it's pretty tiny and may not be strong enough material. I'll have to take a look at the wood samples I've got and perhaps some Tufnol sheet as an option. I think tufnol will be your best option here. It's what I used on the 7 1/4" version of this brake valve as it was way more durable and workable. Love it though, an amazing piece of detail! Did you stand there moving it back and forwar going "pshhtttt.....pshttt" as if it worked? My friend did that when he first made his brake valve...... Adam Hi Adam, I might have some phenolic as another option. The Tufnol I've got seems a bit coarse. I probably don't need to be very clever with the outside shape, I can file it to suit once the tricky part of attaching it to the handle is done. No sound effects though, just trying to picture if it would get in the way or be strong enough. |
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Post by Deleted on Sept 30, 2018 8:05:55 GMT
Is it 'two halves'? I can't tell from the angle of the full-size picture...If so perhaps cheat it, the wooden handle looks a greater diameter than the metal handle so a one-piece wooden handle could be turned up and slipped over the tongue...A small recess could be cut/filed/machined to represent the split if desired. Assuming the metal work is black as in the picture, the cut could be painted black and then varnished over with the wood part. No one would ever know and it would be stronger (more durable) than built up in separate pieces.....just an idea...  Pete |
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Post by Roger on Sept 30, 2018 8:16:02 GMT
Is it 'two halves'? I can't tell from the angle of the full-size picture...If so perhaps cheat it, the wooden handle looks a greater diameter than the metal handle so a one-piece wooden handle could be turned up and slipped over the tongue...A small recess could be cut/filed/machined to represent the split if desired. Assuming the metal work is black as in the picture, the cut could be painted black and then varnished over with the wood part. No one would ever know and it would be stronger (more durable) than built up in separate pieces.....just an idea... Pete Yes, It's two halves, but it doesn't have to be really. I might just try what you suggest, it would certainly be stronger in one piece. |
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Post by Roger on Sept 30, 2018 10:24:56 GMT
Ok, thanks for the advice on the handle, this is what I did in the end. I drilled an undersized hole in a piece of Tufnol and pressed the handle into it in the lathe while there was enough material around the handle to prevent it from bursting the material. Once pressed in, I turned the outside and parted it off.  20180930_105216 by Roger Froud, on Flickr The end was finished with files and emery cloth to get the finished shape.  20180930_111245 by Roger Froud, on Flickr |
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stevep
Elder Statesman
Posts: 1,073
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Post by stevep on Sept 30, 2018 12:56:52 GMT
Looking absolutely fabulous Roger.
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pault
Elder Statesman
Posts: 1,500
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Post by pault on Sept 30, 2018 17:15:49 GMT
Hi
Love the detail of the brake valve.
I did have the experience of a gauge glass breaking when a 7 ¼” gauge loco derailed. As is often the case the gauge glass fittings were not done up all that tightly, when the loco derailed the gauge glass drain pipe which was unusually, dead straight went down onto the rail head. The force of this turned the fitting a small amount which broke the glass.
I was then trying to close the shut off cocks with the pricker. What made this a lot more difficult was the fact it was the day before the highest temperature ever recorded in the UK was reached. Whilst you could hear the steam with the air temperature in the low 30’s °C you could not see it. But you most certainly could feel it when it was blowing in your face or on your arm.
I know of one loco which has slightly captive balls in the gauge glass fittings arranged so that the flow of steam from a broken glass will fit the balls into the fitting to shut off the steam, but I have never seen it tried in anger.
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Post by Roger on Sept 30, 2018 18:23:06 GMT
Hi Love the detail of the brake valve. I did have the experience of a gauge glass breaking when a 7 ¼” gauge loco derailed. As is often the case the gauge glass fittings were not done up all that tightly, when the loco derailed the gauge glass drain pipe which was unusually, dead straight went down onto the rail head. The force of this turned the fitting a small amount which broke the glass. I was then trying to close the shut off cocks with the pricker. What made this a lot more difficult was the fact it was the day before the highest temperature ever recorded in the UK was reached. Whilst you could hear the steam with the air temperature in the low 30’s °C you could not see it. But you most certainly could feel it when it was blowing in your face or on your arm. I know of one loco which has slightly captive balls in the gauge glass fittings arranged so that the flow of steam from a broken glass will fit the balls into the fitting to shut off the steam, but I have never seen it tried in anger. Hi Paul, Glad you like the way it looks. I hear what you're saying about the water gauge fittings. Maybe it's worth considering using some kind of thread locker. I'm just a bit concerned that the fittings might take too much force to remove them if I do that. Perhaps just a smear would be ok. That's a clever idea about the captive balls. Hopefully the shut off valves will work if they're called upon. |
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Post by doubletop on Sept 30, 2018 19:30:51 GMT
Hi Paul, Glad you like the way it looks. I hear what you're saying about the water gauge fittings. Maybe it's worth considering using some kind of thread locker. I'm just a bit concerned that the fittings might take too much force to remove them if I do that. Perhaps just a smear would be ok. That's a clever idea about the captive balls. Hopefully the shut off valves will work if they're called upon. Roger It is looking good. I'm not sure about the captive balls idea and the panic that sets when there appears to be no water in the glass because the balls have stuck for some reason. Try this. No packing washers, or back nuts required. Medium strength so it holds the fittings where you want them and they won't move until you want them to tds.us.henkel.com/NA/UT/HNAUTTDS.nsf/web/D7FBEB99187DD7EB852574C7005CE384/$File/5770-EN.pdf"Been there done that" situation in my case and had tried all the tricks. This stuff literally fixed the problem. Pete |
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pault
Elder Statesman
Posts: 1,500
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Post by pault on Sept 30, 2018 19:39:21 GMT
The design is such that the balls have to be lifted by the flow of steam, in the almost 40 years I have known the engine there has never been a problem with the balls "sticking"
Would agree with the Loctite solution
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Post by Roger on Sept 30, 2018 20:25:51 GMT
Hi Paul, Glad you like the way it looks. I hear what you're saying about the water gauge fittings. Maybe it's worth considering using some kind of thread locker. I'm just a bit concerned that the fittings might take too much force to remove them if I do that. Perhaps just a smear would be ok. That's a clever idea about the captive balls. Hopefully the shut off valves will work if they're called upon. Roger It is looking good. I'm not sure about the captive balls idea and the panic that sets when there appears to be no water in the glass because the balls have stuck for some reason. Try this. No packing washers, or back nuts required. Medium strength so it holds the fittings where you want them and they won't move until you want them to tds.us.henkel.com/NA/UT/HNAUTTDS.nsf/web/D7FBEB99187DD7EB852574C7005CE384/$File/5770-EN.pdf"Been there done that" situation in my case and had tried all the tricks. This stuff literally fixed the problem. Pete Hi Pete, Thanks for that, I'll seriously consider adding a little to the threads. I'm not a fan of relying on something like that on its own though, I think a mechanically seated fitting that locks home at the right angle is preferable to one floating on Loctite before it goes off. I don't doubt that it works, I just prefer an 'Engineered' solution for the primary locking function with the Loctite as backup. |
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Post by doubletop on Oct 1, 2018 2:18:12 GMT
Roger It is looking good. I'm not sure about the captive balls idea and the panic that sets when there appears to be no water in the glass because the balls have stuck for some reason. Try this. No packing washers, or back nuts required. Medium strength so it holds the fittings where you want them and they won't move until you want them to tds.us.henkel.com/NA/UT/HNAUTTDS.nsf/web/D7FBEB99187DD7EB852574C7005CE384/$File/5770-EN.pdf"Been there done that" situation in my case and had tried all the tricks. This stuff literally fixed the problem. Pete Hi Pete, Thanks for that, I'll seriously consider adding a little to the threads. I'm not a fan of relying on something like that on its own though, I think a mechanically seated fitting that locks home at the right angle is preferable to one floating on Loctite before it goes off. I don't doubt that it works, I just prefer an 'Engineered' solution for the primary locking function with the Loctite as backup. Roger I know what you mean but some would argue that loctite is an engineered solution. I'd guess that there are those amongst us, with e Mech Eng background, who would be able to quote many cases of 'glue together' engineering and in some pretty testing situations. Pete |
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Post by Roger on Oct 1, 2018 6:50:40 GMT
Hi Pete, Thanks for that, I'll seriously consider adding a little to the threads. I'm not a fan of relying on something like that on its own though, I think a mechanically seated fitting that locks home at the right angle is preferable to one floating on Loctite before it goes off. I don't doubt that it works, I just prefer an 'Engineered' solution for the primary locking function with the Loctite as backup. Roger I know what you mean but some would argue that loctite is an engineered solution. I'd guess that there are those amongst us, with e Mech Eng background, who would be able to quote many cases of 'glue together' engineering and in some pretty testing situations. Pete Hi Pete, This is true, it's just a personal preference really. Amateurs don't have the pristine conditions and controlled processes to guarantee the success of bonded solutions, so it's not quite the same as using these things in industry. Fortunately, the sealing element of the fittings is catered for by the 'O' rings, so any 'glue' element would be icing on the cake to add another level of security when it comes to the fittings coming loose. We're so lucky to have such a rich array of adhesive products at our disposal. |
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Post by chris vine on Oct 1, 2018 9:06:59 GMT
Hi Roger,
I think you are missing the obvious trick here.
Why not just follow the prototype and install four little studs with nuts for each fitting.
I reckon they will be around 12 BA, which is quite coarse work for you!!!
Chris.
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Post by Roger on Oct 1, 2018 9:56:06 GMT
Hi Roger, I think you are missing the obvious trick here. Why not just follow the prototype and install four little studs with nuts for each fitting. I reckon they will be around 12 BA, which is quite coarse work for you!!! Chris. Hi Chris, Now there's a thought, albeit a bit late! Believe me, I've contemplated such thoughts, and then immediately thought better of it. I'm a fan of twee details when they're non-functional, but I can imagine the nightmare of having that sort of watchmaking on functional parts. Hopefully the completed model will look reasonably scale, yet be robust enough to withstand the rigours of a hard life. Time will tell. |
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Post by simplyloco on Oct 1, 2018 12:51:04 GMT
Hi Roger, I think you are missing the obvious trick here. Why not just follow the prototype and install four little studs with nuts for each fitting. I reckon they will be around 12 BA, which is quite coarse work for you!!! Chris. Hi Chris, Now there's a thought, albeit a bit late! . Hi both. I have M1.2 threads all over my Brit, and they are quite secure. Just don't drop your nuts...  John |
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Post by Roger on Oct 1, 2018 14:59:32 GMT
Hi Chris, Now there's a thought, albeit a bit late! . Hi both. I have M1.2 threads all over my Brit, and they are quite secure. Just don't drop your nuts... John Hi John, Have you used them on live steam flanges to provide the mechanical force to seal them? I think Adam might have used that on some injector flanges. |
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Post by simplyloco on Oct 1, 2018 15:17:48 GMT
Yup! I've used the German made hi tensile ones from Polly. As yet untested...
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Post by Roger on Oct 1, 2018 15:40:21 GMT
Yup! I've used the German made hi tensile ones from Polly. As yet untested... It will be interesting to see how that works out. I might be tempted to go down that route for injector flanges unless I can hide a larger thread and have dummy flange bolts. I'm not sure I'd want threads that size in a boiler flange though. |
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Post by chris vine on Oct 1, 2018 18:39:46 GMT
Hi Roger and John,
One problem I have with Bongo's backhead is that it is difficult to unscrew the fittings because they all foul on each other. There is a sequence and much more stripping than should be necessary.
The four tiny studs solution would solve all of this...
Chris.
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Post by simplyloco on Oct 1, 2018 19:19:47 GMT
Hi Roger and John, SNIP The four tiny studs solution would solve all of this... Chris. You mean like this ...?   DSCF0006 by inkaboat, on Flickr |
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