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Post by GWR 101 on Oct 23, 2019 21:44:23 GMT
+1 I have been at this game for nearly 60 years and thought I had seen it all. Regards Paul.
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jma1009
Elder Statesman
Posts: 5,913
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Post by jma1009 on Oct 23, 2019 21:58:10 GMT
Hello Roger,
Stunning, as others have commented.
I am not at all sure the top of the cover is large enough in diameter to 'look right' and conform to what us GWR fans would regard as the correct external profile and shape.
But I will await the end result.
At least it is in brass not gunmetal as gunmetal is the wrong colour metal for a GWR safety valve cover.
Cheers, Julian
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don9f
Statesman
Les Warnett 9F, Martin Evans “Jinty”, a part built “Austin 7” and now a part built Springbok B1.
Posts: 961
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Post by don9f on Oct 23, 2019 22:07:23 GMT
I first came upon this thread back when you were making the boiler water gauge frames and they really impressed me. I have continued to be even more impressed ever since!
Fantastic work
Cheers Don
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Post by David on Oct 23, 2019 22:33:39 GMT
Very impressive! But the full size one was full of dents and didn't fit as well as yours will. Perhaps if it was scaled down it would be as good as yours.
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Post by Roger on Oct 24, 2019 7:00:08 GMT
Hello Roger, Stunning, as others have commented. I am not at all sure the top of the cover is large enough in diameter to 'look right' and conform to what us GWR fans would regard as the correct external profile and shape. But I will await the end result. At least it is in brass not gunmetal as gunmetal is the wrong colour metal for a GWR safety valve cover. Cheers, Julian Hi Julian, I hope it's close, it's made to the Works Drawings so it ought to look right unless 1501 had a different style.
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Post by ettingtonliam on Oct 24, 2019 7:20:31 GMT
Its awsome! I wonder how closely the guys in the Swindon sheet metal shop bothered to follow the Works drawings, when they had made hundreds of these covers before over the years, or if they just did their own thing? Anyway, you are making it to the drawing, so theres no arguing with that.
If you did intend to make it look like the one 1501 is wearing now, now you need to make a little tiny hammer and hit it all over!
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Post by 92220 on Oct 24, 2019 7:44:31 GMT
A beautiful job, beautifully carried out!!!!!!!!
Bob
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Post by steamer5 on Oct 24, 2019 8:26:24 GMT
I knew it would be good, but good doesn’t even come close!
Cheers Kerrin
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Post by simplyloco on Oct 24, 2019 8:49:19 GMT
Good job Roger. As a qualified fitter/machinist I could legitimately comment on your methods, but I wouldn't have the temerity to suggest to a major contributor such as yourself that it was the wrong shape, size or colour! Especially if it was made to Works drawings! Life really is too short... John
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Post by Jim Scott on Oct 24, 2019 9:29:42 GMT
Crikey indeed! When I consider the number of opportunities available to cock this up it seems miraculous that it is at this almost finished state. My tired brain would have made an unrecoverable mistake long before this point. Else my trembling fingers would have allowed it to drop onto a hard surface...
Impressive just doesn't cover it...
Jim S
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Post by Roger on Oct 24, 2019 9:53:35 GMT
Crikey indeed! When I consider the number of opportunities available to cock this up it seems miraculous that it is at this almost finished state. My tired brain would have made an unrecoverable mistake long before this point. Else my trembling fingers would have allowed it to drop onto a hard surface...
Impressive just doesn't cover it...
Jim S
Thanks Jim, Having a reliable machine is absolutely vital, no missed steps or significant backlash can be tolerated when it's such a thin section. You do have to be ultra cautious with the setups, especially since there's no usable reference on the axis you can use. Without an externally available reference it's hard to register one operation with the next. It's also only symmetrical about one axis and it's easy to confuse which way round it is. That's because the boiler is tapered and so is the base of the skirt. You have to accept that it might go horribly wrong until it's finished the last cut, so I won't tempt fate just yet. It's just doing what I hope is the finishing pass on the inside of the rim and that's another few hours to get the kind of finish I'm looking for. At least if it does go wrong, the programs and strategy have now been proved, so it's not quite so bad if I need to start again.
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Post by ettingtonliam on Oct 24, 2019 11:44:01 GMT
Roger I don't know if its a trick of the light or not, but in the photo of the cover that 1501 currently wears, there seems to be a horizontal join line just level with the top of the top feed covers.
After all these years and several owners, one of whom was NCB it would not surprise me in the slightest that somewhere along the line the cover had been modified/repaired or replaced. It isn't nearly as good a fit on the boiler cladding as yours will be, either.
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Post by Roger on Oct 24, 2019 12:35:44 GMT
Roger I don't know if its a trick of the light or not, but in the photo of the cover that 1501 currently wears, there seems to be a horizontal join line just level with the top of the top feed covers. After all these years and several owners, one of whom was NCB it would not surprise me in the slightest that somewhere along the line the cover had been modified/repaired or replaced. It isn't nearly as good a fit on the boiler cladding as yours will be, either. I think you're right, I'm pretty sure it would have been made in two parts, and that is likely to be at that point. Another view from a higher angle confirms that there is some kind of transistion at that point. You can see that there's a slight flare where it joins the top of the shoulders, and it's that slight change in shape that appears to go all of the way around. Whether that's the result of a repair, or an original manufacturing artefact is hard to say with certainty. The top feed seems to be common to other GWR locomotives, and this boiler was borrowed from another design. It seems unlikely that the design was modified to suit 1501 since it should be the same as what it was borrowed from. So I think what you're seeing is probably a manufacturing artefact that's probably inevitable when you join two parts like that. They do it on musical instruments much better, but there's no need to go to that level of quality on a locomotive. The bottom line is that the Works Drawings show a smooth transition at that point and there's no hint of how it's supposed to be made. Whether that Works Drawings are intended to truly represent what was fitted to 1501 is a fact that's lost to us unfortunately. Hopefully it will fit and look plausibly like what's on there. I'll be happy if it meets that criteria.
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Post by delaplume on Oct 24, 2019 14:19:35 GMT
Have a look at this -- youtu.be/anVa4uer0jw -- for a quick view of GWR safety valve covers being made by}-----------Apprentices !!
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Post by Roger on Oct 24, 2019 14:26:45 GMT
Have a look at this -- youtu.be/anVa4uer0jw -- for a quick view of GWR safety valve covers being made by}-----------Apprentices !! Do you have a timestamp for where that's shown, I can't see it? Maybe 1501's were made by an apprentice then! That might explain a lot.
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Post by Roger on Oct 24, 2019 15:27:37 GMT
This is how it looks after the final finishing pass. I measured the thickness of the rim before the last cut, and decided that it was going to end up 0.15mm too thin, so I moved the Z-axis reference up 0.15mm and took the last cut which should have removed 0.2mm That means that it's created the correct inside diameter and got into the tight corner where simulated rolled edge finishes. The big ridge is where the two profiles meet and it didn't quite go deep enough. 20191024_134714 by Timothy Froud, on Flickr So it was back onto the lathe to remove that very carefully. I've used felt tip pen so I can see where it touches. 20191024_141027 by Timothy Froud, on Flickr Then the front blended in ok, I turned the compound slide to just under the angle of the inside taper and you can see where it's removed the material. 20191024_141745 by Timothy Froud, on Flickr 20191024_142157 by Timothy Froud, on Flickr I wasn't happy with the definition of the inside of the rolled edge, so here I'm floating the tool into the groove with the toolpost loose and the lathe stopped obviously! I could feel it engaging with the transition point so I locked it up there and set the DROs to zero. 20191024_143715 by Timothy Froud, on Flickr Again I used the Felt Tip pen to show where it was touching, and you can see it's done that close to the edge. 20191024_144106 by Timothy Froud, on Flickr The top of the rim was a bit flat and the inside needed a little polishing so I did that using the Grinder workhead. 20191024_144719 by Timothy Froud, on Flickr 20191024_145626 by Timothy Froud, on Flickr Holding this is pretty awkward, but the inside of the fixture provided a way to do that along with a scrap of Silicone rubber sheet to make it grip with very little force. A Junior haxksaw blade made short work of cutting out the remaining bridge. 20191024_151044 by Timothy Froud, on Flickr That was tidied up freehand with a file. The two sides are exactly opposite each other, so that made a handy guide for the file to follow with a bit of care. 20191024_151234 by Timothy Froud, on Flickr So, this isn't quite sitting down as it should, it's fouling the edge of the safety valve flange. 20191024_155732 by Timothy Froud, on Flickr It's particularly bad at the edges. 20191024_154026 by Timothy Froud, on Flickr I've filed those parts and it's much better, but I think it's going to foul the outer nuts that hold the flange in place. 20191024_155746 by Timothy Froud, on Flickr This is what it looks like with bolts simulating the nuts on the flange. It's about 1mm too high really... 20191024_160134 by Timothy Froud, on Flickr ... although the bolt heads are particularly thick. I think the solution is to machine the flange down a little, it's 4mm thick, so way thicker than it needs to be really. 20191024_160157 by Timothy Froud, on Flickr
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Post by Cro on Oct 24, 2019 15:34:18 GMT
Have a look at this -- youtu.be/anVa4uer0jw -- for a quick view of GWR safety valve covers being made by}-----------Apprentices !! Do you have a timestamp for where that's shown, I can't see it? Maybe 1501's were made by an apprentice then! That might explain a lot. At 16:00 there are a few images.
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Post by delaplume on Oct 24, 2019 17:34:24 GMT
Thanks Adam-------I hadn't set the parameters quite right when I put that link up....
Roger, ---now that you've removed the complete safety valve assembly you might like to consider replacing the 4 locknuts and fitting 4 spacer tubes under the 2 bridge pieces ??............These were to prevent the crew from tightening down the 4 top-nuts and thus increasing the boiler pressure and locomotive power...with the very real risk of a boiler explosion....
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Post by Roger on Oct 24, 2019 18:38:00 GMT
Thanks Adam-------I hadn't set the parameters quite right when I put that link up.... Roger, ---now that you've removed the complete safety valve assembly you might like to consider replacing the 4 locknuts and fitting 4 spacer tubes under the 2 bridge pieces ??............These were to prevent the crew from tightening down the 4 top-nuts and thus increasing the boiler pressure and locomotive power...with the very real risk of a boiler explosion.... Hi Alan, That's a good idea, but I can't do that until I know the length of the spacers.
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Post by andyhigham on Oct 24, 2019 18:42:12 GMT
Instead of machining the flange, could you counterbore the holes and secure the assembly with cap head screws or countersink them?
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