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Post by Deleted on Nov 12, 2014 10:51:15 GMT
This is getting quite close now, and it starting to really look the part.
Cheers
Tom
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Post by Jim on Nov 12, 2014 11:28:41 GMT
To me it's the one let down of the Brits, that awful long regulator rod. I used to drive the first Winsons Brit to run quite regularly, that was always it's let down. The 9F and Standard 4 I'm familiar with are much better having shorter rods to a dome mounted regulator. Thanks for the heads up Ed. I had been told about the regulator rods flexing and I'm keeping it in mind that some sort of discrete support may be needed, if such is possible. I believe it was also a problem on the full sized Britannias too leading to a support for the regulator rod being added between the cab and middle crank. Jim |
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Andrew C
Part of the e-furniture
Posts: 447
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Post by Andrew C on Nov 12, 2014 19:15:37 GMT
Maybe it's possible to design a more balanced regulator that keeps the operating forces to a minimum? Thing is Roger it sort of is balanced. The drive direction is reversed on this centre pivot so one rod is in tension when the other is in compression. I think Jim was intending to use a commercial stop valve similar to the ones that the Modelworks locos had and people like Station Road Steam swear by. I enlarged the rods slightly so it flexes less. Once I get round to painting it should not be noticeable. I hope  Andrew |
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Post by Roger on Nov 12, 2014 19:27:28 GMT
I see what you mean, but I was thinking about the actual valve itself. I'm sure I remember a design where the internal forces on the regulator almost balanced out so it took very little force to open it. I suppose you could have something like a piston valve, that has similar properties.
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Post by Jim on Nov 12, 2014 20:37:19 GMT
You're right Andrew I am using a ball valve as the regulator which handily can be easily adjusted via the hex ended bronze retaining collar.  Roger I seem to recall seeing the design for a balanced regulator type valve too but I'm too far down the track to contemplate that at this stage. From all reports here where they are used a lot, ball valves work well. I will do a trial steam up, when I get to that point, to test the regulator among other things. A modeller friend found to his horror on the first steam trial that the Teflon valve seats had expanded in the heat jamming the valve closed..very fortunately. He dismantled the valve, removed a few thou from the valve seat and all has been well since. I've made up a couple of sets of spare valve seats as like most things, they do wear over time. Jim |
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Post by Roger on Nov 12, 2014 21:34:39 GMT
That ball valve looks like it ought to be pretty good. I know what you mean about getting so far and not being able to change course. There are some things on SPEEDY I'd like to change but it's too late now. I guess all builds are like that in some way or another.
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Post by Geoff (Carlisle) on Nov 12, 2014 22:45:12 GMT
Hi Jim, regarding the regulator rod, yes there is a bracket halve way along the side of the firebox. This was not on as new but applied later which makes you think that they had trouble with the rod. Now it has been mentioned before on these pages advising to increase the rod size to 4mm or 5/32". Everything is looking good Jim.
Geoff (Carlisle).
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Post by Deleted on Nov 12, 2014 22:59:13 GMT
This is timely for me as I was just discussing earlier today the possibility of using a ball valve as a regulator on the Britannia. I am no where near that stage yet but I am trying to look ahead and be prepared. Thanks for the info.
Cheers
Tom
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Post by Roger on Nov 12, 2014 23:21:30 GMT
Another thought might be to make the section of the rod that's in compression out of Silver Steel which would be a lot more resistant to bending than mild steel.
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Post by Jim on Nov 12, 2014 23:28:15 GMT
Hello Geoff, I think it was on JJ's site 'Britannia Builder; that increasing the diameter of the regulator rods was the way to go. Getting way ahead of myself (again) I have already checked a rod cut from a local source that looks ideal for the task. By the way if the boss comes asking about a missing heavy duty coat hanger..mums the word.  Jim |
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jma1009
Elder Statesman
Posts: 5,922
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Post by jma1009 on Nov 12, 2014 23:31:19 GMT
hi jim
i found that stainless steel coat hangers 3/32" dia were ideal boiler handrail material in 3.5"g plus 5"g!
cheers,
julian
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Post by ejparrott on Nov 13, 2014 10:21:04 GMT
The rear section of the rod is the problem because it's a 'push' action to close the regulator...which often doesn't!
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Post by Jim on Nov 13, 2014 10:48:02 GMT
Following this discussion I'll be interested to see how easy or hard my ball valve is to operate once in steam. At present it's not hard to operate and quite smooth. Julian's suggestion of stainless rodding must be considered too. I shall report back though it may not be for a be a while yet. Jim |
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Post by ejparrott on Nov 13, 2014 11:58:52 GMT
I would go with stainless rodding, maybe take it up a size, perhaps to a metric size, see what looks ok without looking 'heavy'
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Andrew C
Part of the e-furniture
Posts: 447
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Post by Andrew C on Nov 13, 2014 16:40:51 GMT
I have only steamed Robert Burns twice for about 1/2 an hour to an hour each time the regulator ( a ball valve one) has worked flawlessly. can't say the same for the non return valves for the lubricators  I know JJ has has run his Brit for one or two seasons and don't think he has had any problems but hopefully he will tell us. Andrew |
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Post by Deleted on Nov 13, 2014 17:01:22 GMT
I have only steamed Robert Burns twice for about 1/2 an hour to an hour each time the regulator ( a ball valve one) has worked flawlessly. can't say the same for the non return valves for the lubricators I know JJ has has run his Brit for one or two seasons and don't think he has had any problems but hopefully he will tell us. Andrew I've witnessed JJ's brit running on the club track a number of times...runs beautifully....  Pete |
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Post by Deleted on Nov 13, 2014 17:52:28 GMT
On the subject of the ball valves ... if I may ... what size would one look for to use on a 3/4 scale Brit?
Thanks,
Tom
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Post by Jim on Nov 13, 2014 19:47:30 GMT
On the subject of the ball valves ... if I may ... what size would one look for to use on a 3/4 scale Brit? Thanks, Tom Hi Tom, I honestly can't state a specific size but what I looked for was a ball valve that had an opening through the valve close to that of the steam pipes so that there is no 'wire drawing' of the steam or constriction of the steam flow. I'm sure others here such as Ed could give you a more specific answer Tom. Jim |
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Post by Deleted on Nov 13, 2014 20:07:03 GMT
I found that the 3mm regulator rods supplied by Modelworks flexed in use, so I changed to 5/32" mild steel rod (slightly less than 4mm) and that has worked perfectly, and I think looks fine scale-wise. My valve is an ITAP 1/4" BSP F/F PN50, shown here with its linkage:  It's fairly stiff - I bought a second one from www.chandleryworld.co.uk for about £3 (search for 'ITAP') but it was much the same - and it doesn't seem possible to dismantle or adjust it in the way that Jim can with his version. However, the complete setup works perfectly well. Tom, I'm not sure if these valves come in a size smaller than 1/4" BSP, but you might be able to fit this in your smokebox. Regards, John |
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Post by Deleted on Nov 13, 2014 20:09:24 GMT
Thanks Jim ... not impeding the flow at all makes sense. The plan calls for a 3/8" steam pipe to the regulator so I guessing that a 3/8" ball valve would suffice. I just need to see if there is room in the smokebox for one that size.
Cheers
Tom
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