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Post by Deleted on Sept 21, 2020 11:46:03 GMT
Haha.. sorry John, seems our posts crossed.. thank you for that...  |
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61962
Seasoned Member
Posts: 129 
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Post by 61962 on Sept 22, 2020 0:08:11 GMT
Eddie with your experience on your A4 do you think this is possible...I was thinking with the front curved running boards removed that this might be possible? If so I could fit the outside cylinders without the valves...seems possible in my head as I can't see the cylinders needing removing full size just to fit new bobbins? Hi Pete,
The 'conventional' Gresley engines had a demountable piece in the front curved section to allow removal of the outside valves from the front. The inside valve was removed from the back. From experience awkward but doable. The A4 outside valves after the valences were removed came out the front without having to remove any casing or footplate. For some A4s a small cut out was necessary in the edge of the casing to pass the end of the spindle and can be seen on 60009.
You are absolutely right that the cylinders didn't need removing to access the valves. Piston and valve examinations were required at 18000mile intervals so on the ECML the Gresley pacifics ran around 90000 miles between overhauls, in about twelve months, so P&V exams came at about ten week intervals, requiring removal of the carbon that built up in the bores and piston and valve ring grooves. Fortunately our models don't suffer from carbon build up, probably because of the amount of oil we throw at them. My A4 hasn't had a P&V in twenty years. Perhaps I should schedule one!
Eddie
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Post by Deleted on Sept 22, 2020 9:12:11 GMT
Thank you for that very informative post, Eddie, your experience and knowledge in these things is invaluable to those of us building these wonderful machines. Thanks for confirming that removing the front curved section was the way to go for adjusting the valves, both full size and on the model, after all, there's not that much difference between the two. Yes, I can see why the middle cylinder valve comes out the back, perhaps this is why the spindle is fitted in reverse for this cylinder? It does look tight though, it's one of the first things that I'm going to check once I have a spindle and bobbin assembled. I best get this thing running properly before fitting the boiler as I can't see any adjustment being done once it's fitted? I may have to make up some suitable tools for removing the cover nuts that are closest to the frames?
I think that I now have the design for the bobbin clear in my head, many thanks to all involved in helping me understand the principle.
Thank you
Pete
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Post by Deleted on Sept 22, 2020 17:48:38 GMT
Evening all, at last, I have made a start on the spindles/valves, as explained in the blog entry I'll be following Jim Ewins lead on the bobbin design although the bobbin itself will be using different materials, the bobbin will be covered in part 2, here's part 1 to begin with...  4472flyingscotsman.co.uk/spindles-and-valves-part-1/Pete Edit: Just to say to members of this forum, my thanks for all the input on this and other subjects during this build... thank you |
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pault
Elder Statesman
Posts: 1,502
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Post by pault on Sept 22, 2020 22:08:51 GMT
Hi Pete
At the risk of asking a couple of stupid questions or maybe I am missing a few things, how much adjustment have you got on the valve ‘carrier’? there doesn’t seem to be much thread showing on the valve spindle. Also how are you going to turn the valve carrier to adjust it and then hold it while you lock it? I would also expect a nut and lock nut for the valve so it can float?
On the locos I have worked on with this arrangement there have been specially made tools, one which fits inside the other which allows the valve to be unlocked, moved and then relocked whilst holding the valve.
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Post by Deleted on Sept 22, 2020 22:29:33 GMT
Hi Paul, you can't see much thread because currently, the bolts are very much overlength, I'll cut them down when I have finalised the length of the bobbin. The front end of the bobbin top hat will have two holes for a 'C' spanner of some type, as seen in John's photos. The large nut will either lock against the top hat to stop end-float or I may add a further small nut to lock against it to give free'er movement on the co-axial float. With custom made tools I will be able to adjust the carrier once the smaller lock nut on the spindle is loosened.. that's the current plan which can always change as I begin to make the next parts tomorrow. There will be float as the carrier will be given a slightly larger hole than the bolt OD. I will have a number of tools to make, I'll leave that until I can see how much room I have inside the liner/steam-chest. Hope that makes sense, it should be clear in the next update, once I have it fully clear in my own head that is... Pete |
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Post by silverfox on Sept 23, 2020 8:48:05 GMT
Peter
I shall be watching this with interest, so expect some questions later on !!
Slight O/T when i was on another forum asking about the GE disc codes ,he sent me a picture of the LNER lamps with 6(SIX) different glass colours!
I don't think i will bother with getting additional lamps to convert!!!
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Post by Deleted on Sept 25, 2020 20:12:47 GMT
Lots of work involved in this one but it's nice to be able to tick the box, well nearly, have one final job to do, details in the entry...  4472flyingscotsman.co.uk/spindles-and-valves-part-2/Next week I'll do the final fettling to fit the valves and then finish off the outside cylinders ready to hopefully being fitted to the frames for the final time. Pete |
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mbrown
Elder Statesman
Posts: 1,796
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Post by mbrown on Sept 25, 2020 21:30:07 GMT
They look lovely Pete. Is that PTFE or Flourosint?
Malcolm
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Post by Deleted on Sept 25, 2020 21:36:45 GMT
They look lovely Pete. Is that PTFE or Flourosint? Malcolm Fluorosint....first time I've machined it...cuts well |
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Post by jcsteam on Sept 25, 2020 22:38:20 GMT
They look lovely Pete. Is that PTFE or Flourosint? Malcolm Fluorosint....first time I've machined it...cuts well Hi,
First time ive heard of that material, is it a variation on PTFE? Temperature resistant and easy to machine? Could be useful for other applications, can someone PM me some info as to where to find suppliers ect. (could be useful for work too, as well as hobby use). I don't want to distract from the thread too much.
Regards Jon
PS Still following updates 
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rrmrd66
Part of the e-furniture
Posts: 339
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Post by rrmrd66 on Sept 26, 2020 6:44:14 GMT
Hi Jon Yes it's a modified PTFE loaded with mica (?) I believe to give it better material characteristics.
See: Fluorosint® Enhanced PTFE www.mcam.com › products › advanced-160-220-c › fl... M Metals Darlington supply it. Cheers Malcolm |
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Post by Deleted on Sept 26, 2020 9:01:33 GMT
Hi Jon As Malcolm states, M-Machine Metals supply Fluorosint, I bought 6" of 3/4" bar, IIRC the price was just over £10 per inch. It's been seen on eBay too although usually more expensive. Time will tell how good it is, I have high expectations of it when compared to the usual plastics used such as PTFE and PEEK. Fluorosint expands much less and has a similar expansion rate to alloy/bronze, it keeps its shape too. Regards Pete PS: good luck with the Juliet... |
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Post by simplyloco on Sept 27, 2020 13:06:01 GMT
Hi Pete. I was in The Works bookstore in Ryde and I found a OWNERS WORKSHOP MANUAL for Flying Scotsman! A super book produced in collaboration with the NRM. Reduced from £22.99 to three quid, so I bought one! They had loads of them, but I assume that you have one already!
John
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Post by Deleted on Sept 27, 2020 13:29:28 GMT
Hi Pete. I was in The Works bookstore in Ryde and I found a OWNERS WORKSHOP MANUAL for Flying Scotsman! A super book produced in collaboration with the NRM. Reduced from £22.99 to three quid, so I bought one! They had loads of them, but I assume that you have one already! John £3?.. wow, that's a good price...yep I have it, in fact I have it twice although at the time when buying the second copy I thought it was something new? I was a little annoyed buying a book with a new title to discover it was an exact copy of the manual but in a smaller format...very naughty of the NRM. I kept both though, they are excellent reads.. Cheers Pete |
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Post by Deleted on Oct 6, 2020 11:47:10 GMT
good day all, lot's of work going on with 4472 just now, no blog update yet but I wondered if anyone can help me with her draincock design as fitted when new. It looks to me that I can get away with some commercial fittings here with a few changes which will save me time. I know that I'll need to add some short pillars to match full size as the draincocks in the photo's that I have sit further below the cylinders than one might think or has seen on other models. That's fine, I have scaled off some photos and now have an idea of how low they sit below the cylinder and how long the pillars need to be between cylinder and draincock. Now, I have a question, does anyone have drawings of the original fittings or can guide me through what I can see in this enlarged photo of 1470's draincocks as built in 1922. There seems to be more going on here than just the linkage from the Bowden cable, any ideas what chaps?  Pete |
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Post by Deleted on Oct 6, 2020 13:08:25 GMT
I have this photo too of her showing her prepped for the Wembley exhibition in 1924/5. In this side on image, you can see what looks like two pipes or links going to the draincocks just under the cylinder and not part of the crosslink below connected directly to the draincock. What are these for, where was the cylinder pressure readings taken from, could these have something to do with that? As with everything on this build, new questions are forever arising....  Pete |
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Post by Deleted on Oct 6, 2020 13:15:12 GMT
Another picture showing a little more detail, this is from later and so these pipes/links were still there for my chosen era.  Pete |
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Post by Deleted on Oct 6, 2020 13:43:23 GMT
Now, these two images I can model from.. this is from a better quality picture of the loco on the tilting rig that's in one of my reference books that I have closed in on and enlarged. Still, no idea of what they are, look more like link adjusters than pipework? Perhaps they are connected to the crosslink between the two draincocks and the arm to them is hidden behind the draincock body?   Pete |
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Post by Deleted on Oct 6, 2020 14:11:41 GMT
After a little more digging and thanks to some info pasted on FB I now know that what I am seeing is relief valves to the draincocks and after a search found some images on the SNG overhaul site. So, I think that I have enough to make something that at least looks like the original, similar to that seen below but not exactly the same. Lot's more work but hey, that's what makes this game so much fun...   Pete |
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