Elmham Market in EM

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James Spooner

James Spooner

Western Thunderer
Project Advent has gone on hold for a day or so as I wait for some electrical connectors to arrive so I have turned my attention back to the Ivatt. More fettling of the chassis has got it running smoothly and I have filed the backs off the return cranks so they lie in the right direction.

The next item on the agenda, given I propose using the tender weight to hold the rear of the engine down, was to construct a suitable robust drawbar at the right height so the front of the tender hangs off the back of the loco. This I also managed to do this evening and the whole assembly seems to run OK up and down my very short workbench track. I will take it for a slightly longer stretch on Daisy Sidings tomorrow evening at the EMGS area group meeting and see how it performs there. A couple of photos attached.

Nigel


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James Spooner

James Spooner

Western Thunderer
Now that Project Advent has been handed over to my son I have turned my attention back to the Ivatt. I have added a coupling for the tender and chipped the loco, to make sure it all works in DCC before tackling the valve gear. It quite happily walked away with a couple of dozen wagons, which is the longest train I could fit in my fiddle yard, as well as negotiating the tightest curves on the layout, so I’ll regard that as a success and move on to the next stage. A link to a video is attached.

Nigel

 
James Spooner

James Spooner

Western Thunderer
I’m just emerging from almost two weeks of Mrs B and I hosting various members of the family, so progress on Elmham Market (especially with Project Advent) has been limited recently. May I take this opportunity to wish everyone a very happy and peaceful new year and hope that your modelling plans come to fruition.

Before I make any more progress on the layout I need to go into the man cave and give it a complete clean and tidy up after the mess I created on Advent. Then, as I alluded earlier, I really must focus on the scenery. After that, who knows, maybe even an extension…?

cheers

Nigel
 
James Spooner

James Spooner

Western Thunderer
D6356 said:
Nigel, happy clearing up!! Re extension surely a "deviation" ?
robert
Click to expand...
Well, not really so much of a deviation as I’m not trying to circumnavigate a lake that had blocked a previous route and it does reach a part of the attic that other railways haven’t yet reached so I am happy calling it an extension! No doubt see you soon in TLC…

Nigel
 
James Spooner

James Spooner

Western Thunderer
It was cold in the man cave today so I chickened out and progressed the Ivatt valve gear instead. I’m taking it very gently as there seems to be great potential for things to go awry so, unusually for me, I am actually reading the instructions carefully and trial fitting everything before firing up the soldering iron. That, I suspect, means progress will be slow, but hopefully sure. A photo shows what I have achieved this evening. I have left the casting flash on the ends of the slidebars until I can measure the distance between the backs of the cylinders and the motion brackets. I don’t want to cut them too short!

Nigel

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James Spooner

James Spooner

Western Thunderer
Progress has been slow today, largely because I think I have gone down with some form of man flu and feel generally pretty achy and disinclined to do much. However, a heavy dose of painkillers meant I felt able to continue tackling the Ivatt valve gear. Still slow progress, partly because the forty plus year old etches are pretty crude by today’s standards and need a lot of fettling to fit. The quality of instructions isn’t helping either so it is definitely a case of fit and test twice, then solder. One side of the motion bracket is now finished and it fits in its slot in the frames. Photo attached.

Nigel

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D6356

D6356

Western Thunderer
A lot of laminations on the bracket so soldering up hits the "fun" button. Defo take it slowly and carefully or an overheated bent mass awaits.. I have a 3mm 9F that awaits the courage for this sort of punishment. Get well but best to do it well rather than quickly.
Robert
 
James Spooner

James Spooner

Western Thunderer
Not suffering quite so much from man flu today so hit a number of outstanding Ffestiniog tasks, with Mrs B and the dog went for a long walk over the commons to clear my head, then returned to the valve gear.

What wasn’t helping was the instructions were setting out an order using an alpha system (also replicated on a drawing) but not cross referenced to the etch. I resorted to taking a copy of the etch and then labelling each item up and that has helped no end.

Following the instructions I was then able to start some sub assemblies. So far I have drilled and tapped the joints for the crossheads/connecting rods and they fit, finished the motion bracket soldering and made the return crank/return rod/radius link sub assemblies. More tomorrow I hope…

Nigel

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James Spooner

James Spooner

Western Thunderer
I seem to have hit a problem with the Ivatt valve gear. I have been faithfully following the instructions and was feeling quite pleased with progress. I wasn’t happy with the expansion link being made of whitemetal so, to give it some extra bearing resilience I soldered the rivet holding it to return crank rod to the expansion link itself so the rod rotated on the brass rivet. I also bored out the link where it moves around the die block and inserted some brass tube with an inside diameter of 0.8mm, which allowed me to solder in some brass rod to hold in the radius rod and expansion link to the die block. All well and good so far.

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I then assembled the expansion link/return crank rod assemblies to the motion bracket adding the radius rods as I went and again, all seemed to be hunky dory.

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I have also cut and shaped the slide bars on one side as well as trimmed the front driving wheel crank pin and filed back the screw holding the connecting rod small end to the crosshead.

At this point I thought a trial fit of progress so far would be sensible so assembled what I have made on the right hand side. The problem I have is that the radius rod seems far too short. It should extend well forward of the crosshead as it takes a part of the valve movement from the combination lever, which is driven at its other end by the union link. As you can see from the photos the radius rod is several millimetres short of where it needs to be.


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I’m pretty sure I haven’t made a silly error (although happy to be proved wrong!). I have used the Millholme chassis, so the wheels are in the right place. The other datum points of the motion bracket location and cylinder location are again fixed by slots etc in the kit. At the moment, the only solution I can come up with is to estimate the additional length required on the radius rods and solder on a pair of extension pieces with a backing fillet of nickel silver for strength. I have decided to pause for the evening in case something blindingly obvious hits me overnight or the collective brains of WT can point out the error of my ways!

Nigel
 
simond

simond

Western Thunderer
Nigel,

is the radius rod you have fitted intended for a loco where the lifting link is ahead of the expansion link?

This may be a silly question…

atb
Simon
 
James Spooner

James Spooner

Western Thunderer
Hi Simon

That is certainly one potential answer to the puzzle. If that is right, it means forty odd years ago someone packed the wrong etch into the box, which I suppose is possible, although it doesn’t help my predicament.

What also doesn’t help is that I can’t find a detailed drawing of the Ivatt. The ex LNER classes are well served by the Isinglass drawings, and the GER by the late Lyn Brooks’s excellent drawings. When I start to move off familiar territory there seems to be a paucity of drawings though. If I could track down a drawing I could then, with some reliability, fashion an extension or a new rod out of nickel sheet…

I’ll keep pondering!

cheers

Nigel
 
Dave Holt

Dave Holt

Western Thunderer
Nigel.
What a pain!
There is a 4 mm drawing of these locos by Roche in the Ian Allan book of drawings. Measuring the published drawing (not ideal, and the Roche drawings are considered by some to be a bit fanciful), the radius rod should be 18.67 mm centres.
Looking at your model, the expansion link brackets look a bit large, perhaps moving the pivot too far back? The drawing shows the pivot to be 4 mm behind the motion bracket. Your photo tends to suggest this error as, with the wheels positioned at front dead centre, the expansion link should be square to the radius rod but actually looks to be sloping back slightly.
I've got a Brassmasters chassis kit for the Bachmann Pig and the radius rods measure 17.67 mm centres, so a bit of a discrepancy, there.
Sorry if I've just confused the issue.
If you decide to stretch the existing radius rods, the front boss should be in the middle of the valve cross head guides, irrespective of the true scale length.
Dave.
 
Dave Holt

Dave Holt

Western Thunderer
Just to throw in a further option; I've just measured the Bachmann radius rod - 17.33 mm. Actually, that ties in fairly well with the Brassmasters rods, as they have a forked front joint and the required joggle in each layer will shorted the hole centres slightly.
I wonder how Tony did his model, as it doesn't appear to have the issue?
One other thing to note is that on the Ivatt locos, the motion bracket is vertical, not square to the sloping cylinder CL, as is usual.
Dave.
 
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