Finney7 47XX Build (started during Lockdown)

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Focalplane

Focalplane

Western Thunderer
Since we are back in house hunting mode I have only been reading this thread and not responding or doing anything new. All of a sudden I am on a steep learning curve that wasn’t necessary in building the David Andrews Castle chassis (though that is not yet finished, being out of reach).

Always happy to learn, though, but readers of this thread may need some patience. We are off on the “location, location, location” trail tomorrow.

Thank you for all the kind suggestions!

Paul
 
oldravendale

oldravendale

Western Thunderer
That's an interesting comment, Paul. I'm not familiar with the DA Castle as I've never built one, but all the outside cylinder locos I've built have benefited from a 10BA screw and reversed bearing, although not all have needed the bearing to be countersunk - the King Arthur is a case in point. In fact in the last few years I've looked very closely at a number of prototype locos and some of the clearances are minuscule - sometimes even a small finger will not fit the gap. Those clearances can't be reproduced in a model and in some cases minimising the depth of the bearing above the coupling rod may be essential.

Indeed some prototypes actually utilise countersunk bearings for the same reason.

Brian
 
Focalplane

Focalplane

Western Thunderer
I wish I had the Castle chassis with me, but then if I did I wouldn't be tackling the 47xx. Anyway, some progress this evening, the four driving axles are in and running a little tight - I have broached the coupling rods at the absolute minimum for the brass top hat bearings and at least two holes need opening up a bit. A job for tomorrow. The springs (really they are keepers) are soldered in and I have temporarily fitted the cylinder sub assembly with the front axle crankpins below the slide bars. I can see there is only minimal clearance!

OK, bon nuit!

Edit just to add, the Castle is a four cylinder loco, the 47xx and others are two cylinder locos with a larger profile within the outside motion. Perhaps that's the difference.
 
SimonT

SimonT

Western Thunderer
Brian's comment brings the phrase 'Practice Bleeding' to mind.;) If the CPL crank pin nuts replicate the real thing correctly and work straight out of the packet, why build something else? I shall be using them this afternoon when I put the test build new cylinders for the F7 GWR outside cylinders onto the chassis of a 28XX. As the nuts are correct, they are given so if there is any interferance there is a problem elsewhere. As an aside, Carl told me that Tony Reynolds did the masters for the CPL crank pin nuts.
Is this the time to point out that this problem doesn't exist in S7?:p:p:p:p:p:p:p
Simon
 
simond

simond

Western Thunderer
SimonT said:
Brian's comment brings the phrase 'Practice Bleeding' to mind.;) If the CPL crank pin nuts replicate the real thing correctly and work straight out of the packet, why build something else? I shall be using them this afternoon when I put the test build new cylinders for the F7 GWR outside cylinders onto the chassis of a 28XX. As the nuts are correct, they are given so if there is any interferance there is a problem elsewhere. As an aside, Carl told me that Tony Reynolds did the masters for the CPL crank pin nuts.
Is this the time to point out that this problem doesn't exist in S7?:p:p:p:p:p:p:p
Simon
Click to expand...

well, I’ll bow to the experience of those who have built S7 locos, but where the clearance of TRT is measured in units of “less than Brian’s little finger”, it might be the case that some unprototypical adjustments are necessary.

gentle leg pulling aside, is the dimension across the outside of an S7 wheelset very different to its 0F counterpart? Longer axle, thinner wheels?

atb
Simon
 
oldravendale

oldravendale

Western Thunderer
SimonT said:
Brian's comment brings the phrase 'Practice Bleeding' to mind.;) If the CPL crank pin nuts replicate the real thing correctly and work straight out of the packet, why build something else? I shall be using them this afternoon when I put the test build new cylinders for the F7 GWR outside cylinders onto the chassis of a 28XX. As the nuts are correct, they are given so if there is any interferance there is a problem elsewhere. As an aside, Carl told me that Tony Reynolds did the masters for the CPL crank pin nuts.
Is this the time to point out that this problem doesn't exist in S7?:p:p:p:p:p:p:p
Simon
Click to expand...
Hi Simon.

I don't doubt that the CPL nuts work well. However, I have no experience of them and it's quite possible that the supplied bearings could be used (as long as the owner has a 10BA tap, of course) without having to wait for a delivery.

I'll have a look at them out of interest when I next see Paul - this year, next year, sometime - never??:)

Although I don't model in S7 either I mirror Simond's comment - I thought clearances were all a lot tighter with S7? Asked in total ignorance, of course.:p

Brian
 
SimonT

SimonT

Western Thunderer
Rather than quote the specs of the GOG and S7 Group, I thought I would mic up some Slater's wheels to try give us a bunch of apples. Mixed meataphor rather than mixed specs!

Fine Scale BtB of 29.2mm, wheel width of 3.81mm giving 36.82 mm over tyre face.
S7 BtB of 31.33mm, wheel width of 3.22mm, giving 37.77mm over type face.

So S7 wheels stick 0.475mm further out. Of course this isn't the problem area as the bosses stick out further. I cannot measure this at the moment as my didgital vernier has a flat battery, my 'proper' mechanical vernier has gone walk about and my micrometer doesn't open wide enough:mad:.

S7 works for me because every thing is where it should be. FS frames are closer together to allow for the narrower btb and the play required to go around small radius curves. This means lots of packing to control the side play. It means wider wheel splashers (on the inside) and wider footplates to match. Above the footplate frame extensions get compromised. I find the FS building that I am doing for F7 incredably frustrating as up till now I had only built S7 under gubbins. Each to his own!

Brian,
I can help you as there is a Hall here in the F7 stock I am holding. I can even provide you with a brand new gucci set of cylinders to build while you QA the new instructions!;)

Simon

Paul,
thanks for the hijack!

Simon
 
oldravendale

oldravendale

Western Thunderer
Hi Simon.

Thanks for that update. As I've never studied S7 it is actually instructive for me.

Maybe unfortunately, maybe not, when I started building in 7mm I had no previous experience of model building (well, not seriously anyway) and didn't even know about the existence of S7. I was not a Guild member or member of a club so had no contact with other 7mm modellers. I bought a Jim McGeown kit for a Jinty and train of three wagons (including a guards van) - all for £100 + wheels + motor and gearbox and built all according to the provided instructions. Other models followed before I had time to join a club and by then I was well on the finescale path.

Whether I'd go S7 knowing what I know now is a moot point. On the whole I'm happy with finescale, and if I'd gone S7 I'd be unable to run my locos at my club which is strictly finescale. It'd be a dilemma which I'm now not prepared to face.

Having said which I admire all good model building so it matters not a jot or tittle to me.:D

B
 
SimonT

SimonT

Western Thunderer
For completeness, the result of a new battery:
FS 38.18mm
S7 40.28mm
I think that some of the problems of fitting of rods/pins/crosshead for GWR locos comes from there being no relief at the back of the coupling rods. Front rods on a 2884.
Capture.JPG
The wheel will be at the top, the con rod is at the bottom. The space between the front coupling rod and the con rod is 2.16mm. Allow the crankpin nut 0.5mm thickness, the crosshead 0.7mm and you still should have plenty of clearance if the cylinder centres haven't been mucked about with.
 
Focalplane

Focalplane

Western Thunderer
All fascinating, no one is hijacking! Currently house hunting but will be home this evening to comment.
 
SimonT

SimonT

Western Thunderer
Sorry Chaps, but I have slightly mislead you. I have some locos with FS wheels on S7 axles (Don't tell the S7 Commitee;)) and without thinking I measured one of those as the rods were in the right place to be able to measure over the bosses. I have some locos that are pure S7 and fitted with the very tasty wheels made by Slaters for the S7 Group. These are 37.43mm over the tyre rims and 39.54 over the bosses.
SimonT out.
 
Focalplane

Focalplane

Western Thunderer
Opened the box for the Collett 4000 gallon tender and then noticed that the axles need 2mm extensions. One of the three Slaters’ wheel packs has them, the other two don’t. The correct set is apparently old stock and the extensions must be bought separately. The story doesn’t end there, though. Just be warned when ordering the wheel sets that you must order item 7319 as well, except it isn’t listed on the web site and AFAICS cannot be added to the basket.
 
SimonT

SimonT

Western Thunderer
Paul,
Thanks for the heads up. We were aware of the change at Slaters but were given no details. I'll add the info to the instructions and to our corporate knowledge folder that sits on the stand (when I remember to bring it and the others remember to look at it;)). Slaters had said that they would use up the old stock first; they obviously did half way through your order!
Simon
PS. Anyone who builds an outside crank loco from F7 should not buy the Slaters outside cranks as they do not fit our kits. The replacements are in manufacture but are locked down in a factory somewhere in England.
 
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