Finney 7 LNER A4

[P A D]

I could resist this no longer, so out came the pale blue boxes. Here's what's inside starting with the loco. The milky bar boiler, horn blocks cast brass and nickel silver parts, plus various screws, nuts and bolts and assorted bits of wire. The Slaters wheels are of course not included. As with my Finney A3 I've gone for standard 3/16 axles and wheels throughout to suit my own personal preference. Some modifications will be required to accommodate these, but that's my choice. I'm still waiting for the white metal castings and instruction book, but I can press on without them as the instructions are on the F7 website.


The brass etchings.

And the nickel silver.

Here are the corridor tender parts. All brass etchings plus some brass and white metal castings, plus various bits of wire, nuts and bolts etc. There is also a very comprehensive instruction booklet which again, can be viewed on the F7 website.

Here's the cast resin boiler that will save a lot of construction time.




Good job I don't like white chocolate. I might be tempted to eat it!

A modest start has been made, starting with the tender frames. First job was to fold over and solder the slots for the wheels. The two frames were bolted together to line them up and then clamped in the vice to open out the slots to 3/16 inch using a chain saw file. After that the keeps were folded and soldered, the holes for the compensation beams opened to 1/8 inch and the 3 spacers added and soldered up.




Different design approach to MOK but just as pleasurable to build.
Cheers,
Peter

 

[Dikitriki]

We've now got the instructions and castings for you.....

Richard

 

[P A D]

Perfect Richard.
Look forward to receiving them.
Cheers,
Peter

 

[P A D]

The compensation beams are now added. For the front 2 axles there's a laminated double etch beam fitted centrally on the tube between the frames, that pivots on 1/8th rod. The rod was carefully soldered on the outside of the frames to retain the tube and beam. At the rear there are two single etch beams places either side, with the tube having been cut in the centre so the beams pivot independently.


The cut outs at the top of the beams prevents them fouling the rod for the brake hangers, if they are left across the frames. This is highlighted in the instructions, but was not mentioned in the Martin Finney originals.


Here the rods for the brake hangers and the wheels have been added. Washers are provided to take up the side play in the axles, but they are for the thinner "Finney " type. I used 3/16 washers left over from another kit.


This shows the clearance provided by the cut outs in the beams for the brake hanger rods. You can of course cut the rods inside the frames, but I think they are more robust to leave across the frames.



Everything works as it should so next up will be the water pick up and then the brake gear to complete this sub section.

Cheers,
Peter

 

[John57sharp]

Looking forward to following this....

 

[dibateg]

Another perfect build coming up! It will be inspirational...

 

[Shedman]

Peter

Do you ever think about what will be involved in the `taking apart` that you will have to do before painting - or perhaps you paint in stages?

Terry

 

[P A D]

Thanks John and Tony.

Terry, as far as stripping down for painting is concerned, it depends on the prototype. On my Gladiator Duchess and Finney A3 I thought it advantageous to be able to remove the boilers from the runn ing plate and in the A3 case, the cab as well. The A4 boiler is very much like an upturned boat hull and does not need removing for painting. I will make the hand rails removable and the cylinders and valve gear.

The tender is designed to break down into three sub sections, the tank, the running plate/frames and the chassis. I don't paint as I build. When it's all done and dusted and running, then I strip it down.

On with the build. Here are the brake hangers and shoe parts ready for laminating. 16pieces.

To line up and hold the two halves, I pinned them to the edge of a piece wood, then soldered the edge of the blocks. Then I removed them, held in a pair of pliers and soldered the straight edge of the hangers.


Then there were eight. Either by luck or design, all the tabs were on the straight edge so were easy to clean up.


To space the hangers off the frames, I used short lengths of brass tube that I believe I bought from the jewelry section at hobby craft.


To space the blocks off the wheels a piece of card was wedged in between the and the rim.

I made a start on adding the cross wires and pull rods but then ran out of time. The rods are soldered to the hangers with the inner pull rods in place but still loose. The outer pull rods are seen below.

And a view from the underside. The inner pull rods will be soldered so they are in line with the frames. The outer ones will be set slightly further out than is prototypical, to allow the wheels to be removed easily. I'll check the spacing on the A3 and set them the same, as that worked well.


I must say I am not a big fan of this system, but have to admit it works very well and is very simple to do. On my Acme A4 corridor tender the outer axles are fixed with the middle two floating. That works well also, but the compensation give smoother running on uneven track.

I'll also be building the loco chassis fully compensated, using the Finney hornblocks. It will be good to compare it to the A3, where I built it with the front and rear axles fixed and the middle one floating.

Cheers,
Peter

 

[Genghis]

When I got this far with the build I couldn't resist rolling the chassis over small obstacles placed on the workbench so that I could watch the compensation working. Small things please small minds...........

 

[P A D]

When I got this far with the build I couldn't resist rolling the chassis over small obstacles placed on the workbench so that I could watch the compensation working. Small things please small minds...........

Not at all David. Boy will be boys!
No point in having nice toys if we don't play with them. I did exactly the same with the A3 chassis when I got this far, but up to now I have resisted the urge.

Cheers,
Peter

 

[Cliff Williams]

I add a small section of brass at the side of the rubbing surface on the pivot arms where it rubs on the axle out of habit. Increases the contact area in case the mileage is greater on the finished model. Lovely start to the build.

 

[P A D]

I add a small section of brass at the side of the rubbing surface on the pivot arms where it rubs on the axle out of habit. Increases the contact area in case the mileage is greater on the finished model. Lovely start to the build.

Hi Cliff,
Very good point. The front beam is a double thickness laminate, but the rear ones are single etches. I'll take you up on that and also do it on the A3. Not that the models will ever get enough mileage to wear the beams, but a future owner might benefit. Maybe the F7 boys will consider adding a supplementary etch with two extra beams????
Cheers,
Peter

 

[mickoo]

Don't forget to reduce the beam where the flat piece will go or else your tender ride height might be too high

Nice clean work so far

 

[simond]

You don’t have to solder the bearing piece betwixt the beam & axle, it’ll work just as well as a doubler, alongside, as long as the lower edges coincide.

Best
Simon

 

[Peter Cross]

Is brass any better than nickel silver? As long as it is different to the axles, the wear rate will reduce. Surely the width is the important part to reduce the point load and reduce wear.

 

[simond]

I’d not expect NS & brass to be wildly different.

Bit of background reading (though it’s 40 years since I studied tribology!) here if you need something to get your teeth into

http://home.ufam.edu.br/berti/nanomateriais/8403_PDF_CH07.pdf

Best
Simon

 

[P A D]

Tribology: noun - the study of friction, wear, lubrication, and the design of bearings; the science of interacting surfaces in relative motion.

Thanks for posting that Simon, but for somebody who thinks that compensation is over engineering in small scale modelling, it's way too deep for me.
It seems logical that doubling up the area of contact will spread the load and reduce wear, so I'll go with that. If it doesn't, then nothing lost but a bit of modelling time.

Back to the tender chassis. I used the ubiquitous coffee srirrers to space the pull rods away from the wheels. The inner ones are set slightly further away using the sticks as they are.


For the outer ones I squashed the ends of the sticks in the vice to set the rods slightly closer.


And with the rods in place.


Here's the chassis after removing the wheels, with the water scoop and operating rods ready for fitting.


Here's a view of the underside after soldering the scoop in place. With hindsight, it would be easier to fit the scoop before the brake pull rods. The pull rod for the scoop plus the front brake pull rods and cranks are also show after laminating. One brake pull rod is still to be done (The two parts on the right. The half etched centre sections need careful handling as they are very thin and easily bent. They are fine once they are fixed in place though.


Enjoyable as it is, so far this is just a repeat of the A3 build, as are the running plate, side frames,buffer amd drag beams (more of less). The tender body will be where it gets more interesting, with the different size tank parts and corridor to contend with.

Cheers,
Peter

 

[Shedman]

With the `squashed` sticks, how far away are the rods from the wheels?

Terry

 

[simond]

“It seems logical that doubling up the area of contact will spread the load and reduce wear, so I'll go with that”

I’d concur, soldering a bit of scrap etch to the sides of the compensation beams will do exactly that.

Best
Simon

(Between us, I suspect the article was way too deep for me too!)

 

[P A D]

Hi Terry,
I will check and get back on that. The inner rods are in line with the frames and further away than the outer ones. They look OK from normal viewing angles and give the necessary wiggle room to get the wheels on and off.

Simon,
I have decided to pass on adding some scrap etch to the beams, as it won't be easy to ensure perfect alignment with the beams already fitted. As Mickoo mentioned, there is a risk of altering the ride height. However, it's something to consider for future builds when it can be done in the flat. When I get time I'll have a read of the article as I'm sure it's interesting.

So the brake gear is now completed and the water scoop pull rod added. I screwed up and had to re-do the shaft at the front. I didn't have any 2mm rod so had to use 2 mm tube. Hence the holes in the ends, visible in the side views.


The front end.

And from the sides.



And the rear. All simple and straight forward. It does what it says on the tin.


So one sub-section complete and on with the next. This is the frames, drag beam and buffer beam. Here's the main etch after punching out the half etch rivets. The GW rivet tool is a real boon when doing this.

Here it is after folding and soldering. There are three tiny etches below the cross members on the frames, that are covers for the brake pivots on the real thing. They were added in the flat and cleaned up before folding. There is another for the rear hanger that I will add later when the riveted strips are in place

A quick test fit of the frames onto the chassis showed that some filing was needed to get the chassis in. First the cross shaft at the front was too wide (my fault) and the rear brake hangers were tight up against the spacer in front of the buffer beam. Unless I've done something wrong, it would seem that the fold over spacer on the bottom of the beam extends too far forwards, as I needed to grind off more than a mm to get the chassis in. No big deal but unexpected and better done in the flat.
Mickoo, Any comments?


The ride height is slightly high as I've used 3/16 axles and the frames are only places on, not screwed to the chassis.



The aurora borealis effect on the background is the light reflecting off the brass. Who says modelling is not arty farty?