Stanier 8F in ScaleSeven – part 21: the tender running

In the end I had to take much advice from the fellow-members of “Western Thunder” – a model railway nerds website.  I dismantled the tender and much of the running gear and made sure that all of the compensation mechanism was free to move.   One suggestion had been to twist the chassis, but in the end I achieved much the same effect by introducing a spacer at one corner between the outer farm and the chassis, thus effectively applying a permanent twist to the latter.

The tender now runs:

However I realised that as it is the front wheels lifting off the track by 0.5mm, testing the tender on the S-shaped curve but with a dip in the track might not be good enough: the concavity of the track might keep the front wheels in contact when flat track or even a hump in the track might have the opposite effect and cause a derailment.

So instead I had to raise the centre of the test track and make the tender run over this.  The only realistic way to do this is to pull it behind the locomotive!  This became the first trial runs of the locomotive and completed tender:

It doesn’t run smoothly though – this is because there are electrical short-circuits created between the pony truck wheels and the front locomotive steps, and also between the guard irons on the tender (the metal posts which clear the rails of anything before the wheels run over it on the real thing).  However the assembly never de-rails, which is a triumph!

Small First time Loco and Tender 01

 

 

Here is a picture of the whole assembly as it is now.

 

 

Click to enlarge

Click to enlarge

Stanier 8F in Scale Seven part 19: water scoop mechanism

I decided for some unknown reason to switch to the tender again. Perhaps because having succeeded with the brakes on the locomotive, I wanted to see if I could do them on the tender whilst the technique was still in my memory! So I measured the clearances, and found to my delight that no adjustment was really needed for ScaleSeven: the brake hangers could be soldered into the inner chassis frame and could be adjusted easily to be the correct clearance for the S7 wheels. Excellent. So I insulated the faces of the brake shoes as before, soldered the brake hangers and retried the running of the tender frames – it still works!
Next in the instructions is the water scoop lift gear. This proved to be a real challenge for me. There are times when I wish I was living in the UK (though not many ….) – the instruction sheet is really deficient in this section: “assembly is per diagrams and photos”; two unlabelled pictures and some difficult-to-decipher diagrams. It would have been much easier to be able to look at the real thing, but instead I had to look on the ‘net for drawings and pictures. It was almost too obscure even for the ubiquitous WWW: Google Images of “Stanier tender water scoop gear” produces almost no useful images!  I eventually found some useful stuff – Some pictures of a model 3500 gallon LMS tender, and most useful were pictures of the Duchess and its tender in a Birmingham museum.  I had to work out from their appearance what all the parts were for, and then how they go together.  I hope I was right.

Small Water scoop mech 001The mechanism is mounted under a crossmember of the tender chassis, and appears to be a rod or axle (moved by a long control beam from the front of the tender) on which a number of cranks are mounted. The ones at the rear end (right of photo. here) are aimed to lift the water scoop itself.

On the same axle are mounted levers which lower another device into the water troughs, the levers seen in the middle of the mech. and protruding to the left in the photo. below.
Small Water scoop mech 002
I’m not sure what this device did in real life – I guess that it was a deflector to channel more water from the edges of the water trough into the scoop?
There is also what I think must be a balance weight for the water scoop attached to the axle, seen in the middle of the mech. above (probably in the wrong position). I added to the thickness of the etched parts which represent this.
To make up the mechanism as seen above needed three parts to the frame (25 x 15 x 15mm), a piece of 1.6mm dia. rod, twelve tiny bits of etched nickel silver, half-a-dozen 1/32 brass pins and a HUGE amount of patience.

Small Water scoop mech 003Here it is in position:

Some of the brake gear is also seen, but no water scoop as yet.
If my deductions were wrong about where everything goes, I’m not sure that I really want to know ….

Stanier 8F in ScaleSeven part 16: Brake Hangers

Brake gear.

A problem with all systems where power is picked up from the rails is that brake shoes realistically close to the wheel treads need to be isolated from those on the other side and from the frames, or else short circuits will occur. DC or DCC, I think. Now my system is going to have no pickups from the driving wheels, but the brakeshoes as made in the kit will short-circuit from one side to the other. What options do I have?

My first thought was to make new brake hangers by acrylic/epoxy molding. So I bought a Sylmasta kit and made molds for the brake hangers for the locomotive and tender.

 

 

Small Brake hanger polyester moldingsI then made castings first in polyester (this was the plastic/resin provided in the molding kit):
These were too friable and brittle, however, so by default I tried molding in Araldite, which was more robust, but full of bubbles:
Small Brake hanger epoxy moldings

Even these looked unlikely to survive very long in general use, though. Contacting friends for advice suggested that I was trying to make castings of too much: it would be better to make castings of just the brake shoes.
However to do that meant filing all the brake shoes off the hangers (fourteen!) and both making and fitting accurate copies of the shoes onto each hanger. Then it occurred to me – I don’t need to take all the brake shoe off, just the surface which will be in contact with the wheel tread.
So I found some 2mm wide Plastikard strip, and have carefully filed sufficient off the surface of the brake shoes to glue a strip of Plastikard onto each shoe.

 

So the one on the left has been filed back, and the ones on the right show the Plastikard in place.

 

 

 

Once I came to try to fit them to the frames the next adjustment became necessary. As the frames are set at nearly the correct prototype width, they are much closer behind the wheels than in Finescale. If the brake hangers are fitted as made, the hangers are too far away from the frames, the shoes are outside the wheel rims and the outside parts of the shoes contact the coupling rods and stop them rotating. So now I became more grateful that the main parts of the brake hangers are metal, not epoxy! The two on the left of the picture above have had the posts from which the hangers are suspended shortened, whilst the right hand one is the original length. I think that this adjustment would have been near-impossible using plastic parts.

Now I just have to fit them, one or two at a time, and make sure the wheels still go round after each fitting.

Stanier 8F in ScaleSeven Part 15: balance weights

Just an update.  Partly because of the difficulty painting behind the driving wheels, and partly because I realised that I needed to put the balance weights on the wheels (and this would probably be much easier if I could lie them flat), I partly dismantled what I had done so far to put together the chassis.  Also I realised that the return cranks were on at an exaggerated angle, and although this makes the valve gear move more satisfyingly, I should probably re-do the soldering to make it more realistic (10 degrees is right).

Of course to put the balance weights on is easier said than done. First of all I had to choose exactly which 8F I wanted to model! I found a picture of number (4)8067 which seems to have the right characteristics: a rivetted tender, balance wheels of the earlier type (not all of the weights are crescents) and based in the north of England. So number 8067 it will be.

Both types of weights are supplied in the MOK etches, as pairs (so four of each shape). Using the S7 Group Slaters wheels makes sandwiching the pairs of etches together relatively easy, one on each side of each wheel: the plastic spokes can be cut back a little to accommodate the etches. Not too much on the outer side, though, as the balance weights stand proud of the rims on the pictures I have seen.

Small Balance weights 1I then filled in the gaps between the etches with Milliput filler.

Now seemed a good time to use Birchwood Casey metal black on the rods and valve gear, to obtain a good “polished steel” finish. I used Hi-Chem “All-Surface Primer” on the wheels (probably only available in Australia, but I’m sure motorcar paint shops anywhere would have a similar product) – it’s a marvellous very thin and very effective metal primer: it sticks to anything, in my experience even glass or granite benchtops! Therein lies a separate story, as you might imagine ….

Small Balance weights 2

 

 

Finally, a “dirty black’ initial topcoat. My engine is going to have a realistic (I hope) weathered appearance.

So there you are.

David

 

Stanier 8F in Scaleseven part 14: putting the boiler on the frames

It’s beginning to look a bit more like an 8F (admittedly I have placed the pony truck in place and the smokebox door just for this picture, though).

Small Boiler meets framesA question however: when I started this project, I saw the picture of a lovely model 8F in brass-and-whitemetal finish. I was looking forward to the day when mine might look similar – but how can that be done if I am also going to have to paint parts of it before I complete construction?
I guess it doesn’t matter really, but if I am to have a realistic painted finish in places like the frames behind the driving wheels, surely this will have to be done by taking the wheels off.  Especially if I wish to have a good finish on parts like the springs, which are right behind the wheels, of course. As you’ll observe from the above picture, I haven’t put the braking gear in place yet. Once I have done that the wheels will be very difficult to take off. At present the wheels can be removed easily, because the excellent design of the MOK kit allows the motion bracket, valve gear and wheels to be removed as a unit.

Small Boiler meets frames 2So, how do other modellers manage it?
How do you make a whole brass-and-whitemetal kit up, and later get a good finish on it, without giving yourself a huge amount of unnecessary work dismantling all the careful modelling done to put it together in the first place?

 

Answer (I think): you cannot.  On the ‘net are articles describing how people have made up a model completely, then have to spend lots of effort systematically pulling them apart so that they can then be painted!  When it comes down to doing that, I do not think pictures of the unpainted model are so important, so I will paint the frames behind the wheels at this stage (and probably most of the stuff in-between the frames also).

Small Chassis dismantled 1First stage, take the wheels and the motion off the frames.  Fortunately this doesn’t prove too difficult.

This will also give the advantage that I can put the balance weights on the wheels whilst they are flat on the desk, rather than mounted on the frames.

Small Chassis dismantled 2The frames themselves will be easy to paint I hope, although I will have to mask off the sliding hornblocks (bearings) for the driving wheels, and avoid painting the compensation mechanism on the insides of the frames.

 

The balance weights will have to be chosen.  I hadn’t realised, but there are many variable configurations of balance weights between difference individual locomotive which are otherwise indistinguishable.  So I will need to find a picture of a locomotive in the area where I want to model (not too important) with a rivetted tender (which I think looks nicer), and then try to match the available parts from my kit to make the appropriate balance weights on my locomotive.  So, where do I find a side-on view of a Stanier 8F, pulling a tender with lots of rivets on the side, on the Settle-Carlisle Railway (or, at a pinch, anywhere in Lancashire or the North-West?

Stanier 8F in S7 part 13: rolling the smokebox.

Onto the best bit (for me) – building the loco body (I’ve never built a tender before, but that should be good as well).  Actually going on to building the superstructure may be good mainly because I am stressed out about making the wheels go around without binding, so when the chassis is complete I breathe a sigh of relief and relax ….
Early on in the build comes the boiler and smokebox construction.  Now the instructions say that both are “pre-rolled”, but only my boiler was treated this way.  The smokebox was a pair of flat etches (there is a beautiful thin overlay with all the detail on it).  So this is the dilemma: I have never tried to roll a piece of flat metal into a cylinder, so is this the right time to start?  Do I risk ruining my lovely MOK kit, or do I beg someone to roll it for me?  If so, who?  Or do I buy a special rolling tool (about $90 here in Aus., which I may never use again)?
The instructions talk about rolling the (much thinner) overlay using a metal bar and some cloth so press it down onto.  So the main structural part of the smokebox should surely be bend-able in the same way ….
So I try rolling the (0.5mm thick) nickel silver sheet with a bar about 25mm diameter, using towelling as a base.  The curve of the result was the sort of bend that on trackwork you could easily run an 0-8-0 around without gauge-widening (that has surely to be the ultimate “in-joke”).
Small Smokebox and boiler 01
However I thought about this for a while and decided that the problem was with the surface that I was rolling the sheet into.  So I used instead of cloth a strip of the neoprene wet-suit material that I use to provide a springy surface for my trackwork.
Using this as a base, the next curve in the smokebox was maybe 20cm diameter, and adding layers of the squashy neoprene allowed a tighter radius to be made.  I had to use a smaller diameter rod as well (about 15mm) but in the end the 38mm diameter smokebox could be formed.  nerve-wracking, but satisfying in the end.
Small Smokebox and boiler 02Having the formers to make the accurate cylinder was useful as well.  This picture shows the copper wire (from mains electricity cable) used to squeeze the inner cylinder of nickel-silver down onto the formers.  Thicker copper to hold it in place, then thinner copper to squeeze the metal down.
Small Smokebox and boiler 03After that it was easy (relatively) and both the smokebox and the taper-boiler could be made accurately.
You can see in the above picture that I slightly over-did the curve on the detail overlay, but that did not matter in the end.
It is now, for the first time, possible to look at a preview of what this kit is going to be like when it is finished.  OK, I accept, it takes a deal of imagination still ….
attachFull46110
David

Stanier 8F in S7 part 12: running the chassis for the first time.

The 8F is progressing well, and I have been able to fit the special parts and run the assembled chassis for the first time!

Small The first run on test track 1

 

It was a great moment to see it move for the first time.  After I cleaned my test track, it ran for the first time with almost no hesitation.

 

Small The first run on test track 2

I decided to try running it with the connecting rods in place but before I try the return cranks, etc.  I had to wait to try out the running until the tender pickups were done.

The third picture shows the tender pickups: the compensation mechanism is still able to work (I have left loops in the wires to allow this, but there’s still a lot of gear to go into those spaces, so I’m not sure how well this will work) and the temporary connections visible going to the loco. chassis on the right. The split axles can be seen.

Small Tender electrics

It doesn’t look much like an 8F, and the motion isn’t all connected yet but it shows that the tender pickups are working and that the assembly so far is acceptable.

It runs better forwards than reverse at the moment, but goes reasonably smoothly at 7V drawing 100-200 mA, and it’s still running without any lubrication.

S7 Stanier 8F Part 11 “Obtain a running chassis”

The instructions are a little terse at times, such as this: “Obtain a running chassis” !

Small Obtain a running chassis 01

After a struggle, this is where I am now at:

 

Motion bracket, etc., in position on the frames.

Motion bracket, etc., in position on the frames.

However it will take a little while to describe how I reached this point!

 

This is what I had constructed so far:

I had bought the special ScaleSeven wheels, but it turned out that  the wheels rims/tyres had been made to S7 standards, but the central boss part of the wheels was far too thick.  I was lucky once again to be able to enlist Richard Davidson’s help, and he used his lathe to thin down the wheel centres by about 0.5mm each.  This extra space on each side would be crucial to allow the wheels and coupling rods to turn behind the slidebars and crossheads without catching.  Even with the wheels thinned down, it is a very tight fit.  It was simply not going to be possible to fit the manufacturer’s crankpins, washers and nuts.

Wheel BoltOnce again, Richard has been the saviour.  He manufactured four specials crankpins – bolts to go through the coupling rods from the outside.

I decided that on the first axle the special crankpin could be used without a washer inside, as the coupling rod was slightly thicker around the crankpin, giving clearance over the wheel centre.  For the second axle, though, a washer would be needed between the special crankpin and the wheel boss, as the articulation in the coupling rod would foul the wheel centre otherwise.  For the third and fourth axles the Slater’s crankpins could be used.

Small Annotated Obtain a running chassis 02Shown here are the different crankpins in place.

When I first put the axles in the frames, bolted the retaining plates to keep them there, attached the coupling rods loosely and turned the chassis over: JOY – the chassis could be pushed forward and the wheels all rotated with minimal binding.  Too easy, as they say here in Aus.

“Too easy” in fact ….  Once I tightened down the crankpins the binding started.  I am not sure what the correct way to sort this out is, but Richard had once shown me how to push the frames along, and when the wheels stopped rotating, move each segment of coupling rod sideways with a pair of forceps to see if it moves: even a little movement shows that this is not the part which has stuck.  When a crankpin with no movement is found, the hole in the coupling rod probably needs to be enlarged (with a small tapered reamer).  I slowly opened out the holes in the coupling rods where the binding was occurring.  At least with the articulated coupling rods this is made easier.  However it also became obvious that on one wheel the countersunk central bolt holding the centre of the wheel to the axle stood out too far and was scraping against the coupling rod – the bolt had to be filed back just a little.

This all seemed to take ages, and the special crankpins were difficult to take out each time – I had to buy a “pin chuck” (like a very small drill chuck) to hold the circular heads of the crankpins.  However in the end I did “obtain a running chassis”, although one without the connecting rods, etc in place.  I couldn’t then resist a trial fitting of my Portescap motor and ABC gearbox, to see it all turn for the first time!

Using the Slaters crankpins and their “top hat” bushes made the coupling rods stand out an unrealistic distance from the wheels, so next action was to thin down the flange of the top hat bushes (almost removing the “rim” of the “top hat”!), and shorten them so that they are only slightly longer than the thickness of the rods.

Small Obtain a running chassis 03After all of this, fitting the cylinder/slidebars/motion bracket assembly revealed that all the work was being rewarded, with a small but definite clearance between the front crankpin and the crosshead on the slidebars.

The connecting rods were still not fitted, so next was to attach these to the crossheads.  There was nothing in the instructions about how to do this.  There is a post coming out of the recess in which the small end of the connecting rod fits, about which the rod will move.  I cut this off flat with the crosshead rear (the was no way it could be allowed to protrude!).  After some thought I measured the post: 2mm diameter, and made two tiny circles of flattened nickel silver wire (curled around a 1.9mm drill, then flatted between a steel ruler and a granite benchtop with a hammer (lucky the household manager was out again).  I could then solder the wire circle around the post to hold the connecting rod in place.

Small Obtain a running chassis 05Connecting the connecting rod then allowed me to see the next difficulty – the expansion links have to be made very carefully so as to hang just wide of the connecting rod.  I had not done that (it’s not easy to see this difficulty before this latest part of the construction), so some reconstruction is going to be needed now.

 

S7 Stanier 8F part 10. Curving the tender sides.

I have started on some of the bodywork for the tender. For someone like me, this threw up some significant difficulties due to my lack of expertise: how to bend the top edge of the tender sides? I have bent sheet metal before, to make the Belpaire firebox of my industrial Garratt, but this was brass, and not a particularly wide sheet of metal, either. The nickel-silver sheet for the tender side requires an even bend along a length of about 11cm. Dave Sharp from MOK has instruction about how to do it, but they are sketchy. The bend covers a height of about 3.5mm in the side, so I worked out that as the bend was through about 45 degrees, a bend of about 8mm diameter would be about right [8×3.5=28mm, divided by Pi = approx. 8mm diameter].
Small Bending the tender sides 01The instructions show how to draw lines on drafting tape inside the bend, to position it accurately. This is good, but how to make the bend? My first try was to place a slightly smaller diameter drill to bend around, and clamp the tender side in my big vice.

However I simply couldn’t bend the nickel silver!
In any case, the drill wasn’t really long enough, and the ends might not bend properly. I was talking/e-mailing Richard at the time, and he suggested I buy a longer rod, of slightly smaller diameter than the bend I wanted to make, and then either roll the sheet over the rod using a rigid metal plate to transmit even pressure, or clamp the top edge of the tender side in the vice and bend the body over the bar. I suppose it was a little foolish of me to try to do it the other way around, but somehow it seemed right to bend the bit that is supposed to be bent, rather than bending the body down whilst holding the part which is supposed to be bent, upright in the vice!
I started to try to bend the sheet over a piece of 1/4 inch (6.3mm) aluminium rod which I found, on our granite kitchen benchtop (the household manager was out), but it was very difficult to bend, and also I thought that this technique might not produce a discrete bend in the flat sheet of the tender side (if you see what I mean), but rather make it a nice continuous curve in the metal sheet. It was impossible to hold the rod still relative to the sheet metal whilst trying to make the bend.
Small Bending the tender sides 03So, back to the vice. The trouble now was to hold everything at once, to allow the rod and the tender side to be exactly positioned. So I used masking tape to hold the rod against the aluminium angle used to make smooth jaws in my big bench vice, as shown on the left.

Small Bending the tender sides 04

Then I put the tender sides into the vice and could adjust the position so that the start of the curve was held in between the rod and the vice, the other end of the curve being above this (in the picture one can just make out the second line):

This finally allowed me enough leverage, using a thick rigid steel rule, to make the bend in the tender sides.
Small Bending the tender sides 06

Small Bending the tender sides 05It also allowed me, using the same technique, to form the vertical curves at the front of the tender sides (a bit out-of-focus in the picture, sorry).

HAPPINESS !

David