David's Workbench

[Colonel]

Now that's a very interesting toy!

 Buoyed up by at last having a rolling chassis, moved on to fitting the pickups this afternoon.

 Another of those fiddly jobs, especially with a loco as small as this. The usual copper clad strip epoxied to the inside of the frames, with 0.5 mm phosphor bronze wire for the wiper pickups themselves.

 Took a fair bit of thinking to work out the best positions, both to hide the wipers and wiring, but also to find room to fit them all.  Couldn't find a way to fit ones to the trailing wheels, but have put some on the pay coach , so there are eight wheels covered. The model isn't going to have to do much more than shuttle on & off the layout but Initial tests show it is already able to pull itself along, though some lead [or maybe a lump of brass rod] in the the boiler should help matters, especially as it will be right above the drivers.

 

 

[Colonel]

Looking at recent comments on Alan's workbench, am finding there are issues with the Battle of Britain loco - though some [all?] of them may be down to build faults, rather than the Acme kit. No idea how old it is, or who the original builder was, but when it came to fitting the valve gear, quickly found that things were wrong, not least the bracket holding the expansion link had been soldered too far back. This  led to the radius rod being unable to reach valve rod from the top half of the cylinders.

 The solution was to move the bracket forward and suddenly, everything started to fit. The Premier Components valve gear parts, being profile milled nickel silver, are nice and chunky, but don't come with with aforementioned valve rods, so I had to make them, using nickel silver wire for the rod itself, to which a short pieces of brass tube was soldered. Then filed a flat on this to which I soldered a link from an old fret of steel inside motion parts, which was then bent twice at 90 degrees to align it with the radius rod.

 I've used 12 and 14ba nuts and bolts to assemble the valve gear parts, although I've now run out after doing one side, so am awaiting an order from Squires to complete the other side. However, have at least been able to test what I've built so far, though wasn't surprised to find some more fettling was needed. The loco was built as a static model and while the coupling rods roll well enough, one of the connecting rods was fouling the centre crank pin, so this needed filing back to clear.

 The valve gear has been about 90% ok, but there is a clunk which I think I've traced to the valve rod and combination lever - see below:

 The combination lever is the part that 'hangs' vertically from the valve rod [the cranked piece sticking out of the top cylinder]. I've fitted a short link from the top of the combination lever to the U shaped bracket running across the frames, but the valve rod is still flapping around.

 Now, I've only ever fitted outside Walschaert's twice, both more than ten years ago, so if anyone has any ideas, please let me know. For example, one option might be fix the valve rod in the cylinder, to stop it moving at all, letting the rest of the motion take up the slack, but not sure if this will work.

 More pictures below may [or may not] help. You'll see the tapered reamer now has a better [temporary] replacement in the form of the cut down cocktail stick. This will eventually be replaced with some nickel silver wire when I  make up the other side.

 Meanwhile, things are progressing on Sidhe, aka the Fairy/Sprite pay train. 

 First, I added some weight, both to the front end of the boiler and in the side tanks, both nicely over the driving wheels. With that done I could then put the outer skin on the tanks. With hind sight, I should probably have used some thin brass for this, as the 20thou plasticard split on the curve on one side, needing some epoxy to fill the gaps.

 Other work has included front buffer housings [nice brass ones I had in store], cab steps and the two boxes, one each side, below the footplate. No idea what they were for though... The smokebox door came next, along with some beading around the splashers. I tried making a chimney this morning and not having any suitable brass rod, though I'd try turning one from dowel. However, as you can see, it didn't work out, because the wood I used is not dense enough. Oh well, now need to put in an order for some more brass rod.

 You might just notice that the frames have been primed and painted, but there are still plenty of jobs left, including cab interior detail, boiler fittings, various hand rails & so on, so a while to go before painting.

[Mol_PMB]

You’re a braver man than I to tackle that valve gear in model form. It’s bad enough to get right in full size!

Sidhe is coming along very nicely! 

[Horsetan]

1 hour ago, Mol_PMB said:

You’re a braver man than I to tackle that valve gear in model form....

In 4mm scale, Bradwell, Finney and Brassmasters - and a few of the more recent South Eastern Finecast - kits allow you to make the valve gear reversible if you want to go that far....

Rude not to have a go.

[Colonel]

A Chatham Club member did it back in the early 90s on an 0 gauge LMS Crab   2-6-0, using a Portescap RG7 to move the gear and a second one to drive the loco. At the time, remember I wasn't alone in being very unimpressed at the use of an expensive motor just to move a small part of the linkage a few millimetres. Thinking about it now, it was seriously clever stuff in that pre digital age. 

 Not for me though - but I have put working inside motion in my Sligo Leitrim 'Large Tank'. Fiddly, but easier than Walschaerts. That said, in model form, valve gear isn't as daunting as it might seem. Building a working chassis can be far more time consuming.

[Colonel]

 A few days off recently, as I accompanied my wife, who is a member of Rochester Choral Society, on a tour of the Barcelona area, singing in a number of cathedrals and basilica - culminating in an International Mass in the Sagrada Família, no less. Nice weather, excellent singing [none of it by me], along with good food and wine too. Starbucks and others take note: a coffee in Barcelona is only about two euros, a glass of wine four, AND they fill it up too. 

 Anyway, since getting back have been doing battle with the Bulleid pacific. Assembling the valve gear is fairly straightforward, checking it will run smoothly is another matter, simply because with so many parts, there are so many variables: things to catch on something else, fixings to come loose, etc etc.

 Above, you can see the chassis hooked up to my ancient [over 40 years old] H&M Clipper. When testing locos and chassis, it is very much my first choice, being a very basic controller: if the model runs well with it, chances are it will work even better with something more sophisticated.

Have mostly used 12ba nuts and bolts to hold the gear together. Ensuring they don't catch on other parts of the motion is obviously important - likewise not coming undone either!

 Still some tidying up to do, while [below], the eccentric cranks on the centre driver are proving troublesome as I can't find a reliable way to hold them in the correct positions.

 Mostly they are ok and I've had the chassis running on the bench for a couple of hours in total, including at full speed in either direction. Nothing has fallen off, which is encouraging and were this my own loco, I'd probably put up with it, because I'd know what to do, but this is someone else's model, so it needs to be both right and robust. 

'Tis certainly a handsome beast though and also the largest loco I've ever worked on too.

 

 

 

[Colonel]

 I've taken the Bulleid Pacific as far as I can at the moment. Now need to take it down the Club on Tuesday, to see how it performs on the two 0 gauge layouts. One is an Inglenook type, the other is our tail chaser , North Circular, so it will be interesting to see how it copes with Peco 6' radius points and the outer circle of the same radius on the main layout.

 So, back to the Pay Train, for a bit of light relief and have spent the weekend producing the main boiler fittings: chimney, dome and safety valves. This meant getting out my 'micro lathe'. Very much a halfway house between using a drill chuck and files to turn up basic components, compared to even a basic lathe, it has nevertheless helped me produce quite a few things - though I shudder to think what true model engineers would say!

 Here is said machine: there's a three jaw chuck on the left, with just a pointy thing on the right [am sure it has a proper name], so you need to find the centre of the brass rod [or other material],  to set it all up.

 The micro lathe came with this plastic gizmo which helps scribe multiple centre lines. Not terribly accurate, but have found if you do lots of them, even if the lines don't meet up in the centre, you can still mark a centre point as shown below. You then drill a fairly deep hole for the pointy end to go into. Locking this into the brass rod obviously stops things flying off when turning takes place.

 The lathe isn't very powerful, so how found it is a case of many passes with the cutting tool, doing about a quarter of a millimetre at a time, so as not to stress the motor, finishing things off with files. Tedious, but effective. I keep thinking about buying something better, but for the limited amount of turning I do, it is probably not worth it.

 The chimney turned out ok, but the dome [above] turned out too small. Bear in mind I'm working from basic, small scale plans and grainy photos, but it didn't look right, on the loco. Waste not, want not, I cut off the base and used this to mount a white metal casting of a pair of safety valves. 

 Luckily, found a white metal dome in my spares box. It was too tall, but about the right diameter, so I filed it down and hopefully, it looks the part.

  So, the little loco is starting to look the part at last, albeit still a way to go.

 

Edited 2 hours ago by Colonel

[Mol_PMB]

Lovely! Your miniature humans must be looking forward to pay day!

That tiny lathe looks like a useful tool. I have a reasonable hobby milling machine but no lathe, and I keep wondering about getting a small lathe, but perhaps not quite that small. Interesting to hear about your experiences with it.

 

 

 

[Galteemore]

That’s coming on very nicely indeed