7mm On Heather's Workbench - Aintree Iron: an Austerity adventure

[Heather Kay]

Progress is slow. That's my fault, but there are some things you can't rush. I also have this habit of avoiding doing things that are causing me problems, so I've been doing some other bits of the build while the problem bimbles about in the lower memory registers in search of a solution.

I tried using a sprig of fine wire as a hornblock retainer.



It kind of worked, but it would need more than one wire to be efficient. At this point, I decided it would be a good time to fit the frame overlays and get around to fitting the frame spacers ignored by the instructions.

After some more bimbling, I decided what I ought to do next was make up the coupling rods. Instead of actually doing that, I made up the actual valve gear. Don't ask. It just seemed the right thing to do.



Oddly, a relatively relaxing, educational and interesting excursion. For those that like that sort of thing, you'll be glad to learn the slotted link castings allow the gear to be reversed ALTRT. The valve spindles needed quite a bit of careful fettling to get a nice smooth movement, and I am currently unsure of how to fit the return cranks. Another problem to leave to bimble about.

Oh, and I remembered I had some CPL cast crankpins nuts, which included a pair suitable for use behind waggly bits. That saved me a little bit of engineering, at least I hope it has.

Onwards!

 

[OzzyO]

Hello Heather,

one of the best ways of fitting the return crank is drawn below,

Use two top hat (T/H) crank pin bearings tapped 10BA top to top. Check the fit of the coupling rod on the inside one with a 8BA or is it 6BA washer (W) and a bit of play, then check the length of the second top hat (T/H) with the connecting rod, cut the screw to the length of the two top hats then remove the outer T/H and cut the screw about 15 thou. shorter, and then put the T/H and tighten fully home. Then solder the return crank (R/C) in place. You can then unscrew the (R/C) and fit to the valve gear. When your happy with the running remove the R/C and add a bit of nail varnish to the screw and screw the R/C in place.

OzzyO.

 

[Len Cattley]

Hi OzzyO, you have helped me out with a problem I will have in the future, thank-you very much

Len

 

[Heather Kay]

I now have sore fingers and a crick in the neck, but at least all the waggly bits are prepared and more or less ready to fit.



Rather than rivets to join the coupling rods, I plan to use nuts and bolts.

Now I need to fit the hornbobbins and axlebluds.

 

[OzzyO]

Rather than rivets to join the coupling rods, I plan to use nuts and bolts.

Now I need to fit the hornbobbins and axlebluds.

Before you go to far with the waggly bits I'd say that you want to get the hornbobins and axlebluds sorted out, if you don't it could come back and bite you on your bum. But you may like that sort of thing?

OzzyO.

PS. some nice looking valve gear, if your going to use nuts and bolts for it please use steel ones if you can. Brass ones just look so wrong. I have used dressmakers pins with the head filed to look like a nut for some valve gear before.

 

[Heather Kay]

The whole reason for the digression into the valve gear was having to make up the coupling rods for hornguide setting out. In for a penny, I decided I might as well get it out of the way.

Good point about steel over brass. I'll have to dig about, but I think perhaps chemical blackening might suffice in a pinch. Bolts might be overkill for the coupling rods, as they don't make a lot of movement aside from round and round.

Note to self: get some steel Ns, Bs and Ws in stock.

 

[Heather Kay]

Nearly forgot, 90733 is attending the Severn Valley Railway steam gala in March.

http://www.svr.co.uk/SEItem.aspx?a=65

Sadly, the model might be complete before then, and I have other duties on or around that weekend.

 

[OzzyO]

I use this fellow for just about all my nuts and bolts (no connection just a satisfied customer), the prices will be out of date and are only used to show the sort of stock that he has.


PS. 6BA x1/4" socket counter sunk screws are vere handy to have in stock!

 

[Heather Kay]

 

[Heather Kay]

Baby steps. That seems to be the best way to tackle this thing.

The time came to get the loco frames on wheels. I'd been putting it off long enough. Procrastination is one of my middle names, after all. As you may recall, one of the plans was to try and use the kit castings, perhaps with some mods, while another plan was to replace the castings with third party etched hornblocks, perhaps repurposing some of the nice kit castings for the look of things.

The more I thought about it, the more I thought the kit system might actually work. Here is my reasoning: The hornblock has a recess for the spring to sit it; under normal circumstances, the block sits on a bolt, with the spring providing downward pressure to keep the wheel on the rail; if the end of bolt is also sitting in the recess, it will tend to retain the block in the guides.

Nothing for it but to try.



Well, you could blow me down with a feather, because it actually does work! Consider my flabber well and truly ghasted.

I have elected to use the whitemetal cast units for the electrically driven axle under the firebox/cab. The other three axles are sprung. You will note the leading axle needed a couple of holes drilled through the frame spacer - yet there are already holes, which leads me to believe this spacer is etched bass ackwards.

I'm going to play trains on the test track to see if the system holds up. It does mean I have to temporarily perch the boiler casting on top for some weight to compress the springs. If that works out okay, I shall give some thought to electrical pickup and motors.

With so many wheels, the temptation is to collect current on as many as possible. I'm already planning on all-wheel pickup on the tender, so that's eight wheels already. Should I even bother with the loco? Well, I would like some insurance, so I intend to fit wipers to the leading driver, and perhaps plungers to the driven wheels. The other pair can go without. Ten wheels collecting juice ought to be plenty.

I wonder how chilly it is in the upstairs workshop…

 

[Heather Kay]

Giving the motor and gearbox a gentle workout before they are installed during the week.

 

[farnetti]

If you have space between the axle box and wheel hub rear, which I suspect you will, as casting is attached to the inside of the frame thus you should have at least the frame thickness to play with, then I'd simply plate the outside of the axle box with 5 or 10 thou plus suitable hole for the axle. You may have to widen the slots in the frames a fraction to get the flange of the overlay plate to fit.

Or, if your tight for space then add another 5/10 thou fillet around the base of the axle guide to space it away from the frames to accommodate your retaining plate.

View attachment 40770

Green, overlay plate to retain bearing.
Red, additional plate if clearances tight.
Blue line, probable kit frame slot width.
Pink line, revised frame slot width to clear retaining plate.

Personally I'd widen the slot in the frame to take the retaining flange width than have to add the extra red clearance plate.

I spent a few minutes scratching my head over the problem, came up with an idea, scrolled down to post it and found Mickoo had the solution but described it far better than I would have done.

Ken

 

[Heather Kay]

I seem to be acquiring a lot of sub-assemblies, yet the main build seems to be slowing. Of course, sub-assemblies mean less fiddling later, and all of a sudden the loco is finished.

But not quite yet. However…



Test fit of the wheels, coupling rods, running plate and frames. Of course, it's impossible to resist posing the boiler and cab…

In order to fit the frames to the running plate, I've had to disassemble the fireman's side injector.



Both cold water feed pipes have had to come off, as well. I realised they were getting in the way of fitting the frames to the running plate, and also had to pass through openings in the frames under the cab. In the end, one full set of injector pipework had to come off as a result of my mangling.

Still, nothing that can't be fixed.

I haven't built many locos in my time. This one is only the second kettle I've built as a professional builder. For many years, I have dreaded fitting wheels and the various connecting rods. Horror stories of how hard it is to make it work without tight spots or misalignments haunt my dreams. Yet, either I am supremely lucky or this stuff has got easier to build, because I put the coupling rods on this morning expecting all kinds of minor issues, but the chassis rolled freely along the test track!

Please tell me the horror stories were true, because I seem to be blessed.

 

[Heather Kay]

I thought I was getting somewhere. Lots of fiddly bits, and a few steps back and forth.

Yesterday I set about fitting the motor, and working out wiring, including a plug system between the loco and tender. Most of that is now pending. I drilled a couple of holes so the boiler casting can be screwed onto the running plate, and glued the smokebox saddle to the boiler casting.

That doesn't seem like a lot, but it seemed to take FOR EVER!

Today I was going to carry on with wiring, as in actually doing it. Then I got sidetracked by fitting the motion brackets. There's no positive location marking on the frames, so I've had to begin fitting the motion and cylinders…

At the same time I realised I had fitted my radius rods back to front, so a step back to disassemble all the good work I did the other day!

Here's where I am so far today, and I have still to actually attach the bracket to the frames!



Looks pretty, though. I'll need to plug the valve guide ends to stop the valve rod and cross head popping out accidentally. I'll also need to plug the slidebars, but I'm not sure there's anything in the kit.

 

[Heather Kay]

I think the secret to this valve gear game is taking your time and testing things as you go.

Having fitted the various slide bars to the cylinder block, I clamped everything to the frames and tried to see how much space was left for the leading driver.



This is from below, in case it wasn't obvious. I reckon, folding the rear view mirrors back, you'd get a bus through that.



I might shave a little of the bottom right corner of the front motion bracket plate where it might just foul the flange of the leading driver. With a recessed crank pin nut, and perhaps a gnat's crochet shaved off the boss of the coupling rod, I might just get away with it. Oh, and some washers to inhibit sideplay.

 

[dibateg]

Making progress Heather and looking pretty tidy. I usually make up one segment of valve gear at a time, make sure it works then add the next bit. Con rods first then return crank to expansion link, one side then the other. Then expansion link to valve and combination lever etc. It usually works...
Regards
Tony

 

[Heather Kay]

Cheers Tony.

Yes, that was pretty much what I've been doing. I'm happy that I have a relatively free-running chassis, and once I get the motor fitted I can let it trundle for a bit on the rolling road before I set about fitting the valve gear properly. I'll start with the connecting rod, and repeat the running process, then add the rest of the gubbins in stages.

I must get that motor fitted and wired in. Sadly, it looks like a Sunday shift now, as I have a things planned for Friday and Saturday.

 

[Heather Kay]

I'm still not at the motor fitting stage. Perhaps I ought to do it for the change of scenery, as I seem to be getting a bit bogged down with leading crankpins clearances.



For numerous reasons I don't want to trim the crankpins at this stage. I don't plan on fitting the valve gear until I've got the chassis motorised, so this is all a little speculative at the moment. What you see here is the coupling rods and the CPL recessed crankpin nut. I'm happy that this solution saves me some engineering with larger BA crankpins and tapped Slater's bushes. I do, however, need to recess the nut into the coupling rod, so a little careful drilling needs to be done, then a shade more filing off the back. At the same time I think I'd be wise to file a fair bit off the front of the coupling rod boss. It wouldn't hurt to lose a bit off the back of the piston cross head too.

So, that's a bit of work to go. Meanwhile, the motion bracket will need a little adjustment.



On the real thing, and probably in S7, the motion bracket mounting plates wouldn't foul the flange like this. I'm afraid some surgery is going to be required on the lower front corner of the bracket. Alternatively, I could slide the whole assembly backwards a mill or two. It's a compromise, absolutely, but if it help things fit without fouling it is probably worth it.

The other thing is to limit the front axle sideplay. JLTRT provides etched washers on the frames and rods sheet, half full thickness and half half thickness. I've fitted two half thickness washers on the axle, but now the axle boxes are providing the sideplay. I may have to look at a retaining system to prevent that but not so it prevents the sprung movement. I could, I suppose lock it all solid, but I would rather not!

So, having got myself bogged down, I went outside for some fresh air hoping to be reasonably employed changing out the car's rear wiper for fifteen minutes. Damn these modern cars where such things take seconds. It took longer to open the box with the new wiper in it!

I guess I should get this thing powered up before I lose the plot.

 

[Heather Kay]

The motor and plunger pickups were installed this morning.



Last night I fitted the SDK spring castings. Because the frames were half-etched to take the etched spring details, I had to carefully file down each casting till it clicked into place. A dab of solder paste and the RSU fixed things.



The motor shaft was chopped back, and a bracket extension made so the supplied restraining loop would actually reach the frame spacer! A little surgery to the running plate cleared the bracket and bolt.



This shot shows the bracket arrangement. I've had to chock the motor with a short length or copper wire to stop it bouncing back and forth under power.

The plunger pickups collect current from the rear wheels only, all remaining collection via the tender wheels. This means there's no noticeable wiring and the wires to the tender can be made to look like the various brake and water pipes.



It looks incongruous, but this is the first self-powered test of the chassis. Next step to wire up the tender, organise the interconnecting plugs, and fit the other two axles and coupling rods for a gentle running in and checking session on the rolling road.

I feel I am making progress at last.

 

[Heather Kay]

Right, where were we?

Ah, yes, I remember…

Progress seems painful at this stage, but I keep plugging away. Having got the chassis motorised and electrified, I set about adding internal details.



The four sandboxes inside the frames went in, low-temp soldered in place. They have fixing pegs cast in, but there is a lack of relevant holes in the frame etch, at least relevant to where the sandboxes go anyway. As I was researching the sanding pipe runs for later, I realised there was a pair of sandboxes missing. There are boxes between the two trailing axles, fitted to the outside of the frames.

I dived into the Bits Box, and found some lumpen castings that might be formed into something about right. I then wasted a good while failing to make them the right shape. An email to Laurie at JLTRT begging for a couple of spare sandbox castings has been sent. While they're not quite the right shape, they are the right size and can be adjusted.

There are various sub-assemblies that clutter up the bench by this stage, and I thought it high time they began to be fitted in place. Then I realised assembly A can't be fitted until assemblies C and D go in, both of which are dependent on assembly B. In this case, it would be lovely to fit the cylinders, but with the slidebars in place you can't fit the front axle. The motion brackets kind of depend on the slide bars being in place, and don't forget the brake hangers, and of course the running plate can't be fitted until the cylinders are in place…

Do try and keep up at the back!

In a fit of lunacy I fixed the main motion bracket castings to the frames, only later realising I couldn't fit the cylinder assembly. I managed to finagle the cylinders in as a test fit, which happily revealed some dodgy soldering. To help the cylinder block and slide bars fit later - after the wheels are in place - I have ground away some of the rearmost slot. You can just make it out in the photo.

It seemed a good time to apply some chemical blackening to the outer bits of the frames, which I did.

I have now fixed the 14BA bolts in for the brake shoes to hang from. The next step is to fit a pair of wheels and find out how long the brass tube spacers need to be.

The cast brake shoes have had black styrene glued to the wearing faces to help with electrical isolation. I've done all eight shoes, even though something is telling me I needn't have bothered on the non-current collecting wheels. Not doing it would be silly, though. Obviously.

In between all that, I have constructed the pony truck. There's an unhealthy amount of sideplay on the axle, so I've fitted some of the etched washers to eliminate it. Nothing worse than a pony truck axle swinging about as well as waving from side to side! I am not sure whether the truck needs additional ballast, or side control springs. This may become more obvious when road testing begins in earnest.

I reckon there'll be some paint slapped about on the frames later. I don't think there's anything left to fit, apart from the oiling box pipe runs. Hmm. Could be fun.

If I get some paint on the frames, while it's all drying I might get the boiler detailing going.