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

[Heather Kay]

You've built way more locos than I have, Paul. For this build I have been following the general outline of the instructions.

I'm pretty confident the frames will fit well - expect that statement to come back and bite me!

 

[dibateg]

Sounds like a typical jltrt kit, too many parts or none at all! They are always very helpful to get you sorted mind.

Tony

 

[Heather Kay]

The story so far… Or: previously on Western Thunder…

Yesterday I finally found time and mojo to get back to this build. It was time to climb the north face of the frames. Before that, from experience, a lot of filing had to be done. What I mean is where some kit designers allow for etched cusps, others take a more laissez faire attitude to them. It took a couple of hours of cleaning up to get the frames in a respectable form so things might slot together without much sweariness.

Then I decided to tackle the cylinders.



A central thick nickel silver etch folded up to form the basic shape, and two half-etched brass bits form the covers. Some time was taken to get the covers more or less the right shape before soldering to the carcass. I didn't want to try and form the shape while soldering it together, as that's asking for trouble - just see the travails I have had with the Ivatt 2-6-2T Best Beloved built that way…

Meanwhile, the frames waited patiently for the erectors to finish their cups of tea, or get back from the pub, or whatever it was that frame erectors did in their downtime.

Today, I decided to continue with the instructions and fit the slidebars, cross heads and other cylinder details.



These parts are pretty hefty - and pretty nicely executed, it has to be said - brass castings. It took a fair while to separate things from their feed sprues, and tidy up. I have this fetish for cleaning back mould marks and so on, so the array of weaponry I chose in my task can be seen: files coarse, fine and very fine, sanding pads and taper broaches. I paid particular attention to cleaning up the slide bars so the cross heads were a smooth but not loose sliding fit. This did involve some careful filing with a square needle file to clear the cross head casting to let the slide bar fit in, but other than that all went well.

My plan is to glue the cylinder front castings on, and potentially solder the slide bar castings for strength and adjustability.



Ah. The main cylinder front casting fits in its hole, but the valve cover won't until I drill it out. Okay, so what about the other side?



Right, so the slide bars will fit in their hole, but the valve guide castings won't.

At this point, feeling a bit under the weather, I felt hauling the pillar drill out and drilling four holes was just too much. I called a halt on proceeding.

I wonder if the frames will be put together tomorrow? It might be nice to get a rolling chassis this week.

 

[Heather Kay]

I nearly forgot! In all the excitement of sorting out the beginnings of the waggly bits, I checked the instructions for building up the pony truck. I like to think ahead, and it seemed a good time to find out how the thing goes together.

It's not mentioned in the instructions. At all. Nada. No mention of pony trucks whatsoever.

I guess this will be the first WD Austerity 0-8-0. My, what a front overhang that will be!

 

[Tappa]

Heather, our build is slightly in front of yours in that we are onto fitting the driving wheels. However, the front driver seems to foul the sidebars! I'd be interested in what happens to your build when you get to that. I'll take a couple of snaps tomorrow to show where we are upto to explain.

Jeff

 

[Heather Kay]

Hi Jeff

Yes, I had a thought the front wheels will foul the slidebars. Once I have things fitted up I might have to either widen the cylinder spacing or skim the leading wheels down and thin the gear.

Looks like some fun will be had in due course, especially to get the thing to negotiate six foot curves.

 

[Heather Kay]

Today I asked Laurie at JLTRT if he could send me the missing part of the instructions for the pony truck. To be fair, this kit is quite elderly, and things have been improved and updated since this copy was produced, though I was told the instructions are still rubbish! (From the horse's mouth, so they do listen!)

The replacement boiler casting also turned up today, so I now have most of everything I need to finish this loco. Famous last words!

The frame erectors came back from their Caribbean holiday today. Plenty of careful filing for fit, and I discovered the original builder had managed to break one of the folds. I guess that was the point where the extra set of frames etches were acquired, only they didn't have the spacers on them, and the builder gave up and bunged the whole thing on Fleabay or something.

Anyway, the problem is not as bad as it sounds, just needing some tender attention with the hotting stick and a square.

Once I'd got most of the frame spacers attached to one frame, I could test fit the other frame and try the cylinder block for size. There followed some mild head scratching as I pondered where some extra space might be achievable to clear the leading drivers.



Note the R on the cylinder stretcher? I think that was supposed to designate the rear of the block. Indeed it is possible to fit the cylinders into the frames the other way round, but the eagle-eyed will spot there is an extra pair of holes below the main slidebar holes, which aligns with the holes in the slidebar castings. It will be noted also there is an etched slot in the frame spacer that coincides with the deeper stretcher on the cylinder etch.

Anyway, etch and instructional errors aside, you can see the cylinders are nice tight fit in the fine scale width frames. I assume, given S7 spacers in the kit, the builder must chope the cylinder assembly in half to accommodate the extra. Nothing unusual.

I turned to some calculations to work out how close the model is to the real thing in terms of widths and so on. I'm not good with numbers, so this took a while! I needed to work out the scale factor from the print of the GA I have. Knowing the wheel diameter is 4ft 8.5in, this gave me a print diameter of 44.5mm. Eventually, my brain cell, assisted by the more mathematical brain of Best Beloved, came to the scale factor of 0.742. Multiply known dimensions (converted to millimetres) by the factor to give me millimetres on the model. So, across the outside of the cylinders in this case gave me 60.8mm, and I confirmed this on the brass bits.

So, the cylinders are the correct scale width. How that works on an S7 model is anyone's guess!*

To give me some extra space behind the slidebars, therefore, I think I will split the cylinders and shift them outboard by a half millimetre or so. I will have to make up a wheelset with the crankpins in place, and then fit the cast hornguides and stuff, then juggle with connecting and coupling rods to see if I can squeeze a bit more here and there. I think it is fair to say there will be precious little, if any at all, sideplay allowable for the leading drivers. It looks like a rolling chassis this week is not going to happen after all.

I might need a bit of a lie down before that.

* Quite simply, an S7 builder files back half-etched rebates in the various slots to accommodate the wider frames, keeping the correct scale outer dimension. Obvious, really.

 

[Tappa]

Heather, a couple of pictures as I mentioned. Although the front driver isn't fitted into the axle (because it won't work if it is!), you can see how much may need to be removed from the back of the slide bars.

Jeff

 

[Heather Kay]

Eep!

Thanks Jeff. That is food for thought.

Today I have been rather fruitlessly fettling the lovely hornguide and hornblock castings, because I don't think I can actually use them. I haven't taken any pictures today, because I've decided to take another tack to springing the leading three axles. I will try and cover what the plan is over the weekend.

 

[OzzyO]

Heather, you may want to think about some thing like this. Back of the rods at the top of both photos. The counter bore is about 0.5mm deep, It would have been better with a flat bottomed drill.


The crank pin nut in position on the front driving wheel, crank pin screw still to be trimmed down, it's just a Slater's one tapped 10BA and reversed.

OzzyO.

 

[mickoo]

Heather, a couple of pictures as I mentioned. Although the front driver isn't fitted into the axle (because it won't work if it is!), you can see how much may need to be removed from the back of the slide bars.

Jeff

View attachment 40723 View attachment 40724

Jeff, are those S7 frames? If not, I can imagine some swearing from those that did want to try S7

 

[Heather Kay]

It seems at every turn now I come up with problems.

Let's take hornguides and hornblocks as today's example.



Lovely, aren't they? We are looking at the component parts for one set of driving axle hornblocks, hornguides and springs. We are viewing them as if from inside the frames.



Here they are, sort of put together. There should be a coil spring in the top, but you get the idea.

So what's the problem? Well, there's nothing to stop the hornblock from working its way out of the hornguide, save for the spring and presumably the weight of the loco on top.

Here's the outside of the problem.



The block just pushes through from inside the frames. There is precious little to stop it working back out again.

This has caused some noggin scratching, it has to be said. The instructions - I know, I know - show this assembly as a more orthodox hornblock with slots, inserted into the guides and retained from the bottom.

My head is not in the right place for this kind of stuff today, and that's without adding in the organisation of current collection - a tale for another day. Let's just say the plan is to assemble one set of guides and blocks using low-temp solder, and try an idea for size to retain the blocks. If that doesn't work, plans B and C involve third party replacements. In either case, I shall have to make up the coupling rods, while I still have to apply the frame overlays, which may need drilling for plunger pickups or not depending on which way I decide to go.

See what I mean? I can well understand why by brain cell has decided it's all too much for it today!

 

[Rob Pulham]

Hi Heather,

This is one of those where I am not sure whether a 'like' is the right thing... Would it be possible to put a pin inside the spring to restrict from sliding outboard in either direction?

 

[Heather Kay]

Rob, there will be a bolt in the top to adjust ride height. The idea is the wheel will drop under spring pressure if it encounters a rail deviation. You knew that, of course!

There's another alternative: build the thing rigid. The rear axle will be rigid anyway, being the electrically driven one. There's a complete set of solid castings for the horngubbins, so it might be an option if things don't work out.

 

[Rob Pulham]

Rob, there will be a bolt in the top to adjust ride height. The idea is the wheel will drop under spring pressure if it encounters a rail deviation. You knew that, of course!

DOH!!! - ignore the fool at the back.......

 

[mickoo]

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.



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.

 

[Tappa]

Jeff, are those S7 frames? If not, I can imagine some swearing from those that did want to try S7

Sadly not. The S7 frame spacers are clearly marked as such and so we didn't use them. Tomorrow night will see some head scratching to see how we progress.

Jeff

 

[Tappa]

We had the same problem and built the chassis solid. I am confident our track laying will not cause us problems!

Jeff

 

[OzzyO]

Hello all,

Mick's option is the easiest with the plate fitted to the outside.
If this is not possible you could try this. This will be a bit more work, drill a 1mm hole at the top and bottom so the edge of the hole is in line with the inside face of the horn-guide, you could go for the middle or near the outer edge. The hard part will be the next bit if you don't have a mill, cut a corresponding slot down one edge of the axle box, put the axlebox in the horn-guide and fit a length of 0.9mm wire in place and you should have an axlebox trapped in the horn-guide.

Hope the sketch helps.
They do look a bit nice and could be visible on the inside of the frames.

OzzyO.

 

[Heather Kay]

Some cracking ideas forming. Thanks everyone!