Gadgie's workbench

[RichardClayton]

There has also been some progress with the WD. The cylinder back and front have been assembled, with the front and back covers fitted into place using a 1mm drill bit and the gland casting for correct location. The glands should actually be hexagonal rather than round. Dave Bradwell acknowledges this in the instructions, but I'm not sure what to do about it. One option might be to drill out a nut and fit it over the lost wax casting. Another might be to ignore it ...

 

The cylinders are bolted to the top part of the inner frames using the holes provided. These were tapped to hold the inner frame spacer in place during bending of the inner frames. However the thickness is not great and I have soldered nuts underneath the spaces to make sure that the fixture will be secure.

 

I have also made up the footplate, which is three laminations of brass including an overlay, and makes up into a reassuringly solid and flat structure. Much better than the rather flexible whitemetal footplates the come with other kits. The rivet detail is lovely too. The cylinders and smokebox saddle are not fixed in place yet, for reasons I shall come to.

 

 

One of my big concerns with this kit is the clearance that will be available between the back of the crosshead and the front crankpin. My plan is to set up the front axle to have minimal (tending to zero) sideplay, and recessed crankpin nuts. I have a set of Markits deluxe crankpins, and I plan to use the threaded bushes from these with a 14BA countersunk screw inserted into Gibson wheels in the normal way. The outer lamination for the front coupling rod has a large hole to accommodate a recessed nut, and the Markits bush is a nice fit, but will need some filing down I expect. The next stage will be to make up the slidebar and crosshead, and to do some sums.

 

 

I have also acquired a High Level gearbox, and one of Chris's new coreless motors. I'm pretty sure this lot will fit neatly into the firebox and allow drive to the third axle, which would be my preference over fourth axle drive. However the gearbox is unlikely to fit between the axle bearings that have been supplied, so I have a choice of reducing the width of the bearings and hornguides, or using some High Level space saver hornblocks. This is a complex kit, and there are some significant challenges ahead. I hope I will anticipate at least some of these, but I'm bound to miss something, and that will give you, dear reader, something to look forward to!

 

Richard

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[RichardClayton]

The WD now has slide bars, coupling rods, and a crosshead, which has yielded some useful data about clearances, as well as some lessons that might come in useful for anyone else building one of these kits. Unfortunately I didn't take many photos at the crucial moments, but hopefully you will get the gist.

 

The slide bars are made up of laminations aligned with two pins of 0.45 mm rod at each end. The top and bottom layers are handed (i.e. should only fit one way round), and the assembly should be foolproof. But I managed to end up with an odd set of laminations on one side that wouldn't fit together. I have no idea what went wrong, and was reluctant to unsolder a completed slide bar, so I carefully drilled a new hole to align everything and I think I have got away with it. My advice? Take great care with these parts, lay them out on the bench, and don't rush.

 

The crossheads are made up from a folded etch. The instructions tell us to add a nickel silver top piece, then drill out holes for five pins (0.45 mm rod again), which are inserted and filed flat to form bolt heads. The crosshead and top part both have etched grooves to accommodate these pins. I thought that I would be clever and insert the rods first, as shown. Fitting the top plate was then made much more difficult because it would not fit without filing the rods almost flat. So my advice is to follow the instructions!

 

 

Assembly of the articulated coupling rods is by two rivets, formed of soft brass. All went well, until I loaded them onto my chassis2 pro jig. One set was marginally (about 0.15 mm) shorter than the other, and the problem was between the first and second hole. This was annoying, and I really didn't want to start enlarging coupling rod holes at this stage. 

 

 

So I filed off than back of the rivet and knocked it out (very gently). It was very slightly bent, and when I compressed it, it must have deformed just enough to pull the coupling rods very slightly. A small tweak, and reassembly yielded two sets of coupling rods that are the same length, within a reasonable tolerance. Unfortunately there wasn't enough of the rivet left to form a solid joint, so (heart in mouth) I applied and removed a hot soldering iron very quickly and managed to produce a joint flooded with 145 solder without seizing everything up solid. Phew. My advice? Take care flattening those rivets.

 

So we are now down to the tricky question of clearances, and I have been doing some measuring with digital callipers, and some sums. 

 

The Alan Gibson wheels are a pretty consistent 2.3 mm wide, so combined with a 16.5 mm back to back (for EM) we have a distance over wheel sets of 21.1 mm. There is no coupling rod boss on these wheels, and I'm planning to file any slight irregularity on the front of the wheels flat. The distance from the back of the crosshead to the frames comes out consistently at 4 mm, which is reassuring. With 15.9 mm across the outside face of the frames, this gives a total distance between the inside of the crossheads of 23.9 mm. So on each side we have (23.9 - 21.1)/2 = 1.4 mm, which feels positively luxurious. The coupling rods are 0.75 mm thick, so assuming an extra 0.25 mm for a shim washer on the crankpin and a slightly protruding crankpin nut, there will be as much as 0.4 mm clearance. The trick will be to absolutely minimise side play on this axle, but it looks like this is going to be do-able.

 

The next set of calculations were not so encouraging though. The wheel bearings supplied with the kit are rather chunky, and are 3.3 mm wide. I have a High Level LoadHauler gearbox, which is 10 mm wide. 10 + 2x3.3 comes out at more than the back to back for EM.

 

So one option is to use the High Level slimline horn blocks that I bought as insurance at the same time as the gearbox. This decision raises interesting questions about suspension. I had been planning to go with springing on each axle, as is designed into the kit. This has worked very well on my J27. But  inserting and extracting the spring wires turned out to be activities that tested my patience. In an idle moment at work today, I found another account describing the construction of one of these kits, again in P4. Lord Colnago confirms that the WD presents a similar test of sanity. The rest of my life does a pretty good job of testing my patience, so I am wondering about going with CSBs instead. The ever helpful CLAG site has the fulcrum spacings for the WD as a worked example, and I have got plenty of surplus over scale handrail knobs.  At the same time I can see advantages to using High Level hornblocks throughout -- they should be much easier to fit than what is supplied in the kit.

 

If you have persevered to the end of this post, and have any thoughts and/or opinions, then I would be interested to hear them.

 

 

 

 

 

 

Edited October 18, 2021 by RichardClayton
Edited to fix typos

[RichardClayton]

Having read through some other posts on RMweb while reading up on other modellers' experience of CSBs, I have discovered a jewellers' trick that I could have used to lengthen my errant coupling rod -- gentle taps with a light hammer -- thanks John! 

 

[RichardClayton]

Well I’ve decided to go with CSBs, and a set of High Level hornblocks arrived at the weekend. Some more sums were needed to set the vertical height for the springy beam itself, and the horizontal spacing for the spring supports — handrail knobs of unknown origin —  used the CLAG worked example. Unfortunately drilling the holes for these did not go 100% well, a lack of attention resulted in a wandering drill and a hole that was about 0.5 mm below the intended location. I fixed this by soldering some 0.8 mm rod into the hole, filing it flat, and drilling again, by hand this time.

 

 

 

More soon …

Edited October 25, 2021 by RichardClayton
To remove typo

[RichardClayton]

So the High Level horn locks have arrived and been assembled. These really are things of beauty, and almost foolproof.

 

 

I then fitted them using my chassis jig and the coupling rods. These are upside down, but it is the distance between the holes that counts. This photo shows the first group of horn guides in position but not fixed — the eagle eyed reader may notice that they aren’t all aligned to slide vertically.

 

 

Then it was time to replace the jig axles with the long ones to fit the other set of horn guides.

 

I’m kinda committed now, and I won’t know if this CSB business is going to work until this model is a lot further down the line. So As a distraction I have started on the tender …

[RichardClayton]

In parallel I have been finishing off the J94, which now has glazing, coal, couplings (at the back), and a suitable coating of filth. She still needs a crew, but is definitely getting there, and may get to stretch her legs on South Pelaw at the weekend.

 

 

The daylight under the boiler is especially pleasing.

 

 

And is hopefully an improvement on where we started.

 

[RichardClayton]

Time for an update on the WD. The tender is complete, and was a straightforward if time consuming build. I have opted to use Markits WD handrail knobs. They are about 0.8 mm diameter, so not far off scale, and much easier than drilling rod.

 

The boiler and firebox have been rolled (thanks to Pete55 for the loan of his rollers!), and the locomotive is starting to look quite WD-like.

 

 

And so to the job I have been putting off — fitting wheels to axles, fitting the coupling rods, and then getting them to rotate. My usual approach is to fit one wheel using a drill press and a flat surface — in this case a small vice.

 

 

Next the bearings are fitted, with a quick check the everything is the right way round.

 

 

Followed by a gentle squeeze in my GW quartering jig, using a back to back gauge to set the distances correctly — the axles had already been filed to the correct length.

 

 

I have now begun the laborious process of fettling the coupling rods to get it all running smoothly. So far the wheels rotate, but stiffly.

[RichardClayton]

Getting the chassis to run smoothly took some time. I needed to fettle the horn guides, some of which were not exactly perpendicular, and the quartering was a little out. I decided to make a quartering jig, probably more time consuming than buying one of the commercially available offerings, but satisfying nonetheless.

And so to the thorny question of clearances behind the crosshead, something that I have been worried about since starting the kit. The coupling rods have a recess, which nicely accommodates a filed down Markits deluxe crankpin bush, and there is a nice gap between the bush and the back of the crosshead. Phew. Just goes to show that careful measurements at each stage pay off.

 

 

[johndon]

Nice work Richard, looking forward to see it romping round South Pelaw...

[RichardClayton]

Ideally clanking rather than anything more refined or high speed -- does anyone know if there is a sound chip that captures the rather unique sound of these beasts?