Part 16 - The Chassis Cosmetic Details 3
The WheelsMissing from the wheels at this stage were not just the balance weights, but also the cosmetic axle centres which are part of the Exactoscale wheel system. I had not worried about either of these up to now as all the necessary bits were quite simple and supposed to be there, either as part of the wheels “package” or provided by the kits. Somehow, life is never quite that simple.
Balance weights.
The GER was very given to having standardised designs for bits of their locos, boilers for instance, and thus bits built into one class could show up on another as they passed through the melting pot which was Stratford Works. Considering that the wheels under the J65 and J69 are essentially the same 4’0” 10 spoke 10” throw design, they were clearly not that standard when you start considering the balance weights that were cast into them. The J65s cylinders had a shorter stroke, and hence a different crank axle, to those on the J66/7/8/9s, so the balance weights were bound to be a bit different.
None the less both kits came with etchings for balance weights which I just assumed would be a doddle to fit, so I didn’t worry about doing that till very late in the day. Well I won’t do that again. In future I will be sorting out the balance weights out right back at the very beginning. The two classes presented different problems.
By the way, if you happen across a picture of a Buckjumper with rather different wheels, you need to know that loco’s not intended for passenger work had totally different unbalanced wheels with lots more spokes.
J65For some reason the GER fitted the first 10 built of these locos (including 155 my subject) with a balance weight design all of their very own. This dispensed with the traditional crescent shapes and add significantly to their character. The non-driven axles (front and back) had balance weights that totally in-filled the space between the spokes opposite the crank pin. On the driven centre axle, a square ended balance weight is fitted in the more usual place against the rim. This bridges three spokes, the ones either side of the crank pin and the one in advance. The second ten built had wheels with balance weights that looked much more like, but were smaller than, other Buckjumpers.
The snag came when I tried to apply the balance weights provided in the kit. Particularly those that were supposed to be applied between the spokes on the non-driven wheels. These may well have fitted on whatever wheels were available when the kits were designed. On the Exactoscale wheels they just dropped through the hole between the spokes. That said they were not far out, so I laminated them onto some scrap brass sheet and filed out slightly larger ones with a little lip (less than 0.5) all round. Particularly given the lip round the edge, these now fitted nicely and were superglued in place. The balance weights destined for the driven axle were also wrong in as far as they covered more than 3 spokes and one end were a strange shape, presumably to avoid the crank pin. Surprisingly, removing the extra odd shaped bit at one end and squaring up that end leaves a good representation of what should be there. Again these were superglued on.
buck j65 bweight.jpg
Note that it was at this stage that the J65 became a 2-4-0.
J69Again, the kit comes with a set of balance weights which didn’t satisfy. Those that were fitted to the prototype were really quite beefy, and those on the driven axle were particularly large, partly enclosing the crank pin. Those in the kit were distinctly anaemic by comparison. They did fit the wheel curvature, so I used one as a pattern for the curvature of the rim and filed up new ones which extended rather further round the wheels. That was fiddly, particularly where the driven axle ones fitted round the crankpin. As the wheels are lightly dished getting them to fit flat against the rim and the spokes wasn’t easy, particularly the big ones on the driven axle. They were again fitted with superglue.
buck j69 bweight.jpg
In both cases, a close look would reveal that they were just thin overlays, so I filled in behind them with epoxy putty, which also helps to glue them rather more securely in place.
Axle endsThese are nice little disks of turned stainless steel which are supposed to be a good fit into the hole in the centre of each wheel that are visible in the picture at the end of the last posting. Unfortunately, this supposition was not borne out in reality. They were just a touch too big and no way could I get them to go in. Oh ***. I wasn’t at all sure how Exactoscale managed to get me into this position, but this appears to be a bit basic. I did wonder if I’d missed a trick of some sort and given the right approach they would happily pop in? Anybody else been here? The instructions (if you can find them, they are no longer available off the internet) are silent on this topic.
Anyway, in my world they were all accurately machined to 3.00 mm +- 0.01, and they weren’t going in unless they were no larger than 2.90, which isn’t much but apparently it was enough. Fortunately, they are turned with a step on the back which I could grip in a collet in the Dremel, and I was able to “turn” off the excess 0.01 against a file. They would then go in.
Once they are in, the question arises what you do if you ever want to get them out again. This you will need to do if you ever want to disassemble a wheel set again, after all one of the Exactoscale wheel advantages was/is supposed to be that multiple re-assemblies should be possible without them becoming loose on the axle. This all became that bit more pressing for me as it turns out that once you’ve turned enough off so that they will go in, they go in rather to far, and are not flush with the surface of the wheel as they should be. When I first put them in, I hadn’t worried about all this too much and I had been applying a light coat of water soluble PVA to ensure they stayed in place. Reviewed after the event, being recessed into the wheel just didn’t look right at all.
After an hour or so soaking in water, some could be popped out again, some couldn’t. As they have a small turned indent at the axle centre it proved possible to drill those that wouldn’t come out 0.5mm neatly in the centre. Once this hole was deep enough it gave a 0.5mm rod sufficient leverage to pop them out. When I finally put them in again, a small pad of blutack was used to ensure they stayed flush with the surface and they were all lightly drilled so they looked the same. I stuck with the PVA, as pressing on one edge should brake that bond quite easily, given the soft pad of blutack underneath.
Buck j69 wheel centres.jpg
This picture shows the starting position, with a couple of the end caps in view. The second shows the problem with the end cap deeply recessed and drilled so it can be removed. The third shows the hole packed with blutack, and the last has an end cap flush with the wheel face, as it should be but not yet drilled so it matches the rest.
Here ends work on the chassis.
RC 35580
You do not have the required permissions to view the files attached to this post.