Start in ‘O’ gauge – Part 2
Our locomotive building expert Dave Lowery upgrades a Bachmann ‘56XX’ with an etched brass chassis kit from Comet Models.
Bachmann’s ‘OO’ gauge ‘56XX’ is a fine model, with plenty of detail to admire on the bodyshell and a reliable mechanism. However, the chassis inevitably has a slightly ‘hefty’ nature, due to the fact that it’s based around a solid metal casting. That’s not a criticism of the model, it’s an inevitable feature of a RTR model, especially one who’s design harks back to 1990s practice.
For modellers aiming for greater finesse, there’s the option of a replacement chassis kit from Comet Models. Comet has been offering etched metal chassis kits for years, with a large number of steam locomotive classes on offer, and most of them are designed to suit specific RTR models. They offer great value and are ideal for upgrading older models in particular, while also offering the ideal means of teaching yourself how to erect an etched chassis without the financial commitment of a complete locomotive kit.
The chassis pack contains a pair of etched brass sheets, consisting of sideframes, ‘OO’ spacers, coupling rods, brake shoes, brake pull rods and balance weights. Along with the chassis kit, you will also need a new set of driving and trailing wheels and crankpins; each of these is available in the Markits range. You’ll also need a new motor and gears, with the Mashima MH1624 motor and Comet gearbox being recommended. However, I used a slightly smaller Mashima 1620 unit and a Markits gearbox set. Mashima motors are no longer in production and can be tricky to obtain these days, although they can be found on internet auction sites and some suppliers still have stock of certain models (such as Scale Link). However, some suppliers are offering other brands, such as Canon, as potential replacements, so it’s worth doing a bit of shopping around.
There were a few challenges with this kit.
Firstly, the etched fret is a little on the flimsy side and is really designed to be built with hornblocks and working suspension. Because we are going to keep it simple and build a rigid chassis, you’ll need to stiffen up some areas of the sideframes, particularly around the axleboxes, where there is a gap on each side that needs to be bridged. I filled these gaps with brass rod, soldered into place. Additionally, where the etched leaf spring detail meets the ‘J’ hangers is a potential weak spot, so I also added a touch of solder here to add some strength.
Otherwise, it all went together without any problems, although great care has to be taken to ensure the frames are aligned correctly. When it came to the two spacers B and C, at each end of the chassis, it’s worth adding them once the chassis has been built and test-fitted into the bodyshell. You can then use the original chassis screws to locate each spacer and then solder it into the frames, taking care when applying the hot soldering iron.