This week I have another replacement part to share with you. As with most of my replacement parts, this was a request from a customer who has one of these locomotives with a damaged part.
The Airfix class 14xx 0-4-2 model has been around since the 1970s, and was a mainstay on many UK model railways as they were the only maker of the model. It’s had several upgrades over the years as the model moved to Dapol and then to Hornby but the original can still be seen running today.
However, constant use over time will always cause parts to wear out and with the 14xx it’s the main drive gear that starts to go. The original chassis had a thicker gear which can be seen at the top in the image below. The thinner gear is for one of the newer chassis introduced under the Dapol line. Interestingly Daopol also moved the traction tire to the other wheelset.
The metal worm gear on the end of the drive shaft drives sits directly over the main axel drive gear and the metal eventually wears down the plastic gear, especially if the wheels get jammed up or start to bind, due to lack of lubrication.
The gear in the image below is still in good condition, but you can see the teeth are intentionally not square to the axle. This makes the mesh between the two gears smoother and improves the running of the loco.
Using the original I was able to 3D model a replacement. Because the gear is thick, 3.18mm, it should be strong and hard when printed in Shapeways Smooth Fine Detail material.
The test prints came out very well and were immediately ready to use. The hole in the center has been printed slightly smaller than the axel size to ensure a good tight fit. If it’s too loose the gear will spin on the axel. If it’s too tight the new gear may crack. To allow for any 3D print shrinkage or oversize on the axel, I’ve 3D printed two gears; one has an even smaller hole to allow for any differences mentioned above. It’s always easier to remove material if it’s too tight than it is to add some!
To identify the two different gears I’ve marked the side of the gear with the smaller axel hole with a hole in the sidewall as you can see on the gear on the right.
The replacement pair of gears for the Airfix OO 14xx are available using the link here.
As long as I can find an original gear, even if it’s cracked or damaged, I can replicate it using 3D printing, so contact me if you’re in need of a new gear that you can’t get hold of.
Next week I hope to have some more to share with you on the HO DT6-6-2000 project, the brass etches are in production, and the different variants of body shells are being drawn.