In February of this year, I shared with you my design for a replacement set of Bachmann OO Chassis Fasteners & Washers; you can find the post here. Since then I’ve had some requests to do the same thing for the N Scale Bachman US locos. So in this week’s post, I’ll share with you my design for a replacement set.
Unlike the OO set, Bachmann still has the N Scale version listed on their website as spare parts, but they’ve been out of stock for some time. The fasteners in question are used in the older locomotive designs from the 1980s. A typical example of this is Bachmann’s GP50 as shown below.
The chassis is a split frame design also used in several other locomotives, such as their GP40 and U36B models. It’s held together by the two chassis fasteners at the bottom corners of the chassis.
Viewed from the other side you can see the screw heads which pull the fasteners tight.
With the screws removed, the chassis separates and the trucks and motor will drop out. You can see the fasteners and a washer still in the upper chassis section.
The fasteners will push out and the washer will drop off.
Both the fastener and washer are made of plastic to electrically isolate the two chassis halves. The washer also acts as a spacer to correctly position the chassis halves.
As with the original OO versions, with time the type of plastic used hardens and becomes brittle, so when the screw is removed the cylinder part of the fastening breaks off of the rectangular sections as shown below.
Interestingly the OO and N Scale versions at first glance appear to be the same, but after doing some measuring I discovered the N Scale fastener is shorter and fatter. This means the N Sale washer also has a larger hole. Below you can see my OO fasteners and washers in white compared to an N Scale original one in black.
Using one from the GP50, it was easy to modify the existing OO version to create a new fastener for repairing N Scale Bachmann locomotives which have suffered from this part failure.
As with the OO set, the hole in the middle of the tube section will need to be cleaned out to remove the 3D print residue before the screw can be inserted. For the N Scale fasteners, I use a 0.8mm drill bit in a pin vice.
The inside of the tube has not been threaded for the metal screw so it’ll work as a self-tapping screw, cutting its own thread the first time it’s inserted. But if the tube is blocked, the excess material will create too much pressure and the tube may crack.
These replacement fasteners and washers can be used on a large variety of Bachmann N Scale locomotives and I’ve made them available in a set of 6 here and a set of 12 here. I thought it best to make the smaller set start at 6 so you have a few spares just in case something goes wrong.
These little fixes are ideal for 3D printing components, so if you have an idea for a part you’d like to see 3D printed please drop me a message, I’m always interested to hear what fellow modelers are working on. You can get in touch through the contact page.