It's been a while since I've done anything about the rolling stock for the layout. Most of my modelling has been concentrated on loco building, but I knew I would need some stock to go behind a loco so my attention has turned back to rolling stock. One of the first things needed is axleguards for wagons. There are some etched brass ones available from the S scale parts store, but I would be looking for ones which would be more suitable for Caledonian and other Scottish pre-Group companies, and I wanted sprung axleguards as well.
I had already drawn up artwork for sprung axleguards to go under the Drummond four-wheelers which had worked fairly well but needed a bit of fine tuning. So I opted to adjust the original artwork to (hopefully) improve operation and got PPD to re-etch them. And last week, a nice shiny sheet arrived back from Lochgilphead.
Ten sets are laid out as individual sets so that if there is a possibility of the axleguards being wanted by others, individual sets can be broken off quite easily.
An individual set in close-up.
...and the individual parts broken out of the etch with the tabs folded up, along with an Exactoscale 1.5mm OD parallel journal bearing and a spring from (in this case) 0.0085" guitar wire. Just below the spring wire you can see the holes for the spring in the base, when it is folded up.
A dry run with the parts. the spring acts on the tab at the top of the bearing carrier and it also holds the carrier in place, as does the axle when it is in place. The bend in the spring wire, as seen in the previous picture, prevents the spring moving right and the lug at the left prevents it going too far in that direction. The spring is inserted from the left, bending it gently over the lug to get it in the hole.
The intended method of assembly is to insert the bearing carrier until it sits on the lugs at the top of the "W" iron, then flex the spring wire to get it to sit on the lug on the carrier. The spring wire can be flexed by gripping the projecting end and wiggling it around. The operation has to assume that there is no easy access to the spring and bearing carrier from the inside since a 3' 7" coach wheel does a good job of covering everything up.
The first adjustment to make to the etch was to bevel the tops - left - to allow the spring to be flexed over easily. Also, the lugs at the top of the "W" irons were reduced from 1mm long to 0.5mm to make slipping the bearing carrier up over them a lot easier.
I also need some parallel journal axles. The S scale Parts Development department had investigated getting them produced but the minimum order quantity was something like 10,000.
We reckoned that might have supplied the next two generations of S scale modellers.
So I worked out a way of producing my own. I've finished up turning the points off the Society's pin-point axles (plenty of them
), drilling them 1mm and inserting short lengths of 1mm silver steel rod held by small dabs of cyanoacrylate. This works well and takes only a few minutes per axle in the lathe
This is the assembly complete with the axle to check that everything fits and works.
...then the assembly with the wheels on the axles. I'm still fiddling around to find out the best way of getting the spring in the right position. Sometimes I get it in position in a couple of seconds and at other times, I have to fiddle around for quite a while before I get it right. I'm also going to fit it in an underframe in case anything gets in the way and fouls the flexing of the spring. I'll also have a try out with wagon wheels since I suspect that the smaller diameter wheels will allow easier access to the spring from the inside and the external flexing of the wire won't be required.
The total movement of the springing is 1mm with the correct height of the vehicle being when the spring is at mid travel.
The original etch was designed to use the Exactoscale 2mm diameter bearings and I opted to use the smaller 1.5mm diameter bearings for the redo, but I think I will revert to the 2mm diameter bearings for any future etches. The bearing projects through the carrier and locates in the slot in the "W" iron. What I didn't realise is that the smaller diameter bearing is also 0.25mm shorter, so doesn't project as much through the carrier. This means that the positioning of the "W" irons needs to be quite precise. The longer 2mm diameter bearings will give an extra 0.25mm of projection which will give a good bit more leeway in the positioning of the "W" irons.
Jim.
