I managed to move on a bit with the axleguards after being diverted to do a bit of layout construction and also some driving wheel construction for another modeller. I am trying to get a fair bit of weight into the underframe to get the weight of wagons up to what I might need. Using the tables I posted a short while ago, I reckoned on using 0.008" guitar wire with a 0.5mm deflection for the normal ride height. With a total deflection of 1mm designed into the system that would give a wagon axle end +/- 0.5mm movement. Using the tables, this meant a wagon with 14mm between spring pivots would need an all up weight of around 60grms to give an 0.5mm deflection with the 0.008" wire.
I machined the solebars and headstocks for the underframe out of 5mm x 2mm brass strip with rebates in the upper ,inner edges to take the 15thou nickel silver floor such that the floor and the top of the frame parts were flush.
The completed underframe
...the underside...
...and a closer shot of the end. The weight of the this underframe is 31 grms.
The underframe is to go under a Caledonian 6 ton van Diagram 3 goods van. The early examples of this van had vertical, external panelling. Later versions had horizontal planking, but both versions had exactly the same dimensions and fittings, so I aim to build several of both types.
All the parts for the body were milled, with the sides and ends in the centre and lower right, the floor and inner "ceiling" with partitions at the top, and the outer skin for the solebars with all the nut and washerplate detail to stick on the plain brass solebars at bottom left. I found it surprising that this small pile of styrene amounted to 21 grms.
The inner body frame was built up...
...then the outer parts were stuck on and placed on the underframe...
and the deflection appears to be just under 0.5mm, as predicted with Russ Elliot's formula.
And just to show that I am trying to keep up with Messrs Page and Cook...
... you can just about make out the nuts and chamfering on the curb rail.
I also persuaded one of the solebar detail strips to stay in place to show the effect. I intentionally left off the wagon number plate since you can read some of the details on the plates in S scale and I will opt to etch them separately.
The axleguards have worked quite well but I need to adjust some of the measurements since the bearing carriers show a tendency to drop out on occasions. The main reason is that I reduced the size of the lugs which hold the carriers in place with the intention of making it easier to fit the carriers, but went a bit too far - easy to fit, easy to drop out!!!
. So the next etch will have the lugs enlarged to avoid the problem. I also overcooked the undercut allowance for the bearing holes and slots and the fit is distinctly agricultural.
But they will be adjusted for the next etch,
My next act will be to try adding some bits of lead sheet in the "U" channels of the "W" iron assemblies to get the weight up to around the 60 grm mark. I'm also aware that I am probably not going to get anywhere near 21 grams weight for the styrene body parts of an open wagon, so I will want to see if I can get the underframe heavier to compensate. I can always drop back to 7 thou wire, but I would rather stick with one gauge of wire for every wagon.
It will be a bit quiet on this front for a week or so until I get the February S Scale Gazette produced and get the Yate exhibition out of the way.
But the next job will be finding a way of making the distinctive Caledonian three bolt buffers.
Jim.