Three-dimensional parts are formed by folding. On an etched brass
kit, the fold lines are normally half-etched on the inside of the fold.
You’ll be able to fold most parts using smooth-jawed pliers. For longer
parts folding bars are desirable.
Other useful tools include a bench vice, a good pair of tweezers, a set
of Swiss files (get a full set of cheap ones and then buy quality
replacements for the three that you use the most), a pin vice with a
selection of drills from 0.5mm to 2.1mm plus a few larger sizes that
you use regularly (2.6mm for axle bearings etc), some square-nosed
pliers and some very pointed-nosed ones, preferably with smooth
jaws. Buy cheap tools first and duplicate the most used ones with
quality.
Try to complete all high-temperature soldering before attaching any of
the cast whitemetal parts. These can be attached with two-part epoxy
resin such as Devcon or Araldite Rapid. Ensure the surfaces to be
glued are clean and free of grease.
A better alternative is to solder your white metal castings using Carrs
70 degree low melt solder and Carrs red label white metal flux. The
iron should be run at a much lower heat so that you do not melt the
castings. I have a domestic light dimmer switch and plug socket fixed
to a piece of wood, wired up with a lead and 3 amp mains plug to the
input side of the dimmer switch and the output of the dimmer switch
into the plug socket (remember to continue the earth). Plug your 40
Watt iron (25 Watt iron won’t work) with a clean and freshly tinned bit
into this and experiment with adjusting the switch until you find the
range of temperature at which the solder melts, but a scrap casting
does not. Note as the iron is running at a lower voltage it will take
longer to heat up, so when you think the adjustment is correct do
check a few minutes later on another scrap casting to see that it
doesn't melt. Then scribe a mark on the switch knob to indicate this
position.
When attaching white metal fittings to brass the surface of the brass
must be tinned with 145° solder, to allow the solder to grip. The
surface of the casting at the joint should be burnished bright. The
casting can then be soldered into place with 70° solder and fillets of
solder run into any gaps with no risk of melting the casting.
Don’t load the iron tip with a lot of extra solder, but work the joint in 1”
lengths, bringing in small quantities of solder. Brass is a very forgiving
material and if you get something out of alignment, use heat from the
iron to desolder the joint before starting again. For complicated
assemblies, it is a good idea to only tack solder parts together. You
can then make adjustments by desoldering until you are happy with
the location of parts and then solder solid.
When you need to laminate two or more layers of brass together,
align the parts and carefully clamp them together, either in the vice or
by holding them with miniature crocodile clips. Run flux around the
edges, and then go around with the soldering iron. Clean up
thoroughly afterwards.
To fit small parts and overlays on to a larger assembly, such as
strapping to a wagon side, when you need to prevent finely detailed
areas such as planking becoming clogged up with solder. Tin the back
of the small component first, then hold in place on the model and apply
flux. Carefully wipe the tip of your iron on a sponge to remove any
solder from it (dry iron), and then touch it against the parts to be joined.
After a few seconds you’ll see molten solder bubbling from the edges.
Remove the iron, still holding the parts in place, and allow the joint to
cool. An alternative is to use solder paint (I would recommend Carrs
188 solder paste). As the name suggests, this is a flux and solder in
one. Simply apply a thin coat of solder paint to the back of the
component instead of tinning. Still apply a small amount of liquid flux
before you solder the part into place.
Any surplus solder should be removed using a craft knife, I find No 10
curved scalpel blades ideal, then burnish clean with a glass fibre
brush. With practice, you’ll learn how to use the minimum amount of
solder to do the job. Flux is corrosive so, after each soldering session,
give your model a good scrub with washing up liquid or Jif. After a day
or two, any remaining flux residues will show as a green film, which
should be washed away.
To cut parts from the fret, use a sharp Stanley knife on a piece of
hardboard or a pointed scalpel blade on a block of softwood. Remove
tags and burrs with a fine file.
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