Main frames and components that are hidden from view should be constructed using the heaviest plasticard available. Once you have decided on the thickness of plasticard, remember to deduct this from the overall external dimensions. With the shape drawn on the plasticard and using your P-cutter and steel straight edge, scribe lines fractionally outside the required final edges. This will give you the minimum amount of cleaning up: it is easier to cut a line than to sand one. The P-cutter scribes a V-section in the plastic (this must also be allowed for). On thinner plastic card a single pass of the cutter should be sufficient; on 2.0mm plastic you may need
two or three. Under no circumstances cut through the plastic with the cutter; the most accurate method is to snap it. The edge of a table is ideal; with the scribed line on the exact edge of the table, support the remaining plastic with even pressure and apply firm downwards pressure. If necessary ensure even pressure by using the steel straight edge;
smaller sections can be held with pliers and snapped. On the very thinnest plastic use your hobby knife to cut a groove similar to a plough with surplus plastic either side of the cut, which you will need to sand down after removal.
Once the plastic is cut or snapped it will need cleaning up. Use a medium grade wetordry paper. Do not sand in one direction only; however many movements you make in one direction, turn the plastic 180 degrees and repeat. The True Sander described in the tools chapter is especially designed to produce 90 degree or straight lines.
Joints
When two pieces of plastic are to be joined then you will need to decide on the joint.
Many modellers always adopt bevelled joints (bevel: a surface that meets another at an angle other than a right angle) even for 90 degree joints; personally I always use butt joints on right angled joints. The only consideration is to deduct the respective plastic thicknesses from the overall external thickness. If you have raking 90 degree joints, then make a template of the required angle, or use a stainless steel protractor for setting or checking angles once the two surfaces are glued together. Use a plastic solvent for the initial set, leaving for a few minutes until the plastic cures. If the joint is to be exposed then apply the super-glue with fine wire to the internal face of the joint.
You can afford to be less immediately precise on the external joint. Generously apply both super-glue and baking powder to the complete external joint, finishing off with super-glue to seal the powder. The super glue/baking powder should be proud of the joint.
Depending upon the extent of the filler, choose an appropriate file to remove the initial surplus. Use wetordry number P320 with water on one flat surface; then change to the other surface and repeat. You will observe that both the plastic and the filler will become matt as you sand. Between these two will be a small area of glossy untouched plastic. Change grades to P600 and continue. As you gently sand, this area of gloss will slowly decrease.
Use your eyes and touch to judge when you have a perfectly clean joint. Not only will you have a clean, precise joint but the super-glue/baking powder will have added enormous strength.
With non-90 degree bends you will need to bevel the joints. Without the super-glue/baking powder you will need very precise bevels; with this method, near enough is good enough!
Obviously, try for the best joint possible, but the excess filling method will mitigate any bad bevels. All surfaces should be wiped over finally with P1200 wetordry.
Left and above
Examples of the type of super-detail work which can be achieved with fine brass of various cross-sections, etched brass detail, lead foil, and plastic. These components were made up for the author's 15cm sIG 33 auf Fahrgestell PzKfw II.
Right
The completed 15cm sIG 33 (see also Chaper Nine).
CONVERSION & SCRATCH-BUILDING
Below
The resin winch from the Bergepanther; this was the test shot from my plastic master. The main gearbox and large drum were made from laminations of plasticard; the wire cable is from nylon - this is preferred to cotton, which frequently has minute surface hairs which only become apparent during the dry-brushing process.
Bottom
Resin, plastic, white metal, copper and brass were all used in the modelling of this pulley and frame.
Lamination
If the item you wish to construct is over 2.0mm thick then you will need to laminate the plastic. If the component needs to be e.g.
8.5mm thick, I would choose four sections of No.80 (2.0mm) and one No.20 ( 0.5mm).
From the template of the required shape cut out the five identical shapes and glue them together. Apply super-glue/baking powder to the exposed surfaces, and sand these to a clean, precise finish with wetordry. It is normally appropriate to make the template a little oversized to allow for gluing errors.
Once again, remember never to sand excessively in one direction only - use the 180-90-180 degree technique.
To make circular objects I use the compass cutter to cut the plastic. Sometimes, however, the object is too small for the radius of the cutter, or the thickness required is in excess of the tool's capabilities. Your motor tool can also be used as a small lathe. If you need to reduce the diameter of the disc then drill a hole in the centre of the circle (the compass point is your marker) of the same size as your mandrel. Fix the disc to the mandrel, and at the slowest speed sand the disc down to the desired diameter. You can laminate discs in the same way as described above, allowing an extra 1mm over the required diameter before cutting from the card. Laminate the discs, drill through the centre, install the mandrel, and repeat the sanding technique. If the motor tool can be clamped then the side of a knife blade can also be used to reduce the diameter of the disc. Always finish off the disc with P1200 gauge wetordry.
This Panzerjäger was one of my first substantial conversions, using plastic, brass, copper and while metal. Very fine brass L-section rails are used on the gun cradle; U-section brass on the base of the barrel enables it to travel back and forth, making it easy to remove during the painting stage.
Even though this model would be described as a scratch-build, I consider it foolish to totally construct items such as e.g. the road wheels and tracks, when Model Kasten markets such outstanding products. There are very few models which are 100% scratch-built - they invariably incorporate some purchased accessories or spares.