MODELLING TIPS  (Model Slipway Kits)

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TOOLS

To build one of our models, the following is the minimum required: a sharp modelling knife (Stanley knife), scalpel and spare blades; a large cutting mat or hardboard sheet; a jigsaw or bandsaw; a steel rule or straight edge; a pair of spring calipers; small clamps or clothes pegs; a small vice; hand drill or small drill and bits (from 0.5mm to 10mm); mini-drill with a 25mm dia. tungsten cutting disk; a selection of files; a couple of small screwdrivers; miniature spanners; pliers and side cutters; tweezers; small artist's paint brushes with wood handles (for gluing); wet and dry sandpaper of various grades (100, 200 and 380) and a sanding block; elastic bands; masking tape; tape measure; a 30W soldering iron, solder and flux (if you wish to solder).

STYRENE PLASTIC

Styrene sheet or more commonly called plasticard is available in different thicknesses. The advantage of plastic over wood is that it has a smooth finish that requires no filling (other than on joints) to give a non-grainy finish. With many vessels in steel, wood with a grain does not look right. Plastic does not splinter and smooth holes can be drilled. 

Before applying a primer or paint, it is always best to flat off a shiny surface. 800 - 1200 grit Wet or Dry works very well, especially if you wet it first and work with a gentle, circular motion.

Printed Plastic: Using a steel rule, lightly score the material with several strokes. Place your thumbnails either side of the score, and with your fingernails on the underside, raise this line up towards you. This will cause the plastic to fracture along the score line and then simply bend away from you and the part will snap out. Complex shapes can easily be 'chased' along all pre-scored lines. Cut well outside the marked outline of a curved component, then file or sand back to the correct profile. If a raised ‘burr’ is left along the cut edge it can be removed by dragging a Stanley blade along that edge.

Die-cut Plastic: The die-cut parts are not fully cut through. Place your thumbnails either side of the score, and proceed as above. It is helpful to mark the numbers onto the pieces with a soft pencil, and then rub them out before painting.

CNC-cut Plastic: The pieces are not fully cut through. Using a new blade in either a scalpel or Stanley knife follow against the cut edge of the part and remove the part from the sheet.    If a raised ‘burr’ is left along the edge it can be removed by dragging a Stanley blade along that edge. It is helpful to mark the part numbers onto the pieces with a soft pencil. 

Bending Plastic: Place the area to be bent in hot water and gently bend. Alternatively, place the area over the edge of the bench and run it back and forth. If you have to curve strips of plastic along their length, hold between finger and thumb at the centre, pull your hands apart bending down as you pull - this will curve the strip to a gentle radius.

Drilling Holes in Plastic: Styrene does not like heat and a power tool that runs fast generates heat. It is advisable to use a hand drill or a slow power drill.

Assembling & Gluing Plastic: Assemblies of die-cut or printed parts (superstructure etc.) can be made easy if the parts are held together and built up using 4-5mm strips of masking tape. This will ensure close tight joints and most of all, allow you to stand back and check for accuracy before applying the glue. 

The best type of glue is liquid polystyrene glue of which there are several brands available. This is applied either with a bottle cap brush supplied or a small paintbrush. Simply brush along the inside of the joint and the liquid glue will 'capillary' along a good fitting joint. Keep the glue away from taped areas. After a few minutes the tape is removed and the joint can be re-glued on the outside. A note of caution: avoid using excess adhesive - it works by dissolving the plastic and too much will create deformation. This glue will evaporate quickly if uncapped.

If a joint looks stepped or untidy, it can be fettled, sanded and scraped clean (with a Stanley blade) after a few hours when the glue has thoroughly dried. If done well the joint is almost invisible! Practice on scrap plastic in order to perfect your own technique. When gluing the deck to plastic deck supports, always rough the surface of the plastic to give it a key.

VACUUM FORMINGS

Pencil in the trim line. Using a sharp modelling knife, score the plastic heavily around the trim line, and carefully snap away the waste material. Remove as much waste material with a knife or scissors as possible. Final trimming of edges is done by rubbing the component with a circular motion on, or with, a piece of medium-grade abrasive paper taped to a flat surface.

Before gluing vac-formed parts together, have a "dry run" using thin strips of masking tape to hold them together.   This will allow you to make any necessary adjustments. Vac-formings do not require priming before painting if you use plastic enamel paints. Wash with a little detergent before painting.

GLASSFIBRE (GRP) HULL

The hull is produced from a split mould and there may be a joint line in the centre of the moulding.  Remove this line using a fine file and fine sandpaper. The hull needs to be rubbed down with 380 wet or dry abrasive paper to matt the surface and provide a key for the paint. If a hull is slightly distorted due to being laid on its side for a long time or stood up on end, it is possible to bring it back to shape by warming it with a hair dryer.

Drilling holes in the wrong places in the glassfibre can be easily fixed. From the outside of the hull cover the hole with a piece of masking tape.  Mix up and pour some gel-coat resin from inside, alternatively car body filler paste will do equally well. When set, remove tape and rub down flush with wet and dry abrasive paper. If necessary apply more filler. Reinforce the repair from the inside with a shallow ‘mound’ of filler.

To cut out freeing ports   or large openings in the glassfibre hull, proceed as follows:- mark in pencil, then drill a series of holes along the slot and open up carefully with a small flat file. File from the outside inwards only and don't drag the file back out as this can chip the gel-coat.    

Alternatively use an electric mini drill with a 25mm dia. Permagrit tungsten cutting disk.  Hold the drill with both hands as it can tend to grab and jump.    

If you need to remove glassfibre from inside corners use a Permagrit cone wheel.     available from Permagrit Tools, UK.  Do take appropriate precautions (i.e. gloves, eye protection, face mask) when cutting and sanding fibreglass.

WATERLINE

To determine the correct waterline, mark it off at the bow and stern, from the plans. Sitting the hull on the stand, mount a pencil to a block of appropriate height and draw the waterline lightly by sliding the block round the hull.    

GLAZING

Clear plastic material for cutting out the various panels required to glaze the wheelhouse and portlights can be cut exactly like plastic styrene although it is much more resistant to scratches. Glue in place with Weldbond, RC Modeller's Craft Glue or clear contact adhesive (UHU, Bostik etc.) after painting the model. The glue used by aircraft modellers to attach the clear canopies to the fuselage will do the job. It comes under several brand names. It is a PVA type glue which goes on white but dries clear.
Note, the glazing sheet has a protective film on each side; remove only from one side for gluing, them remove film from the other side when finished.

WHITE METAL FITTINGS

Clean up any flash, or mould lines on cast metal fittings, using fine files or fine sandpaper. Surfaces, which are to be flat should either be filed or rubbed across a sheet of Wet and Dry paper glued to a surface (use a contact adhesive). Apply a coat of primer or matt white paint before final painting.

Spraying and painting small fittings like railings and vents can be a bit of a trial. Drill a piece of flat wood at intervals to take the parts, then cover in double-sided sticky tape; push the parts into place to be held firm by both tape and hole. You can then spray away to your hearts content and they will stay put. 

PHOTO ETCHED BRASS

Use a sharp modelling knife/wire cutter/scalpel to separate the components ensuring this is done on a firm surface. Snip through the tags and clean up the tag scars by holding the part in pliers and using a fine file or sandpaper (P400 or even finer). If a part has to be folded, support up to the line of fold and fold in one go, holding the part in pliers and using the blade of a screwdriver to fold.

For assembly use thick Superglue, UHU, Araldite on a grease free surface. Brass is ideal for soldering.  Apply a coat of primer or matt white paint before the final paint.

PROPSHAFT

To install the propeller shaft and tube, drill a hole into the hull using a drill smaller than the tube diameter, and then open it up with a round file. Before fixing the prop shaft/tube to the hull, using emery paper lightly abrade around the gluing area in order to provide a good key. Use masking tape to hold assemblies in place and to allow final adjustment.    Apply a small amount of epoxy to hold in place. When set and you are happy with the alignment apply more epoxy over the joint inside and outside the hull. When dry, sand with medium grade sandpaper.

Applying grease into the propshaft tube or "stuffing box" is not always the best idea. A tube packed with grease can create a lot of drag on the rotating shaft, which can slow the motor and cause poor performance and overheating. It is recommended to apply light machine oil to the bearing ends.

FILLERS

For fibreglass: holes and gaps can be filled using a ‘soft’ paste car-body filler available from car accessory shops or DIY stores. When the filler has hardened, sand flat with fine wet or dry paper.  

For plastic: again use a ‘soft’ paste car body filler, or, Humbrol plastic filler available in model shops. Alternatively make your own filler by adding styrene shavings to any suitable solvent such as acetone in a small glass jar, screw the lid on tightly to keep the solvent from evaporating and leave overnight. The plastic will dissolve and form a putty. You can then use it as a paste to fill any gaps etc. If the paste is too thick, add more solvent - If it's too thin add more plastic. 

ADHESIVES

Adhesives may be in tube form (polystyrene cement) or in liquid form such as Humbrol Liquid Poly or MEK (methyl ethyl ketone) which is best applied with a brush. The technique is to apply a few drops of the solvent and the glue will run down the joint by capillary attraction. The following glues are recommended:

Fibreglass to plastic: two-part epoxy (Devcon, Araldite, Speed Epoxy) - 10 min. or 1 hour. 
Plastic to plastic: ordinary plastic solvent (Revel, Liquid Poly, Slaters, MEK). 
Whitemetal to whitemetal: two-part epoxy (5min.) or thick superglue (Pro-Bond, MFA etc.) 
Whitemetal to plastic: two-part epoxy or thick superglue.
Wood to plastic: two-part epoxy, thick superglue or contact adhesive.
Brass to plastic: R/C Modellers craft glue or thick superglue.
Rubber Fendering: contact adhesive (UHU, Bostik). 
Window glazing: Weldbond, RC Modeller's Craft Glue or clear contact adhesive (UHU, Bostik etc.)

MOTORS & MOUNTS

There is such a variation in motor performance that, generally, it is best to follow the kit manufacturers recommendations. To remove the motor in seconds, a simple motor mounting can be made using triangular blocks of wood and rubber bands. Proceed as follows: fit the motor to the coupling and shaft, hold the motor to roughly the correct position to assess the size of the blocks. Cut blocks to suit your application. Pre-drill and fix hooks or large head screws. Apply epoxy glue to the underside of blocks and place either side of the motor. While the glue is wet the blocks can be pushed inward to raise and align the assembly. An alternative method of installation is to screw or bolt the motor to a block or blocks glued to the hull

SPEED CONTROLLERS

You need to know the stall current of the motor to determine the rating of the speed controller (this applies to cars, boats or planes). You will need the motor and battery you will be using, and an ammeter or an electric test meter. Proceed as follows:

1. Set the meter to the highest amperage scale, e.g. 10 amps

2. Connect one terminal of the motor to the battery (-). Connect the battery (+) to the meter. Connect the meter to the motor.

3. The motor will run and show a meter reading. If it shows a negative i.e. backward reading simply swap meter wires. It will show something in the order of 1-2 amps while free-running.

4. Apply a pair of pliers to the motor shaft (using a piece of cardboard or cloth to protect it) and momentarily stop the motor. The meter will now show a much higher reading. This is the stall current, it could be 10 amps or more.

5. If the meter reading is below 10 amps you can use a 10 amp speed controller. If it shows anything between 10 and 20 amps, then you must use a 20 amp speed controller. If more than 20 amps then change the motors!

HANDRAILS STANCHIONS

Shaping and Soldering:

1. Abrade/clean the entire length of wire with fine emery.

2. Apply flux to the entire length of wire and tin the entire length.

3. In general handrails follow exactly the stanchion holes therefore drill the holes in the deck first then lay the wire over the holes and shape it using pliers (allow extra length for corners etc).  If you need to duplicate railing, i.e. two, three or four rails, simply  tape another wire to the “pilot” rail and use it as a master.

4. Cut all (tinned) uprights overlong and place them into the pre-drilled holes in the deck. 

5. Hold the top rail onto any upright - usually an end one is easier - and solder them together. Use a clip to dissipate the heat away from the plastic.  

6. Now on to the next upright and solder that one to the top rail, and so on. You do not have to worry about getting them even spaced, upright or even tidy, just make up a one-piece entity, which will stay together. This will probably look a mess but do not worry.

7. Go back to the first rail joint, de-solder it and re-align it. This will now be easy as the rest of the assembly is rigid and holds itself together. Use engineer's squares to get the uprights at the same angles. 

8. Proceed with the remaining uprights, de-soldering and re-aligning them.

        If short lengths of wire have to be soldered between the uprights:

9. Hold the cross piece with tweezers and solder one end in approximate position. The second end can be soldered in the correct place as the first end is already fixed. Now go back and re-solder the first end into position. To get all the cross pieces the same height it is advisable to use a wood block as a spacer.    

10. Always place a clip lower down near the plastic deck to dissipate the heat away from it, as you do not want it melting and making the hole in the deck bigger. 

When the handrail assembly is complete, carefully lift it up from the deck and clean with cellulose thinner. Then paint it. When the model is nearing completion replace the handrail assembly in the original mounting holes in the deck. A drop of superglue can be applied to the base of the uprights.