Confederation Marine Modellers
Styrene has become well-established as a modelling material. It is unaffected by water, has no grain, and can be painted. It is available in flat sheets and structural shapes of different thicknesses and sizes. The most versatile is the flat sheet from which almost any part can be made.
Cuts - straight and curved.
Cutting styrene is a little like sailing a boat. With a knife, you don’t so much cut the styrene as push it out of the way, as the boat does the water. And if you try cutting the styrene with a power saw, you’ll probably find it melts together again behind the blade, as water runs together behind a boat.
You can cut styrene with a knife. You can either score it and snap it, or cut it right through. A small box cutter is very convenient because the cutting edge can easily be restored by snapping off the end. A craft knife has the advantage that it is slightly easier to control because the blade is fixed firmly in the holder. In pushing through the styrene, the blade forms a ridge either side of the cut. This can be removed in a couple of ways; either by running the back of the knife along the edge, or by extending the blade in a box cutter and bending it down on the styrene so that the cutting edge lies flush, and then skimming it along the sheet at the edge, cutting off the ridge.
Another way to cut styrene is to use a cutter such as the Olfa P-800 plastic cutter knife (Picture 1). This actually removes the styrene as it makes the cut and does not leave a ridge. It does leave an angled edge to the cut, which you may not want.
A good pair of scissors will cut styrene up to 0.030” thick. A pair of pruning secateurs are useful for cutting the structural sections. It is easy to cut straight lines by using a rule as a guide. A steel rule with a cork backing minimizes the chances of the rule slipping as you score the sheet styrene. Curves which are arcs of a circle can be cut using one of the tools mentioned in the pages that follow.
Curves which are not circular arcs are more difficult and, if you are not comfortable doing it freehand, one of the most useful tools is a set of French curves. (Picture 2) They are templates which comprise several different radii. They come in two typical styles, one of which is shown below. The other style consists of several rules of quite large radii, and look like straight rules which have been only slightly bent.
It is a little more difficult to cut 0.060” thick styrene. One of the better ways, and maybe the best, is to use a sheet metal shearing tool, such as the Eclipse Goscut 2000.(Picture 3) This tool actually shears a slot in the plastic and is excellent for straight cuts, and reasonable for cutting curves. These tools are long out of production, but you can sometimes find them on eBay.
A second way is to use a scroll saw. To prevent the plastic from melting and rebonding behind the saw blade it is necessary to keep the workpiece moving through the blade at a reasonable speed.
With practice you will find that you can repeat the scoring process with your cutting tool without the use of a rule, as the blade will follow the groove in the styrene. Two or three passes will allow you to snap 0.060” sheet with ease.
Styrene can be filed, but it will leave a burr of melted plastic along the edge. This is easy to remove just by running your fingernail along the edge.
The information available states that styrene dust is not toxic, but like any dust it is an irritant, so the wearing of a dust mask is recommended when filing or cutting.
Holes – Rectangular
Any size rectangular hole can be made by cutting an ‘X’, joining diagonally-opposite corners of the box, in the hole you wish to open in the sheet. Score the perimeter of the hole, and snap out the 4 triangular pieces one by one.
A nibbling tool (Picture 4) will remove small rectangular pieces, from material up to 1/16” thick. Its most useful application is for making rectangular holes, or just sharp internal corners. The finished hole must be bigger than the cutting head of the tool, and, of course, it’s necessary to start by making a hole through which you can insert the head of the tool.
Holes - circular
Very small holes, say up to 1/8” can be made with a regular twist drill. There are a couple of options for larger holes. One is a step drill.(Picture 5) These come in different sizes, and each drill will open out holes to different sizes. Another option is to use a Forstner bit.(Picture 6) These are also available in a range of sizes, but each tool will only cut one size.
Circles and radii.
An internet search will reveal a variety of different makes of circle cutter. There are two main types, button cutters (Picture 7) and compass cutters. The type that I have found most useful, because it will cut smaller circles than most, is a disc compass called the Circle Scribe. It appears to be available only over the internet from RogatePaper. Another option seen recommended is to use a pair of drafting compasses with 2 points. The best type is the one where the diameter is set by a screw, and has interchangeable points, not the type that you put a pencil into. (Picture 8) Or a compass cutter (Picture 9)
Discs and Rings
The above circular hole cutters can also be used to cut circular discs. The drafting compass, compass cutters and the Circlescribe all leave an indentation in the centre of a disc. It may be stating the obvious but if cutting a ring, you need to alternate between the inner and outer diameter, and cut through the outside diameter first, so you don’t lose your centre point.
For the thicker sheets of styrene, start with a square piece big enough for the circle. First scribe the circle and then scribe four lines at right angles on the edge of the circle. Then snap off the four corners. Depending on the size of the circle you may want to repeat the process with the remaining 8 small tabs. At some point you will be left with small tabs which can be cut off with a knife. The last step is to smooth the edge by sanding it.
Other options include a rotary hole punch. This is a one-handed tool made typically for cutting small holes in leather. These make small discs or holes, up to approx 3/16” and generally in styrene up to 0.030” thick.(Picture10)
Another option is a set of hole punches. These usually range in size from 1/8”up to ½ “. (Picture 11).