Monday 9 July 2018
Peter Clothier demonstrates how to carve this stylised Jack Russell in plywood
Plywood has the advantage that a carving of a good size can be made by gluing up as many layers that are needed to make the required block, and the laminations not only give strength to sections of the carving that would normally be short grained and possibly easily broken, but also give the finished piece an added interest.
Because plywood is made from alternate laminated layers laid at right angles to each other and the adhesive is quite hard, clean carving is difficult and chisels lose their sharp edge quickly. The sample that I used, exterior grade far eastern type, 18mm thick, had a flaw running through it but was easily repaired.
With these points in mind, the Jack Russell project was planned to be made with power tools although it is certainly possible to make it with hand tools and as an alternative, you could also make it from a block of timber such as limewood (Tilia spp).
The first step is to research the subject, which in my case was to take some photographs of our dog Skipper. You may choose to make your carving of a different breed of dog, in which case gather your resource material from photos, the internet, etc, but the process is the same. Make your model using plasticine or one of the self hardening modelling clays. I made the model at the same size as the carving will be because it is much easier to transfer measurements and visually easier to compare forms.
When the model is finished, the plan template can be plotted by means of a try square and pencil.
The side elevation template is a bit tricky to make because it is imperative that the model is exactly at right angles to the surface of the paper. Check this by ensuring that all the feet just touch the blade of the square.
Making the block
Now the plywood block can be made, the size being calculated from the templates. Try to make a generous allowance of about 25mm on all dimensions because it makes the bandsawing much easier. The Jack Russell needed a block 280mm long, 180mm high and 165mm thick – 9 thicknesses of 18mm ply.
When preparing the ply, first mark out the sheet and indicate the top of each piece so that they can all be oriented the same way in the final block. Keep a straightedge for the base of the block and when gluing up, keep the base flat to save having to true it up later.
The ply sheets will be carved in the vertical position. Use waterproof PVA glue, and glue up one piece at a time. Line up and pin each piece before tightening the clamps.
When all the ply pieces are glued up, mark around the side template and draw square lines up and across the block at both ends. It is important that the plan view touches the lines at both ends.
Sawing the block
Use a skip tooth 1/4in blade and cut the plan section first. By careful cutting, it is possible to take off in one piece the front section and the back section. By cutting this way, you can then temporarily glue the block back together using a hot glue gun, and then cut the side elevation.
On the plasticine model, mark a line representing the spine of the dog and push cocktail sticks into the line at about every 25mm (1in) or so. Now accurately transfer the spine line marks on the bandsawn block. These are points that you can use to compare measurements between the model and block during carving.
During shaping, if the spine line gets cut away then replace it; it should be there until it is finally sanded off. At the same time mark out the legs and cross hatch mark the waste wood areas.
I opted to use a Merlin with a tungsten cutter. You could also use a flexible drive machine with a chainsaw type cutter, or the mini Arbortech will work just as well. If you prefer hand tools then the surform and later micro planes are slower but very effective.
The first step is to clear away waste wood by the legs and then gradually shape the body. Once the general form is roughed out, tidy up the surface and begin to define the forms such as the head and outsides of the legs.
Once the main waste wood has been removed, more refined shaping is carried out with a flexible drive machine and coarse carbide cutters: 3/4in ball nose and 1/2in spherical. If you are using hand tools then continue with the surform and also use a coarse riffler. Don’t forget to keep checking your measurements against the model.
Once the outsides of the legs are correctly shaped, remove the wood from between the legs, again using the Merlin or similar tool. Hand tool users may save time by using a coping saw to remove some of the waste and then use a surform and a riffler.
Now the shaping is well advanced, make repairs to any voids or other breaks in the wood. Use off cuts saved from the original block and split off small filling pieces, shape them with a craft knife and glue them in place, and when it dries trim them flush.
With the repairs completed, the final stage is to shape and sand the form using coarse abrasives. I used a Guinevere small pneumatic cylindrical sander, but you might use one of the small drum units that fit flexible drives and multi-tools.
Coarse abrasive such as 60g wrapped around dowel or shaped pieces of wood is a very effective way of final shaping.
Sanding & finishing
Although the majority of the carving can be power sanded you will find that the final stages will need some hand sanding to remove small imperfections.
Use 100grit and then120grit, then soak the work in fairly hot water, leaving it overnight to dry thoroughly. Sand with 120grit again followed by 150grit, and then apply a coat of sanding sealer. Let it dry overnight and then cut the surface back hard with 180grit paper, paying particular attention to any rough areas. Put on a final coat of sanding sealer and when it has dried hard, grey the surface with 0000 fine steel wool and then apply a coat of furniture wax.