The crucifix is a symbol that has been artistically interpreted in thousands of different ways over the years. It need not be perfect. In fact, the chiselled features of Christ add to the character of the crucifix itself. The level of the carving is limited only by the carver's own hands, but is usually left somewhat vague in fine detail. When beginning the carving of a crucifix, it's not necessary to worry much about scale, but it's a good idea to have something to go by. Study some images online. Choose one where the body of Christ stays somewhat smaller than the cross itself in scale. For your first attempt, go for simplicity and make it one piece.
Measure 3 inches in from each side of the mahogany blank on top and bottom. Now using a ruler, extend and connect the two lines the length of the blank--- the upright of the cross. Measure down on each side 3 inches, and 5 inches and connect those lines for the crosspiece. You should have a cross drawing with a 7-inch tail and 3-inch top and side arms. The crossbeam and upright of the cross should each be about 2 inches wide.
Cut out the cross on a band saw. Don't worry if it's not perfect. Now freehand or use your picture to trace the outline of Christ on the cross with a pencil. At the top of the head, the bottom of the feet and the outside of each of the hands, make a mark on the cross and cut down about a 1/2 inch with a hacksaw. Using the band saw, cut away all the wood possible up to the lines keeping the 1/2 inch depth under the body, allowing the body to have a relief above the cross of 1/2 inch.
Cut a line all the way around the drawing with the bench knife. Continue following the line until it's about 1/4 inch deep. Using the 1/2 inch straight chisel begin working it toward the line, rocking it back and forth curling and carving away the wood up to the line. Switch to the 1/4 inch chisel for tight spaces. When the body begins to emerge, switch to the Dremel tool with a small abrasive wheel attachment.
Cut around the legs, arms and body removing wood faster with the cutting wheel. When the relief of the body stands out to your taste, switch to the narrow V-gouge and begin carving out the profile and features of the body and limbs. Switch to the bent spoon to carve between the arms around the head and anywhere a more circular cut is needed. Switch back to the V-gouge and fine tune the detail to the chest, face and limbs until satisfied.