The function of violin edge lines (black and white lines) is not only to enhance the beauty of the violin, but also to cut off the top wire around the edge of the violin. The glued edge lines seal the top wire, allowing the violin board to dry evenly during aging without cracking due to cracks at the top wire. Even if the violin is damaged due to collision during use, the obstruction of the edges will not damage the violin board. The edge of the piano is damaged due to friction or bow collision, and repairing the edge from outside the edge is both convenient and easy to hide traces.

Installation of violin edge:

The edges of the violin and viola are the same, with a black layer thickness of 0.3 millimeters, consisting of two layers inside and outside, and a white layer thickness of 0.6 millimeters in the middle, for a total thickness of 1.2 millimeters. The black layer on the edge of the cello is 0.6 millimeters thick, the white layer is 0.8 millimeters thick, and the total thickness is 2 millimeters. The height is 2.5 millimeters, and the edge height left in the groove after trimming is only about 1.5 millimeters, so a violin edge height of 2 millimeters is sufficient. First, glue three pieces of wood veneer together and cut them into long strips of the desired width. When embedding them into the groove, shape it according to the groove shape and use a curved side panel heater to shape it before embedding it into the groove. The length of the edge can refer to the length of the side panel, but the length of the lower edge should be measured according to the length of the entire side panel.

Before installing the edge line, it is necessary to remove the 1mm margin of the piano edge, as the position of the edge line is based on the piano edge. It can also be temporarily left on, but it should be taken into account when adjusting the distance of the edge blade. At this point, the edge of the piano remains straight up and down, allowing the edge knife to accurately adhere to it. The edge knife can be a double blade or a single blade, depending on individual usage habits. Antonio Stradivari seems to use a single blade edge knife. After adjusting the depth and distance from the edge of the piano, cut the edge groove to the desired depth. If it is a single blade, two edge knives are needed, adjust the distance from the edge of the piano and the cutting depth separately, and cut it twice to the desired depth. The edge groove is a straight up and down groove, with no curvature or uneven width on both sides, otherwise the edge will appear curved. Afterwards, use a flat chisel or knife similar to the width of the groove to hollow out the wood in the groove.

Sometimes it is difficult to directly process the panel to the required depth with a edge knife. The hard autumn wood grain will block the blade, causing it to lean towards the soft spring wood, resulting in curved or uneven grooves. You can first apply a thin adhesive on the edge of the piano to allow the spring wood to absorb the adhesive, which will harden after drying. Then, use fine sandpaper to polish the surface of the piano edge. The edge knife is mainly used for the first cut, to cut a continuous and smooth groove wall, and then deepen the groove along the groove wall with the knife. After reaching the depth, use a narrow chisel or knife to dig out the wood in the groove.

The width of the violin edge groove is 1.2 millimeters, and the distance from the outside of the groove to the edge of the violin is 4 millimeters, so the edge groove is just above the side plate and edge strip. Depth is 2-2.5 millimeters, and controlling the depth is extremely important as the remaining thickness of the piano board under the groove is only about 2 millimeters. The size of the edge groove of the viola is similar to that of the violin, as the skirt edge of the violin board has only been widened by 0.2 millimeters, using the same size of edge groove. The edge groove of the cello is 5 millimeters away from the edge of the instrument, with a depth of 2.5 millimeters and a width of 2 millimeters.