Along the way, a few explanations.First, the mold. Stringed instruments are constructed of wood (most of the time, and this one is in that class). Wood has a tendency to deflect under pressure - that is, it bends when you pick it up or work on it. Since the sides of the 
instrument are made of very thin wood, they will tend to deflect quite a bit while you are attaching the kerfing and the top and bottom. Of course, once the top or bottom have been added to the instrument the mandolin will be fairly stiff, but until then you want to keep the instrument in the same shape as the final product as far as possible because every part added will tend to stiffen it, and if parts are added while the sides are deformed due to handling they will tend to cause a system-wide deformation in the final product. So typically builders use a form to ensure that the instrument keeps true to its final shape wile being worked upon. These molds take many shapes and forms - molds for guitars are frequently made of wood and form the outside of the instrument. My kit calls for a cardboard mold that fits inside the instrument as shown here.
instrument are made of very thin wood, they will tend to deflect quite a bit while you are attaching the kerfing and the top and bottom. Of course, once the top or bottom have been added to the instrument the mandolin will be fairly stiff, but until then you want to keep the instrument in the same shape as the final product as far as possible because every part added will tend to stiffen it, and if parts are added while the sides are deformed due to handling they will tend to cause a system-wide deformation in the final product. So typically builders use a form to ensure that the instrument keeps true to its final shape wile being worked upon. These molds take many shapes and forms - molds for guitars are frequently made of wood and form the outside of the instrument. My kit calls for a cardboard mold that fits inside the instrument as shown here.The process started with selecting a piece of cardboard that the pattern would fit onto (the kit says to use the
"included" cardboard but my kit did not include a piece - fortunately the lid of the shipping box for the kit was large enough to cut a piece out of). I then used a glue stick to adhere the paper pattern to the cardboard and, using an Exacto knife with a fine-tipped blade and a straightedge, I cut the mold out by following the lines (the yellow-green thing in the photos is the cutting mat). First I made a series of straight cuts to remove the bulk of the material, staying just outside of the lines and cutting the waste away. Having done that I cut the pattern out by carefully following the lines with the Exacto knife. I did this in small sections by making cuts perpendicular to the cut line out to the edge of the waste area and then removing the waste by cutting along the cut lines. Here's the final product of this process:
"included" cardboard but my kit did not include a piece - fortunately the lid of the shipping box for the kit was large enough to cut a piece out of). I then used a glue stick to adhere the paper pattern to the cardboard and, using an Exacto knife with a fine-tipped blade and a straightedge, I cut the mold out by following the lines (the yellow-green thing in the photos is the cutting mat). First I made a series of straight cuts to remove the bulk of the material, staying just outside of the lines and cutting the waste away. Having done that I cut the pattern out by carefully following the lines with the Exacto knife. I did this in small sections by making cuts perpendicular to the cut line out to the edge of the waste area and then removing the waste by cutting along the cut lines. Here's the final product of this process:
You can see some of the waste pieces lying off to the left and the Exacto knife I used to the right in this photo.
Once the mold was in place it was time to add the kerfing. Kerfing is actually a process by which a series of cuts are made parallel (usually) to one another in a piece of wood to make it easier to bend the wood. In stringed instruments the work also refers to the small pieces of wood, often triangular in section, which are used to glue the top and back onto an instrument. These pieces are kerfed to make them easier to bend into shape. The purpose of kerfing is simple: the sides of the instr
ument are far too thin to offer enough glue surface to make a secure joint between the top and side. The kerfing is securely glued to the sides and then glued to the top, offering enough glue surface to make a strong joint. My instructions say to use clothespins for clamps since they can be placed very closely together along the sides to ensure even clamping pressure. They also recommend wrapping the clothespins with rubberbands if they have weak clamping force. My clothespins, bought at Wal Mart, had terrible clamping force, so I did this. I started by dry fitting the kerfing to the mandolin to size it and to determine how many clothespins I would need. I fit 23 pins in the dry fit, so I took a few minutes and wrapped 23 pins with rubber bands. I then spread glue onto the first piece of kerfing and clamped it in place using the prepared pins. It turns out that because the pins are significantly wider when wrapped with rubber bands I only used 20 of them. To the left is the first piece of kerfing glued in place. You then repeat the process with the second side (shown on the right).
ument are far too thin to offer enough glue surface to make a secure joint between the top and side. The kerfing is securely glued to the sides and then glued to the top, offering enough glue surface to make a strong joint. My instructions say to use clothespins for clamps since they can be placed very closely together along the sides to ensure even clamping pressure. They also recommend wrapping the clothespins with rubberbands if they have weak clamping force. My clothespins, bought at Wal Mart, had terrible clamping force, so I did this. I started by dry fitting the kerfing to the mandolin to size it and to determine how many clothespins I would need. I fit 23 pins in the dry fit, so I took a few minutes and wrapped 23 pins with rubber bands. I then spread glue onto the first piece of kerfing and clamped it in place using the prepared pins. It turns out that because the pins are significantly wider when wrapped with rubber bands I only used 20 of them. To the left is the first piece of kerfing glued in place. You then repeat the process with the second side (shown on the right).
One final note: the instructions tell you to leave the kerfing about 1/32" above the sides. This will be sanded down at a later moment in the proper shape for the slight bow curve of the top. I tried to do this, and the detail below is the result.
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