A bowstring for a compound bow consists of multiple strands of string material bound together with a material known as “serving”. The multiple strands create a string strong enough to handle the bow’s tension and launch arrows hundreds of feet. Making your own bowstring is challenging, but can be accomplished with the correct tools. The most common technique used for making bow strings is the “continuous loop”, which is suitable for recurve or compound bow use.
Winding the String
Determine the length of the bowstring. Recurve bowstrings should be 3 1/2 inches shorter than the length of the bow. Compound-bowstring lengths should be listed in the bow’s manual or stamped on one of the bow limbs. Alternatively, measure the existing string to determine the proper length.
Calculate the number of strands needed. The number of strands depends on the bow’s draw-weight and the string material’s breaking strain. Figure the number of strands needed by multiplying the bow’s draw-weight by four, then divide that number by the strain weight of the bowstring material. Example, for a 40-lb. draw-weight, using string material with a breaking strain of 10 lbs., you need 16 strands.
Set up the string jig. Adjust the jig to the proper length for the string being made. Set the winding posts to form a straight line and secure the locking bolt. The string length should be measured from post A or 1 to post D or 4.
Tie the end of the bowstring material to the winding post marked A, located on the far left. Wind the string around winding post D on the far right and back to post A. Repeat, until you have wound the number of strands needed around the string jig. One complete loop around the jig equals two strands.
Untie the end of the string from winding post A and tie it to the other end of the string.
Create the Loops
Measure the loop size for your bow, take the measurement from an old bowstring. Typically end loop sizes for bowstrings are between 2 1/2 inches to 3 1/2 inches.
Locate and mark the center of the string between posts A and B.
Mark an equal distance on either side of the center measurement for the loop position. If the loops on the string are 3 inches around, mark the string 1 1/2 inches on either side of the center mark between posts A and B.
Serve the Loop
Pull a 1-inch length of of serving thread alongside the string material between posts A and B.
Wind 10 to 15 turns of the serving thread around both the string material and the first inch of serving thread, binding the serving thread to the string material, but leaving 1/4 inch of the loose end of the serving thread uncovered. Start binding about 1/4 inch past the left end-loop mark to about 1/4 inch past the right end-loop mark.
Pull the free end of the serving thread to tighten the serving binding. Secure the free end to the string material with a drop of glue and allow to dry.
Wind more serving thread over the glued end of the thread. Bind the entire loop area with serving thread, making sure to wrap 1/4 inch past both ends of the loop section.
Set post B so that it is back in line with the center of the string jig. Slide the string around the winding posts so that the serving is on either side of post A. One end of the serving should be about 1/4 inch longer than the other.
Wrap the two sides of the string on either side of post A together with serving thread to form the loop. Wrap the two sides together for 3 1/2 to 4 inches with serving thread. Cut the serving thread from the spool, leave an extra 2 inches of serving thread and loop the loose end under a binding of serving. Pull tight, place a dot of glue on the end and allow to dry. Cut off the excess serving. Repeat steps 1 through 10 on the opposite side of the string.
Wrap the Nocking Point
Remove the bowstring from the string jig. Twist the string several times to compensate for any excess length and string the bow.
Locate the nocking point by attaching a bow square to the string and setting the opposite end on the arrow shelf. Mark the nocking point. Mark the serving area. Mark the top serving point about 2 inches above the nocking point and the bottom serving point about 3 inches past the nocking point.
Wrap the nocking area by laying a 1-inch length of serving thread alongside the string material at the bottom of the nocking area. Wind 10 to 15 turns of the serving material around both the string material and the first inch of serving thread, binding the serving thread to the string material, but leaving a 1/4 inch of the loose end of the serving thread uncovered. Pull the free end of the serving thread to tighten the serving binding. Secure the free end to the string material with a drop of glue and allow to dry.
Cut the serving from the spool, leave some extra thread and loop the loose end through one of the binding loops on the serving. Pull until taught. Glue the end of the serving to the string and allow to dry. Cut off any extra serving.
Wax the string where it is not covered with serving.
Many string-material manufacturers provide a chart that shows the number of strands needed based on the draw-weight of your bow.
Use a serving jig to keep tension on the serving while binding your string.