String Theory

Well, not really string theory.  This has nothing to do with quantum physics at all... or at least I don't think so.  There is physics involved, but don't ask me to do any complex math.

Ok. Bow strings.  I have made several bowstrings now and I have got it pretty much figured out.  Again, they are not works or art, but they function well and I have not had one fail yet.

The string is the most important part of any bow.  A string that stretches will not give you the power you need, and a string that is too stiff will cause vibration and in my mind can also damage the bow.  You can make a string out of just about anything from dental floss to sinew fibers.  I have chosen heavy duty polyester sewing thread.  Easy to find, inexpensive and you get strange looks from the ladies in the fabric store.  Modern bowstrings are usually made with B-50 Dacron waxed bow string material.  This is great but not as easy to find locally at a good price.  I have no idea what the breaking strength of my sewing thread is, but I do know that I will cut my fingers wide open if I try to break the stuff by hand.  When I made my first bow string from polyester thread I was worried about it breaking, the only thing I had to go on was some Youtube videos and a general idea of the thickness required.  Strength comes from the number of strands, so to be good and safe I have gone with a 32 strand flemish twist string for this bow.

First things first.  I had to determine the length of my string.  The bow measures 61" nock to nock (nocks are notches in the bow where the string fits in) A string should be about 4" shorter than your nock length (commonly touted number on youtube). To this you need to add length for the loops that go around the bow at the nocks and also for the twisting back on itself to hold the loop in place.  I use 4" for each loop, plus 6" for the return twist.

Math time:  61-4+4+4+6+6 = 77

I found a scrap board lying next to the garage that was about 68" long so I added a couple of pieces of scrap oak with dowels from arrow scraps inserted to make a string jig.  The dowels are 77" apart and you just wrap strands of string around these until you have the desired quantity of strands. Because I am Tony Stark, and Ironman chose gold and red for his suit, I went with gold and red for this string.  16 strands of each.

16 strands of heavy duty red polyester sewing thread
You can see the gold on the table.

once you have 1 color wrapped around give them a good coat of bees wax.  rub it into the string until the strands start sticking together.  More is better.  I got the wax from Micheals.  Standard natural bees wax. (Looks like a block of cheese on the counter, but as I told my daughter, it is not cheese, it is weapon system manufacturing material.)

Bees wax, not cheese

A good thing to have on hand are some small alligator spring clamps.  They are great for holding string so you can twist strands and not get it all tangled into a giant ball of tangles like I did just after I took the picture of the wax in my hand there, when I cut the strings and promptly let a gust of wind have it's way with it.  Sigh.

Clamp to hold string, very handy.

I always cut one end of the string loops and make sure all the lengths are even from the loop at the other dowel.  I then clamp the far end to keep the string from tangling.  I rub in more wax until the strands become stiff and sort of stick together.  I then measure out 10" (4 inch loop and 6 inch twist back) and attach a clamp holding the two colors close together and begin the twisting process.  I twist the red and gold seperately  in a counter clockwise direction then twist them over each other in a clockwise direction (google "how to make a flemish twist bowstring" to see how this works)  The opposite directions of twist are what hold the string in place, just like any twisted fiber rope.

10" of each color clamped and ready to twist

I tend to hum Chuck Berry tunes as I do this.  It is somewhat time consuming and boring otherwise.  Twist the two colors over each other for 4" then turn it back on itself and twist the 4 strands together to make a spliced loop.  Once the first loop is done I use a clamp to hold it in place while I begin the loop at the other end.  By clamping the finished loop, I prevent any twisting I am doing at the opposite end from unraveling the first loop.

2 complete loops ready to string onto bow.

There are several good videos by various people on how to do a flemish twist bowstring.

These 3 vids are what I used to learn the the technique.  Youtube is awsome!

http://youtu.be/wkjiOkAYzc8
http://youtu.be/7RvOwm4wnwU
http://youtu.be/-QjGEldchhU

The beeswax and pressure from the tension when stretched onto the bow is what holds it all together.  Very ingenious technique created many centuries ago.

Once I had the loops made I put the string on the bow.  The string at this point is a bit long only barely bracing the bow to about 3 to 4 inches.  That is enough at this point as all I want to do is stretch the string a bit and wrap serving thread around the loose ends on my loops as well as wrapping serving around the middle of the string where the arrow will otherwise wear and break the string.

I had to do this with a bare spool of serving thread I picked up from the Calgary Archery Centre.  I recommend buying a string server as this will likely speed up and make the process easier.  Slow and steady, patience helps here.

wrapped up loose ends.  Same on other end.

It helps to rub wax into the loose ends to help them stick down as you wrap.  I ended up doing two layers of serving in the middle of the string to build up the thickness so that an arrow nock would 'pop' on.

unstrung bow with served string.
The red bit is a piece of duct tape I am using as a nocking point.

Once the string was served I unstrung the bow and began the process of twisting the entire string until it was short enough to brace the bow at about 6 inches.

Over the evening and this morning I have shot over 100 arrows through the bow.  It is working very nicely.  I had a bit of string stretch, but that was expected so I just twisted the string some more to take up the slack.

Next on my list for this bow is to finish the nocks.  I am thinking I might want to get creative and do something a little different but I am not sure what.  I guess I will have to surf the web a bit to see if there is anything interesting others have done that I could emulate.  After the nocks I will be doing a lot of sanding to get all the rasp marks out then apply a finish. I will likely paint the back of the bow black again, and then apply a natural red oak finish to the belly and handle area.  I may have the back airbrushed as well.

Stay tuned, this bow is almost done.  might be ready to show off at the range by next weekend