Demystifying the bowstring.
String creep, defined as unrecoverable elongation, is your enemy. Just about the time you think your bow is tuned and shooting well, your string or buss cable begins to creep. When that happens, cams go out of time, nocking points move, and arrows start dancing in unintended directions. Corrective measures, such as putting the bow in a press and adding twists to the string or cable, become necessary. Get a new string, or a new bow, and the process starts all over again.
Many bowhunters are confused about the complexities of today's bowstring materials and manufacturing processes. In the interest of demystifying the bow string, let's take a closer look.
This story begins in the Netherlands at a company called DSM, the exclusive manufacturer of Dyneema, a high-modulus polyethylene fiber (HMPE). Dyneema is the world's strongest fiber and is used in countless products including bulletproof vests, fishing line--and bowstrings.
Two U.S. companies, BCY Inc. and Brownell & Co., are the principle suppliers of Dyneema fibers to the bowhunting industry. Each company has its own alphanumeric designations. BCY calls its product 8125 and Brownell calls its B75 Thin. These are essentially the same material, but the latter is thinner. For example, a typical bowstring may have 24 strands of B75 Thin, while the same diameter string made of BCY 8125 will have 20 strands.
Another material is Spectra, also an HMPE fiber with a little more creep than Dyneema. A new fiber from Brownell, called TS1, is an improved Spectra fiber that is gaining in popularity. Spectra is just slightly faster than Dyneema. What does that mean? Well, a "faster" string is typically a thinner string that transfers a few more feet per second in arrow speed to the same setup.
Vectran is yet another string material popular with competitive archers. Vectran has almost no stretch but it is slower than Dyneema by about four to six feet per second. It is also brittle and prone to sudden failure.
A form of compromise between materials is accomplished when they are blended together in the same string. BCY combines about 35 percent Vectran with Dyneema to come up with materials called 450 Plus and 452. Brownell's blended versions are called Ultra Cam and $4. The blended strings have very little creep and they resist "fuzzing" far better than pure Vectran, but they are less durable and a little slower than pure Dyneema.
Still confused? While Dyneema has some creep, it also has some stretch, and there is a difference. Stretch indicates some elasticity or ability to return to the original shape. A slight amount of stretch is not a bad thing in a bowstring. It equates to more speed and a quieter string.
Creep, however, is a bad thing and eventually will give you headaches when your bow loses its timing/synchronization. Also, if your bowstring creeps you'll gain both draw length and draw weight. If your buss cable creeps you lose draw weight and length.
You can detect string creep by measuring the exact axle to-axle length and brace height of your bow when it is new or shooting perfectly. Compare those measurements after you've shot several hundred arrows. Any change indicates some creep has occurred. Your bow's cams may also have timing marks which will tell you when the string or buss cables have crept on you. If there are no marks, mark them yourself with a permanent marker on the cams where they pass through the limbs. You'll easily notice when something has changed.
If you experience creep--and you will--it's not the end of the world. Simply put the bow in a press and twist the string or buss cable(s), whichever is appropriate. Making such changes can be a hassle, especially if you don't have the necessary skills or equipment and have to take your bow to a pro shop. Either way, you'll likely have to start over in your tuning process, clearly illustrating the value of minimum creep in a bowstring.
The top bowstring manufacturers understand the inconvenience of string creep, so they strive to eliminate it from string material before it's made into a bowstring.
This is where things get fuzzy. Those processes are highly guarded secrets, and the companies I contacted wouldn't allow me to use even benign photographs of their equipment for fear the competition would discover how they do what they do.
What they do is remove most of the creep from their strings, either one fiber at a time or as a group, by building them under extreme load, as much as several hundred pounds. Once the fiber has the majority of the creep "pulled" out, they are made into bowstrings. The strings are then "served" in the necessary places. Some companies use up to 200 pounds of pressure when winding the serving. That makes for a very durable serving that protects the fibers and won't separate in stress areas such as around the cams and roller guards.
Any string, even a custom-made prestretched bowstring, will require at least 100 arrows to be shot through the bow to "shoot in" the string and cables. That settles the string into the mechanics of the particular bow and will take out most remaining creep. If necessary, a couple of twists will put your bow back where it belongs, hopefully to stay.
The primary reason to use a quality no-creep string is to keep your bow performing consistently over time. But for any bowhunter, an equally important reason comes into play, and that's zero peep rotation. A string with the creep removed will not rotate your peep out of alignment as you draw. That allows you to use a peep without an aligner device, such as a rubber cord. I have one bow with a Winner's Choice string and cable set and another with a Stone Mountain set, and the peeps on those bows have come in consistently for the past two years. That's extremely important to me as a bowhunter, especially in tense moments of truth.
FOUR OF THE TOP bowstring manufacturers--Winner's Choice, Stone Mountain Bowstrings, Zebra Strings, and TailorMaid Archery Products--each has different string-making philosophies.
"Approximately 95 percent of the strings we manufacture are made from BCY 8125," said Mike Slinkard, vice president at Winner's Choice. "We developed our proprietary stretching processes around that fiber, but we can also do well with other materials. When it comes to speed and quietness, we just believe that 8125 is the best all-around fiber." Winner's Choice also offers X-Coat, a unique coating that works into the serving and protects it from abrasion.
Dave Olive, at Stone Mountain Bowstrings, also favors Dyneema.
"Everyone is using the same basic materials so you have to be better at the process of building strings," Olive said. "Our Dakota Pre-Stretched strings are twisted and stretched under 800 pounds of tension. Then they're served under 200 pounds of pressure."
A string company with a special "twist" is Zebra Strings. These strings are built with a patented process that uses counter-rotating twists in the two bundles of fibers. The intent is to reduce rotation and keep your peep sight coming in consistently. The philosophy regarding both material and process is also a bit different.
"We use a proprietary blend of Dyneema and Vectran in a patented string material we call 1425X," explained Aaron Brooks, Manager at Zebra Strings. "We don't pre-stretch our strings. We feel a pre-stretched string is louder and the Vectran helps reduce creep. We do serve our strings under tension but we don't believe in serving our end loops. We just don't see an advantage at this time."
Of course, an increasing number of custom string manufacturers are offering more choices, and some bow companies, such as PSE, make their own bowstrings for many models and fit their high-end bows with custom strings.
It's extremely Important to wax your string and cables often. A wax with silicone in it will penetrate the fibers and accomplish two important goals. Wax prevents moisture from being absorbed into the string, which can affect performance. Waxing also provides fiber-to-fiber lubrication, which prevents wear.
To prevent serious abrasion, regularly check string grooves in the cams and wheels on your bow for nicks and dings. If you drop your bow or bump a cam on a rock, a burr can form, which can damage the serving. If you find any broken fibers on a string or cable, replace it immediately.
Some experts disagree on whether to wax the end-loop servings on bowstrings and cables. Personally, I do not wax these servings because I fear the wax will collect sand and grit and introduce it into the cam grooves, causing wear and maybe even some noise.
The bowstring has become high-tech and complicated. I haven't mentioned all the different string materials available, or even the serving materials to choose from. The best advice is to use a quality string, take some benchmark measurements of your bow, become familiar with the tinting marks on the cams, and occasionally do a spot check to make sure everything is where it should be. You'll be rewarded with long, consistent, trouble-free service from your bowstring and buss cable.
Okay, so this probably hasn't simplified this very important piece of equipment for you, but hopefully it demystified the bowstring just a little.
BCY INC., 697 Middle Street, Middletown, CT 06457; (860) 632-7115; www.bcyfibers.com
BROWNELL & COMPANY, PO Box 362, Moods, CT 06469; (860) 873-8625; www.brownellco.com
STONE MOUNTAIN BOWSTRINGS, 10636 Hwy. 12, Orofino, ID 83544; (208) 476-7811; www.stonemountainbowstrings.com
TAILORMAID ARCHERY PRODUCTS, INC., 3627 11th Street, Wyandotte, MI 48192; (734) 246-3182; www.stringmaker.com
WINNER'S CHOICE CUSTOM BOWSTRINGS, INC., 58000 Industrial Park Rd., John Day, OR 97845; (541) 575-0818; www.winnerschoicestrings.com
ZEBRA STRINGS, 919 River Road, Sparta, WI 54656; (608) 269-1235; www.zebrastrings.com
|Printer friendly Cite/link Email Feedback|
|Title Annotation:||Tried and True|
|Date:||Dec 1, 2004|
|Previous Article:||If the broadhead works ...|
|Next Article:||Shot placement.|