Crossbow Dampener

With the increasing crossbow popularity, hunting and sport shooting advances have been made to enhance its performance. More recently, noise levels have been reduced by dampening string vibration but not all manufacturers offer such accessories, particularly for their older models. With the crossbow having many features of a firearm the gunsmith will become increasingly more involved in the service and repair of the modern crossbow. Learning more about them is a definite plus for us.

As currently designed, high performance crossbows are very noisy to shoot. Such noise can reach the ears of a deer with sufficient time for the animal to react to bolt or arrow flight, often resulting in poor hits or misses. Much of the noise is created by the bowstring overtravel, beyond straight, as the string propels the arrow. This overtravel can be as much as an inch or more, producing a loud reverberation on rebound. This twang or resonance can be much reduced with string dampening methods.

Allowing the string to be stopped by some form of padding, as it reaches a straight position on arrow departure, is a viable way to quell the sound. Various forms of rubber make good string stops when properly positioned at each side rail near center where the arrow is released. The rubber pads are extended on parallel arms at the sides of the crossbow beam or barrel. The string stops must be sufficiently soft inside with an outer shell or layer durable enough to prevent string cutting.

The use of composite materials may be required in the process. Here’s how I made and installed noise dampeners for a 175 pound Magnum X2 from Ten Point Crossbow Technologies (tenpointcrossbows.com). The X2 had two existing parallel-tapped holes on each side of the crossbow frame, so I made up a pair of parallel arms to retain the rubber string stops. These were shaped from 7/16" x 5" stainless rod stock.

At top, the limbs and frame (prod) are shown with grooved rail or barrel along with the crossed-string timing cables and main string comprising the primary power source of the crossbow. The bolt or arrow fits the barrel channel driven by the string power. Over 2,450 inch pounds of power are delivered by a 175 pound crossbow string resulting in a very loud noise as the string comes to a stop. String stop noise dampeners help to reduce this.

Stainless steel 7/16" rod stock with rubber suction cups and firm rubber pads. Bottom view shows finished left string stop. A two inch section of each arm was milled half-flat with holes spaced at an inch for the 8-32 attaching screws. A section of the opposite end was then turned to 5/16" for 1/2" and threaded. A 2-1/2" section of the rod was then turned to 5/16" for easier bending, shaping and weight reduction.

The necessary bends were made on the rods to space the string stops away from the crossbow beam centered with rubber bumpers at string center. Making Rubber String Stops We gunsmiths must work with what we have in our creative efforts and this fit right in here. I found a pair of suitable suction cups with existing holes and bonded a pair of harder rubber quarter-inch-thick discs to these. They attached perfectly to

Such craftsmanship is typical of the demands of a gunsmith/machinist in making special parts where needed for gun or crossbow. The one on the right shows the simplicity of string stop attachment. The units are firmly held in place with four 8-32 hardened socket head screws. the threaded end of the arms with a washer spacer. The outer rubber discs have the approximate hardness and texture as a common automobile tire tread and will withstand many hundreds of bowstring impacts without damage.

Note, a 150 pound crossbow string will generate more than 2,100 pounds of power. The string stop noise dampeners, as applied to this crossbow, reduced noise by approximately 30 percent as measured by a sound level meter. The sound produced is noticeably different as well. It is more of a thud than a metallic twang. As I discovered, arrow let-off is more uniform, resulting in somewhat more consistent accuracy as well.

The arrow appears to depart from the string more uniformly as opposed to the string actually following the arrow The rubber stops are just touching the bowstring. The 175 pound peak weight of this Magnum X2 is capable of generating 2,450 inch pounds of power against the string stops. Undampened, such noise can cause animals like deer to jump the string, resulting in amiss or wounded animal. Initial tests indicate from 24-30 percent reduction in noise with this crossbow.

Results while hunting have not yet been determined with this bow, but should prove most favorable. All-in-all, this addition to a crossbow is well worth considering. Application to each crossbow will differ some, but the creative gunsmith can see through that. AG provement over nonuse of this feature. This group shows the result of 20 shots with modified 25-inch arrows.