The Evolution of the Riser

2012-MidasIn this series I am going to discuss the evolution of the riser or the structural strength of the bow which houses the handle, to which the limbs are attached and other various accessories.  Originally the riser and the limbs were actually one piece, as you would see in a bare bow or instinctive bow, however in most modern bows the riser is completely independent component.

Historically, the original construction material was wood and sometimes combinations of different types of wood. Other historical materials included horn and sinew (A piece of tough fibrous tissue uniting muscle to bone or bone to bone; a tendon or ligament) to create composite bows.  Beautiful laminated wooden bows and risers are still manufactured for lightweight, beauty, tradition, and style.

1212210010_L1Although some bows are still manufactured from various laminated hardwoods and are quite durable, the development of other modern components with materials such as carbon arrows and various strings, wooden risers were strained.  Therefore bow makers were forced to invest in the development of other more durable materials for competitive archers to maintain that competitive edge.  Competition target archers need enough arrow speed with great sight marks, with minimal string creep, since they practice a lot of shooting (anywhere from 150 – 1000 arrows a day).  Wooden bows will eventually break under the additional loads of pressure applied from the stress and strain.

Today there are two primary types of risers used by Olympic target archers, CNC machined aluminium and Carbon fibre or a combination of the two.  In the past, other materials and manufacturing methods were used such as forging and casting.

Forging

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This method hammers a metal bar under high temperature and high pressure that results in an extremely strong riser. Typically forging is an expense development process which requires machining, straightening and painting with very few variations.

Casting

ben-castingUsually a mix of aluminium and magnesium were developed with either die-casting or sand-casting methods.  Still available in the market today with low-to-mid range bow are a relatively cheap to make once you have the mould.

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CNC Machined Aluminium

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A computer controlled method to machine a riser from stress-relieved aircraft grade aluminium alloy until they weigh less than 3 pounds. Sometimes, in order to reduce the costs, risers can be extruded through a die to minimise the amount of machining required. CNC risers are usually anodised to provide a hard wearing finish.

Carbon Fibre

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A method of layering synthetic fibres usually over a dense foam core mould, which is cured with resin epoxy to develop an extremely strong and lightweight riser. Although this method can be expensive to develop and test with, the process has almost infinite number of possibilities in terms of strength and flexibility of design.

Currently, the market is primarily CNC Machined Aluminium with overlayed Carbon Fibre to gain the best of both worlds. Who knows what the future holds for risers as target archers look to find the competitive edge and manufacturers investigate in cost savings.

Aiming without a Sight

instinctiveAllen asked…

Hey been reading your articles while I’ve been waiting for my archery gear to come in. They have been very informative. Just getting into archery and I’m not going to be using a sight right away. Any tips and advice on aiming without a sight? Thanks

Personally, I have always learned to shoot with a sight however you should check out Charles Archery Blog’s - Various methods of aiming the traditional bow. This is an excellent blog and will provide great methods for shooting without a sight.

 

Arrows Series – Part 2: Measurements

As we start to dive deeper about arrows, my goal is to simplify the information so young archers can have a good basic understanding; it is not meant to be all in compassing or a physics lesson, remember I am still learning too. Therefore, the next step is to understand how arrows are measured and how to determine draw length.

The Archery Trade Association (ATA) formerly the Archery Manufacturers and Merchants Organization (AMO) has the following standard for measuring draw length:

AMO DRAW LENGTH STANDARD

For Manufacturers

Draw length is a specified distance, or the distance at the archer’s full draw, from the nocking point on the string to the pivot point of the bow grip (or the theoretical vertical projection of a tangency line to the pivot point parallel to the string) plus 1 3/4”. Draw length from pivot point shall be designed at DLPP (Draw Length Pivot Point) and shall be called TRUE DRAW LENGTH.

EXAMPLE: 26 1/4” DLPP plus 1 3/4” is the equivalent of 28” draw.

For Dealers and General Use

For practical reasons not requiring precise terms, draw length is the distance, at the archer’s full draw, from the nocking point on the string to the back of the bow at the arrow rest.

EXPLANATION: The standard Manufacturers is consistent with the Bow Weight Standard as related to the pivot point. The DLPP plus 1 3/4” is compatible to previous concepts of draw length. Draw length for Dealers and General Use relieves the burden of preciseness not required for general use and facilitates determining arrow length. THIS STANDARD SUPERSEDES THE PREVIOUS STANDARD.

This can be technical and confusing, however with most recurve risers, the distance of the draw length pivot point (DLPP) to the front edge of the riser is 1 ¾”. Therefore, in general terms…

Your approximate draw length is equal to the distance from your string to the front edge of the riser at full draw.

You could use a measuring tape to measure this distance however unless you have a very consistent anchor point and good form you will have varying results, since you should measure several times. Therefore, any archer who is at the point they are fining tuning arrows for high-level of performance they should consult a professional. Otherwise, I would suggest you use the following simple method to determine your draw length.

Arms Length method

Using a ruler (or other straight stick), place one end in the “V” of your neck (where your neck meets your chest ) and relaxed, reach straight out until your palms touch the ruler. At the point for your fingers is your approximate draw length. Your arrows should always be at least 1” to 2” longer than your draw length for safety reasons and young archers often need to set their arrow length little longer ( 2” to 3” ) to allow for growth.

This gives you a basic understanding of draw length and how arrows are measured, however, things get very complicated for young competitive archers who are still developing and growing in size once you add-in arrow stiffness and flex, arrow cost, type of equipment and bow weight.

It is important to understand how things are measured so you can understand why you are using the arrows you have.  I highly recommend you visit your local archery professional for assistance.

Twisted Limbs

Arguably, the MOST important part of the bow are the limbs, since the movement of the limbs transfers energy to drive the arrows to the target. Investing in well-manufactured limbs can be the best move any archer can make. Since consistency is the number one requirement for any archer, you want to avoid any twists. Wood/Fibreglass limbs perform well however can be prone to warping in areas where temperature changes a lot. Carbon fibre layers help strengthen the limb and reduce the tendency to twist.

After purchasing a new set of limbs, one of the first things an archer should do is align their limbs to their riser. Alignment of the limbs means the string should appear to run right down the center of the limbs thru the center of the riser.

I highly recommend the purchase of a new set of limbs for any archer; however, the purchase of a good used set can be an option for a new archer who is still learning the sport. When purchasing a used set remember any twist will cause inconsistent flight of arrows, check for limb distortion (often called limb twist). Viewing the bow strung with the limbs from either end of the bow, if one or both of the limbs have a slight twist, you may have limb twist.  If the distortion is only slight sometimes it can be cured with one of three methods.

1)       Cold Bump Method

Attempt to straighten the limb using the “cold bump” method. If a limb has developed a slight twist from improper stringing, this method often will correct the problem. Grab the bow by the riser with your dominant hand. Use your other hand to grip the bow limb slightly above the twist. Slowly twist the limb in the direction opposite of the distortion, and then quickly release the limb. Repeat this process several times until the limb properly is aligned.

2)       Warm Wet Submerge Method

Submerge the twisted limb in a tub of hot water for 3 to 4 minutes. The water should be no warmer than a hot bath, around 105 degrees Fahrenheit. This is just hot enough to mildly loosen the glues in a laminate. Remove the limb from the water, then slowly twist the limb in the direction opposite of the distortion. Release the twist slowly and examine the limb for straightness. Repeat the twisting procedure several times until the limb is straight.

3)       Low Heat Method

Twist the limb in the direction opposite the distortion and hold it in place. Have an assistant heat the limb using a hair dryer. Hold the hair dryer 6 to 10 inches from the limb, and slowly move it up and down the length of the limb. Heat the limb slowly for 2 to 3 minutes, then release your hold and examine the limb for straightness. Repeat the heating procedure as necessary until the limb is straight.

In my opinion, it is not worth playing with twisted limbs or possible physical injury and especially where ranking is important, competitive archers should not risk the possible performance dip . New well-manufactured limbs are very forgiving of a poor release, feel smooth and are more affordable than ever. Cartel Doosung and Bow Korea offer a complete line of limbs for everyone including introductory limbs, the new Midas MPS limbs for intermediate archers and MK Archery Vera/1440 limbs for competitive archers.