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关于Easton X10箭杆上的C码(重量码)完全官方解读

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发表于 6 天前 | 显示全部楼层 |阅读模式
今天正好在某个群里又聊到X10箭C码的问题,按照之前从各种大神那里以及国内外论坛看到的一些解读讨论了一下,又不放心,仔细重新搜索了一遍。这一搜搜出了惊喜,答案就在伊斯顿的官网上,有一种柳暗花明又一村的感觉。
这篇官方完全解读发布于今年年初,作者是George Tekmitchov,伊斯顿资深工程师、射准产品经理。时间有限,我就不逐句翻译了,简要提炼一下这篇文章说了哪些重点。文末放上原文,有时间有能力的朋友可以通读一遍,原文链接是https://eastonarchery.com/easton-weight-codes-sorting-out-the-mystery/


伊斯顿重量码揭秘

1. 挠度是反曲箭支中最为重要的规格参数,对于密集度的影响最大,重量和直度的重要性排在挠度之后。(这也是伊斯顿C码诞生的基础,后面会提到。)伊斯顿在上世纪90年代让当时的美国名将Denise Parker做了一个持续六周、每天都进行的70米箭支测试,证实了挠度对于环数的影响。


2. Easton A/C系列射准箭——X10, X10 pt, ACE, ACC, ACG,或者Pro Field这些箭支上都会印有C几(比如C2、C3)的字样,这些字样被伊斯顿称之为“重量码(weight code)”。于是一定有人问挠度聊的好好的,怎么就开始扯重量了。为了解答这个问题,作者提到我们必须首先了解一些箭杆的原材料知识,并引入了“杨氏模量(Young's Modulus of Electicity)”的概念,即一个描述弹性系数的参数。

3. 有经验的射手一定都知道铝制箭杆的一致性非常优异,其原因是铝合金的弹性系数非常稳定。比如XX75铝箭,其材料弹性系数接近于10,400,000单位,不论生产于1964年还是上个星期,只要是标注规格相同,其硬度重量挠度都没有什么差别。而对于碳来说,事情就没有那么简单了。商用碳纤维材料的弹性系数可以相差到正负两百万个单位,这是一个不小的差值。很多高端箭所用的碳的弹性系数为46,000,000单位,除非厂商对此采取更多的控制措施,否则材料的弹性系数可以从44,000,000单位到48,000,000单位,这种差异就相当可观了。

4. 另外一个变量是粘合碳纤维的环氧树脂或者其他聚合材料,它们和碳的使用比例必须严格控制,使得箭有一致的组合硬度。甚至连起始物料的年份都是一个对硬度影响不小的变量,因为它影响了一些制作过程相关的其他变量。上面提到的任何一个变量都会对箭支硬度产生不小的影响,如果不加以严格控制,变量层层叠加,箭支挠度就会出现非常大的偏差。

5. 伊斯顿采取了很多重要步骤来确保挠度的精确。首先作为业界最大的碳纤买家,伊斯顿只从最顶级的碳纤维供应商那里采购,并直接供应商一起对材料进行严格检测、精挑细选。第二,伊斯顿箭支的所有碳铝结合的制造过程都是在自家盐湖城的工厂里进行,每一步都严格和精细。

6. 尽管用了最好的原料,采用了最精良的制作工艺,但箭支还是有一些重量差异上的问题。有两种方式来解决这个问题:第一是制造时严格控制箭支重量,对同规格箭支的挠度差异有所宽容,这会造成箭支密集度上的牺牲;第二是严格控制箭支挠度,允许其产生细微的重量差异,然后再根据箭支重量进行分组。伊斯顿采取的就是第二种方式,这也是"重量码"的诞生由来。伊斯顿将箭支生产到特定挠度,然后给每支箭称重,精确到0.1格令,最后将箭分类到相应的重量组(即C几)之中。

7. 当你拿到一打伊斯顿X10箭,上面会印有一些数字,这些数字是什么意思呢?我们举一个例子来说明:
906 A/C/X10 410 Series A
Aluminum Carbon X10 C.2

906代表内管规格,9/64英寸的内径和0.006英寸的壁厚,所有的X10箭内管规格都是以此为标准的。
A/C/X10 代表箭支型号,A为铝,C为碳,X10是系列
410是静态挠度值,每ATA标准下0.410英寸的曲度值(注意:该标准对于梭型箭有特定的测量方法)
Series A(或者B、X、J等等)表示对于该规格箭支的设计修订系列号,这是为了防止多年以来材料或者其他规格上出现的变化而提出的。但是这个系列号很少会更新,可能十多年才会更新一次,而且也不会对箭支的表现有什么影响,射手将不同系列号的箭支混用也会打出很高的密集度。
最后就是本文的重点“重量码”C.2。正常来说,在保证挠度标准的前提下,某一挠度规格的箭支(可能同一批次有几千支箭)中最轻的箭和最重的箭的重量差异在5-6格令,这就保证了相邻C码之间的箭重量差异不超过1格令。这样做的重要性在于:
  • 对于所有(涵盖所有批次)ACE和X10箭支,某个重量码的箭,最重和最轻的箭重量差异不超过1.5格令(0.097克)。
  • 所有包装成一打的ACE和X10箭支,单打内的箭重量误差在+/- 0.5格令。
  • 一个射手可以轻松混用同挠度相邻重量码的箭支(比如C.2和C.3)而对集中度几乎没有影响,因为在你截箭、粘头粘羽、甚至粘箭杆贴纸之后,这种箭杆之间的极微小的重量差异已经被模糊了。实际上,即使是最高水平的射手,也很难察觉3格令的重量误差。



文末当然是再强调了一遍伊斯顿大法好......

当然很多顶尖射手都有提到像我们国内业余比赛的距离用X10这样的箭其实是有些杀鸡用牛刀,不过玩的开心也没什么好指摘的。伊斯顿的揭秘让我看到更多的是世界先进制造商的精细化和专业化程度,也许能对国内的厂商有所激励和促进吧。




EASTON WEIGHT CODES- SORTING OUT THE MYSTERY
By George Tekmitchov, Easton Sr. Engineer/Target Product Manager


When it comes to finger shooting recurve bows, there is no more important arrow specification than arrow spine. Yes, weight and straightness are very important.  But, consistent, correct arrow spine for each and every arrow being shot from a particular setup is paramount to grouping performance. The reason is simple and obvious if you have ever seen the behavior of an arrow shaft leaving the recurve bow. All of a shooter’s arrows must bend in the precise same manner on every shot, shot to shot, in order to group.

While most accomplished archers seem to know this intuitively, I once undertook a project to determine exactly how spine tolerances affect score. After all, when it comes to target archery, score is all that really matters. In the 1990’s, I arranged a test in which American archer and Olympic medalist Denise Parker shot a specific dozen arrows every day for a six week period, carefully documenting every single shot and its impact point on the target at 70 meters. Half of the arrows Denise was shooting were properly matched in spine, while the other half were at a tolerance used by a non-Easton shaft. The shafts were blind coded and mixed and visually identical, so Denise had no idea which ones were which.

At the end of the six week study, all of the data were examined, and we found that there was a two point

difference in raw score for every 12 arrows shot- the same two point margin that decided 80% of the World and Olympic matches of that era, and still decides most sets in the current competition match format.

It might seem obvious how important spine is, but there is nothing quite like real-world proof to see how important.

Now, if you have ever looked at a set of premium Easton A/C target shafts- X10, Pro Tour, ACE, ACC, ACG, or Pro Field, you may have noticed a somewhat mysterious code on the labels, or laser engraved onto the shaft surface- “C2” or “C3” or some other combination. This is what Easton calls a Weight Code. The purpose of this article is to explain what these weight codes are,  and what you need to know about them.

“But wait- you started talking about the importance of spine, how does that relate to weight?” -we will get to that shortly.

In order to understand weight codes, first you must know a bit about the materials used to build arrow shafts. Specifically, you need to know a little bit about how the stiffness-to-weight of a given material is expressed. Engineers use a dimension known as Young’s Modulus of Elasticity, usually simply referred to as “elastic modulus”, to express this property.

All experienced shooters know that when it comes to pure consistency, there’s nothing better than aluminum as a shaft material. Within a given alloy, the stiffness to weight ratio of an aluminum arrow is amazingly consistent. As long as the dimensions of wall thickness, diameter (inside and outside) and concentricity are spot on, the stiffness (spine) of the arrow will also be spot on.

The reason is simple. Aluminum alloys have extremely exact elastic modulus values from one arrow production batch to another. For example, XX75 alloy is always very close to 10,400,000 million modulus- whether it was made in 1964 or last week, the stiffness to weight, and the spine of a given size XX75 arrow will always be exact because all 7075 aluminum alloy has this exact stiffness to weight property.  (It’s noteworthy, this is independent of the tensile strength of the material, so long as the material isn’t stressed to permanent deformation.)

Not so with carbon fiber. Commercial carbon fiber can vary by more than plus or minus two million modulus– a relatively huge amount. For instance, one typical fiber used in many premium carbon shafts has a modulus of 46,000,000. But, unless an arrow manufacturer takes the extra steps needed to improve upon the normal material variation, this could range from 44,000,000 to 48,000,000 or more. This is a huge variation.

An additional variable is found in the epoxy or other polymer resins used to hold the actual carbon fibers together in the arrow shaft. The percentages of resin to carbon must be held to a very tight tolerance to keep this under control and produce a structure that has a consistent “bulk modulus”- that is, the stiffness of the combination of materials, in this example, epoxy and carbon fiber, which is something all carbon fiber composites have in common. But, the ratio is subject to variation from several process and material related issues.

Even the age of the starting material is another variable, which can have a tremendous effect on the stiffness properties, because this factor affects several process related variables which in turn affect the final outcome.

Any single one of these variables can substantially affect the stiffness of the arrow. Combine the variables that are possible, and you can see that some carbon shafts can have a tremendous spine variation if this combination of factors is uncontrolled.

Spine is so important for accuracy, that Easton takes many important steps to mitigate the effects of these variations. First, as the largest carbon buyers in the archery industry, Easton works directly with the companies who make the carbon fiber, to obtain only select material lots, which are as close as possible to the exact stiffness needed for a given design. Using only select materials from the world’s premiere carbon fiber manufacturers, and continually testing the materials as they are prepared for use, minimizes most of the carbon fiber variation.

Another important factor is that Easton does all of the A/C arrow fabrication in-house. From the construction of the super-precise aluminum core and accompanying preparation to the carbon wrapping, curing, machining, straightening, and other finishing operations, Easton carries out each step entirely in their facilities in Salt Lake City, USA.  This insistence on total control over all of the many processes and steps required to create each arrow shaft helps ensure quality.

Still, even using the finest carbon fiber available, and precisely controlling the other variables is not enough to completely eliminate the variation.  Yes, the shaft to shaft spine is held to an incredibly tight tolerance, but there’s still weight to deal with.  There are two approaches to dealing with this issue.

First, one could simply finish the arrows to a given weight, and allow the spine value to float. This would result in the performance problems mentioned at the beginning of this discussion.

The second way is that one could construct arrows to the exact spine needed, as that is the most important consideration for arrow shaft accuracy and consistency- especially for finger release. And then one could sort and identify the arrows for weight grouping purposes.  This is where the importance of weight codes comes into play. Easton produces every arrow to the precise spine specification required, takes the additional step of individually weighing each and every shaft to 1/10th grain tolerances, and then assigning that shaft to a group- the weight code group.

Weight Codes explained

If you look at the label of an Easton X10 shaft, you might be a little bewildered by the various numbers and codes indicated. Let’s decipher these.

First off there are two separate lines (this is an example, the details my be different from one model or spine to another):

906 A/C/X10 410 Series A

Aluminum/Carbon X10 C.2

Looking at the numbers in order:

First line:

906 is the core tube size expressed as diameter and wall- 9/64ths diameter and 0.006” wall thickness. All X10 sizes are based on this size core tube, so all use the same basic components.

A/C/X10 is obviously the model designation.

410 is the static spine value, 0.410” deflection per ATA standard.  (Note- the standard has specific methods for measurement of a barreled shaft.)

Series A (or B or  X or J for example) is the design revision for that particular size shaft. In case of any changes to materials or other specifications over the years, a separate series is issued. This is done very infrequently- once a decade or so-and does not affect arrow performance- any of these can be mixed by a shooter with no effects on grouping.

On the second line (or laser-etched into the surface of the shaft)  is the “C-code” or weight code, which is the subject of this article.

In the case of the specific arrows in the photo, you can see the designation C.2. When a production run (of many thousands of arrows) is created, each arrow shaft is individually weighed after final spine-tuning, and the entire population of arrow shafts can be charted (as with a bell curve) for weight. Typically, there is about a 5 to 6 grain total spread from lightest to heaviest among the thousands of arrows in a given run of a given size, and this is subdivided into less than one grain increments for assignment to a specific code- and even finer graduations for each individual dozen.

Here are the key points to understand the significance of this.

• All ACE and X10 weight codes cover a total spread of 1.5 grains (.097 gram)

• All packaged ACE and X10 shafts are held to a weight tolerance of +/- 0.5 grains in that specific package

• It is easily possible for an archer to mix shafts from two adjacent weight codes with no ill effect (”heavy” C.2 and “light” C.3 for example) because by the time you cut the shafts, apply fletching, points, and perhaps an arrow wrap, the fine distinction in weight between one group and other is “blurred” a bit.  In reality a three grain spread is undetectable by even the highest level archer.

In summary, spine is so important to arrow accuracy, Easton goes far beyond the rest of the industry to ensure that you receive both the specified spine and matched weight for every premium target shaft such as X10, X10 Pro Tour, A/C/E and A/C/G produced.  Weight codes help ensure that every premium shaft you purchase of a given size and code will correctly match those you already have, or will obtain in the future.

This is one of the more significant reasons why weight-coded Easton shafts have been used to win more than 99% of all individual and team medals in all World Archery competition since 1996!


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