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Snowboard Design & Construction Part 2: The Core

25 February 2021
Snowboard Design & Construction Part 2: The Core

In part two of our snowboard design and construction series we're going to take a look at what's going on inside your snowboard.



Snowboard Construction


The majority of snowboards are constructed using a technique known as sandwich construction. This type of construction places layered individual elements in a mould (like laying up a sandwich), which is then are placed in a press and subjected to heat and pressure. This bonds all the elements of the board together to form the snowboard.

The individual elements of the boards' construction dictate the riding characteristics and determine the board's performance.

Snowboard construction


The Core


The core is the board's heart; it's where the main riding characteristics and performance originate. Get the core design wrong, and no matter how much fancy material you add to it, you're going to get a board that doesn't work right.

Over the years, manufacturers have developed and refined core technology, evolving from simple ply and foam designs in the early days of the sport to complex multi stringer composite and wood designs of today's high-end boards.

To understand the principles of core design, we need to understand what the core is delivering to the board's performance. Understanding this makes it easier to see how different technology and materials used in the core bring additional benefits to your riding.

 

Flex

The core controls the flex of the board through the length. Manufacturers manage this flex in a variety of ways. The first of these is the wood type. We'll go into more detail on the specific characteristics of different wood types later on in this section but the first thing to look at is how manufacturers lay up the core to maximise its performance. The best place to start is by looking at what wood is.

Wood is a naturally formed polymer that consists of parallel strands of cellulose fibres that are bonded together by lignin. These long chains of fibres make wood exceptionally strong. They also have a high resistance to stress and have the ability to spread the load along the length of the fibres.

Wood

Although that all sounds pretty technical, it gives us an understanding of how different woods deliver different characteristics. All wood is formed by this combination of cellulose fibres and lignin. Where these species of wood differ is in the density of the cellulose fibres. If you have more fibres for a given area, the wood is denser. What this means is that the characteristics of the wood changes. The wood becomes more robust and has an increased resistance to flex, but, on the downside, it becomes heavier.

If we go the opposite way and reduce the amount of fibre, the wood becomes lighter and weaker. This is where the core designer's skill comes in; they look at the board's desired characteristics, then select woods for the core, subject to the density, stiffness and weight of that wood type. These woods generally range from laminates of medium density woods such as Poplar and Aspen in more price-sensitive board to more complex combinations of different woods and composites in higher-end boards. The core builder lays up the core using a process known as vertically laminating. This process allows the designer to create a precise and very specific flex profile.

 

Vertical Laminating

Vertical laminate cores are formed by laminating strips of wood along the length of the core. These are created by glueing strips of wood together, forming a block with the wood grain running along the block's length.

Vertical laminating

You can see in the picture above how the vertically laminated block on the press is built up from the strips of wood in the foreground. These strips are glued together and then compressed by the press. Where vertically laminating comes into its own is how you use the different species of wood. If you take, for example, a medium density wood such as poplar and create the core block from only strips of poplar, you get a mid-stiffness board that has a consistent flex through the length.

Vertical laminating: one type of wood

However, if you want to create specific riding characteristics within the board, you can introduce wood from different tree species. These deliver different characteristics and can be used to add strength or give an increase in performance.

By laminating different wood species, you develop specific flex and performance/riding characteristics to different areas of the board. You can also add strength zones. So, for example, if you have a core constructed mainly of Aspen, but you then put a stiffer, harder wood along the edges, you give the board a more lively feel through the turn

Vertical laminating: edges

If you run a harder wood through the middle tip to tail, you'll give the board a more poppy feel through the length. Hardwood blocks under the bindings help reduce the likelihood of inserts ripping out and reducing the chances of core compression.

Vertical laminating: stiff middle

By combining harder, stiffer stringers through the middle of the board and along the edges, you get a more powerful core both through the length and on edge. This combination is used on higher-spec boards, where performance is the essential criteria.

Vertical laminating: edges and middle

As you can see, the wide variety of woods give the core designer carte blanche to create the optimum performance for specific boards. But it's also a balancing act; too much hardwood and the weight goes up, and the board begins to feel dead under the feet, too much lightweight wood and the board becomes weak and loses performance.

To add an extra element to the boards' performance, you can take further advantage of the grain structures ability to transfer energy along its length by using it to direct power to specific areas of the core. Burton takes full advantage of this with their EGD core profile. EGD adds wood stringers running perpendicular to the main wood stringers along the edges underneath both the toes and heels. As the fibres now run straight out to the edges, you get increased energy under the feet, improving edge hold and feel.

Vertical laminating: EGD

 

Core Profiling

Now we know how the core is laid up, the next stage of its construction is profiling. Profiling is the process the raw core block goes through to create its flex through the length. This next section is going to look at the different core profiles, what they do and how they affect the performance of the board.

In simple terms, the flex through the board's length is determined by the shape and profile of the core. The boards designer creates a predetermined flex pattern by milling material away, which delivers particular flex characteristics and allows the designer to control the board's performance. 

The more material you remove from the core, thereby thinning the profile, the softer the flex is in that area. By looking at the board's side profile, you can see where the material is thinned down to deliver softer flexing areas of the board.

These profiles are dependent on the performance requirements of the board and generally follow specific trends.

Positive Core Profile

The Positive core profile is thicker between the bindings and thinner towards the nose and tail. This gives a more powerful feel under the bindings giving you increased response through the turn increased edge hold.

Negative Core Profile

The negative core profile again reduces the core thickness at the tip and tail. However, unlike the positive core, it also removes some of the material between the bindings, thinning the board's middle. This profile gives the board a playful tip and tail with a solid feel under-foot. The thinner middle section softens the flex in the centre of the board, delivering a softer, more playful overall ride making it ideal for more park-focused boards.

Even Core Profile

The even core profile removes material at the tip but progressively leaves more material as you move towards the centre of the board and then reduces the material at the same level towards the tail. This gives the board a consistent flex from tip to tail and tail to tip. Although similar to the negative core, the even core has a more progressive transition from thin to thick to thin. This gives a more predictable and progressive flex.

Manipulated Core Profiles

Manipulated Core Profiles

Over the past few years, we've seen designers become more elaborate with core profiling. By machining thick and thin zones throughout the core's full length, it's possible to dial in particular performance characteristics. This process allows the designer to match the flex perfectly with the target rider. This most visible proponents of this process are Burton with their Squeezebox and Salomon with their Popster profile.


Core Woods


In this section, we're looking at the most commonly used core materials; these show you the performance characteristics of each of the wood types, where and how they are used to add specific performance into the core. Don't get too hung up on the technical data; it's just there more to show you the difference between each of the woods and why those manufacturers use that species of wood.

 

Poplar

Name: Poplar (Populus spp.)
Type: Hardwood
Other
Names:
Includes European black poplar, Canadian poplar, balsam poplar, cottonwood, and various varieties of Aspen
Sources: Grows throughout N. America, Europe, and Asia
Appearance: Generally straight grained and "woolly" with a fine, even texture. Creamy-white to pale brown heartwood and sapwood.
Physical
Props:
Most species are typically soft and light with low ratings for strength, stiffness, shock resistance, decay resistance, and steam bending. Moderate movement in service.

Poplar is probably the most commonly used wood in snowboard core construction; its combination of low weight and durability combined with a medium stiffness make it the perfect choice for snowboard designers. With a tight grain structure and consistant flex, poplar delivers the perfect characteristics for the construction of snowboards.

Poplar can be used to form the whole core as in most low to mid-price boards or as the main component wood of a higher-end core which will be reinforced with harder or more dense woods.

Poplar comes from trees in the Poplus family and is grown in most of the Northern Hemisphere. There are approximately 35 different species of Poplar tree including Aspen.

The description of the core usually gives you an indication of where the core was manufactured; if the core is described as poplar it is usually sourced in Europe where as a core listed as Aspen is usually sourced in the US.

 

Poplar


 

Aspen

Name: Quaking Aspen (Populus tremuloides)
Type: Hardwood
Other
Names:
Also known as Aspen and trembling Aspen
Sources: Grows in the north-eastern and north-central United States
Appearance: Straight grained with a fine, uniform texture. Greyish white to greyish-brown heartwood and lighter-coloured sapwood. Often sold as poplar or cottonwood.
Physical
Props:
Soft, light, and low in strength, stiffness, decay resistance and shock resistance. Dents very easily.

Like Poplar, Aspen is a derivative of the Populas family of trees. Therefore the performance characteristics of Aspen are almost identical to those of poplar.

As the 2 kinds of wood are almost identical, there is very little difference in the way a board made from Aspen rides compared to that of a board made from poplar.

Generally, Aspen's use in the core is more geographic; typically, cores sourced in the US are manufactured from Aspen whilst European, and China-sourced cores use traditional Poplar.

Again as with Poplar, Aspen can form the whole core or as the main constituent of a higher-end wood core.

 

Aspen


 

Beech

Name: European Beech (Fagus sylvatica)
Type: Hardwood
Other
Names:
It is also known as English beech, Carpathian beech, Danish beech, and others according to country of origin
Sources: Grows in Europe and southeast Asia
Appearance: Generally straight grained with broad rays and fine, even texture. Pale cream to pinkish-brown heartwood that darkens to a pale reddish-brown.
Physical
Props:
Hard and heavy, with high bending and crushing strength and moderately high stiffness and shock resistance. Poor dimensional stability and decay resistance.

Beech is the first of the harder woods to be used in snowboard cores. These stiffer woods are used in critical areas of the core to help deliver a more specific performance. As these woods are denser and stiffer, you can add snap and torsional rigidity into the core to give an additional performance in specific areas of the board. You wouldn't want to create the whole core from beech as it is A: Too Heavy and B: Too stiff, making the board pretty lifeless.

 

Beech


 

Birch

Name: Birch (Betula alleghaniensis)
Type: Hardwood
Other
Names:
It is also known as Silver birch, Weeping birch, Downey birch, and others according to country of origin
Sources: There are around 60 different species of birch that grow in temperate climates. Mainly sourced in Northeast North America.
Appearance: Heartwood tends to be a light reddish brown, with nearly white sapwood. There is   virtually no colour distinction between annual growth rings.
Physical
Props:
Birch is a hard, close-grained. Most birch is straight-grained, although the  straightness of the grain is dependent to some extent on the growing conditions.

Birch is similar in performance to Beech in that it is used to give the board more pop and power. Thanks to the orientation of the grain, it's also really good at transferring energy along its length making it great for enhancing strength and drive down the edges of the board.

 

Birch


 

Paulownia

Name: Paulownia (Paulownia Fortunei)
Type: Hardwood
Other
Names:
Also known as Princess Tree, Pavlovnia, Phoenix Tree, Kiri
Sources: Grows in China, Laos and Vietnam.
Appearance: Fine-Grained. Knot free, Pale-brown heartwood and almost white sapwood.
Physical
Props:
Very Light, hard, One of the highest strength to weight ratios of any wood, good dimensional stability, and poor decay resistance.

Paulownia is one of the new woods used in snowboard manufacturing. It has several properties that make it attractive to snowboard designers. The first of these is its combination of lightweight and strength. Weighing not much more than super light Balsa wood, Paulownia has a strength rating closer to the traditional woods used in core building. This combination allows board designers to create a very lightweight board as they can use more lightweight material than you would be able to use with more traditional woods such as Balsa, with little to no strength properties.

Another significant advantage of using Paulownia is that it grows at a fast rate. The tree is being cited as a cure to deforestation as it's grown so rapidly. At the moment, Paulownia is only really used on high-end boards. When using Paulownia, manufacturers typically use a denser wood than standard to offset the weaker nature of the Paulownia, which ensures a lighter core with added strength.

 

Paulownia


 

Bamboo

Technically not wood but grass; Bamboo has characteristics that make it an excellent material for snowboard construction. It is lightweight but very dense and very strong torsionally; this gives it great strength and much rebound when bent out of shape.

The beauty of Bamboo is that it can be used in a variety of ways because of its unique properties. Bamboo sheet can be used as a structural layer reducing the amount of environmentally harmful materials in the board or as a part of the core to give added pop to the flex. Bamboo is generally either run through the board's length to liven up the flex through the length or along the edges of the core to increase power and response through the turn.

Bamboo grows very fast; sometimes up to 4ft in a day. This makes Bamboo one of the most environmentally sound materials used in snowboard construction.

 

Bamboo


Don't forget to check out part one to learn about snowboard shapes, profiles, and sidecuts. Stay tuned for parts three and four coming up in the next few weeks, or watch the videos now on our YouTube channel.


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