Advanced Metal Knowledge
We all love the natural beauty of a large section of timber, cleverly incorporated into a classic piece of engineering, but what limits what we can do?
We hate to say that anything is impossible, but there are a few obstacles that may arise as dimensions get bigger. As part of the manufacturing process for all wood, large tree trunks are taken through a large band saw and are rough-sawned down to the desired size. Broadly speaking, it’s the original size of the log that will determine the finished size. However, transport and handling need to be considered when you’re talking big.
To ensure a true cut every time, the band saw blade is very rough, with large teeth, designed for extensive use with big timber. Due to sample size, there are always cut lines on all rough-sawn timber. Once the timber is sectioned down and processed into smaller sizes, then these markings will be removed. However, with larger sections of timber, there is a limit to the size of what can be commercially planned so generally these sections are left as they come from the machine.
For sections that are used for seating, like our Pueblo range (click here), then the surfaces are prepared by hand and any variations in the grain structure, knots, etc are smoothed out to ensure it is safe to be sat on. Alternatively, they can be hand planed so have a smooth surface but generally will be slightly uneven due to the hand processes involved.
With large section timber, as there is minimal further processing, surface markings and grain variations will be present. These are not to be seen as defects, but character with this style of timber section. In contrast, where you have smaller sections that have been more finely processed, this is not normally present.
Dog Marks
Several tons of tropical hardwood can become a real threat if the timber jumps when being worked by a powerful band saw. It is therefore imperative that a tree is clamped down tight to ensure that it never jumps or jams when going through the saw. To do this, large clamps called ‘dogs’ pin the tree to the deck while it goes through the saw. These dogs exert many tons of pressure, and of course, do not go without leaving marks. See image:
Grain variations and markings
When we are working with large sections, we have to take what nature gives us, so will include knots, heartwood, sapwood, etc. again whereas with smaller sections, selective filtering can remove these, but is not economically viable with very large sections.
For more details on this, please view our blog (Understanding Moisture in Timber). However, we need to touch on it just briefly for this topic. Moisture content is at its highest when it is first processed and slightly reduces over time, and this can be done in 3 ways: 1) use the timber as it has come from the mill and over time the moisture will slowly reduce – this is referred to as ‘fresh-sawn’. 2) store the timber in open-sided barns until the moisture content reduces to around 20% – this is referred to as ‘air-dried’. 3) take the already ‘air-dried’ timber and further dry it in large commercial ovens until the moisture content is down to around 10% – this is referred to as ‘kiln-dried’.
So what? Well, the maximum thickness that timber is cut for air or kiln-dried timbers is 100mm – once plained down this finishes at around 80mm. The maximum section for fresh sawn is as big as described above. So, if you require large section timbers, then fresh-sawn is the only option.
There is no clear-cut answer to this. We can only go as big as the tree itself, and then what the capacity of the machinery used. Different species of trees grow to differing sizes so often the species would dictate the maximum size. Also, transportation and handling on-site need to be considered as well.
We would recommend getting in touch at the design stage to see what would be possible and what would not. It may require booking trees to get the dimensions you would like in your design. Therefore, the earlier you get in touch the more likely you are to be able to achieve the required dimensions.
Usually, our opinion for large timber sections is to simply go for it. We love the natural, big statement feel of large section timbers. Our Specification Team can guide you through the options available.
