The Tree Guild of WA
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PRODUCING VALUE ADDED TIMBER BI-PRODUCTS

AKA MILLING

Many Arborists are familiar with timber milling in form or another. Not many, however, stop to think about what they are actually producing. Apart from an attractive and unique slab or board, the product of their labour is much more. They have (as the title suggests) a value added bi-product which is not readily available commercially.

Urban milled timber is an environmentally sound product and a logical progression when the removal of a tree is required. The continuity is maintained when the same people that cut the tree down, come back to mill the trunk.

C.P.D. Trees use several milling apparatus for various applications. Our Lucas Dedicated Slabber is well suited to logs up to 1.5m diameter and 7m long. This is powered by a 16hp motor and makes quick work of large logs. A 5m long cut in a 1m diameter Red Gum takes about 15 minutes.
We still have an Alaskan mill and a 088, for the 12" to 24" diameter logs. For perpendicular cuts, we use a Stihl Mini Mill and a 046. This comes in handy for cutting thick, heavy boards in half, or trimming +1.5m logs down to a diameter where we can mill them.

There is a growing community interest in the recycling of tree waste, especially as timber slabs. Some of our clients have engaged our services solely because we could follow up and provide a milling service also. Being in the tree during the dismantling process gives me a better idea of the exact parts of the tree that may best be suited to milling. Subsequently, I can remove these parts intact and with due care to maximise the viability of the project.

Selecting timber suitable for milling and assessing viability;

*Do you have a use for the slabs?
*Does the timber in the trunk look healthy?
*Is the timber free from steel, sand, termites
and other materials that would damage the saw?
*Is the procedure going to produce an equitable
quantity of slabs to justify the cost of milling?
*How much would it have cost to cart the timber away?
*Is the trunk in the center of the canopy and under uniform stress?
*Do you have somewhere to store the slabs for 2 years or more?
*Are you prepared to monitor the stack and maintain if required?
*Can the trunk be felled, SAFELY?

Setting the log for milling:

Setting the log is most critical for the trunk, as this is the heaviest part of the tree and the most time consuming to manage into a correct position. If the trunk is felled onto stout 10" diameter branches, it can be easily chocked to prevent movement whilst milling, and provides good ground clearance to get the lowest cut possible.
It may not be possible to have the trunk milled immediately, so keeping it off the ground will decrease the likelihood of soil or insects or water contaminating the wood.

In a perfect world, one end of the trunk would be higher than the other. Milling downhill utilises gravity and makes the job so much easier and quicker. Even a slight gradient will expedite the process.

When setting multiple logs for simultaneous milling, all logs should be parallel to each other on the same gradual slope, and some space between them to allow individual chocking. While we can mill up to 1.5m width, it is slightly faster to operate around the 1m size. The bearers that the logs are to be placed upon, can be notched prior to placement to secure logs whilst milling.

Quarter sawing Vs back sawing:
To quarter saw, one would cut the slab at right angles to the growth rings and parallel to the medullary rays. If applied in the correct use, this timber is very strong and designed to bear loads.
Quarter sawing is possible by integrating milling devices, but not viable. There are various methods of quarter sawing and all of them are more time consuming and wasteful than back sawing.

Bear in mind the following:

I would welcome any feedback, factual or anecdotal, from interested persons. Feel free to offer any info to Val for publication in the newsletter. Happy milling.

Mick Byrne.