About two weeks ago I posted an article about the trees I've met on Vancouver Island, and mentioned the surrounding circumstances of how I got to be there. Now I want to tell a bit more about my friend's project of building his earthship, or more exactly about the preparation for this project, that is milling the trees cleared on his property to make material for the building.
So instead of pounding tires, it was the mobile sawmill that got me so interested in seeing, and getting to know how to use it. Mobile means, it can be hitched to a vehicle as a trailer, but needs to be set up firmly, with concrete footings, once it is in its place of operation.
The Mill
The mobile mill in question is a modified Mighty Mite with full hydraulic controls driven by a VW turbo diesel engine, capable of milling logs of up to 6 meters (20 feet) in length. As for the diameter, they can be as thick as they grow. The real big ones of 90 cm (2 ½ feet) or more we decided to save for later, once we’ve got the mill figured out properly, and practiced on the ones as small as 30 cm (1 ft) or so.
It is not easy to get the cut right, especially with logs that are not exactly straight… but it’s all a learning process. Needless to say, at first we were producing a lot of wastage, but as we all know, there is no such thing as waste only things in the wrong place. So luckily for everyone, Tony’s wife Susan has decided to build the right place for woodchips (yes, a chipper came in super useful) and rooty tangles: a large Hügelkultur. She is just as much interested in Permaculture as Tony is natural building, so obviously, there are a lot of interests I have in common with both of them. A Hügelkultur is a way of composting organic material in large mounds. Let me come back to that one later (in another article) and focus on the milling instead.
Maneuvering Heavy Logs by Hand
The first step is to move the log onto the mill. This requires at least two people, armed with peevies, known from typical 19th century photos of bearded fellows posing with the tools of their trade. These pointy poles with movable hooks are still used to give the logger leverage in moving the weighty hunks of wood into position. Once they are sitting parallel to where the mill runs, they must be secured in place using the so called log-dogs. These are heavy steel spikes, running on rails perpendicular to the logs, and pushed into the wood firmly with a spring mechanism. These powerful devices make sure that even the heaviest logs stay in place while being cut, but the steel springs can just as powerfully kick back if not handled with care, and possibly break the sawyer’s legs.
Just Press Down and Go? Not Quite!
Once the log is firmly attached, the mill can be fired up. There are two engines, one running the three blades, the other one the hydraulics controlling their positions. The main blade makes vertical cuts, taking slices off of the log, and the two small horizontal blades cut lumber of the required size out of the slice, all at the same time. This leads to the mentally engaging part of milling, requiring good planning in what sizes of cuts to make to maximize the use of the wood.
The first slice is bound to be round on one edge. Though it is usually not used for construction, it could make rustic looking wall coverings, if cut decently. As we move closer towards the center, the slices get wider, giving us more options in the sizes. The tricky part is cutting the depth. Since the horizontal blades can cut a maximum of 13 cm (5 inches), we have to cut the wider pieces of lumber standing on their depth instead of on their width. What makes it even more interesting, is that only the top horizontal blade can be moved apart from the other one. The lower blade only moves in unison with the top one. And very importantly, they must never be lower than the zero point (unfortunately not absolute) which avoids the blades hitting the log-dogs.
The Inevitable Learning Curve
Complicated enough in theory? Just try it in practice! It will raise entirely new and unexpected issues, especially having to do with repositioning the whole set of blades at an exact distance from the previous cut, to make the lumber uniformly wide and thick at all points of its length. If we add a less than perfectly straight log, which may move away from the blade due to its own force exerted on itself as it’s being cut, the entire operation may become overwhelmingly complex. Mistakes are unavoidable, such as the chipped teeth (fortunately they are field replaceable), caused by getting too close to the log-dog. However, as it is the case with all dark clouds, there is always a silver lining. So when we took the machine apart to change the broken teeth, we also discovered a bushing in need of replacement. Since safety always comes first, we decided to suspend milling for the time being, and continued once the new part was in, and the mill back to ship-shape. In the end we didn't get to mill as much as we'd wanted to, at least during my time there, but managed to build a roof over the machine, as well as prepare ample material to build a few sheds for the winter.
But Why?
So what is the whole point of it all? Why would you go through all the trouble of dragging a mill onto your property in form of an oversized trailer, pour concrete footings and probably build a roof for it, only so you could cut some tree trunks into boards? Mind you, the mill itself is a very basic one, never capable to compete with the speed and accuracy of high-end industrial saw-mills. Moreover, why would I want to volunteer my time and travel great distances to work with one, and then write with such enthusiasm about it?
Efficiency in Scale
Well, the most obvious reason is that it enables you to turn your own trees into dimensional lumber for your construction, or even furniture. Makes sense, but to really see the difference, one only needs to visit the nearest lumber yard, and check out the prices charged for the material needed for let’s say a simple tool shed. For sure, the wood growing on the property is only as “free” as the combined costs of machines / operators / fuel etc. needed for clearing the area, preparing and stacking the logs. The purchase, transport, and installation of the mill comes additionally, not to mention the time spent on learning how to use it, still more fuel, as well as possible repair jobs, which are always part of the package. So for one simple shed it is clearly not worth going through all that trouble. But for making several sheds, and then an entire Earthship, then possibly further structures, or maybe even lumber for selling / gifting / bartering, etc. it makes a big difference. Especially, if the resources are locally abundant, they should have a reasonable priority over stuff that’s brought in from off site.
For this post I used pieces of text from my blog, and original pictures I published on facebook.