Cutting Slabs with a Chainsaw Mill

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This is a lot of fun.

It’s dusty as hell (literally every crevice chocker full of sawdust), loud to the point of hearing damage, hot and seriously hard on the back/shoulders. But the finished product of a sleek, smooth, beautifully patterned slab of seasoned hardwood timber is worth all that and more.

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Let’s start with the ‘why’. I wanted to cut our own slabs for walls and flooring and explored the options. You can buy a small, portable Lucas sawmill for about 15,000 which has a slabbing attachment and is raved about by all and sundry. They really are a fantastic bit of kit, one person can move it to the log and build it up around the log. You can then cut timber to whatever dimensions you want or slab if desired. It has a simple low-HP petrol engine which is economical and the design is simple, safe and without affectation. Really cool, and if I had a lazy 15k, I’d be there in a flash.

The other option is a chainsaw mill. This is a simple contraption that bolts to the bar of your chainsaw and allows you to cut logs into timber.

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The one I bought is a Westford Slabbing Mill simply because this is the one sold at the Stihl shop in Zillmere where the bloke struck me as something of a slabbing gun. There are a lot of others about and before I bought this, I was about to the buy the Granberg Alaskan MKIII which has great reviews and I’m sure would do a great job.

Might segue here to a story. I attended a forestry field day in SE Qld  and at one point a number of forestry people were sitting around talking. I mentioned I was keen to do some slabbing and indicated that I was tossing up between the Lucas and a Chainsaw Mill. They rapidly and universally poo-pooed the Chainsaw mill with one bloke even offering me the one in his garage which he said he never bothered to use. The main problem they raised is that Aussie hardwoods are just too hard for a chainsaw mill. You just can’t cut ironbark with them as you will blunt the chains and bugger the saw and never get through anything. I took it on board and left that day with a Lucas firmly in my sights. When the ole bank balance came into those same sights a little while later, the Chainsaw mill came back to the fore with a vengeance, and here I am…After cutting 20 sq meteres with no chainsaw issues, I am ready to call BS on the above in any case.

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The mill comprises a simple attachment which clamps to the chainsaw bar at two points. It has a depth gauge to set the thickness of the slab being cut and two guide rails on which the whole chainsaw/mill sits as you push it through the log. That’s it, as simple as that, 200 bucks and you can slab anything depending on two things – the size of your chainsaw and the size of the Chainsaw Bar. I bought the Stihl MS660 to use for the mill. It is 92CC, the second largest Stihl you can buy and, frankly, it is not big enough for seasoned hardwood. If you stumbled on this site, are looking to cut seasoned hardwood, and are wondering (like I was) whether to go the Stihl MS660 or the MS880, go the 880. The counter-argument to that is that the MS660 can still be used for big chainsaw jobs around the farm whilst the MS880 at 15kg is just too big to lug around for any length of time.

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The picture above shows the freshly sawn slabs before being trimmed up. You can also see the ladder with screws coming out of the rungs. These are screwed into the top of a fresh log in order to give you rails to sit the chainsaw mill on for the first cut to ensure a level depth. The ladder needs to be screwed down tight as there will be a lot of weight and friction. Once that is done, you take off the “lid slab” off the log and the rails can sit on the freshly sawn flat surface below for the second cut.. You keep going until you get to the bottom of the log. The video below was the second cut and shows what I mean;

It takes about 10mins to do a metre so it is slow going if you are cutting long 3-4m board as I am doing. You do have to push the mill through the wood so it is hard work.

Once cut, I was trimming the ends with a circular saw which is a simple process. You just measure the distance at each end the same (say 25cm) and score the timber at that distance on each end, then run a chalk string line between each mark, then run the circular saw down that chalk line to get a clean, square, plank.

The boards ranged from 15cm to 40cm at the ends, not a bad width of slab. The longest I have cut is two at 5.6m which nearly spans the cabin.

We laid these on the joists and gave them a natural timber oil (clear) to protect the ends from splitting and ensure they do last forever. They look frigging fantastic and will be very memorable as time goes on.

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Problems we encountered were nothing to do with the slabbing, the joists are too far apart at 3m and tophat isn’t the right material for joists, waaaayyy too much bounce. It is perfect for roofing but forget it for joists, stick to C-section or timber. Anyway, we only realised how much bounce after we had put half the slabs on so this will be an ongoing issue to remedy another day. The second issue is that is needs some underflooring as there are gaps and there are cracks and I can only imagine these will get bigger over time. For the 6m x 6m living area, we will put yellowtongue down first.

This process takes time, serious time. I estimate it would take 2-3 weeks of non-stop work to get the full 12m x 6m cabin floored.

In summary, the chainsaw mill is simple to use but daunting to get started with. If you are considering it, I can really recommend it. The Stihl chainsaw has stood up to the punishment and is continuing to cut after several weeks of plowing through thick, seasoned Aussie ironbark.

It is actually about as safe as you can get with a chainsaw as the bar and chain are buried in a big  lump of wood most of the time. There is no kickback possible and even if the chain breaks at high speed there is nowhere for it to go so it just sits there in the log. It is easy, really easy so bite the bullet and give it a go. I often finish a slab and look down in awe. They really are a wonderful way to use timber as the final, finished look of the grain, patterning and deep colour is just beautiful.

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