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Swingmill Blades
Part one of a five part series about circular swingmill blades.
Part 1: Blade Identification
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What is a swingmill?
A swingmill has a single circular blade that pivots; moving forward sawing in horizontal to make the first cut, pivoting to vertical at the end of the log, and then moving back to its starting position as it saws in vertical. Your dimensional board can now be removed from the log, completely edged and square. Peterson Portable Sawmills in New Zealand were the original designers and manufacturers in 1989.
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Blades
Here’s a brand new blade straight out of the box. The holes in the blade are called Strobe Slots, where small planer knives or ‘Strobe Knives’ can be mounted. With Stobe Knives installed, furry timber is milled easily, with the strobes cleaning away the rough surfaces in the sawing path, allowing the blade to continue sawing unhindered. Strobe Knives can make all the difference between a two-hour job and a two-day job. Plus the slots allow water to travel through and lubricate both sides of the blade, reducing uneven heating.
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Next is a perfectly good, working blade from the field. This particular one is five years old, and is owned by an operator who works his blades hard. Even so, this blade is in very good condition, and the marks and colors are completely normal.
The brownish areas behind the teeth are sap and sawdust marks.
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This blade has been left in the rain a few times - you can spot some rust pitting in the dark dotted areas. Minor pitting like this is not a big deal. Nevertheless, a blade should not be left wet for weeks at a time, as the pits can get quite deep and then weaken the structure of the blade.
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Now here’s a blade you may think is destined for the scrap heap – but not so! This blade is still fine. It’s just covered in surface rust from moisture in the air during long-term storage. All you need to do is give the area around the mounting holes a light sand with very fine sandpaper, to ensure it can mount flush and tight to the hub. The rest of the rust will come off with your first few boards. |
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The number of teeth on a swingblade changes the performance. For example, fewer teeth with a thinner tooth are better for hardwoods, yet more teeth and wider teeth perform better in soft or fibrous timbers. More teeth give a better finish, but can be slower cutting as each tooth is only taking out a small bite. It’s important that a manufacturer gets the balance right between horsepower, plate thickness, number of teeth and tooth width, to give optimum performance.
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Buy genuine; it’s safer and more effective
If you are considering getting a replacement blade made locally instead of purchasing from the manufacturer, you may need to think again. Each brand of swingmill has carefully designed their blades specifically for their mill, unlike bandsaws which are often generic.
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A swingmill blade’s artistic design, shape, and patterns are automatically internationally copyrighted to the original designers. Inferior quality blade copies can also make sawing a real nightmare; if the plate is too thin it will vibrate about, be hard to push, and cut rough.
Safety also has to be considered when it comes to details like ensuring the blade screws are completely level with the surface of the blade. A blade that has CE Safety Certification should have a maximum rpm stamped on the body, to ensure it is not operated beyond a safe working speed.
If you ever have a problem with the manufacturer’s blade, you can always get support from them. So considering a good blade can last you 6-8 years or more, it’s a smart decision to just get a new blade from the source you can trust.
Next Month: Part 2: Re-Tipping & Sharpening
Copyright K Browne 2008
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