Saw shop tech: questions and answers about cordwood saws.


Vern Burke, SwiftWater Edge Tool Works

Skowhegan, ME

It’s time for a special question and answer session! I’ve been seeing so many questions come through about cordwood saws, this one is going to be just about them.

For those not in the know, a cordwood saw is a 30″ circular cross cut saw, usually powered by a tractor or a dedicated engine, and used to saw bolt length wood into stove length firewood. These saws are usually run by flat power belts from the tractor PTO or shaft driven directly for the newer ones. A properly tuned up cordwood saw can be FAR faster at working up firewood than a chainsaw (and, arguably, safer).

The first question is regarding the proper speed to the cordwood saw at. Existing PTO powered saws are normally set up already to run at the standard 540 rpm tractor PTO speed.

The actual running speed of the saw itself is set by the way the saw blade is “hammered”, usually 800-900 rpm for a classic thin blade or 1300 rpm for a thicker Vermont Woodsman type blade. At the right rpm, the blade will actually “stand up” straight. This can be seen by eye as the tractor or engine throttle is adjusted (the ONLY time you should EVER get anywhere near in line with the running blade!). If you purchase a used cordwood saw blade and you don’t know what rpm it’s hammered for, this is the way to tell. Blades can be re-hammered for different speeds but this requires a very specialized saw shop.

So, what happens if you run the cordwood saw blade at the wrong speed? Anything from not cutting straight and taking more effort to cut (minimally off) to actually setting up a ripple in the blade and possible structural failure (way off).

The second question is about slipping flat power belts driving a cordwood saw. Flat power belts tend to slip badly if they’re over tight ( counter intuitive to the way modern V belts work). Under load, a properly tensioned flat belt should “suck in” around the pulley, giving extra traction and avoiding slipping.

The last question is about telling if a cordwood saw blade is dull. That’s easy, just watch the cordwood saw videos on YouTube, 90%+ of those saws are terribly dull. Smoke from the blade, overly hard sawing, or lots of pitch buildup on the blade (not enough set) are the clear indicators that a cordwood saw blade needs attention!

Visit me at any of the following locations:

Elm Plaza, Waterville, ME (Mondays)
Arundel Flea Market, Rt 1 & Log Cabin Rd, Arundel, ME (Fridays)
298 W Front St, Skowhegan, ME (all other days)

If you’re looking for a special tool, please drop me an
email and let me know and I’ll restore one just for you!

SwiftWater Edge Tool Works provides mobile sharpening services across Maine and mail in services around the world for handsaws, carbide blades, planer knives, hand planes, chain saws, knives, scissors, hair clippers, router bits, and almost any blade!

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