In this 30-minute video, wood sculptor David Groth runs through his process for breaking down a gorgeous redwood log into 4″ thick slabs that he plans to turn into some outdoor benches for his koi pond. The person videoing him asks a lot of basic and thoughtful questions and Groth is really informative with his answers, making this a very educational and interesting video for anyone [raises hand] who doesn’t know that much about the science of wood growth and the ins and outs of the lumber milling process.
In the video, Groth uses his handmade Alaskan mill to cut the log into perfect slabs. An Alaskan mill is a jig that attaches to a chain saw so that the saw can be suspended from the top of the log to a precise depth. Frequently, as in this video, a rail is attached to the top of the log at a level height and that’s what the mill is suspended from for the initial cut.
Here are a few of the things I learned from watching this video:
Negotiating a Heart Crack
Most boards have a “heart crack” that runs through the heart wood. When cutting a board, you need to determine where the crack is and how it moves through the tree. As Dave points out, this crack frequently twists through the log. In the video, he marks the crack on both ends and then rolls the log so as to minimize the exposure of the crack in the resulting milled lumber.
Removing the Sap Wood
Because this wood is going to be used outdoors, Groth removes all of the outer sap wood (seen here in the pale green outer ring). Outdoors, it would quickly rot. If his benches where going to be used indoors (or in other indoor applications), he would rip the entire width to gain the extra dimension in the lumber. The outside sap wood is cut off and stacked for drying and turning into firewood.
A Sharp Blade Cuts a Straight Line
Dave sharpens the teeth on the saw blade before removing the sap wood. Making sure the teeth are equally sharp and sharpened to the same angle helps to prevent the blade from traveling and producing a line that’s not straight.
A Careful Set-Up Helps Ensure a Perfect Cut
Taking the time to carefully mark a level cut-line on both ends, removing the top bark, and installing a top rail helps in milling out straight and level lumber. Removing the bark makes it easier to nail the rail securely to the log. Once the rail is installed and level, Dave measures down to his desired depth to make sure everything is level and square. If all goes well, when he gets to the end of the log, the blade should exit at the line he drew onto its end.
The Simplicity of the Alaskan Mill
Alaskan mills can get somewhat elaborate (and expensive). Groth’s mill is as simple as they get, a couple of threaded rods that attach to the saw bar, wooden spacers (at various thicknesses) to create the desired depth of the cut, and a top board that either runs along a rail or an already leveled-off and cut surface.
Shims Along the Way Prevent Chain Binding
As the cut is made down the log, shims are hammered in behind the mill to help prevent the cut top from pressing down on the saw bar and binding the chain.
Alaskan Mill Plans on Instructable
David Groth’s video provides most of the info you would need to make your own Alaskan mill. But if you’d like a somewhat fancier, sturdier metal-based mill, there’s an Instructable for building one out of 40mm X 40mm profile T-slot aluminum. Link: Chainsaw Mill Build, Use & Tips n Tricks.
You can see David Groth’s chainsaw art on his website. And you can subscribe to his YouTube channel here.