sawhorses - Wood Tools

IlIDIointers haven't changed rnuch over the last fewdecades. But recently, several ntanufacturers have' borrowed an old woodworking concept to makea jointer a better, cleaner-cutting tool.To understand this concept, think about using a handplane. Conventional wisdom says to skew the blade atan angle to the workpiece.The result is a shearing cutthat leaves a snoother suface and prevents tearout.Dire Straights - unfortunately, most joinrers don'rallow you to cut this way.This is due to the design ofthejointer cutterhead - it has straight knives that chopin a motion that's perpendicular to the edge of theboard (Illustration, below left).Thrs can cause tearout, especiallywhen you're working with highly figured wood.Evidence of this chopping motion can also be seen inthe tiny wood chips straight knives produce.The Spiral Solution - Recently, the concept ofskewing a hand plane at an angle has been incorporatedinto the design ofjointer cutterheads.'With knives thatwrap around the cutterhead in a spiral, these tools shearthe wood fibers, rather than chopping them (lllustration,below right).The result is a smoother cut that produceslonger shavings - and requires a lot less sanding.To the Test - This distinction became especiallyclear when I compared a straight-knife jointer cutterheadwith a spiral cutterhead.To truly push their capabilities,I set the depth on the two jointers for aggressive, 1/s"-deep cuts.Then I jointed the edge of a 1,0/ 4 maple boardon the two machines. The results shown in the Photobelow speak for themselves.Turn to page 84 for an overview ofthe spiral cutterherdsyou can use on yourjointer.Shoight Kniveschop wood,cousing chotlerteoroutSpirol Knivessheor wood foro smoother surfoceSTANDARD SPIRALCUTTERHEAD CUTTERHEADA Edge groin wos gougedseverely ofter o poss over oiointer wiih stroight knives. Spirolknives left the some edge smooth.WORKBENCH f] DECEMSTN 2OO5