Thursday, March 28, 2013

V4.12 - Setting those pesky knives, Part 2

Continuing our ongoing discussions about the Jointer, we were talking about setting the jointer knives. If I recall correctly, we last mentioned that the jointer knives need to be set dead-even with the outfeed table.

There’s a reason for that and here it is.

The way a jointer does what it does is because the knives remove material as the wood is passed over the spinning cutterhead, that has the knives installed in it. The amount of material that gets removed is determined by the depth setting of the infeed table. For example, if you set the depth at one-eighth of an inch, then one-eighth of an inch of material will be removed as the wood passes over the cutterhead. As that one-eighth inch of material is removed, the outfeed table must support the fresh surface of the wood. It can do that because the outfeed table is set dead-even with the peak of the knives.

So, how to get there from here? Some jointers have threaded screws that raise or lower the knives. Some jointers (I dare say ‘most jointers’) have small springs under the knife that push then up when they are loosened. The basic idea is that you would place a straight edge onto the surface of the outfeed table, let it hang over the cutterhead and raise the knife to touch the straight edge. This must take into account the rotation of the cutterhead, so the touching of the knife to the straight edge must be done at the very top of the cutterhead’s rotation. This is a very difficult thing for the inexperienced person to get the hang of. Fortunately, someone invented a ‘helper’ that makes this a much easier chore.

Let me introduce you to the “Jointer Pal”. This device consists of two magnetic bars that are held together and spaced appropriately with round rods. The unit is placed on the outfeed table and the magnetic bars pull the knife up to the bars, which are dead-even with the surface of the otufeed table. As the knife hangs there on the magnetic bars, you allow the cutterhead to rotate freely and center up, as you tighten the knife locking bar crews. No need for the springs, or the adjusting screws or any of the tricks of setting jointer knives that were learned with blood sweat and tears.

The Jointer Pal is one of the coolest ideas to ever make a dreaded chore sooo much easier than it was before.

If you have a jointer and don’t have a Jointer Pal, you owe it to yourself to get one and make your life a bit better.

Send your questions or comments to: and we’ll see what we can do to help you.

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