Uneven wear on jointer blades

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I don't know what you mean by parallel.
I did it by putting the indicator bearing over the knife and rotating the cutterhead. As each knife passed it would raise the indicator bearing. What is wrong with that? It doesn't have to be at TDC, but then you don't know if they are even with the outfeed table; just that they are even to each other.
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Toller wrote:

The 'parallel' he is talking about is a machinists set up tool. It's a rectangular bar of steel with precisely parallel edges and faces. Normally it is also ground very smooth.
Laying the indicator tip against that smooth face is easier than trying to get it to hit the knife edge. That's all.
You are right, TDC is irrelevant. What IS relevant is that the relationship (angle and distance) between the cutters and the indicator tip not change between measurements.
Bill
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I don't know what you mean by parallel.

The parallel is a machinist's parallel. Usually sold in pairs, typical size might be 6" long, 1" wide, 1/2" thick. Precision ground parallel and flat on all faces, hardened steel.
Most dial indicators have a convex contact. If you want to accurately set the jointer knife, you have to make sure that when it is exactly at TDC it is hitting exactly the lowest point of the contact. Pretty tough to do unless, as with Ed's jig, you fix the knife at TDC and run the contact over it.
If you put a parallel in between, you don't even have to make sure that the indicator is on a wide, flat stable base. You can use it on a magnetic base. It may not read the same when you set it up on the other end of the knife, but that doesn't matter. The only thing that matters is how much the knife lifts the parallel when it rotates.
John Martin
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When I saw the wear pattern on the old set I realized

Could be as simple as having the grinds at somewhat different angles. Makes the one blade more vulnerable to chipping on a fragile edge than the one ground properly. Never had the courage to lay a stone on the outfeed and make that secondary bevel like some books recommend, but that is even less subject to wear in theory.
Also gets them nuts on with the level of the outfeed without fiddling....
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