question about using a dial indicator for jointer knives

I bought a dial indicator and base in my never ending quest for precision. How high above the body of the cutterhead should the edge of the knife be?
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High enough to equal the outfeed table.
Seriously, as long as can see some flat below the bevel in the back, I'm happy. It's the first statement that's important.

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On Sun, 25 Jan 2004 6:33:14 -0700, mel wrote

You should strive to give the blades the most support possible. I'd sink the blades as deep into the cutterhead as possible while still allowing for chip removal and proper outfeed table adjustment.
Using a dial indicator on a pointy rotating object is a lesson in futility. You can never really know where top dead center is. A straight edge and feeler gauge or some other method to index the cutter head was a lot easier for me.
-Bruce
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With the little ends that come with most dial indicators, I agree. However, the ends are just screwed on and places like MSC and Enco sell replacements. I bought a relatively large diameter end that works great for setting jointer knives. Just get the dial indicator more or less over top dead center and turn the cutter head by hand. The largest reading will occur at top dead center.

Even though I have a dial indicator and homemade jig to hold it for setting knives I find it faster to use a straight edge on the outfeed table. I've found that when the knife makes a faint "snick" without lifting the straightedge the knife is about 0.003" above the outfeed table which has been just about perfect on the last two jointers I've owned. Having the knives at the same exact height as the outfeed table gives me convex edges.
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I looked in the MSC catalog and wasn't sure what to get as a replacement tip for my dial indicator. Could you give a little more detail?
Thanks,
Jim
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Here are individual ends:
http://www.use-enco.com/CGI/INPDFF?PMPAGE 5&PARTPG=INLMK32
They also sell a set for $5.25 that gives you a variety of ends:
http://www.use-enco.com/CGI/INPDFF?PMPAGE 6&PARTPG=INLMK32
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wrote:

Of course you can. Use the dial indicator to find top dead center on the cutterhead. Then scribe a line on the fence, aligned with that position. The cutting edge is at TDC when it aligns with the mark on the fence.
-- Doug Miller (alphageek at milmac dot com)
How come we choose from just two people to run for president and 50 for Miss America?
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On Sun, 25 Jan 2004 13:26:28 -0700, Doug Miller wrote

As pointed out by another poster you really need a flat head (versus the ball head) to make life easier. On my Jet 6", I use a 6" rule as a "stop" that I align the flat surface of the blade against (blade flat that protrudes from the cutter head for the rabbeter rests flush on the end of the rule. The long side of the rule rests flat on the infeed table lowered way down). This gives me very consistent cutterhead indexing. With the cutter head locked down thusly, I use a machine parallel and a feeler gauge to get the blade height even across the outfeed table. I then repeat the setup for the other two blades. No need to find TDC with this method. I then raise/lower the outfeed table until the blade just "ticks" against the parallel while I rotate the cutter head by hand (unplugged of course! I also remove the belt). I figure this gives me 0.002-0.004" of blade above the table. If I make the blade lower (flush) or higher I get convex surfaces to a slight degree. Ideally I thought the blade had to be dead flush with the outfeed table but I guess there is a small amount of springback as the cutter chops the wood.

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I have the Delta 8" jointer (DJ-20). The knives should be .012" above the cutterhead body. The figure is in the manual. I suggest you consult your manual or contact the manufacturer for the correct amount.
Preston

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Or, better yet, experiment. I had one jointer that liked the blades to be 0.003" high. The other liked them 0.006" high. Not sure what caused the difference.
Joint a couple boards. If they don't touch on the ends (convex boards) lower the outfeed. Keep doing this until the boards are straight and touch along their entire length. If you lower the outfeed too far you'll start getting snipe on the trailing edge. You should be able to get it perfect, where the boards are straight and you get no snipe. If you can't, it's better to have a little snipe than convex edges - just cross-cut off the last 1/4" where the snipe occurs.
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You know that one is referencing the cutterhead, the other the outfeed, don't you?
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No, I missed that. 0.012" above the cutterhead doesn't seem right. I've never seen a jointer knife riding that low in the head.
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0.012" above the outfeed table doesn't seem right either...
-- Doug Miller (alphageek at milmac dot com)
How come we choose from just two people to run for president and 50 for Miss America?
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DJ-20 is that minimum-exposure "parallelogram" mechanism, isn't it?
Don't own one, but no reason to suppose that a revolutionary design wouldn't incorporate other differences.
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It is the parallelogram adjustment. I believe that my Jet planer is .015" above the cutterhead. You don't want much or there is too much of a bending moment.
Preston

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Folks: I use a dial indicator to set jointer knives. Because I have a round ball on the indicator I use one of the knives that I removed which is pretty flat and lay it on the outfeed table with the majority of it resting on the outfeed talbe and with just enough of the other end directly on top of a knife.I then zero the incicator on top of the knife which is the 0 mark relative to the outfeed table and begin to rotate the cutter head until it lifts the knife. I can then determine how high the knive is relative to the outfeed table and make adjustments from there on in. Tedious I know but effective and accurate.
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hmmm.....downloaded pdf manual for the dj-20 and it says .060"
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