DJ 20 knive creep

[woody dixon]

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I am trying to change straight knives on a dj20 jointer with a dial indicator. There was an old thread here that Rick Lizek posted to where he suggested using the jack screws to raise the knive above the outfield table then tapping them down while slightly snugged to zero out. This way the final tightening does not raise the knives at all. He locked the cutterhead with vise grips on the cutterhead shaft at the front of the jointer. As you can see from the attached picture, you cant get to my cutterhead without removing the cutterhead block. My upward creep is about .008" no matter how careful i am. Trying to tap down without locking is useless for me since I cant see how close i get to zero with everything moving and there is no bracing against the tap. I tried to pm Rick but that wouldnt go through. I think his method will work if i can lock the cutterhead. I tried wood wedges but after a couple taps the cutterhead starts to move. Anyone have any suggestions.?

Woody Dixon
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[Andrew Hughes]

If I’m understanding your post correctly you are trying to hold the cutter head when the knives are top dead center.
Since you have a pulley drive how about using the pulley to lock the head in position. When I set knifes in my jointer and I have time I go around the head three times. First to get them all in the pockets gibs tightened slightly. Second time set them as close. The third I have a look to see if one is low and how close they are to each other. Then I do the final set. My goal is to set them out from the head as close as possible. Then I adjust the height of outfeed table.
Good Luck

[Bill Dufour]

Set them up 0.08 before tapping down to seat them.
Bill D

[woody dixon]

If I’m understanding your post correctly you are trying to hold the cutter head when the knives are top dead center.
Since you have a pulley drive how about using the pulley to lock the head in position. When I set knifes in my jointer and I have time I go around the head three times. First to get them all in the pockets gibs tightened slightly. Second time set them as close. The third I have a look to see if one is low and how close they are to each other. Then I do the final set. My goal is to set them out from the head as close as possible. Then I adjust the height of outfeed table.
Good Luck

I think this may work. I went down a put a vise grip on the pulley belt and clipped it inside the frame which locks the cutterhead. Is this what you had in mind? Your sequence is sort of what i was doing but unless i go high i ended up with the knive being low in the middle and there is no screw there to lift. Going high all around seems to make the most sense. The gradual tightening also helps. I also think you have to have some friction initially to hold the knife in place. I'll let you know how this works. Very frustrating procedure though.

Woody

[Andrew Hughes]

One point I’d like to make before i set knives I determine the straight ness of the edge. I have one set that curved along the length. I sharpen my knives myself 12 inches long. My fixture for grinding almost always leaves them with a crown in the middle. Because of the curve.
I keep this in mind when they go into the head they will be a bit higher in the middle.
Good Luck

[Mel Fulks]

One thing I’ve done is make wood spacers to put under both ends of knife . Then I would just slightly tighten two screws to keep them from
moving. Did that all around then tightened all around coupla’ times ,little at a time. If you send your knives out for sharpening and they
come back not straight ,find another place. We did that once and the old guy asked why we were not bringing them to him. I told him and
he bought a new machine, that’s problem solving !

[John TenEyck]

Have you considered using a knife setting jig? The magnetic ones make it pretty easy.

John

[woody dixon]

Have you considered using a knife setting jig? The magnetic ones make it pretty easy.

John

Complete failure today. Never could get the cutterhead locked for long. Fooled around with the motor pulley/belt but could not see how to clamp it so it wouldnt move at all. Tried wedges with 4 oem screws which i ordered and thought it was working but when finished my tapping down had moved the cutterhead so everything was about 0.015 " low. Found a very old magna set and tried that. Didnt have instructions but lined up the line on the jig with tdc, loosened the knife all the way and retightened. Far side 0.004 high as was middle and near side was 0.007 high. I pressed down on the magnets when tightening and gradually did them.

I didnt mention this but the aluminum insert on the outfeed side is 0.005 lower than the outfeed table. That's why i switched from a 1-2-3 block i was using as a base for my indicator to a magnetic base which rested entirely on the outfeed table to take measurements. I also put the indicator on the magna set out of curiosity and the end over the knive was about 0.015" higher than the part over the outfield table.

For whatever reason I think i have to lock the cutterhead and tap down to zero. Can anyone tell me a way to easily do this? Absolutely nothing else is working.

[Andrew Hughes]

Have you seen the video Bob Vaughan made years ago using a dial indicator to set knives. It’s possible to set them without locking the cutter head.
The next best way to set them is stick drag method. If I were you I would spend time perfecting the stick drag.
Give yourself time to think up a solution to locking the head.
My jointer has a hole on the side of the head for each knife to lock the head. The hole was done at the factory for grind knives on the machine.
I cannot offer any other solutions. I am confident you will find in time.
Good Luck

[Tom M King]

I use a thin stick of Boxwood, and set them by feel while swinging the head back, and forth with the wrench. Takes about 30 seconds per blade. I haven't used a dial indicator in decades. You can feel the knife rubbing on the wood. Take the slack out of the gib screws so the blade stays in place, but is still not too tight to move one. As long as the strip of wood stays on the outfeed table, you can't push one down too far. When you can feel the knife rubbing the wood without lifting the wood, it's right. You can feel less than a thousandth of an inch. Again, takes about 30 seconds per blade. Works for handheld planers and such too.

I have no idea what any measurements would be, but piece of Cypress run against the grain reflects window light after slow feed, after sharpening knives on my waterstones. There were tiny scallop marks that a close eye can see, but I couldn't catch them in a photograph. If you need measurements, carry on. I measured with a dial indicator something over 25 years ago, but forgot long ago what the projection was because it's not important. I only care about results.

[Mark Wooden]

+1 with Tom
I use the same method as Tom for setting knives in both my jointers, a 6" and an 8" and like him, have for years. My results are pretty much the same as his- if it looks right and the smoothness feels right, it is right.
Trying to get things within .001" on a jointer- which isnt a finishing machine- may be very satisfying to some, but I much prefer to get on with my woodworking, get the job done and then go fishing.

[woody dixon]

Ok tried simple solution tonight but not completely successful. Probably dont have Tom's feel because when I raise the knive to just touch it goes too high so the knife moves. "Then I have the same problem as before trying to knock it back down. Everything moves without a locked cutterhead and it is very imprecise. I have it close and will try to joint some wood to see if it will work. How did you handle adjusting the knive lower if you went too high? I tried pushing and hitting another stick laid over the blade and outfield table but the angle is all wrong and you just end up with a glancing blow. Don't know whether you saw where I found the outfield table aluminum insert is about 0.005 " lower than the outfield table. This has some effect i guess on the stick method. Do you think this is something i should fix? if so, I know I have to take the cutterhead out and lower the tables, but can I shim it leverl or do I have to buy another insert ? Thanks for everyone's input and help

[Kevin Jenness]

If the aluminum lip is not damaged you should be able to adjust it even with the table. You may have to remove the table or cutterhead to access the fasteners. It should not affect the function except for very short pieces and should not cause a problem in knife setting if you use a long enough (12") drag stick.

The stick method is very sensitive - a .001" height difference will result in about 1/16" change in the horizontal distance the cutterhead carries the stick, depending on the head diameter. I set the knives for a 1/16" carry and that usually works or may require raising the table .0005" or so to be right on. I do use an indicator for adjusting the outfeed but not for setting the knives.

Change out one knife at a time. Get the knife set as close as possible with the gib screws tightened just enough to hold it in place and check the carry distance. If even, snug the screws up a bit and check again. If it squirms, knock the high spot down with the butt end of a screwdriver and raise the low spot with the jack screw and tighten to finish. Repeat with the other knives and check that they are equal, make a test cut, then adjust the outfeed height if necessary. Take your time and you can get them +/- .001". With practice it shouldn't take more than 1/2 hour. I don't find it necessary to lock the cutterhead. My 16" 4 knife head lacks jack screws and takes me about 45 minutes. I use carbide knives to minimize knife changes.

[Izzy Charo]

After struggling to do this for years on my DJ-20, I replaced the head with the Shelix head. Installation was not too difficult, and it's been a pleasure to use.