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Thread: Tips for jointing long boards

  1. #1

    Tips for jointing long boards

    I am having a difficult time trying to edge joint some 8' boards. I'm not able to get as straight of an edge as the shorter pieces that I normally joint. I tend to get a cup in the middle. I am sure this is because of my technique. My table length is 59" and I have a 40" long fence that is 6" high on my jointer.

    Is my difficulty the nature of the longer boards?
    What can I do to improve my results?

  2. #2
    Join Date
    Dec 2010
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    Longer boards are harder, to be sure. But if your jointer tables are coplaner it's just a matter of technique and practice. A cup in the middle suggests your tables might be sagging on the ends, or you are not holding the board high enough to start and finish which is easy to do when the board is long and heavy. FWIW, your jointer beds are plenty long enough to get a straight edge on an 8' board. I manage on an Inca J/P which had tables less than 40" long combined.


    John

  3. #3
    Join Date
    Jul 2007
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    NE OH
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    Timely. I've just been jointing 10' and 12' boards on my relatively short jointer. I mentioned in another thread that I bought a couple of Bora PM-2700 expandable roller stands and they have made all the difference since the stock is fully supported both on infeed and outfeed and I can concentrate on technique and not keeping the board on the tables. I spent a fair amount of time to get the supports exactly co-planar with the tables, especially the outfeed side. If your board is more than twice as long as your infeed and outfeed tables, you really need extra support.

    Since you are asking about edge jointing, a few things I have found helpful: If your boards have a crook, and most long boards will, concentrate on the ends first (arrange the board so the crooked ends of the board are down) and don't take full length passes. Start feeding, transferring pressure to the outfeed table as soon as you can, but don't bear down with a lot of pressure, just enough to keep the board on the tables. As soon as the knives stop cutting, stop and return the board to the beginning. After a few passes (depending on depth of cut), move the board toward the outfeed without downward pressure until the knives start cutting again. Take a couple of passes on this end of the board. Now you are ready to take full length passes, but again, don't put much downward pressure on the board, concentrate on keeping pressure against the fence. On a long board, even a fairly wide board, it takes very little pressure to flex the board downward against the crook and that is counterproductive. Until you get the hang of it, you may find it helpful to snap a chalk line on the outer face of the board that shows what a straight edge will be; then you can more easily visualize where you need to remove stock to get to a straight edge.

    The same concept works if you just have a wavy edge and not much crook; just don't force the board down against the tables; allow the jointer to find the high spots and remove them. Chalk line trick works for these boards too.

  4. #4
    Join Date
    Jun 2014
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    Western PA
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    If you put two jointed edges together, what is the gap between the two boards? 1/16", 1/8", more? 1/16" in the middle over 8' wouldnt bother me, and i would clamp it closed. Some call this a "spring joint". I call it a poorly jointed edge, but you can get away with it. 1/8"+ is where you should take action and correct the edge. Like John said, i doubt its your technique, but rather your tables are out. Have you ever checked them? Try focusing all your pressure ONLY on the outfeed side when you joint the edge next. Is it better or the same? Finally, if its close, you can take a hand plane to the far edges of the boards and get it closer to an acceptable gap in the middle. If youre touching on the ends with a 1/8" gap in the middle, then you only have to remove 1/32" from the far ends of the edges. thats a swipe or two of your plane for each board.

    After the project when you have time, i would take a hard appraisal of your jointer. Its good to get very anal with dialing it in properly. I just put together a 93" by 38" walnut island, and my jointed edges were laser straight next to one another. My jointer's tables are a bit longer than yours, but you should be able to get workable results from 59" long tables.

  5. #5
    Join Date
    Feb 2014
    Location
    Lake Gaston, Henrico, NC
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    8,973
    Sight down the board, and develop an attack strategy. Table length makes for easier handling, but doesn't limit the length of boards that can be jointed. I see so many people having trouble who think they have to run the whole length of the board every pass. If I sight one, and see a hook on one end, the first pass(or several) may only run 6" of a 16' board over the cutterhead.

  6. #6
    I can be difficult trying to feed a long board while maintaining down pressure on the outfeed table.

    I've found wearing rubber coated gloves helps me grip the wood better.

  7. #7
    I second Patrick's post: While the cup is intellectually bothersome, if it's small enough, it may pull closed acceptably. I would joint your two edges as best you can, then put a piece of notebook paper along the joint. Clamp it 'normally'. If it holds tight everywhere under reasonable pressure, the edge is flat enough.

  8. #8
    Join Date
    Dec 2006
    Location
    Toronto Ontario
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    11,247
    My jointer is setup to produce a concave surface of a couple of thousandths of an inch over 3 feet.

    If you joint 2 boards and place them edge to edge, how big is the gap?

    Regards, Rod.

  9. #9
    So far I have been able to refrain from debating. Jointer Perfectionists Anonymous is helping me. And unlike some other
    help groups ...they serve drinks.

  10. #10
    Join Date
    Jan 2017
    Location
    Marina del Rey, Ca
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    Use a track saw to straighten the edge.
    "Anything seems possible when you don't know what you're doing."

  11. #11
    Quote Originally Posted by John TenEyck View Post
    Longer boards are harder, to be sure. But if your jointer tables are coplaner it's just a matter of technique and practice. A cup in the middle suggests your tables might be sagging on the ends, or you are not holding the board high enough to start and finish which is easy to do when the board is long and heavy. FWIW, your jointer beds are plenty long enough to get a straight edge on an 8' board. I manage on an Inca J/P which had tables less than 40" long combined.


    John
    John, What do you mean by " holding the board high enough"

  12. #12
    Quote Originally Posted by Matthew Curtis View Post
    I am having a difficult time trying to edge joint some 8' boards. I'm not able to get as straight of an edge as the shorter pieces that I normally joint. I tend to get a cup in the middle. I am sure this is because of my technique. My table length is 59" and I have a 40" long fence that is 6" high on my jointer.

    Is my difficulty the nature of the longer boards?
    What can I do to improve my results?
    If you put the boards edge-on and they don't match to your liking, you can always tweak the fit with a hand plane, a Stanley #5 would be sufficient (everybody should own one.)

  13. #13
    Join Date
    Dec 2010
    Location
    WNY
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    9,645
    Quote Originally Posted by Matthew Curtis View Post
    John, What do you mean by " holding the board high enough"
    Probably a poor choice of words. What I meant was that the board has to be parallel with the tables. To get rid of a crook that's high in the middle you have to hold the board so that the middle is parallel with the tables. To better see what I'm trying to describe, snap a chalk line on your board to show what you need to remove, with the chalk line tangent to the arc in the middle of the board. You'll see that you have to remove a triangle of wood at each end. To do that you have to hold the board parallel with the joint tables with each pass. You will only remove a tiny bit of wood on one end with the first pass, then progressively more with each pass. I often work both ends first to remove most of the crook, then one or two passes over the entire length to get a straight, smooth edge.

    John

  14. #14
    I've got a crummy 6 inch jointer. It is good for boards about 4 feet long, 5 if they are already pretty straight. Below is what I have found.


    1. In general don't edge joint boards any longer than you need to. It may sound logical to thickness plane and edge joint all your lumber ahead of time, but it is better to thickness plane then rough cut for length. The shorter the piece the more accurate the edge jointing will be.
    2. If the board has any significant cup, high spots, unevenness, etc., cut them out before you run it across the jointer. The longer the board, the more it will want to follow curves and dips. At some point you can't fight it anymore. I usually take a straight edge (chalk line will work also), mark a line about a quarter an inch from the edge, cut the line on the band saw, and then run it across the jointer.
    3. At some point the boards will be too long for the jointer (for me that is about 4 feet). For those, I do the procedure above and then hit the edge with a jointer plane and then run it through the table saw with the hand planed side against the rip fence, and then use the table sawn edge as the jointed edge.
    4. The alternative of course is to just screw an already straight board to the board to be edge jointed and run it through he table saw.


    For most of what I do, 4 foot boards are enough, which is how I have survived with a 46" jointer. Someday though it will turn into a decent 8" jointer. Someday.

  15. #15
    For a long board convex side up so a banana with either tip on the cast table and belly up to the sky.

    First throw the pressure on the outfeed table only right out the window with a long board like this and short machine.
    Second gently from the trailing edge of the board guide the leading edge of the Board over the cutter. Don’t force the board down to the out feed table in the slightest until you can hear then see that your past the concavity and wood is making contact on both jointer tables both in front of and behind the cutter. At this point yes it’s import to shift your pressure to the other side of the cutter head. But nothing crazy just make sure you don’t let the board sag off the end of the unsuported outfeed table.

    Take very small bites as to no vibrate the leading edge off the cutter as you will be largely pushing from the back or trailing edge of the board for most of the cut. Also take small cuts till your board gets closer to flat.

    Hope that helps. Extension tables help. But it can be done without you just gotta read the wood.

    One other thing. Sometimes wood just wants to continually release tension the same exact way. At times I just throw the board in the trash and start with a new one. If it’s expensive lumber I consider my other options. But if it’s a critical piece that Must remain flat and straight in the trash the problem board goes.
    Last edited by Patrick Walsh; 11-14-2019 at 9:26 PM.

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