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Thread: How good is good enough? Milling for glueup

  1. #1

    How good is good enough? Milling for glueup

    I've got some well documented issues getting long boards perfectly flat on my jointer. I'm thinking if they are at least pretty flat, I can try forcibly get them as even as I can during glue up, and worse comes to worse, put some hours of handplaning and sanding in to eventually get a flat top. I'm losing hope that I can tune this machine or my technique enough to get these boards perfectly flat-- so how close is close enough?

  2. #2
    consider using dominoes or biscuits to align your boards as you glue, which should help.
    I've never had a table glue up that didn't require cleaning up with a jack and smooth planes.
    there's a reason they make wide bed thickness sanders.

  3. #3
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    When gluing I try to minimize excessive clamping pressure to overcome any out-of-flat condition as I feel that will add additional stresses that will try to relieve itself when the clamps are released, in addition to squeezing out too much glue in places. Edge gluing is obviously different than face gluing, in that edge gluing is not quite as strong as face gluing, and there will still be a tendency for stress relieving. So, as Richard mentioned above adding biscuits, or dowels (my preference), will add strength to the glue-up. Also battens under the table top, if attached, will further keep things together over time.
    For me, if I couldn't get perfectly flat joints I'd try to decide what would be acceptable to me as a glue joint in terms of the resulting glue line. If unacceptable, then I'd locally plane the humps down. Over stressing the glue-up to begin with could add potential problems over the long term.

    Forgot to mention that the use of cauls will keep the boards aligned during glue-ups.
    Last edited by Al Launier; 12-18-2018 at 12:09 PM.
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  4. #4
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    For edge gluing if the boards aren't perfectly flat, I run them through the shaper with a glue joint cutter, using a stock feeder.

    The feeder makes sure the boards are flat when going through the cutter, and the wedge shape of the profile aligns the boards during clamping.

    Now, obviously if the boards are very thick or way out, a feeder won't flatten them.

    If your boards are that far out, you'll need to plane or scrape the assembly after gluing.

    I normally just use a cabinet scraper or a scraping plane............Rod.

  5. #5
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    Garbage in = garbage out. If your stock is out more than say 1/16" over 6' then I think you need to take another look at your jointer to see if the tables are parallel and that the outfeed table is set correctly with respect to the knives. Spend whatever time it takes to get flat stock; everything after will be easier.

    John

    More thoughts:

    Is your stock at EMC with your shop? If it's not it will cup if you just face joint one side and don't plane the other side. You can accommodate a slight mismatch in MC with the EMC of your shop by face jointing one side, then planing the other side, then alternating sides until you get to your target thickness.
    Last edited by John TenEyck; 12-18-2018 at 11:39 AM.

  6. #6
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    Place holder . . .

    Sorry guys. I had more to say than I wanted to say on a phone and I thought I would be right back . . .

    I hate to see people become frustrated with a situation that seems to show no improvement despite our dedication. We've all been there on some facet of the craft at some point. I didn't see anyone asking if the OP was just setting himself up for failure; over-driving the machine's headlights, so to speak.

    What size/model of jointer are we talking about here? If you are trying for 72" lengths of 8/4 on jointer with a 30" infeed and no additional support it is a non-starter as far as achieving well jointed stock is concerned. I have 40-odd inches of infeed which is plenty for most furniture parts but, I still find myself doing this often enough:

    joint long stock (1).jpg . joint long stock (2).jpg

    There are always things that will push the limits of your machines. The jointer is one of those machines that relies on a consistent feed path for proper operation. If you do not supply that you will get sub-optimal results.

    As to your specific question, I always find it is safest to answer "if it is close enough for you, it is close enough". You are not required to make other people happy in this craft unless your income relies on it.
    Last edited by glenn bradley; 12-18-2018 at 3:44 PM.
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  7. #7
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    For the way I work, I only do a rough flattening, if that, before glueup. Mote important for me to the edges to fit together properly. Do final flattening after glueup. Hand planes and ROS.

  8. #8
    When gluing up long boards I usually have to tweak an edge or 2 with a hand plane:

    First, do a dry clamp-up and mark any high spots.

    I have good luck laying a low angle plane on it's side on a flat bench.

    I slip a strip of 1/2" ply under the board that needs a trim and use the bench top as a shooting board.

  9. #9
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    Quote Originally Posted by glenn bradley View Post
    Place holder
    Place holder ???
    Thoughts entering one's mind need not exit one's mouth!
    As I age my memory fades .... and that's a load off my mind!

    "We Live In The Land Of The Free, Only Because Of The Brave"
    “The problems we face today are there because the people who work for a living are outnumbered by those who vote for a living."
    "
    Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery." Winston Churchill

  10. #10
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    Quote Originally Posted by Al Launier View Post
    Place holder ???
    He didn't have type to type a response and intends to come back to it...hopefully within the 24 hour edit window.

    OP, some good advise already. "Perfectly flat" can be a challenge with any one board so as has been noted, you deal with that after you get your panel assembled, either by hand or, perhaps, with the help of a wide belt you can contract to use or put your panel through for final flattening. And even boards that are "perfectly flat" can move slightly between when you mill them and when you glue them up a few minutes or hours, or days later. 'Nature of the beast...
    --

    The most expensive tool is the one you buy "cheaply" and often...

  11. #11
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    I didn't see whether the jointer was being used to flatten both sides of the board? I doubt that you could get both sides flat enough by jointing them both rather than jointing the first side and using a planer to get the boards to the same thickness and flattening the other side in the process. This may not be the problem, but I didn't see a mention of a planer (other than hand planing) in the original post.

  12. #12
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    John

    I truly do not mean to be a jerk, but something is amiss in your milling technique that needs to be corrected.
    Your boards should come off the jointer one side flat,and one edge at 90 degrees to the flat, jointed, face. They will not be the same thickness, but they need to be flat on one side. Trying to pull boards into alignment is a major butt pain, and will just lead t other issues with the final glueup itself. You will fight that large panel the whole way. BTDT, but I think so has everyone else at one time.
    Close enough for me is every board lying on a flat surface, and butted up against another board, has no gaps. The faces can have a little difference along the edge in height, maybe at most a 32nd, but I shoot for zero.
    The wood will want to find a new equilibrium point and sometimes bowing can occur, but it really needs to be kept at minimum.
    Once I am done milling the boards for a large panel, if I am not gluing them up immediately, I clamp them to each other, or the edge of the work bench, until I am ready to glue them up.

    As I said earlier, I'm not trying to be a jerk, or nitpick what you're doing. Large panels are very difficult for the person working alone in the shop when the wood is cooperating. When it's not, then it can become a major butt pain.
    "The first thing you need to know, will likely be the last thing you learn." (Unknown)

  13. #13
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    Quote Originally Posted by john schnyderite View Post
    I've got some well documented issues getting long boards perfectly flat on my jointer. I'm thinking if they are at least pretty flat, I can try forcibly get them as even as I can during glue up, and worse comes to worse, put some hours of handplaning and sanding in to eventually get a flat top. I'm losing hope that I can tune this machine or my technique enough to get these boards perfectly flat-- so how close is close enough?
    It sounds like the OP is questioning why he cannot get his boards equally thick on his jointer.

    If he is hand planing after glue up the issue is unlikely edge related, since he mentions hand planing after glue up to make the boards flat. So he most likely is wondering why he cannot get his boards off the jointer with parallel surfaces. It sounds like he does not have a planer.

    Perhaps the OP could confirm if the issue is with the board edges, or the flat wider surfaces of the boards.
    Too much to do...Not enough time...life is too short!

  14. #14
    Cauls help to make a flat glue up. Mike Henderson did a great tutorial on using cauls.

  15. #15
    Quote Originally Posted by Bill Space View Post
    It sounds like the OP is questioning why he cannot get his boards equally thick on his jointer.

    .
    If he was wondering about that, he was missing a machine: the thickness planer. It is close to being impossible to produce equally thick boards using the jointer alone.

    Simon

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