Flattening a large table?

[Travis Fatzinger]

Hi,

I just glued up a large table top from 5, 1.5" thick hickory boards. The dimensions are 42" by 60". I'm not sure what happened but it is frowning at me. The edges are crowned down nearly 1/4" when I put a straight edge across the 42" direction.

I have virtually no hand plane experience, I have an old No 4 and No 5 but all I'm doing with them is making the tear out in the hickory worse. I probably don't have them sharpened properly.

If I ordered something like a Veritas bevel up Jointer plane, would that work well for flattening this, even though I have no experience? Or would I end up with a bigger mess and a $300 tool sitting in the box?

Luckily this is for our house and I think it will bother me more then anyone else. Unfortunately, I need to have this finished sooner then later.

Thanks for any tips.

[William Fretwell]

Is it just the edges that crown down or does it wave across the whole top?
A new plane is not going to solve your problem. If you have to plane down almost 1/4" of the whole top that won't work. You could flip it over and just plane down the edges.
You could see where the edge board starts to bend down, rip off that part flip it over and glue it back on.
You will need to sharpen the planes you have or resort to a rotary sander.

[Christopher Charles]

Hello Travis,

Sounds like a great project. I agree that a new plane isn't likely the best solution here. A couple of options are to rip, rejoin and reglue to correct the crown, and/or take the top to a local cabinet shop with a wide belt sander.

I'm assuming that the wood you are using is dry and acclimated to the shop, i..e, that the crowning is from imperfect joining rather than movement after glue up.

I'm sure others will have good suggestions as well.

Best,
Chris

[bridger berdel]

If the bow is even across the whole width it might be from differential moisture absorption sitting on your bench. If so, flip it over, dampen the concave side and leave it overnight weighted to flat. Also, a panel that wide is going to move a lot with changes in ambient humidity. The structure of the table needs to be such that it can hold it flat while giving the top plenty of ability to expand and contract. If you don't build in this ability for the top to move while being held flat it WILL self destruct.

[bridger berdel]

1-1/2" hickory is a massive top. The stretchers to hold that flat will be pretty beefy.

[Bill McDermott]

I think this ight be a design feature you intended so that anyone spilling their drink gets it in their own lap, not their tablemate's.
Kidding aside, did this happen after you attached the top to the table base?
If yes, how is the top attached?
If no, how stout is the base across the underside of the top? And could you add battens without messing up the design?

[John Vernier]

Halfway through a project is a rotten time to pick up a new skill like hand planing, and hickory is not an easy wood to plane in the best of circumstances. I would consider ripping the joints (or some of them) apart and re-glueing to straighten things out. One important question: Was the top flat when you first glued it up, and warped later, or was the warp evident as soon as the clamps came off? If the joint edges were out of square to begin with, due to a bad angle set-up on a jointer or table saw, then you need to address that problem before re-jointing, or it will just happen again. If that isn't the problem, it may be that the boards needed to acclimate longer before milling - they just had some more warping to do before stabilizing, in which case ripping and re-glueing may be the best solution, possibly alternating the boards to cup up and down if they persist in being squirrely. Also remember,when you glue up the top, to alternate your clamps top and bottom, to equalize the tendency of the clamps to bend the panel out of plane.

If you get comfortable with your hand planes, they are a better solution for this sort of problem than sanding - and given your top thickness, you could probably pull it off. I had to fix just such a warped top years ago with nothing but a 6" RO sander, and it wasn't much of a solution. Those are some hours I'd very much like to have back. If I were going to fix this top by planing, I would want a longer plane to finish the flattening process, but most of the work would be done with a no.5, which you have.

[Robert Engel]

I agree with John ^.

We really need more information to help you. Where did you obtain the lumber? Was it air dried or kiln dried? If you purchased surfaced lumber from a supplier it was kiln dried. Think about where you stored the wood, how you stored it and for how long. For 8/4 lumber, I would sticker it and let it acclimate for at least 1 month.

If it was flat right after the glue up and the cupping occured over time then the boards were not acclimated enough. As they dry, they cup and if one board's neighbor cups the same way the cupping is multiplied. Also, if the panel was exposed to sunlight or moving air, unequal drying occurs and the top of the panel will curves.

Second, how did you prepare the edges? If they were not jointed properly minor errors will multiply with each board. If using a jointer be sure to alternate faces against the fence. This will ensure any error will cancel out.

Yes, hickory is a very difficult wood to work with. After you rip the boards be sure to orient all the boards so the the grain in the same direction. You will probably still have difficulty.

Set up your hand planes with extremely sharp, preferably slightly cambered irons. Close the mouth down and take light passes. Skewing the plane is a trick that increases the effective angle, mimicking a high angle frog.

You've got quite job ahead of you. With winding sticks and a straight edge and a lot of patience and sweat, you can get it reasonably flat.

[Stewie Simpson]

Skewing the plane is a trick that increases the effective angle, mimicking a high angle frog.

Robert; skewing will lower the effective approach angle.

[Travis Fatzinger]

Thanks for all the replies but I thought you guys would encourage me to buy a new tool.

Seriously though looking back I think it is a moisture issue and not a joinery issue. Checking with long and shorter straight edges I found that two out of four joints were really the main offenders. When I glued it up, I was paying more attention to which side of the board was nicest, not looking at the edge grain. The three worst boards all had the grain running the same way and were located in the middle of the table, causing the curve down.

I just ran those two joints through the table saw. I'll try gluing it up again. Also, since this is large and heavy, I've been working on it outside and such which can't be good for the moisture content.

Thanks again for all the ideas.

[Andrew Pitonyak]

Yeah, you need to buy a new tool that I am selling for far more than it is worth

So you are seeing tear-out with your existing hand-planes. If you have a well behaved board, are you able to plane that with your existing planes?

I recently tuned up a plane that was:

1. Configured in such a way that it would NEVER work (the blade was upside down and therefore stuck way too far out the bottom).
2. The sole was sufficiently out of flat that it would never work.
3. Very dull blade

And a few other things wrong with it.

This is why I ask if you are able to plane some other board with it. That would seem like a logical place to start before you start worrying about how to fix your table top. You might have already stated this and I missed it.

If you really want to buy something new, you might want a larger / longer plane (like a 6, 7, or 8). If you lived closer, I would let you try mine.

Depending on where you live, if you have trouble with the plane proper (ie, trouble on other boards), maybe someone local can help you tune it up. If you are simply concerned that your blades are not sufficiently sharp, I can probably sharpen a blade for you. I might even have a spare blade that you can borrow and try to see if it works in your plane; just need to promise to send it back. But if you can do crazy things like easily cut paper or shave hair off your arm, it is probably sharp enough.