tabletop glue-up went poorly and now is not flat. what to do?

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Forum topic by GestureWithoutMotion posted 05-22-2018 12:33 PM 3409 views 0 times favorited 32 replies Add to Favorites Watch
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3 posts in 807 days

05-22-2018 12:33 PM

Topic tags/keywords: tabletop flattening sapele

Hey there, first time post here. I am building a trestle table out of sapele. When it came time to make the tabletop, I dimensioned my lumber and joined the boards with biscuits. However, I suspect that I cranked down too hard on the clamps, as now my tabletop has a wave to it. I have not yet attached it to the base, but wanted to get guidance from y’all on the best course of action going forward. It is 1” thick, and I think I can afford to take it down to 3/4” before it will be too thin. It is 45” wide, and the wave is only really noticeable when viewing it from the end grain. Some of the options I’m considering:

1) find a local cabinetmaker/woodworker that has a drum sander or planer that can accomodate a 45” wide piece

2) use a router sled setup like people use to thickness slabs

3) make breadboards for the ends and bolt down the top to the base hard to remove the wave

4) rip it apart and glue it up again

I’m all ears for suggestions or pros/cons of the above. If anyone knows a shop in the Washington, D.C or Boston area (moving there in two weeks), I’d love a recommendation if I decide to go with option 1

32 replies so far

View bondogaposis's profile


5803 posts in 3153 days

#1 posted 05-22-2018 12:40 PM

Sharpen up your hand planes.

-- Bondo Gaposis

View ppg677's profile


221 posts in 1658 days

#2 posted 05-22-2018 12:40 PM

Been there, done that. I would rip it apart and try again.

View RobHannon's profile


337 posts in 1332 days

#3 posted 05-22-2018 12:50 PM

1) May work if you can find a shop with a big drum sander. If there is nothing near you in DC, I would check Baltimore.

2) Should work but take a lot of care in the setup. The sled will need to be stiff of you will get a big bowl. Needs to be setup level or you will end up with a big wedge. If you have the hand tools, you should take Bondo’s advice above.

3) I don’t think that is a good idea at all. Begging for failures down the road of wither the slab or the breadboard.

4) Lot of work but for sure can fix the issues.

In your shoes I personally would rip the glue joints with circ saw and start over on the glue up. Hand planes would be less work if you have the tools and the skills, but I do not have either.

View waho6o9's profile


8917 posts in 3379 days

#4 posted 05-22-2018 12:58 PM

Rip it and caul it up.

These cauls work well too:

View edapp's profile


342 posts in 2231 days

#5 posted 05-22-2018 01:15 PM

Rip it

View Aj2's profile


3173 posts in 2600 days

#6 posted 05-22-2018 01:32 PM

That top looks too thin for the base.
Making it thinner will make it less likely to remain flat

-- Aj

View bilyo's profile


1133 posts in 1904 days

#7 posted 05-22-2018 01:32 PM

I recommend the advice above; saw it apart and re-glue. Before you re-glue, make sure the boards are flat and, most importantly, make sure the edges are square. Make sure your jointer fence is square to the tales.Then mark the board surfaces that will be the exposed table top and alternate those surfaces left and right as you joint the edges. This will compensate for any slight out-of-square, and help your glue-up stay flat.

As mentioned above, use cauls top and bottom to hold it flat while the glue dries. those cauls inboard of the ends, where the centers can’t be clamped, can be slightly bowed so that more pressure will be applied in the center area as the caul ends are clamped.

View 000's profile


2859 posts in 1701 days

#8 posted 05-22-2018 01:37 PM

Agree with above. Re cut them.
Use the Cauls as suggested.
And, it may be easier to glue it up in 2 halves, then put the 2 halves together

View AAL's profile


91 posts in 2228 days

#9 posted 05-22-2018 01:50 PM

The consensus above is what I think you should follow. It would be easier and less work to rip the boards & start over. Personally, I think 1” is too thin for a table top of that size and would be far too thin if you were to remove the warpage however you decided to do it.

-- "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

View GestureWithoutMotion's profile


3 posts in 807 days

#10 posted 05-22-2018 01:55 PM

sounds like I have my answer. What do y’all think is the best way to rip the boarts? Putting it through a tablesaw seems like a bad move given the size and the fact that the bow will prevent me from cutting the boards with parallel edges. Circular saw would work but I guess I’d have to make a guide 65” long?

View msinc's profile


567 posts in 1305 days

#11 posted 05-22-2018 02:01 PM

That top looks too thin for the base.
Making it thinner will make it less likely to remain flat

- Aj2

My sentiments exactly…making it thinner will also make it look even more out of place on that base. My suggestion is to get thicker lumber and try again. Not just a little thicker either. I would suggest you think about significantly thicker to allow for flattening with a router sled after warping and still having enough wood to no longer appear “too thin”. I would also suggest you figure in enough thickness to account for three very probable things…first, thick enough to finish with whatever warp you encounter. Next, thick enough to allow for planing with a router sled initially to get it flat and finally thick enough to allow for a second trip on the router sled which is typical on a top like this.
Right now, I doubt planing off 1/4” will make it truly flat, so think about an extra 1/2 inch the first time and maybe 1/8” up to possibly 1/4” the second go around. Thick wood often harbors trapped moisture and every one I have done moved some after the first planing. Allowing a little more for warp or glue up misalignment and you can see you are getting into the 2” plus thickness range to start out with. I cant tell you how to build your table, but I would suggest you abandon what you have for a top and use it for something else. By the time you rip it apart and join the edges you will need to add another board anyways.

View TechTeacher04's profile


447 posts in 2333 days

#12 posted 05-22-2018 02:18 PM

Rip and re-glue. The problem looks like ti was caused by a jointer fence that is not perpendicular to the bed. It works if you alternate the pieces it counteracts any irregularity in the angles. Check the joints with an accurate square to verify. Good luck

View RobHannon's profile


337 posts in 1332 days

#13 posted 05-22-2018 02:24 PM

sounds like I have my answer. What do y all think is the best way to rip the boarts? Putting it through a tablesaw seems like a bad move given the size and the fact that the bow will prevent me from cutting the boards with parallel edges. Circular saw would work but I guess I d have to make a guide 65” long?

- GestureWithoutMotion

Make the guide and do it with the circ saw. A big chunk of uneven wood on the tablesaw is asking for trouble.

View Lazyman's profile


5634 posts in 2189 days

#14 posted 05-22-2018 02:26 PM

+1 on rip and glue in 2 halves and then glue the halves together. Use cauls to keep it flat. If you slightly taper both ends of the cauls on your jointer, you’ll get better pressure in the middle.

I would rip it in half (along the nearest joint) with a circular saw to make it more manageable and then do the rest on your table saw with good outfeed support.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

View Robert's profile


3786 posts in 2282 days

#15 posted 05-22-2018 02:52 PM

I’ll try not to be too verbose, but this is an example of the type of issue we all get into at one time or another.

Before you rip the top apart (the best option IMO), it pays stop and think about why this happened in the first place (moisture/wood/saw grain/acclilmation/how stored) or else its liable to happen again!

Unequal drying is usually the root cause of cupping. Its doomed from the start if the wood isn’t acclimated enough. A lot depends on how the wood started out: kiln vs. air dried, rough vs S3S. And how you milled it (incrementally or all at once). IMO 2-3 months stickered in your shop is what I’d be looking at.

Even though it looks like you’ve got a pretty well controlled shop there, always keep the top on stickers & covered to protected from air movement.

I would go ahead and rip all the boards apart on the glue lines and start over. Joint and plane the faces & joint/rip the edges. Sticker for at least a week, then lightly rejoint/replane faces + edges. When all the cup is out, re-sticker for another week.

Once the wood is flat & staying flat, do the glue up in stages, no more than 3 boards at a time. Then glue up those sections, using a hand plant to rejoint the edges.

Keep the top clamped down onto a flat surface and covered.

A breadboard will help if the whole top is going to cup, but not for individual boards like you’ve got there. Even so, I always use a BB for tops that wide.

-- Everything is a prototype thats why its one of a kind!!

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