What keeps your glue-up table tops from distorting?

[Mike Dowell]

This seems like such a basic question but I'm just now getting into building some custom furniture and I've got a couple tables coming up. I plan to make the tops(farm style tables) from Maple stock, and more than likely about 1 1/2" as a final/planed thickness. The tops will be basic glue ups, 5 or 6 boards, depending on width.

What prevents a glue-up, solid table top like this from getting wavy, wonky, cuppy, warpy, etc?

[Mel Fulks]

When facing and planing take off wood mostly on convex side after the other side is dressed. I'm referring to length.
I lay out all boards in final position ,put hash marks to indicate each boards place . Then joint one board face side to fence, next face side out,etc. That is more accurate than depending on the fence being at exactly 90 degrees.

[Mike Cutler]

Mike

I'm really OCD about large panel glue ups, which is essentially what a table top is.
I only use quarter sawn to riff sawn wood, 45-90 degrees to the face.
I pick material that is already as straight and true as can be accepted. I avoid buying cupped or bowed wood for a large panel.
I let it sit as long as I can.
When I machine it, I try to remove equal amount from each side to equalize stress.
All boards, post machining, are clamped face to face until I'm ready to do more work.
I personally like to use mechanical alignment for gluing edges. By that I mean a glue joint shaper bit. I find it easier to pull everything together. Additionally any deviation from 90 degrees, edge to face, is mathematically eliminated.
Orient your grain so that the grain of the boards "runs" in the same direction. It makes it much easier to plane, scrape, sand, etc and achieve a uniform finish.
I like epoxy for joints. Much easier to deal with on a large glue up. The minimal clamp pressure also tends to mitigate cupping across the face.

That's my way. Which might explain why I don't seem get much done, faster.:eek:;)

[Jeff Heath]

Use wood that is properly dried and acclimated to your workspace. You can't go to the wood store, pick out your wood, drive home, and start working it. It should be stacked and stickered to allow for acclimation. After preliminary milling, stack and sticker it again and wait and see if it moves. Final milling will then yield stable material that will behave well while you are doing your joinery and glue-ups.

I stack and sticker my wood for a month or two, in the shop, where it's going to be worked, before work begins. This has yielded very satisfactory results for me for a very long time.

382655

[Matt Day]

Jeff hit the nail on the head.

I don’t fuss about alternating growth rings or whether it’s quarter sawn or not. After it’s properly milled and stable I don’t think that matters. I layout my boards based on what looks good to my eye based on grain and color and figure.

[Chris Parks]

Different strokes etc, I use PVA for one reason, I can let it tack off as I am clamping lightly and the boards don't move then if needed a big hammer and a lump of wood aligns them and they don't move again. After that tighten the clamps and if you get any significant squeeze out you used too much glue. I put 32 table tops together for a restaurant and I found that reducing the glue was the answer as the joined panels will tend to float and move on the glue which is a pain. Most people use too much glue which is why glue ups float and move and they try to hurry the process too much.

[Mark Bolton]

Number one rule. Dont build Pinterest table tops. Guaranteed failure and likely giving money back or law suit.

[Chris Parks]

Number one rule. Dont build Pinterest table tops. Guaranteed failure and likely giving money back or law suit.

I don't follow, can you explain more.

[Mark Bolton]

I don't follow, can you explain more.

Like this
https://goo.gl/images/JeU668

Or this

https://goo.gl/images/a3GX65

Or this
https://goo.gl/images/63CK4D

[John C Cox]

What specifically about the Pintrosities are you pointing out? Just the general shoddy quality of joinery and random wood full of cracks?

[Mark Bolton]

general shoddy quality of joinery and random wood full of cracks?

I like random wood, and I like cracks. We do quite a bit of rustic/character work. You can read many many posts across the forums with makers desperate for help because a customer they sold a table to is now coming after them because the top they bought self destructed. Blowing apart, cupping, self destructing, due to the makers lack of comprehension with regards to wood movement. The Pinterest movement alone has been responsible for likely thousands of tables to be made and sold that later fell apart or suffered major failures for these reasons. You see them daily on the interwebs and at craft shows and shops. We are forwarded pictures from people wanting "that table they saw on pinterest" and its difficult to explain that it wont work and its nothing that can be stood behind with any form of warranty (or that we just wont make it period).

The problems with the construction on those in the links, and thousands more on Pinterest, are plainly clear. I like the look though, and it sure would be handy if we could picture frame a large glued up field from solids like that. Would save a lot of time and sell alot of tables.

[Al Launier]

Personally I like to do the following when building a multi-piece panel.



Dry & settle the wood beforehand in the shop.
Joint the cupped side.
Joint one edge 90°.
Rip to rough width.
Plane crown side flat, then alternate plane both sides to rough thickness. Plane with the grain.
Let the wood set for a couple days to stress relieve.
Sawcut lengths to rough lengths.
Repeat the joint/plane sequence noted above, including jointing one edge square.
After planing to final thickness, plane several boards at a time to final width.
Arrange boards with alternating end grain for final assembly & match mark mating pieces.
Drill dowel holes (my preference - could use biscuits) in edges of mating boards.
Chamfer dowel holes slightly to allow for excess glue.
Glue dowels in one edge of mating board.
Clamp & glue several mating boards together using *cauls to maintain flush/flatness across all boards.
After glue sets up remove glue squeeze-out.
Let the glue cure overnight.
Repeat glue-up for remaining boards & final panel using cauls to ensure mating surfaces are flush/flat to each other.
Saw cut panel to finish O/A size.
Shape edges to suit.
Sand entire top surface.
Finish to suit.
Admire.


* For wide panels (> 12" use cauls that are crowned to ensure positive clamping along center of panel).

[Mark Bolton]

This seems like such a basic question but I'm just now getting into building some custom furniture and I've got a couple tables coming up. I plan to make the tops(farm style tables) from Maple stock, and more than likely about 1 1/2" as a final/planed thickness. The tops will be basic glue ups, 5 or 6 boards, depending on width.

What prevents a glue-up, solid table top like this from getting wavy, wonky, cuppy, warpy, etc?

Searching in the archives here will yield a ton of great info. Our process is what you will read from many here, very similar to Mikes, and has always worked for us. Begin with decent stock, good stock prep, flatten and dimension your parts oversized initially and sticker them for a bit in the shop allowing them to move if they are going to after your initial stock removal. After that assembly for us somewhat depends on the tools you have at your disposal. I try to minimize sanding/surfacing with hand tools (be it a belt sander, hand plane, or random orbit) in any way possible. For that reason we tend to glue up with dowels not for strength but for ease of perfect alignment of the faces to reduce sanding. If alignment is less critical (part going to go through the planer) we may use biscuits instead (faster) but biscuits will still allow 1/32" or more of misalignment on the face. For us the biscuits or dowels just make the glue up go faster and there is no trying to pound boards into alignment. You just glue-up and go. If your working with maple (hard) 1/32" or more is a bear to sand out by hand. When we make a large top we will make sections as wide as will go through our planer (20"). Those may be biscuits or dowels or nothing for alignment if the boards are very flat and match up well. Feed the glue ups through the planer and then dowel them together leaving one, or two for a super wide table, perfectly aligned join that will only require minimal hand sanding to level the top.

For the reasons Chris mentions (boards slipping/scooting on the glue film) we most generally use some form of alignment aid always. I really like Mikes idea of the shaper glue joint but we have never gone to that level. I cant say we have ever worried about too much glue other than that its just a waste. I dont feel it has any impact on the assembly at all other than to have to clean up and throwing away good glue. We strive for enough glue in the joint that you get evenly spaced pearls of glue squeezing out of the joint. Dripping down is too much (happens to us all the time) and if the joint is not full to the edge its too little. We dont get it right 50% of the time but Id rather have too much than too little. I hope to invest in a Pizzi glue pot soon and that may help.

Our main thing is a good glue line rip, a lot of clamps, and as much clamping force as you can possibly apply on long grain glue ups.

Now that we have the CNC its not uncommon to just flatten boards, and glue up an entire top and deck it off flat both sides on the CNC. Major game changer for us.

[Andrew Joiner]

What prevents a glue-up, solid table top like this from getting wavy, wonky, cuppy, warpy, etc?
Nothing prevents it, even with the best wood selection and drying. Good design can minimize it. Discuss this before you build and have your client sign an agreement saying something like:

solid wood table tops are subject to checks, splits and other movement. They should be used in appropriate temperature settings.

[Rod Sheridan]

This seems like such a basic question but I'm just now getting into building some custom furniture and I've got a couple tables coming up. I plan to make the tops(farm style tables) from Maple stock, and more than likely about 1 1/2" as a final/planed thickness. The tops will be basic glue ups, 5 or 6 boards, depending on width.

What prevents a glue-up, solid table top like this from getting wavy, wonky, cuppy, warpy, etc?

1) using wood that has a uniform moisture content suitable for the final location

2) accurate edge jointing and thicknessing

3) glue up with a good glue and adequate clamping

That's it, nothing magic, no biscuits, dowels, dominoes etc required, Oh and no mitred frames around the outside of the table unless you want a future failure.....Rod.

[Mel Fulks]

I use the old slightly open in the middle hollow joints. They are done with a very small adjustment to outfeed jointer table.
While that is often considered unnecessary ,The joints must not be open ANY at the ends.

[Mark Bolton]

I use the old slightly open in the middle hollow joints. They are done with a very small adjustment to outfeed jointer table.
While that is often considered unnecessary ,The joints must not be open ANY at the ends.

Agreed. Spring joints are good practice. Gets tricky on large, multi board, glue ups.

[Brian Nguyen]

Assuming that you've prepped the boards properly (as others already described), you can use either a biscuit joiner or a doweling jig to keep the boards aligned during your glue up.

Also, I use cauls or if I'm too lazy to dig out the cauls... some quick clamps to clamp the seams at the ends. Oh and if it's a long table top, then I'd use a rubber mallet to softly wack the middle into alignment. If the boards are properly jointed, and aligned correctly (alternate up/down end grain patterns), then I'm usually good to go with very minimal touch up planing/sanding afterward.

[Andrew Seemann]

Even if a table top is at perfect moisture equilibrium and absolutely flat upon glue up, it is still only flat at that specific humidity level. If the humidity changes, which it will, the top will no longer be in equilibrium and it will move.

No magic selection of boards, special glue up ritual, or perfect finish will change the fact that wood moves with changes in moisture.

However, when done properly, board selection, glue up, and finish will help minimize or at least not make the problem worse, but they will not eliminate it. This is due to wood having curved growth rings and those curved rings cause the wood slightly cup and uncup across the lines when moisture content (humidity) changes.

Having the boards at moisture equilibrium will mean that they at least worked at one point. If they are way different from each other, the panel may have problems no matter what the moisture level.

Glued up panels tend to be more stable.

Quarter sawn boards will help the most with movement across the grain, but they can be difficult to hand plane and prone to tear out. Additionally some kinds of wood have much more attractive figure when flat sawn than quarter sawn.

Not glueing flat sawn grain to quarter sawn grain helps with thickness stability in the board.

Alternating growth ring orientation will minimize overall cupping, but can make the board wavy. Aligning the growth rings avoids waviness, but makes the overall board very prone to cupping.

Choosing more stable wood with minimal shrinkage will help. Oak, walnut, and white pine for example tend to be more stable. Cherry is supposed be stable, but I found it hit and miss. Hard maple, birch, and beech tend to be very prone to movement. If you have to use maple, soft maple tends to be much more stable than hard, and is usually hard enough for most applications.

Finish will help. More vapor resistant finishes like varnish or shellac will slow the transfer of moisture form the air the most, but they will not eliminate it. Oil finishes have little to no vapor resistance.

Design is the best way to minimize movement problems. Having the table top mount to a frame that can resist cupping is really the best defense, but you will need to allow for movement across the width or you will fate the table to cracking. The thicker the top, the harder it is to resist that cupping. That is probably why most solid wood table tops are around 3/4 to 1 inch thick.


All that said, myself, I just align the boards so they look pretty without violating any of the above too badly, and make sure my design can accommodate movement and resist cupping sufficiently.

[David Utterback]

Learned by experience, do not use old glue.

[Mike Dowell]

All very good input. The first of the two tables will be a 44" round table. It will open and accept a 10" leaf, so the top will be mounted to a pair of Osbourne equalizing slides. I have planned on the boards to be somewhere around 1 1/4" - 1 1/2" thick. I was planning on using maple just because it is hard, not too expensive, and light colored so that I can create whatever color I need to int he finishing process.