I can feel a joint... Anything to worry about?

[Wade Lippman]

I made a table two years ago.
http://wood.lippman.info/oakdiningroomtable
It is made out of 5/4 red oak. I bought the wood at a liquidation auction at a commercial woodworking shop, so I presume it was kiln dried, and it sat in my basement for 2 years before becoming the table.

It was well jointed and glued up with biscuits. I did a good job of matching grain, and after sanding the joints were very inconspicuous.

Now I can feel the joints in places with my finger tips. It is not much, less than the thickness of a sheet of paper, and only in a few places; if I hadn't made the table I probably wouldn't be aware of it. But I did, and I am.

I have only been woodworking 4 years, but I felt some older projects and they are still perfectly smooth.

Is this normal? Anything to be concerned about it? What could cause it?

[Charlie Plesums]

A glue joint expands with the mositure of the glue. If you sand soon after it was glued (within the first day or two... or three), then when the moisture of the glue inside the tabletop dries, the wood shrinks unevenly. I have seen the uneven shrinkage make the joint visible or "feelable."

Could this be your problem?

[Wade Lippman]

A glue joint expands with the mositure of the glue. If you sand soon after it was glued (within the first day or two... or three), then when the moisture of the glue inside the tabletop dries, the wood shrinks unevenly. I have seen the uneven shrinkage make the joint visible or "feelable."

Could this be your problem?

Quite possibly; I am sure I sanded within a day or two of gluing. Maybe the "problem" has been there for two years and I never noticed! (I hope so...)

[mike holden]

Primary rule of woodworking - WOOD MOVES!
Any change in humidity will show a change at joints, especially where the wood crosses grain (horizontal on one side, vertical on the other)
Breadboard ends were developed not only to keep boards from warping but also to camoflage the seasonal movement.
Dont worry about it unless the joint is failing.
This is normal for wood.
Mike

[Scott Banbury]

The orientation of the growth rings in adjoining pieces can cause this.

If one side of the joint is more quartersawn, it will shrink more than an adjoining piece that is more plainsawn due to the differences in radial versus tangential shrinkage.

[Lars Thomas]

Call it character and move on. Mike and scott have it right.

[Jesse Cloud]

Hey Wade,
Two thoughts...
First, your question reminds me of that old comedy City Slickers. Loved the line where Slim (Jack Palance) says "You know, you city folks sure worry about a lot of sh**." The guys above are right. Don't sweat it.

Second, how damp is your basement compared to where you worked the piece and to where it is now?

OK, three thoughts. I have heard advice to bring wood into the shop for a couple of weeks, then rough mill, sticker and let it sit for a couple of days, then mill to final dimension. Charlie is certainly right that it would benefit from a thorough drying of the glue before further processing. And you really should wet it down to raise the grain before finishing, and let the finish cure for a couple weeks. Only problem is that if we did all that, we would still be working on our first project.:eek::rolleyes:

[Chris Padilla]

What kind of glue did you use? Maybe the glue is "creeping" out on you? PVAs (white/yellow glue) can do this.

Biscuits needs a fair amount of glue and so you concentrate a lot of glue in their area which causes the wood to swell in those spots. If you sand things flush only a day or two later, you will have slight depressions where the biscuits are several weeks/months later when all the moisture from the glue evaporates and the wood shrinks.

[Charlie Plesums]

Primary rule of woodworking - WOOD MOVES!
Any change in humidity will show a change at joints, especially where the wood crosses grain (horizontal on one side, vertical on the other)
...Mike


What kind of glue did you use? Maybe the glue is "creeping" out on you? PVAs (white/yellow glue) can do this.
....
This is why I like the small amount of creep in PVA glue... it allows the joint to shift microscopically without warping or breaking the joint.


...Biscuits needs a fair amount of glue and so you concentrate a lot of glue in their area which causes the wood to swell in those spots. If you sand things flush only a day or two later, you will have slight depressions where the biscuits are several weeks/months later when all the moisture from the glue evaporates and the wood shrinks.

When gluing up something like a tabletop, with edge grain to edge grain, the glue joint will be stronger than the wood (it will break away from the joint), thus biscuits aren't needed for strength. They may help with alignment, but I now try to do these simple edge grain glue-ups without biscuits because of the large amount of moisture added in the glue around the biscuits.

[Howard Acheson]

What time of year did you glue up the pieces and what adhesive did you use? Also, how soon after glue up did you finish the piece? Where are you located?

If you used PVA adhesive, that may be the problem.

[Chris Padilla]

When gluing up something like a tabletop, with edge grain to edge grain, the glue joint will be stronger than the wood (it will break away from the joint), thus biscuits aren't needed for strength. They may help with alignment, but I now try to do these simple edge grain glue-ups without biscuits because of the large amount of moisture added in the glue around the biscuits.

Agree...in long-grain to long-grain glue-ups, biscuits only aid in alignment and don't add much, if any strength to the joint. Glue gives you all you need and then some.

What do you think about using biscuits for alignment but then skipping gluing them to avoid the swelling?

[Charlie Plesums]

Agree...in long-grain to long-grain glue-ups, biscuits only aid in alignment and don't add much, if any strength to the joint. Glue gives you all you need and then some.

What do you think about using biscuits for alignment but then skipping gluing them to avoid the swelling?

I have heard of people doing that, but you are then putting a hole in the middle of the tabletop (not an issue if the biscuit is glued in, and replaces the wood that was cut out, but not structurally the same if the biscuit is loose). Structure is probably not an issue, but I hate to insert a weak spot.

I just made a 28" by 119" mahogany (sipo) tabletop. I glued a couple sub panels that I jointed and planed after gluing, and then glued up the final joint by starting at one end, and being sure it was precisely aligned as I added each clamp down the length. When done, all that was required was a ROS. Given that, I would argue that you shouldn't need the biscuits for alignment.