Warping Table Top

[Ed Gibbons]

I face jointed some curly maple. First I ran each piece through a jointer and next the planer. After the glue up, the next day, the top started to warp.

Any suggestions?

[Aaron Hastings]

I face jointed some curly maple. First I ran each piece through a jointer and next the planer. After the glue up, the next day, the top started to warp.

Any suggestions?


The first question is why it warped. How long did you acclimate it? What was the MC?

As for the warping, how about a pic?

[Ed Gibbons]

The piece warped about an 1/8 of an inch. It is not perfectly flat.

The wood had been in the shop for at least 3 weeks before I used it.

[Van Huskey]

I face jointed some curly maple. First I ran each piece through a jointer and next the planer. After the glue up, the next day, the top started to warp.

Any suggestions?


How long after milling do you glue them up? I do the rough milling then let them sit a couple of days, do the final milling let them sit again then if they remain flat I glue up. If you don't the differences in MC within the wood and relieved stress can cause warpage.

[Heather Thompson]

Ed,

Did you run it thru the jointer/planer and then go straight to glue up? Whenever I joint/plane any stock I always let it sit a day or so to see if there is any movement, tension and moisture will release and many times cause movement, also never leave the stock sitting on a flat surface, it needs to breath equally on both sides.

Heather

[glenn bradley]

Like Heather mentions, I mill my parts oversized, let them set a couple days or more. Once things seem stable, I'll mill to finished size and assemble pretty much right after that. If I have parts that are finished size and move on me, I have abandoned trying to recover them and now just make new parts. The piece comes out better, I enjoy the build more and there is always something that I can use the material from the failed piece on later.

[Darnell Hagen]

How did it warp? One big cup across all boards, or each board is twisted? Can you pull it flat by hand? Did you alternate your clamps, one on top, the next below? Did you edge joint to and away from the fence?

[David DeCristoforo]

Ahh... wood. Never sure what it's going to do. I just glued up a table top out of two 18" wide slabs of purpleheart. They were 1" thick "off the shelf" and I did not surface them at all. They were very close to flat to begin with so I just edge glued them and I will see on Monday how nice they are going to behave. Whenever you remove wood by jointing and/or planing, you alter the balance to some degree. All of the suggestions made so far are good and will allow you some degree of control. But wood is wood and, by it's nature, unpredictable.

[Faust M. Ruggiero]

Ed,
If you live in part of the world that requires heat, I'll bet the top is curling up at the edges. Flip it over for a few days and see if it settles out. The top surface will give up more moisture than the under surface in a heated home or shop. I suggest you screw some sturdy flat pieces across the grain on the underside to control the warping until you fasten the top the it's frame. Keep turning it over every few days to maintain moisture equilibrium between the top and bottom surfaces until you get some finish on the beast. Be sure to drill oversize holes in the cross piece to allow the top to contract or it will crack as sure as God made little green apples.
fmr

[Keith Christopher]

I agree with Faust, more likely stress _vs_ true warping from moisture. Often when you plane more on one side than the other you will find this. I like to flip the board often when thickness planing, it seems to help from this happening. As David said however, some boards just behave badly. What is the glue up for ? Table top ? Often these can be corrected when it's a small amount of movement.

[Steve Jenkins]

The most common cause for tops warping that I see is that after they are removed from the clamps they are layed flat waiting to be worked on. the moisture content will change on the top face compard to the bottom face and cause them to warp almost every time. I always set my unfinished tops on edge or cover them with a piece of plastic or scrap plywood if I have to leave them flat.

[David DeCristoforo]

"... they are layed flat ..."

Good point. That's why god gave us stickers!

[Stephen Edwards]

Speaking of purple heart....Last year I resawed an 8/4 X 6" wide piece of perfectly flat PH into two 3/4 boards. The next day both 3/4 boards had about 3/16 cup across the 6" width! I don't know if it was that particular board or what. The PH had been in my shop for about a month. But, it had not been stickered.

Lessons learned for me:

1. Sticker the boards in the shop before milling, even if they're kiln dried and let them sit for a while before milling.

2. Resaw the 8/4 board in half, sticker and stack for another few days before milling to final size.

[Heather Thompson]

"... they are layed flat ..."

Good point. That's why god gave us stickers!


See post #5!!!!!!!!!

Heather:D