Table top movement

[Jeff]

Very subtle, but it delivers the message that the wood still lives and breathes. Two dining tables built during the last two years. Both are about 42" wide.

1. Flatsawn SPF from the BORGs for a friend. 2 x 10s or 2 x 12s ripped at about 6-7" wide. It fit his budget so we went with it.

2. A mix of flatsawn and QS/RS reclaimed heart pine. Roughly 6-8" w x 1 1/8" t. It fit my budget, but it was painful.

Both have breadboard ends so the real feel with your finger tips is obvious even if you can't see.

#1 has SHRUNK about 1/4" total across the width. #2 has EXPANDED about 1/8" total across the width.

I had to laugh and ask myself the question: "Who in the **** is the supposed craftsman that can't cut a flush cut joint?. :icon_scra

 

[Bill Clemmons]

Sounds like the wood from the BORG wasn't quite as dry as they would have you think. Either that, or your reclaimed heart pine was extremely dry.

Bill

 

[CrealBilly]

Did you notice the stamp of that BORG lumber? KD15 AD15?

 

[CaptnA]

I've seen similar situations and had woodworkers ask what I thought happened. A common issue I've found is lots of people don't check the moisture content of "store bought" wood, and often regret it.
Not sure that happened in your case but I know lots of woodworkers never thought about
it since it came from one of the "home centers". "But I bought the wood at XXXX's!"
This friend had a table top that pulled apart the legs as the wood moved. He could not understand what had happened. And he had simply screwed the top to the legs. Wood moves. At least he's a believer now.

 

[red]

I always considered the wood source, time of year I am building the tabletop and where it is going when I built breadboard ends to minimize the amount of overhang (+/-) of my ends.
Red

 

[Jeff]

Did you notice the stamp of that BORG lumber? KD15 AD15?

No, I sure didn't; also never checked it with the LD50 meter. However, I later discovered that BORG stuff is typically about KD 15-20.

The reclaimed heart pine coming in the door was kiln dried-it read about 6-7% MC on the meter (minimum reading for the LD50 is 6%). So it was pretty dry. The resin was set and pretty brittle. :thumbs_up

Here's a handy general purpose chart for EMC as a function of %relative humidity and temperature.

http://www.finewoodworking.com/FWNPDFfree/equilibrium-moisture-content-chart.pdf

Our home averages about 70-80 degrees with RH at 40-45% so an EMC of 7.5-8.5% is expected.

To clarify the point of my original post: Wood movement is something we need to be aware of and allow for in design and construction. Wood lives and breathes! So both of these tables have moved predictably based on their original EMC and the subsequent environment in which they were placed. :icon_cheers

The "Shrinkulator" is handy for calculating these changes so we can predict what to expect.

http://www.woodbin.com/calcs/shrinkulator.htm

 

[JimD]

I usually do not use breadboard ends and never have on a table more than about 20 inches wide. I have built tables and other things with bigger tops but they were just one big glueup. They were fastened down to allow for movement and have worked without issue. I fully finish the underside, however, which I think helps. In other words, on my kids kitchen table tops (1 1/8 oak and cherry) which are about 3 feet by 4 feet I sprayed three coats of the same water based finish as I used on the upper side on the underside of the top before securing it to the base. I did the same thing on big chest of drawer tops.

I do not get hardwood from BORG mainly due to price. Now you've given me another reason to go elsewhere. I wonder what would have happened if all surfaces had been finished with poly. It might have shrunk this much but it would have taken awhile. I am assuming that the underside, at least, was not finished with a finish that seals the wood.

Jim

 

[Larry Rose]

Jeff it just proves you used real wood, not plywood or other mfg. product. I've built several tables over the years and have noticed movement from summer (humid air swells wood) to winter (dry indoor shrinks wood). I just learned to build to accomodate it.

 

[Jeff]

I usually do not use breadboard ends and never have on a table more than about 20 inches wide. I have built tables and other things with bigger tops but they were just one big glueup. They were fastened down to allow for movement and have worked without issue. I fully finish the underside, however, which I think helps. In other words, on my kids kitchen table tops (1 1/8 oak and cherry) which are about 3 feet by 4 feet I sprayed three coats of the same water based finish as I used on the upper side on the underside of the top before securing it to the base. I did the same thing on big chest of drawer tops.

I do not get hardwood from BORG mainly due to price. Now you've given me another reason to go elsewhere. I wonder what would have happened if all surfaces had been finished with poly. It might have shrunk this much but it would have taken awhile. I am assuming that the underside, at least, was not finished with a finish that seals the wood.

Jim

Jim,

Good point about the finishing/sealing. I always finish/seal coat all 6 surfaces to the same level so there's an envelope of finish all around. :BangHead: