Here's why you don't glue slabs of wood cross grain

bffulgham · Post by **bffulgham** » Sat Mar 31, 2012 10:30 pm

(or evidence of what NOT to do)
I was digging through pictures a few days ago and ran across a set I thought I would share.

My Dad's oldest brother lived in Safford, AZ for many years. He spent a lot of time in his wood shop (probably to get away from my Aunt

). He did a lot of little projects to keep busy and made many 3-legged stools through the years.....a bit of a sadist maybe...... If you ever sat on a 3-legged stool, you know what I'm talking about. He gave me this stool at least 25 years ago. It is about 10-12 inches in diameter and about a foot tall.
The top/seat is 2 layers of 3/4" material, and for some unknown reason, he glued the 2 layers together with the grain running perpendicular between the layers. As long as there is no humidity change, no problem. The problem appeared because I lived in a world where we use swamp/evaporative coolers.....changing the air from <10% humidity in the winter to 80% humidity in the summer.

Enough of my blabbering. Here's a link to pictures of the infamous stool.

shipwright · Post by **shipwright** » Sat Mar 31, 2012 11:49 pm

While I agree with your point about the cross grain gluing, I have to leap to the defense of the three legged stool. Well designed they are absolutely stable, never teeter like four leggers and tuck into tight spaces.

I have one in my shop and I absolutely love it. IMHO of course.

[ATTACH]16835[/ATTACH]

Paul M

greitz · Post by **greitz** » Sun Apr 01, 2012 12:10 am

bffulgham- Thank you for the lesson. Pictures certainly speak louder than words. Did the splitting happen over a year or two, or did it take decades?

Paul- Could you please elaborate on "well designed" for a three-legged stool? Yours looks like the the three feet are outside the seat circumference, and the legs are splayed outward. Are those characteristics "standard"?

We have a short three-legged stool that we inherited. The three legs are vertical (not angled), and the feet are well within the seat circumference. (We named it "Killer" after a couple of "oopsies' using it as a stepstool.)

Thanks,

Gary

charlese · Post by **charlese** » Sun Apr 01, 2012 1:32 am

Sorry, Bud; I just can't see the cross grain gluing of two layers of wood on the stool top. Yes, there are splits in the top layer, but when the edges are viewed in 3X, it looks like the two layers would both be classed as face grain. Yes there is some converging grain patterns, but IMHO these are not enough to cause the splits that show as white lines on the top. It looks to me as the wood movement should be vertical (perpendicular to the grain) rather than horizontal. - It has been the curing of the top layer that caused the splits.

It is my guess that the top piece was at a higher moisture content than the lower one when the stool was put together. It looks like the splitting has all occurred in the upper layer.

BTW, three legged stools are particularly useful on uneven floors. This is the type of stool that used to be used in milking barns. They can sit on uneven floors with no rocking. (works like a tripod).

bffulgham · Post by **bffulgham** » Sun Apr 01, 2012 9:25 am

[quote="charlese"]Sorry, Bud]

I'll try to get more pics of it the next time I make it to the farm......
Charlese, the grain on the 2 pieces of the seat run absolutely perpendicular to each other. The last shot in the series gives (maybe) a little better view of the grain. If you click on the small thumbnail pics, you should get a larger image. I agree, the movement is going to be perpendicular to the grain. Both layers are flat-sawn and they try to cup away from each other as moisture content increases. There are cracks on both layers.

Gary, from what I remember, the first crack appeared just a couple of years after the stool was made.

I'll agree with you guys that the taller 3-leg stools can be very stable. The little short stools made by my Uncle are anything but.....if you shift your weight a little off center on these things, they will dump you on the floor every time

Gene Howe · Post by **Gene Howe** » Sun Apr 01, 2012 10:46 am

I've spent many an hour on a short three legged stool....at 5:00 AM every morning, before the school bus came. I agree, they do teeter, a bit. But, I still like milk!:D

dusty · Post by **dusty** » Sun Apr 01, 2012 10:55 am

Gene Howe wrote:I've spent many an hour on a short three legged stool....at 5:00 AM every morning, before the school bus came. I agree, they do teeter, a bit. But, I still like milk!:D

Been there, done that.

Don't want to think about how many times she got fed up and knocked me off that stool.

bffulgham · Post by **bffulgham** » Sun Apr 01, 2012 11:22 am

dusty wrote:Been there, done that.

Don't want to think about how many times she got fed up and knocked me off that stool.

Yeah, or smack you upside the head with a tail full of cockleburrs!

shipwright · Post by **shipwright** » Sun Apr 01, 2012 4:57 pm

greitz wrote: Paul- Could you please elaborate on "well designed" for a three-legged stool? Yours looks like the the three feet are outside the seat circumference, and the legs are splayed outward. Are those characteristics "standard"?Gary

About a year ago I did up a photo tutorial for Mickyd on how to build one. You'll find ithere.
Enjoy.

Paul M

JPG · Post by **JPG** » Sun Apr 01, 2012 11:04 pm

shipwright wrote:About a year ago I did up a photo tutorial for Mickyd on how to build one. You'll find ithere.

Enjoy.

Paul M

'here' is not found!