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Forum topic by HTown posted 11-11-2017 05:31 AM 400 views 0 times favorited 7 replies Add to Favorites Watch
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HTown

77 posts in 1021 days


11-11-2017 05:31 AM

Topic tags/keywords: fww glue joint joining

I’m looking at a small silverware tray that Christian Becksvoort featured in FWW #274 Nov/Dec 2017.
The bottom is glued from underneath directly to the sides. It seems like this would create a cross grain situation that would fail due to differential expansion.

Can anybody explain why this joint wouldn’t fail?

Please don’t take this as a critique of CB’s design, I really admire his woodworking and journalism. Here is a link in case you missed the article:

http://www.finewoodworking.com/2017/09/27/four-handmade-gift-ideas

Thanks.


7 replies so far

View Loren's profile

Loren

9609 posts in 3482 days


#1 posted 11-11-2017 05:58 AM

He mentions using quartersawn pine. Quartersawn
wood moves less. It’s a risk he’s willing to take
apparently on a small box.

A few months back there was a discussion here on
making chessboards where examples were shown
that took risks with wood movement but hadn’t
had any problems. I believe there were also
some examples of failures.

View Andre's profile

Andre

1488 posts in 1640 days


#2 posted 11-11-2017 07:06 AM

From the Pic. it looks like long grain to long grain for 2 sides so shouldn’t be a problem. Could always dowel if really concerned.

-- Lifting one end of the plank.

View jdh122's profile

jdh122

961 posts in 2652 days


#3 posted 11-11-2017 11:11 AM

Quartersawn softwoods move very little (see chart http://www.finewoodworking.com/2013/08/29/calculating-for-wood-movement). A piece of QS eastern white pine 9 inches wide (seems reasonable size for an inbox) that varied seasonally from 6 to 16% moisture content would only see 6/100 of an inch movement from smallest to largest.

-- Jeremy, in the Acadian forests

View bbasiaga's profile

bbasiaga

1005 posts in 1829 days


#4 posted 11-11-2017 02:27 PM

The growth creates stress in a constrained joint. If that stress exceeds the strength of joint, it fails. A mechanical engineering type guy could tell you the strength of as cross grain glue joint and figure out how much stress gets created when the wood grows.

On a small box or tray the amount of growth is small, so perhaps the glue joint is strong enough to survive. Paul sellers made a box on YouTube recently with a cross grain glue joint. Must work on the same principle.

Brian

-- Part of engineering is to know when to put your calculator down and pick up your tools.

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TheFridge

8287 posts in 1320 days


#5 posted 11-11-2017 04:10 PM

I have no basis for this arbitrary measurement but I keep it under 6” or less. I do it on jewelry boxes all the time and haven’t had any problems.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

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HTown

77 posts in 1021 days


#6 posted 11-12-2017 02:03 AM

Thanks for the insight. I decided to go with a loose bottom for a chisel tray I’m making.

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HTown

77 posts in 1021 days


#7 posted 11-12-2017 11:37 PM

So here is the tray I was hoping to build today. More of a till to fit in a drawer. I ended up making a loose panel in grooves rather than gluing the bottom in.
I didn’t have any quartersawn material to devote to this project.

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