Box joints

[kmealy]

This is the second post on (incorrectly built, IMO) box joints.   Using box joints on short grain might work (short term) but is risky putting any force on clamping them tight or stressing once built.  And if you are off 0.002" on your jig, by the time you get to the end of the piece, you'd be off 0.080" or over 1/16", making  a tight fit.  Short grain does not have much strength, or as Roy Underhill says, "Planes of strength and planes of weakness."  https://www.pbs.org/video/woodwrights-shop-spirit-woodcraft/

 

[Gerald]

Box joints on a cabinet , a bit of overkill?

[kmealy]

3 hours ago, Gerald said:

Box joints on a cabinet , a bit of overkill?

When I was doing product design and development, we said, "Just because you can doesn't mean you should."

[John Morris]

I agree this is not the application to use box joints, but I can completely appreciate the enthusiasm this fellow had to experiment and use his/her box joint jig. How exciting that must be to get into woodworking and say hey, I got this jig, and I can't wait to use it, I'm going to use it on everything!

I can fully relate, BTDT.

[kmealy]

23 hours ago, John Morris said:

I agree this is not the application to use box joints, but I can completely appreciate the enthusiasm this fellow had to experiment and use his/her box joint jig. How exciting that must be to get into woodworking and say hey, I got this jig, and I can't wait to use it, I'm going to use it on everything!

I can fully relate, BTDT.

One of the things that turned me off to Norm was seeing him cut half-blind dovetails on a jig to make a base molding for a dresser.   That and his "repetitive safety speech" that really did not tell me anything about safety and his "let's check this for square, yep, perfect" -- I would have much preferred him telling how to correct things that might not go right.   One of my favorite books has a section at the end of every chapter on cabinet building on how to correct errors.

[4DThinker]

21 hours ago, kmealy said:

One of my favorite books has a section at the end of every chapter on cabinet building on how to correct errors.

During the 4 decades I taught furniture design often the mistakes/failures made became the source of inspiration and even nicer outcomes. Minimally they did a better job of making a student understand a quality/weakness of wood than just hearing a lecture about it. 

4D

[kmealy]

2 hours ago, 4DThinker said:

During the 4 decades I taught furniture design often the mistakes/failures made became the source of inspiration and even nicer outcomes. Minimally they did a better job of making a student understand a quality/weakness of wood than just hearing a lecture about it. 

4D

It's not a mistake/failure, it's an opportunity for learning something and design change.

[4DThinker]

17 hours ago, kmealy said:

It's not a mistake/failure, it's an opportunity for learning something and design change.

Not at least until the short grain teeth of the side grain box joint start splitting off. 

All it would take would be an unexpected drop on a corner to start an avalanche of splits. Box joints even made end grain to end grain want to fail.  Look at any old mine explore where they come across box-jointed dynamite boxes that have fallen apart.  Changes in humidity create tiny shear forces between fingers due to expansion/contraction.  The breakdown of glue under those forces over time also speeds up the process of giving up the grip that keeps the joint together.   You never see commercial cabinet makes use box joints in side grain on cabinet corners.  

[steven newman]

Hmmm...

Hmmm..

Hmmm..

.

Not all that hard to do by hand, either