Spring joints? (as on Roughcut marathon)

[abram godshall]

Like many of you, I watched the Roughcut marathon on Create channel. When he did the trestle table, he made a spring joint. How does it work and actually make for a better fitting joint?

Thank you in advance
Abram Godshall

[Andrew Hughes]

Creating a slight hollow helps keep the ends from opening up. Thru the change in seasons.I use a hand plane to create my spring joints very very slight.I believe one should be able to close a slight spring joint by hand pressure.If i close a joint by hand on one end and the opposite side opens there may be a high spot in the middle.That would not be good maybe the glue will hold the ends together.Maybe not.Re jointing boards on a table top years down the road can be tricky or not possible.Hope this makes sense. Andrew

[Simon Dupay]

Old jointers like Northfield's, porters, and Newman's as well as some of the euro machines have an adjustment that would move the table out of plane to make a "spring joint". On a regular jointer taking a light cut in the middle of the board could make a spring joint.

[Frank Drew]

I think the principle is fine, but I never bothered with springing my glue joints. I think using well-seasoned material is the ticket to stable joinery.

[abram godshall]

thanks for your input and anymore appreciated.