Thread: Sliding dovetail in slab table

I have been having real problems with a large Redgum slab table top that was very unstable. It had kept moving and cupping even in a fairly stable environment in my workshop.
In despair I was going to cut it up and give up on this project. I was very lucky and dropped by Woodborers workshop to learn more about sharpening pane blades and mentioned my problem with the slab.

He is a mine of information, he suggested a sliding dovetail, yippee.
Cut the slot on the underside of the slab with a router, cored out the slot with a spiral bit and cut the sides with an 8 degree dovetail bit.
Cut the ironbark dovetail with the table saw set to the same angle. The sliding dovetail fits snuggly into the slot, waxed to prevent binding.

I can't see how the slab can move again. It can still expand and contract with humidity changes but is prevented from cupping be the sliding dovetail.
Thanks again Woodborer.
Suresh