Sliding Dovetail Question

[Jim Knishka]

I dry-assembled a pair of bookcases I'm building out of red oak, with the shelves housed in stopped sliding dovetails. All of the joints were tight enough to have to be tapped home, however some of them have gaps after assembly between the end of the pin and the bottom of the groove.

When I pull them tight with clamps they appear to fit well. I bought some veneer edgebanding with the intent of building up one side of the dovetail but looking at the joints when clamped I don't think they are very much undersized.

How strong is the glue joint on a sliding dovetail? If I glue it up as is and clamp it, will the joint last? Do I need to build up the pins with veneer and re-rout the dovetails?

Thanks for any advice you can give me.... Jim

[Ben Davis]

You'll be good to go with the glue alone. Nearly all adhesives are strongest in the shearing direction and weakest in the tension direction. Every try and slide a piece of tape off a sheet of paper? The dovetail joint takes care of the tension side of the joint.

[Thomas Pender]

I use sliding dovetails for a variety of applications - some folks call them French dovetails. Examples include legs for hall trees, drawers when I want to use side mounted hardware, etc.

I use a jig to cut the insert side and test it with some scrap planed to the correct thickness and then move the fence on the router table back and forth with strips of paper behind the fence and clamp - I want the dovetai to slide with a little resistance and not have to be forced in because the glue will cause the wood to expand just enough to make it impossible to get in once you put the glue on the wood. Sometimes I cut several inserts before I get it right.

Once you apply the glue and slide it in to its full reach it is never coming out. I have made some really large drawers using the method and they are real strong. (1/2" QS White oak for instance. Just last week I finished a cherry hall tree with 3/4" QS feet in a 2" post - there are many methods to do it, but I prefer just using a 1/2" dovetail bit on the table and dropping the peice on it - yes it makes 1/2" hole on the post of the back of a drawer, but if you cut off the top 1/2" on the dovetail on a bandsaw it will slide right over it and hide the hole. there are ways to set up blocks so it cuts the hole just perfectly.

I appreciate this is more information than you may want, but I am rather enthused about this method because of it is so adaptable and yes, strong!

[Charles Lent]

It's only important to get a snug fit at the end of a sliding dovetail, if the end of the joint will be seen. If you make the rest of it that snug you won't be able to get it together when you put the glue on it. If the "end to be seen" doesn't fit very well, I glue a small piece of veneer of the same type wood on the side of the tail at the very end of it and then hand fit and trim it until it fits perfectly and "looks good". Then I proceed with the glue-up. What can't be seen will be fine and will be unbelieveably strong after it's glued because of the amount of joint surface involved. Don't worry if the rest of the joint isn't a perfect fit, just get the visible part right.

Charley

[Jim Knishka]

Thanks for the help guys! Jim