# Dovetails on a 45º angle?



## MN Wild Fan (Mar 15, 2013)

Ok,

I'm relatively new to woodworking, and I've looked for a reference to what I'm attempting do do all over, but I can't find anything close to what I'm talking about.

I want to make a shelf where the bottom is joined to the back with support braces mitered at 45º using through dovetails. Is this possible? Or is the reason I can't find anything like it because it's a bad idea, and wont hold?

I keep finding mitered "half blind, or full blind" dovetails, but nothing like I'm looking to do. I'm assuming that the dovetails on the mitered support beam would have to be cut by hand, but the "section they fit into" on the bottom and back of the shelf would be normal. 

Anyone have any pictures of this in action?

Does anyone even understand what I'm attempting to describe? I'm not sure I did a very good job.

Thanks-


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## tc65 (Jan 9, 2012)

If I'm understanding you correctly, your support braces will have dovetails to connect to the back and bottom of shelf. I don't see any reason why you can't do that. Measure the length of the support board you need (including the thickness of the back/bottom), cut the angle on both ends of the board, mark your baseline(s) to correspond to the thickness of the shelf and back, lay out dovetails and cut away. It shouldn't be difficult except the board will be at a 45 degree angle in the vise while you are cutting the tails.


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## Hammer1 (Aug 1, 2010)

Not sure if is what you mean. This was a ladder rack for my truck, so it's larger than what you would use on a cabinet. The dovetails are half lapped.


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## MN Wild Fan (Mar 15, 2013)

Yes! That's pretty much exactly what I'm looking to do. Just smaller and about two on each side.

Will these be structurally sound enough to support the weight of the shelf and anything on it? (to a certain extent anyway. not like bricks or anything.)

Thanks!


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## Hammer1 (Aug 1, 2010)

Interlocking, mechanical joints are usually superior to many other types of joints and fasteners. I'm lucky I didn't squash the cab of my old truck and my own squash with some of the loads I used to put on that rack. 

An angle brace like this will help support a shelf and also keep the cabinet from racking. It's not a typical way of doing shelving units, since they often have backs. It would be the size of the shelf that matters. Thickness, width, length and where braces are added. 3/4" x 12" x 36" shelf is about as long as you want to go for most 3/4" thick materials. I'd rather stay around 30" in length. Braces placed so they provide support, leaving 30" - 36" shelf span would be an option with longer shelves but you have to think about the front as well as the back of the shelf. 

In most cases, you are better off to either use thicker material or make the shelves with a frame or add a supporting edge band when you want longer lengths. Fuzzy pic of a rabbeted shelf edge band. This can be done all around the perimeter and with wider banding to add the necessary strength. There are many other ways to make stiff shelves, too.


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## Midlandbob (Sep 5, 2011)

Look at the forces in the joint and see if the angles are still performing a function or maybe just decorative. The picture given Shows a joint where the top triangle of the tail has no long grain where forces would be if it were racked. If it was just carrying load down, it would hold the boards together and look "fancy". The strength is in the bottom which has become a dado.


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