Dovetails with undermount drawer slides

Question

To practice my dovetails, I decided to make some drawers for my kitchen cabinets. I'm using Blum undermount slides, which requires the drawer to conform to specific specifications, as well as a few modifications to the basic drawer.

After carefully cutting my dovetails, I started to make the modifications required by the slides. One of these is to cut notches on the back of the drawer below the drawer bottom to allow the rails to run along the bottom of the drawer (see http://downloads.cabinetparts.com/auto/blumtandemplusblumotionnew.pdf, page 11). I've drawn the back of my drawer below: pins on the sides, dado slot for the drawer bottom in gray, and the cutouts required for the slides in red.

No doubt an experienced woodworker can immediately spot the flaw: the notches result in the loss of the bottom pin on both sides! It was pretty sad to cut off the pins I spent so much time on.

My question is this: I'd like to keep using this style of slides on the rest of my drawers. Are those slides just incompatible with dovetails, or is there some trick so that I don't end up with a missing pins?

Some additional context: I invested a lot of time and money building jigs for cutting dovetails, so I'd really like to continue doing dovetails if possible. I'd switch rail styles before giving up on the dovetails, but ideally I could keep the rails and the dovetails with a little help :)

Answer 1

You haven't significantly compromised strength by removing the last pin and the back of a drawer actually doesn't need to be that strong¹ so I don't think it's a big concern.

But obviously it is best not to lose a part of a joint (even if only so the effort to make it isn't wasted!) so I'll list some options for you.

Sticking with the Blums
For future drawers you can simply change the style/spacing of the dovetails and you're golden — no shallow pins there, zero loss of strength once the notches are removed.

If you just can't stand to do uneven pins (they do look odd) you can always use Blum's own recommendation for the no-notch version of mounting, which is included in the PDF you linked to in the Question on page 11:

An even simpler option is don't dovetail the back — nobody ever sees them and nobody really cares but the woodworker LOL And they certainly aren't needed for strength on a drawer back — drawers typically see almost no forces exerted rearwards trying to push the back off. As a result even the simplest option of all, butt joints, are more than adequate for the back of virtually any drawer if glued and pinned or reinforced with skinny dowels².

If a butt joint is unacceptable for some reason, you could use a housing joint (dado joint) instead, although you inherently lose a small amount of drawer volume this way since the back has to be brought forward slightly.

Select different slides
There are different makes of undermount drawer slides and not all require the same positioning. So another option if you must dovetail all four corners and you'd prefer to continue to do them exactly as done already is to simply pick a different style of slide.

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¹ Traditionally both fronts and backs of drawer boxes were dovetailed because they were overbuilding for strength, as well as creating a joint that held together mechanically because they knew from experience that their glues sometimes failed. We don't really have that concern any more, unless you're using a protein glue of course!

² Bamboo skewers are great for this. Short lengths of bamboo dowel are extraordinarily strong and make a great alternative to pins if one wants to avoid metal fasteners for any reason (e.g. so the sides of the drawer remain safe to plane).

Answer 2

I'd like to keep using this style of slides on the rest of my drawers. Are those slides just incompatible with dovetails, or is there some trick so that I don't end up with a missing pins?

I can think of a few solutions, but if you want to keep using dovetails for that rear joint, the simplest solution is surely to just change the spacing of the pins and tails so that the bottom pin is taller than the notch for the slide. Your dovetails don't have to be laid out symmetrically: the back of the drawer doesn't experience a lot of force, and people aren't likely to see the rear joints, so having a taller pin at the bottom rear corners won't hurt.

Answer 3

You don't have to make the notch go all the way to the side of the box. I typically use 5/8 drawer box material and my notch starts 5/8 in from the drawer side leaving the last pin and about half of the first dovetail. Only notch what you have to