Ikea Expedit Hack: A Really Long Bookshelf

I came across this great Ikea Hack a while ago combining two Expedit bookshelves into one long unit. It was exactly what I was looking for, so I spent last weekend attempting it. Before you get as excited as I did, I will tell you the original instructions were bullshit. But the good news is I do have a solution.

The bullshit: Upon following the original poster's instructions, I found myself with a 3/4" gap between the two shelves when I tried to insert the center shelves. I wasn't alone. Another person attempting this hack left a comment with the same problem. Putting the two units together without the center shelves revealed the reason. The shelves measure 27" wide, the opening measured 26 1/4". The original poster did mention he used putty and spackle, and I suspect this gap was part of the reason. Why he failed to mention this 3/4" gap specifically, I don't know.

The Solution: 
Drill a few holes into one shelf, attach the other shelf to it, sans one end. Use some Gorilla Glue to secure it in place.

What You Need:
- 2 2x4 Expedit shelves (You don't need to buy the extra 2x2 shelf as suggested in the original instructions for this hack)
- 1 Drill with different sized bits
- 4 extra dowels (either from another ikea build or from a hardware store)
- Small saw, blade or strong scissors to cut some dowels
- Hammer
Gorilla Glue 
- Napkin and water for the Gorilla Glue (it requires a little water to stick)

Pic 1 - Assemble the two shelves up to this point.
Pic 2 - Since we're attaching another set of shelves on the end of Shelf 1, we'll need to drill the center 4 dowel holes all the way through.

Drill the 4 holes that are already in the center divider completely through the board. Then drill from the new hole side to make a larger opening and clean up any particle board that is stuck. We will be inserting the 4 extra dowels into the top and bottom screw holes, (pic 2.5) so you're going to need to drill them a bit to make them large enough for a dowel.

You'll have to experiment with different drills bits when drilling. Use a dowel to test if the new holes are big enough for them. It should be slightly difficult to push in, but not completely loose.

Insert dowels into all 16 holes on the shelves and use the hammer to push them in all the way. Trim all dowels by about 1/4". This is so they can sit evenly in the center divider. (see Pic 2.5) This helps the two halves be as flush as possible. You can push the shelves together with the center divider loosely to see if they fit. 

Pic 3 - Dampen shelves and center divider and apply Gorilla Glue to the orange areas. It's easier to glue/attach the divider to Shelf 1 first, allow to dry over night, then glue/attach Shelf 2 to Shelf 1.