However, and its a BIG however, I took apart the old drawers and used the existing pieces to narrow them so I knew their size precisely so I knew that they would fit in the space once I put in the sildes
Restructuring the drawers was easy once I came up with a repeatable method. I took off the back using spreader clamps, sawed the sides from the drawer front using a oscillating saw leaving the front of the drawer attached to the front trim piece, removed enough from each side so it was exactly the width I wanted when the sides are reattached. cut the rear to length, ripped the drawer bottom to new width and reassembled everything. REALLY wished I had had the Kreg screw jig when I had done this, but clamps and glue still made it work. Again, this was easy because I was making all the drawers in the vertical cabinet the same width so once I got the hang of destruction, reconstruction was a snap.
I had 3 drawers that were under the counter and no cabinet walls (except on the far sides) to mount to so I improvised. I measured the distance between the back wall and the back of the face frame and then between adjacent openings of the left and center drawers and made a glued up block of plywood pieces (probably would have been quicker to trim down a 2x4) and then attached small metal L brackets that I would screw to the back wall and the back of the face frame. Clamped the slide in place and set the plywood shim against the outside of the slide, fit it flush to the rear wall and the back of the face frame attached it using the L brackets. Then it was a simple matter to screw the slide to that. Since the plywood shim was made to width, it made the attachment for the left side of the other drawer a no measure no brainer . Did the same thing once more for a piece between the center and right side drawer and attached the outside slides (left and right to the cabinet walls). It might sound cumbersome, but the biggest hassle is getting the width of the plywood piece correct and that's why I think in hind sight (such a wonderful tool
) that ripping a 2x4 to width would have been MUCH quicker). Also, in hindsight I might have put an L bracket ABOVE as well as UNDER or better yet some sort of cleat under the plywood bracket to help support the weight, but then that might have been overkill.Anyway, I hope that helps. It is MUCH easier to do than trying to make sense of my explanation.
Then just used a screw to secure it. For the four drawers that were stacked all I did was go from one side to the other top to bottom.
This is also where I put the brackets that attach to the back wall (along with the cleats in between the drawers), but all I did was slide them on to the back end of the slide an extended it to the wall and screw them in place. The more I think about it, the drawer slides added structure to the whole cabinet!! 