Roll Around Tool Cabinet #27: Spacers to be Used to Mount Drawer Slides

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Blog entry by HappyHowie posted 03-15-2017 05:47 AM 1729 reads 0 times favorited 1 comment Add to Favorites Watch
« Part 26: Finish Coats Completed Part 27 of Roll Around Tool Cabinet series Part 28: Jeez Louise, Did I Measure That Wrong? »


In this blog post I am going to reveal how this engineer thinks, or solves some of these woodworking problems; especially if it involves a bit of mathematics. In this case it is simple addition, subtraction, etc.

Many or maybe all of you may want to stop reading right here. That is fine. I am writing this mainly for myself so I have a record how I solved fitting these seven drawers into this cabinet’s bay. Once a problem is solved then the issue seems simple in retrospect. I admit that I had to measure and analyze my situation before I began any work to fit these drawers into this space. It may be obvious of how to proceed for a master woodworker, but this novice guy does not take anything for granted.

For those who want to be spared how I analyzed and calculated my solution, this would be the spot where you should bail out!

To install my drawers into this cabinet I am going to use scrap ¾ “ plywood panels as spacers. Actually, I will use two spacers cut to the exact same length. I will start by mounting the topmost pair of drawer slides, or top drawer. I will cut the length of the spacers so that the slides are located at the proper position indicated by the length of these spacers.. I will explain those calculated lengths or locations a bit later in the paragraphs below. I will use the spacers to hold the slides and the drawer at their calculated height location as I drive in the screws; first to the case’s side panels and then as I extend the slides I will fasten the metal slides to the drawer with screws. Of course, a video would be the best way to demonstrate this process. Maybe I can record a video clip and link it to this blog post. If I cannot devise a process to record it, I hope my written words will be clear enough to explain the process I used for those that are interested and have read to this point.

After the first drawer slides are installed I will simply cut the two spacer lengths down to their next length for the next pair of slides and drawer to be mounted. I will repeat this process until all of the slides and drawers are installed.

Since my cabinet has a face frame, the bottom drawer will be positioned just a fraction of an inch above the bottom rail of this face frame. This rail’s top is ½ inch above the inside base’s top surface. I take that ½ inch length into account when calculating the length of the spacers.

There is also a rail at the top of the drawer bay. I measured the distance between these two rails. That length was 34 ⅝ inches: the measured distance between face frame rails.

To calculate the gap between the stacked drawers and the distance between the two face frame rails, I first summed the heights of all seven drawers. That summation is shown below and totals to 31 ¼ inches.

7 ¼ + 5 + 5+ 4 + 4 + 3 + 3 = 31 1/4 inches is the summation of drawer heights…

Thus, the total drawer gap is calculated by subtracting the summation of the drawers heights from the distance between the face frame rails:

Total drawer gap is: 34 ⅝ minus 31 ¼ = 3 ⅜ inches.

I am using hidden finger pulls routed on the upper backside of the drawer fronts in order to open these drawers. I did not want to use knobs or cut semi-circle holes as what was shown in the Woodsmith plan.

I had picked out and used a beautiful sapele hardwood plank for my false drawer fronts. So since I designed to open these drawers in this manner with hidden finger pulls, I needed gaps above each drawer into which I could place my fingers so I could grasp the coved routed area in order to pull the drawers open. The height of the gaps between each drawer I determined should all be the same, equal. I figured gap calculation to the nearest 32nd of an inch. I thought that would be close enough.

Seven drawers need seven finger holes or gaps. The gap between drawers was easily calculated by taking the total drawer gap of 3 ⅜ inches and dividing that by 7. The result is shown below,:

3 ⅜ divided by 7 equals 0.482143 inches…

Multiple that answer by 32 gives me this number: 15.4. Rounding or truncating 15.4 gives me:

15/32. Inches; this is just shy of a half inch.

I chose to use fractions to the nearest 32nd of an inch instead of a 16th because a 32nd keeps the rounding errors to a minimum when adding up seven gaps for seven drawers.

I did; I went to all of this trouble so I could be as precise as I felt I needed to be in order to mount these metal drawer slides into this cabinet drawer bay

I had two other things to consider.

#1) I wanted the bottom of the drawer slides to be positioned ¼ inches above the bottom of the drawer sides. Say that three times fast…

#2) I need the front edge of the metal drawer slides to be positioned directly behind the ¼ inch thick sapele false drawer fronts. Each drawer front was cut at my bandsaw so I would have a finish thickness of ¼ inch.

To help me position the front of these metal drawer slides I am looking at the center divider of this cabinet. It is a ¾ inch plywood panel with a ¼ inch poplar strip to cover or hide the plies. I will position the front of these slides to that seam line where the poplar strip is glued to the plywood panel. That works for the center panel or left side of the drawers.

However, for the right side of the drawers I have a 1 ½ inch thick spacer made from poplar hardwood. This is what the metal slides will be fastened or screwed to for the right-side of these drawers. To position the front of these metal slides I needed some other device to offset or mark the slides starting indent position. I located some small scrap pieces of maple that I had resawn to ¼ inch thick strips. I will be using this to indent the starting front edge of the drawer slides on this right-side of the drawer bay by indexing it flush to the front edge of the poplar spacers. Doing that will give me the ¼ inch indent to position the front edge of my drawer slide on the right side of the drawers.

Lastly, I wanted to calculate all the space lengths I would need to position all of these drawers to their proper height in this bay. To calculate the spacers lengths I started at the bottom of the bay, the caster base’s surface.

I have summarized those calculations below.

(7) Spacer length for bottom drawer #1: ( 7 1/4” tall)
½ inches
(Note: leave the line when ripping the length of this spacer. Actually, I will cut this spacer separately from the spacers used for all the other drawer mountings.)

(6) Spacer length for drawer #2 that will be a 5” tall drawer.
15/32 + 7 8/32 + 16/32 = 7 39/32 = 8 7/32 inches

(5) Spacer length for drawer #3 that will be a 5” tall drawer.
8 7/32 + 5 15/32 = 13 22/32 = 13 11/16 inches

(4) Spacer length for drawer #4 that will be a 4” tall drawer.
13 22/32 + 5 15/32 = 18 37/32 = 19 5/32 inches

(3) Spacer length for drawer #3 that will be a 4” tall drawer.
19 5/32 + 4 15/32 = 23 20/32 = 23 5/8 inches

(2) Spacer length for drawer #2 that will be a 3” tall drawer.
23 20/32 + 4 15/32 = 27 35/32 = 28 3/32 inches

(1) Spacer length for drawer #1 that will be a 3” tall drawer.
28 3/32 + 3 15/32 = 31 18/32 = 31 9/16 inches

I have marked with a pencil all of these lengths on the plywood spacers plus I have cut the spacers to the 31 9/16 inch length. This is my starting position for the topmost drawer I will mount first to the metal slides. After mounting it, I will cut the spacers to the next length marked as (2) above: 28 3/32 inches. I will continue in this manner until I reach the bottom drawer. For it I have already cut two spacers to slightly over 1/ 2 inch lengths.

-- --- Happy Howie

1 comment so far

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2859 posts in 1499 days

#1 posted 03-22-2017 04:58 PM

I didn’t check your math but the process sounds perfect.

When I use side mounted drawer guides, I always put the guides on so that the bottom of the drawer will be flush with the bottom of the guide.
Then when I layout my drawer fronts (with spacing) I just add 1/4” to the bottom of the drawer front measurement and that’s the size I cut my board.
This always puts my drawer box 1/4” above the bottom of the drawer front. (if that makes sense)

(I usually run a piece of tape down the face of the cabinet and then make the marks for the drawer fronts and spacing on the tape, then measure the marks on the tape to get my board sizes.)

Anyway that’s my system that works for me. ;)

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