How to use Blum Tandem Drawer Runners
The Blum Tandem series is one of the most popular drawer slides available. They’re commonly heralded as the best drawer slide money can buy. From integrated soft-close (the manufacturer calls it Blumotion), to the tool free adjustments, to their massive versatility, it’s easy to see why so many people love these slides. That being said, there are some important things you should know before you pick these up for next kitchen upgrade. First, these slides are a two-piece design. You select the drawer slide with your desired size and features, then you select the locking device that fits your application. Second, the drawer box needs some extra consideration. We’ll get into all those details down below, so let’s jump into it.
PLEASE NOTE: All measurements that come from the manufacturer are in millimeters, including most of these images you will see. We will give inch equivalents in the accompanying text.
Table of Contents
| 1. Sizing and Choosing the Right Runner |
| 2. Choosing Locking Devices |
| 3. Building the Drawer Box |
| 4. Installing the Runners |
| 5. Installing the Drawer into the Cabinet |
| 6. Adjustments and Fine Tuning |
Sizing and Choosing the Right Runner
The very first thing you’ll want to do is measure your cabinet opening. If you’re making new cabinets, carefully consider your design and choices of slides. Luckily, Tandems are incredibly versatile, so chances are good that you’ll find something to work with your design whether you have a face frame or not.
The size of your drawer box will match the size of your runner. So, if you buy an 18” runner, your drawer box should measure 18”, front to back, on the outside of your drawer side material. To make all the sizing easier, we recommend using the same thickness material all around your drawer. For all intents and purposes, it doesn’t really matter what thickness you use for the drawer bottom, but common thicknesses we see are 1/4”, 3/8“, and 1/2”. You can make your drawer sides as tall as you like depending on what you’re going to be storing, so long as you have the proper clearance on your cabinet opening. As for drawer width, you can go just about as wide as you want, but as you go wider you trade off the ability to hold more weight, and at a certain point you will have to use a Lateral Stabilizer to avoid racking and jamming the drawer. We’ll get into more specifics on the drawer box specifications later. Here is a handy chart from Blum describing the critical dimensions for choosing which drawer slide to use.
By far the most popular sizes are 18“ and 21”. If you’ve made cabinets before, you’ll notice the 21” is the perfect size to fit in a standard 24” deep cabinet.
Choosing Locking Devices
Depending on your application you have a good number of choices for your locking devices, or triggers as some people call them. The runners get mounted in your cabinet, and these triggers are how you attach the drawer to the runners. If you buy them from us, we sell them as left and right pairs, but your mileage may vary with other vendors, so check documentation carefully. Here’s the rundown on all your options:
 | Standard |
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 | Standard w/ side-to-side adjustment |
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 | Vertical mount |
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 | Veritcal mount w/ side-to-side adjustment |
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 | Inset/Servo Drive |
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 | Narrow |
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Building the Drawer Box
This is where the Blum Tandems, and undermount drawer runners in general, set themselves apart from most other drawer slides. If you’re more of a visual learner, we’ve got a great video on building the drawer box which we’ll have below. If not, skip down and we’ll dive in.
Once you’ve decided the drawer length, the thickness of your drawer box material, and chosen a slide and locking device, you’re ready to begin on your drawer box. Let’s start with the notch.
The drawer slide will sit right in that notch at the back, allowing the bottom of the drawer to rest on top of slide. Alternatively, you can use a shorter drawer back altogether if you just don’t feel like cutting out notches.
Next, we’ll look at that hole right above the notches. Tandems have a hook in the back that fits in that hole and more securely keep your drawer attached to the runners. That hole is 6mm in diameter by 10mm deep (1/4” x 13/32”). Here are the drawings:
Proper location of the hole is very important. To assist in getting all of these features correct, Blum makes a jig. That same jig will also help with drilling holes for the locking devices. Our part number for that is BT65.1600.
Here is a tutorial on the drilling jig:
If you’re material thickness is 5/8” or less, take your cabinet opening width and subtract 42mm (1-21/32”), the value you get will be your required *inside* drawer width. It’s critical for your drawer box to match that value in order for the slides to fit under the drawer box and hug the inside of that recess like you see here:
If your material thickness is over 5/8” and under 3/4”, you will take your cabinet opening and subtract 49mm (1-15/16”) to get your required *inside* drawer width.
Like we noted at the beginning, and as you can see in the above drawings, you can make the drawer as tall or short as you like so long as you keep 7mm (9/32”) clearance on top, and 14mm (9/16”) clearance on the bottom. This is true not matter what material thickness you’re using. You could even make the sides flush with the top of the drawer bottom and create a rollout shelf. In case you are wondering, 1-7/8” is the actual runner height.
Next, you’ll have to install the locking devices to the drawer. Remember, these are what lock your drawer to the runner. They also allow you easily remove the drawer later on for cleaning or maintenance. The triggers are placed under the drawer box; just shove them right up the front, and into the corners. You’ll see the proper placement along with how the Tandem jig is used to place the pilot holes in this drawing:
Installing the Runners
Now you’re ready to install the runners in the cabinet. The main thing to keep in mind here is runner setback. For nearly every Tandem slide, no matter the material thickness, the setback will be 3mm (1/8”) from the front edge of your face frame or side panel, unless you’re doing inset drawers. Which means the front of your drawer will sit flush with the front of your cabinet. Here’s a drawing:
For an in depth look at runner setback, including inset applications, check out our video here:
NOTE: if you’ve chosen the Tandem Edge slide, your setback will be 4mm (5/32”) from the front of the cabinet.
Installing the Drawer into the Cabinet
Okay! Your drawer box has been prepared. Your slides are installed in the cabinet. All that’s left to do is install the drawer and dial in your adjustments to get everything line up nicely. To get the drawer box into your opening, extend your slides all the way out of the opening, and place your box on top of the runners like you see here:
Once the box is resting on the runners, just push it on home into the opening. You should here a click as your locking devices engage with the runners. Cycle the drawer a few times to ensure everything is moving smoothly.
Adjustments and Fine Tuning
Now let’s get those adjustments dialed in. If you chose a locking device that has side-to-side adjustment, now is the time to take care of that. (If you chose a locking device without side-to-side adjustment, skip to the next step.) This will move the *front* of your drawer side-to-side. Here is how that works:
Next, you’ll want to take a look at the rear of the box where the slide hook engages with the hole above the notch. There will be a little white wheel you can turn. This will move the *back* of your drawer left and right.
If you have a depth adjustable locking device for an inset drawer, you can adjust the depth of the integrated spacer by turning a cam screw from the side like you see here:
All locking devices have the option of height adjustment using the little slider on the bottom near the side edge. Here’s the drawing:
Last, but not least, we have tilt adjustment, located on the back of the slide next to the white wheel we used for side-to-side adjustment. This will tip the entire drawer forward or backward, seen here:
That’s it! You’re done! You just installed a drawer equipped with Blum Tandem slides. We really hope this guide helped you. If you still aren’t getting it, please feel free to give us a call Monday – Friday 8am to 5pm CST at (800) 383-0130 to speak to one of our hardware experts, we will be more than happy walk your through the steps, and help you figure out which hardware you should use on your project. Whether you’re upgrading a single nightstand, or working on a whole apartment building, we can give you guidance.
In addition, you can also find all of the official manufacturer installation information here: Blum.com
Images courtesy of Blum.com