Double drawer slides? Orientation to one another?

[Stuart Welsh]

Im building a custom mount for a flat panel tv and need advice on the slides. The location is a 24" deep built-in originally built for a large tube tv and in the corner of a room. I am now installing a 40" flat screen that when even put on an fully articulating mount will not be adequately visible from a number of seating positions in the room. My plan is to build basically a large drawer that will be mounted on it's side so what would normally be the inside bottom of the drawer will now be the inside back of the tv mount. I will then mount the articulating mount to the drawer. This will allow me to pull the drawer out 20" and then farther out and laterally into the room on the articulating mount.

The tv and articulating mount weigh 29 lb and the drawer weighs 49 lb for a total weight of 80 lb or so. The drawer slides are full extension side mount slides that are rated for 100 lb. While rating wise they will handle the load I worry that a the box and tv when fully extended will create a lot of torque on the slides and fasteners, especially when I articulate the mount.

My solution is to double up the slides and my question is what is the best configuration? Should I stack the slides right on top of one another or create some space between them? If stacked I will probably mount the lower one just an inch or so up from the bottom of the drawer side like the manufacturer recommends and position the other right above it, touching. If I separate them I'll mount the upper slide an inch down from the top of the drawer side. It seems that the separated version would be best at resisting the torque but much harder to ensure proper alignment between all four slides than mounting them directly on top of one another.

Any engineers out there willing to offer opinion?

Thanks,

Stuart

[Tim Bueler]

Stuart, Since it's way easier and cheaper to use what I've got instead of ordering something special I've doubled up drawer slides in a manner similar to what you're describing. Mount both sets of slides to the inside of your cabinet. Mount only one set of slides to your drawer, just as you would a regular drawer. Install drawer. With the drawer fully extended, and all slides fully extended, put just one screw in the lead oblong hole in the slide not yet attached. Cycle your drawer a few times to check for operation. The second slide can be adjusted a bit if needs be via the single screw in the oblong hole. Once you're happy with the operation install the rest of the screws in the second set of slides.

Anecdotally, I think there's more stability in separating the slides as far as possible. For the part inside the cabinet I install the first slide as normal, the second slide I usually rip a spacer out of scrap to get the two perfectly parallel.

I'll be interested to read others solutions!
Tim

[John Lanciani]

Question; why is the drawer so heavy? 50# is just about the weight of a full sheet of 3/4" plywood, seems like an awful lot to hold up a 30# TV.

[George Bokros]

Question; why is the drawer so heavy? 50# is just about the weight of a full sheet of 3/4" plywood, seems like an awful lot to hold up a 30# TV.

My understanding is that a sheet of cabinet grade maple ply weighs about 85#. With only the veneer being different I would think all ply weight about the same

[Warren Lake]

I once put two sets on, one for weight two he wanted soft close when it hit full extension. Blum found it interesting. It was for a musical Keyboard for a guy who did documentaries.

[Stuart Welsh]

It may be over built but what are the top and bottom (these are the front and back if it was installed in the position of a functioning drawer) are 41" wide and 20" deep. That's almost a half sheet in itself. Add the two sides which are 20" x 23" and you are 60" into the length of that sheet. I saved weight (and material) by using 1/2" for the back (bottom on that normal drawer) which is 23" x 41". That back will receive a piece of 3/4 as a backing plate to give the articulating mount something firm to grab onto. Given that this box needs to fully extend and hang on the slides AND THEN take the additional leverage of pulling the tv away from the drawer on an articulating mount an addition 6" and then to the side another few inches I assumed the box needed to have maximum dimensions for torsional strength. Hope this explains my reasoning, I'm sure there are lots of ways for saving weight on the box but this is what I came up with.

[Stuart Welsh]

Thanks Tim for enlightening me in your techniques.

[John Lanciani]

It may be over built but what are the top and bottom (these are the front and back if it was installed in the position of a functioning drawer) are 41" wide and 20" deep. That's almost a half sheet in itself. Add the two sides which are 20" x 23" and you are 60" into the length of that sheet. I saved weight (and material) by using 1/2" for the back (bottom on that normal drawer) which is 23" x 41". That back will receive a piece of 3/4 as a backing plate to give the articulating mount something firm to grab onto. Given that this box needs to fully extend and hang on the slides AND THEN take the additional leverage of pulling the tv away from the drawer on an articulating mount an addition 6" and then to the side another few inches I assumed the box needed to have maximum dimensions for torsional strength. Hope this explains my reasoning, I'm sure there are lots of ways for saving weight on the box but this is what I came up with.

I wasn't picturing it being that big but now I understand. For stability and long term durability I would probably use heavier slides than 100#, and definitely two sets, positioned at the top and bottom of the sides. I would also leave room to add a set on the flat either at the top or bottom if it turns out that you need more lateral stability.

[Tim Bueler]

Thanks Tim for enlightening me in your techniques.

My pleasure! It's not the weight that'll kill you, as you already figured out, it's the dual cantilever.
Tim