Wide Drawer Bottom Support

[Ron Duca]

I have a set of design plans for a four-drawer dresser that I'm going to modify to make into a five-drawer CD/DVD Storage cabinet. The drawers will be 3/4" plywood, 40"W x 18" x 6"D and I will use rabbet and dado joints. I am also going to use ball bearing full extension slides. I originally planned to use 1/4" hardboard or plywood bottoms with a 1/2" strip of 3/4" plywood turned sideways and glued across the width of the bottoms for support. Would that support prevent the drawer bottoms from sagging or should I use something thicker for the bottoms like 3/8" or even 1/2" plywood (without a support strip)?

[Chris Friesen]

ply would make a sturdier bottom than hardboard. You may also consider using a hardwood support in the middle rather than just plywood. (In plywood half the material is going the "wrong way" for what you want.) Given that CDs are not particularly light, you might consider using 1/2" for the bottoms.

Also, most full extension slides are not designed for drawers that are wider than they are deep (aka "lateral" drawers). You may want to bump up the load rating, or get slides designed for lateral use.

[Jesse Cloud]

Hey Ron,
Please don't take offense, but not knowing how much experience you have in this sort of thing, I thought it wise to caution you about a 40 inch wide drawer. Its not easy to get something that big to come out square and ball bearing drawer slides don't have much tolerance (probably about +- 1/32).

If you haven't built something like this before, you might think about making more, but smaller drawers, maybe 20 inch wide... That would avoid the sag problem and lower the risk.

Hope this helps!

[Ron Duca]

Thanks for the advice. This is my first "dresser" and one of the reasons I posted my question was to see what kind of responses I might get to building 40" wide drawers. Most everything I've read suggests limiting the drawer widths to 24". The plan I'm using shows them at 38" wide and recommends using 18" Blum type slides. I was considering the ball-bearing slides because they are heavier duty. The ones locally available are rated up to 100 lbs., but they also say "up to 24" drawer widths".

So, now I guess I'll plan to modify my cabinet to contain two columns of narrower drawers. I'll lose some storage space, but the drawers should be more stable and slide properly.

And now I have another thought. With 40" drawers, would the Blum type slides be strong enough, and would they keep the drawers straight moving in and out?

[frank shic]

ron, as long as you don't exceed the maximal load on the drawer slides and install them correctly, you shouldn't have a problem except for some slight side-to-side movement. i was thinking about your wide drawer problem and another possible solution would be to nail or screw a piece of cambered hardwood underneath the drawer bottom with the bow facing upwards.

[Greg Cole]

Hi Ron,
I have made a couple pretty wide drawers (32" IIRC) for tool storage stuff for the shop at the day job. I wound up using 1/2" ply for the bottom & 3/4 ply for the drawer box itself. I used a "frame and panel" style of construction for the drawer bottom. I used 4" wide 3/4" hard maple for center rail in the middle of the drawer bottom. The rail sticks up just a tad under 1/4" on the topside of the drawer bottom. I also morticed the center rail in place to make it as stout as possible.
We literally toss angle grinders, sawzalls & misc powered hand tools in'em every day...

Worth the price paid...

Greg

[frank shic]

greg has pointed out another great solution: solid wood drawer bottoms! if you don't want to spend the extra time building frame and panel, you could just bevel the edges so that the wood will fit in the dado.

[Cliff Rohrabacher]

I have used 1/2" for some over size shop drawers that I load with heavy stuff. I fully captured the ply rather than slide it in after the drawers were glued up.

[Ron Duca]

Cliff,

I have a beginner's question. What do you mean by, "I fully captured the ply rather than slide it in after the drawers were glued up."? Does that mean you didn't cut a groove for the drawer bottom?

[frank shic]

ron, it probably means that he did not chop off the bottom of the back of the drawer to allow sliding the bottom in through the back and instead had it captured on all four sides with a dado through each.

[Ron Duca]

I've done a lot of research and had decided to go with the Blum Tandem with Blumotion slides. I thoroughly studied the literature and installation instructions and was convinced that I could installed these slides, even though I have never installed them before.

Today however, I went to my local supply store and was ready to order five pair of the slides until the saleswoman asked me if I had ever installed these slide before. I said no, and she then said, "You do know that you've selected the hardest slides to install, don't you?". We further discussed this issue and I left the store, ready to go back to the drawing board.

I'm may be a novice woodworker, but those slides just don't look that hard to install to me. Am I being unrealistic or is the installation really that difficult?

[Jesse Cloud]

[quote=Ron Duca;685981
.....
I'm may be a novice woodworker, but those slides just don't look that hard to install to me. Am I being unrealistic or is the installation really that difficult?[/quote]

Hey Ron,
I suspect the issue with the slides is that there is very little tolerance for the two pieces (one on the case, one on the drawer) that fit together. If your plywood bows a little or the case is a little wider at the back than at the front, the slides will bind or jump loose. If you like the design, my advice (free and thats about what its worth) is to be very anal about getting things square, doing it over if there's more than 1/32 difference and be prepared to put some shims under the slides if things aren't totally square.

Another good approach is to use a 'story stick'. Take a piece of scrap the height of your project and mark the vertical distances for all the slides, dadoes, etc on the stick. Then use the stick to mark the sides of the case. Its a good way to minimize measuring and marking error.

Let us know how the project goes!

[Joe Jensen]

I have a set of design plans for a four-drawer dresser that I'm going to modify to make into a five-drawer CD/DVD Storage cabinet. The drawers will be 3/4" plywood, 40"W x 18" x 6"D and I will use rabbet and dado joints. I am also going to use ball bearing full extension slides. I originally planned to use 1/4" hardboard or plywood bottoms with a 1/2" strip of 3/4" plywood turned sideways and glued across the width of the bottoms for support. Would that support prevent the drawer bottoms from sagging or should I use something thicker for the bottoms like 3/8" or even 1/2" plywood (without a support strip)?

Ron, I've built some wide drawers for the shop and with regular Accuride 100lb slides, the drawer has a hard time going in and out evenly. All the slide manufacturers recommend a different style of slide for wide drawers due to this problem. The drawers sway side to side too much. I have the 100lb full extension top of the line Accurides on 20" wide drawers and they are barely stable enough. I have the Accuride slides for wide drawers on 30" wide drawers, and they are good. But, they are very large and ugly.

If it's possible, I'd say redesign, or don't do full extension slides...joe

[Craig D Peltier]

Hi, just over the past few days I built drawers (3) 55 inches wide. I used half inch birch ply sides and bottom. I used 22inch slides for a built in. KV slides rated for 100lbs. The drawers work fine.Just for good measure I put one support across the depth underneath of 1/2 inch ply in the middle. Heres on e pic of draw.The dog weighs 27lbs.He's the guinea pig.

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[frank shic]

ron, go for it with the blumotion slides! don't let a saleswoman or salesman who's probably never installed them themsevles dissuade you. at the very least, it'll give us all another thread to discuss: blumotion slide installation. although i haven't used them yet, i would definitely incorporate them into my next project if it involved dovetail drawers since they're so much cleaner looking than epoxy slides or ball-bearing slides.