Construction Joinery and Slide Choice for a Large Drawer
Advice on beefing up the joinery and slides for an oversize drawer that might be called on to store files. March 28, 2015
Question (WOODWEB Member) :
I’m building a six foot long kitchen island cabinet with a bank of large drawers on one side. The two large ones on the bottom will be 30" wide, full depth, by 9 1/2" tall. I am planning on using 3/4" ply for the sides and not sure yet whether I want to use 1/2" or 3/4" ply for the bottoms. I will most likely dado the 1/2" bottoms into the sides, or 3/8' rabbeted dado if using 3/4" ply. What’s the best joint for the front and back? This is the first cabinet I have built with such large drawers and I don't want to underbuild them. I have full extension side mount ball bearing drawer slides (75 lb rating). Any suggestions for construction methods other than what I have mentioned earlier?
Forum Responses
(Cabinetmaking Forum)
From Contributor Z:
I'm not sure about what full depth means but if it's 30" the same as the width then the drawer has a 146 pound potential capacity using a BIFMA formula for drawer sizing. You might want to reconsider your suspension choice.
From the original questioner:
It’s a standard 24" depth cabinet.
From contributor V:
Pocket screws!
From contributor B:
Another vote for pocket screws and another vote for a beefier drawer slide.
From the original questioner:
You think I should jump up the weight rating to 100lbs or more for the slides? Half inch bottom sufficient dadoed into the sides with butt joints and pocket screws for the front and back of the box? Any recommendations for quality slides with ample weight ratings and soft close?
From Contributor Z:
In that case the capacity of the drawer is 117+ pounds and the suspension is still worth consideration. Ball bearing slides with 125, 135 and 150 capacity are common and at 30" wide, lateral stability should also be a consideration.
From the original questioner:
Would a dado around all four sides of the box along with a tight fitting glued in 1/2" plywood bottom give me the lateral stability I need? Since its all plywood, I don't see the need to float the bottom. Thanks for the load calculations for the size drawer I need. It’s those details that are invaluable to me. I am not a cabinetmaker full time (only on demand a few times a year) and sometimes get stuck on the unusual construction details.
From Contributor Z:
My reference to lateral support has to do with hardware application. The drawer intended is about the size of a lateral file drawer and should have slides to that end - probably a progressive slide such as an Accuride 4034 or KV 8505. This may be overkill because I don't know how the drawer will be used but it could be stressed to these limits in a normal application.
From contributor D:
Half inch ply construction will be fine with glue and a slot for the bottom on a drawer box that size. With 3/4" sides and bottom and a 75 lb slide and a drawer face you are already maxed out. Drawer slides are rated at half way out it is a static load rating. Use 150 lb slides as mentioned for no problems.
From contributor M:
I recently had to replace several standard Blum guides with HD guides. Although the drawer contents did not exceed the guide rating, the flex/bounce when open made the client concerned so I just exchanged them to ease her fears. Plus attaching at three points along the guide helps. Also you might consider a lateral stabilizer such as Blums zst686tu so keep the drawer stable side to side when open.
From the original questioner:
I found the Accuride 4034 with 150lb rating. Specs say that they are for 24" max width drawer. My drawers will be approximately 30" wide. You think this would be a problem? I also planned the cabinet with spacers on the side panels that will be flush with the inside of the face frame so I can mount the slides solidly with screws the whole distance instead of using the rear brackets. I also found some generic slides at Rockler with a 220 lb rating. Centerline is the name, but I’m not sure how good they are compared to the Accurides.
From contributor C:
You could do a dovetailed box with grass Dynapro 3D slides and you’d be done.
From contributor F:
I second Contributor C - this is not really an unusual size. You will never go wrong with dovetails and soft close under mounts on nearly any drawer. 5/8" side material and 1/2" bottoms will be sufficient.
From contributor H:
I'd skip screwing around with intermediate drawer runners and put in KV 8800, 200# rating. Dovetail is a good construction if you have the money for it, if not, conformat screws work quite well.
From contributor F:
Unless you're a hobbyist I would strongly encourage you to stay away from places like Rockler for your hardware. You'll pay three times for quality products and the knockoffs are not worth your time. If you're so concerned about the drawer construction, you should be equally concerned about how it's going to operate after it's installed. Get an account with Baer supply and you'll get very high quality soft close undermount slides for what you’re going to pay for those ball bearing slides that are equally as ugly whey you open the drawer. As mentioned above, Grass dynapro undermounts are the way to go to impress your customers and have worry free operation for years. I'm not trying to be rude her or dig at you, but most of us have been there, using Rockler and the likes for supplies and have been through umpteen variations of drawer boxes and slides and have now settled on a proven method. Make your boxes with dovetail joints and use a high quality soft close undermount and you'll never go back.
From the original questioner:
I kind of thought that about the Rockler items but wasn't sure. I ordered the Grass Dynapro heavy duty 3D slides. They look like a fantastic slide with the 3D adjustments. I hope to finish the cabinet as soon as I receive everything I need. Thanks for all the advice and especially to everyone that recommended the Grass Dynapro slides.
