Replies

1. 
   RalphBarker | Oct 24, 2012 08:27am | #1

   The span, the span

   A 60" span is pretty wide. You might consider augmenting the front and rear edges of the tray with metal angle or T-bar stock.

2. 
   loydb | Oct 26, 2012 09:15am | #2

   metal

   Would the angle bar need to be attached physically to the drawer slides, or would it just need to be attached to the wood to act as a stiffener?

   Thanks,

   Loyd

1. 
   RalphBarker | Oct 26, 2012 10:23am | #3

   Stiffener only?

   I'm thinking stiffener only, assuming the sides of the tray are hefty (e.g. 3/4" ply). But, a lot depends on the total weight of the tray with the metal stiffeners included. With that in mind, you might need something more than 1/2" #4 screws to attach the tray to the drawer slides.  ;-)

3. 
   loydb | Oct 27, 2012 07:38am | #4

   I could use...

   a glue gun! :)

   My plan at this point is to use 3/4" hardwood for the tray rather than plywood. I'd like to go with Spanish cedar, because of the weight, but am not sure how it will do even with a stiffener. If that doesn't work, it's on to maple or walnut. I was thinking about 1.25" wood screws for mounting to the slides.

   Thanks for your input!

   Loyd

1. 
   RalphBarker | Oct 27, 2012 11:02am | #5

   3/4 inch

   I assume you mean 3/4" for the side, front and back rails, and perhaps 1/4" ply with under supports for the bottom of the tray?

   For something that wide, you might even consider a shallow torsion-box design for the bottom, using 1/8" ply for the skins.

   It's always fun coming up with design ideas for other people's projects. Particularly since any failures are not in my shop.  ;-)

2. 
   RalphBarker | Oct 27, 2012 11:08am | #6

   Another option would be to split the tray into two or three sections. (Hey, if one tray is good, three ought to be way better, right?)

   That would greatly simplify the rigidity issues, allowing a more traditional design approach. Plus, the three trays could be labeled, "his", "her's", and "the dog's" (your dog is on Facebook, right?  ;-) )

4. 
   loydb | Oct 28, 2012 07:57am | #7

   hmmm

   I'm not sure I'm picturing what you're talking about with plywood supports. The drawer glides are heavy-duty (500 pounds rated) with non-removable drawer slides. I'm planning on a single board spanning the gap (with a piece of angle iron attached to the back underside as a stiffener. The tray will be directly attached to the slides with 1.25" wood screws. 

   I'll take some pictures when the slides get here. It has occured to me that I can just mock the whole thing up in the shop and see how it does...

1. 
   RalphBarker | Oct 31, 2012 08:02pm | #8

   Stiffness, stiffness

   Sorta like pizza, pizza. (Significant only if you have Ceasar's Pizza in your area.)

   There are two structural elements that you want to keep "stiff" - the tray frame, and the tray bottom. Assuming 1/4" ply for the tray bottom, considering the 60" span, it will want to sag in the middle over time. Adding little support strips (1/4" x 1/2", perhaps) glued to the underside of the tray bottom will add rigidity.

5. 
   roc | Oct 31, 2012 11:34pm | #9

   Maybe you can make this help you for your drawer

   https://www.finewoodworking.com/SkillsAndTechniques/SkillsAndTechniquesArticle.aspx?id=28101

   Other wise I was picturing using a bowed structure with internal diagonal cables, you know like bicycle shift cables, that you could tension with adjusters to tune the bow so with the keyboard in place the drawer unbows down under the keyboard's weight to where it is flat. (sort of like prestressed concrete beams). 

   :    )

    . . . . just kidding.  I might do something like that but . . .

   nah don't listen to that.  Maybe the Sagulator will help.