critique Desk table design (collapsible)

[brian gallagher]

Hello all,

I am designing a 96" by 30" desk.
will be making 4 of them for a design studio- next week.

Trying to get it to collapse/ interlock and still be stable, I could use angle brackets to solidify it. I will use screws to secure the top +to create torsional ridgidity.

Materials are as pictured:
1", 3/4", 1/2" plywood and 1/4 HDF (high density tempered fiberboard-ie 2 sided masonite)
My cross beams are 5" tall out of 1 inch plywood.
My "leg" panels and "rib" are 1 1/4 plys (1/2ply +1/4 HDF +1/2 ply)
The top is 1/4HDF +3/4ply +1/4 HDF

I have fallen for the striping effect of laminating these materials. They will contrast and reveal at the front edge as in the Photo. I understand this will be a very painful process laborwise but I think that the materials sort of transcend their cheapness like this.


What are your opinions /critiques about this interlock/saddle joint? strength. I am worried about it interfering with your sitting at the desk/ legs if I make it taller than 5".

-One option is to make it say 12" at the joint and arc it up in the middle.
-another idea is to make only one cross beam. make it thick enough to be strong (8-10"?) and place it in the middle of the 30" depth of desk so it won't interfere with your legs/knees.

any comments appreciated,

thanks
Brian

[brian gallagher]

The client cancelled the four desks.
there is other work involved but this was the fun part.
ouch.

I am still interested in comments.
and changed the frame to have a shelf area to give things ridgidity.
I still wonder how stable the Table version would have been.

brian

[Jamie Buxton]

Basically you have a 5"-tall thing trying to prevent the leg panels from flapping around. If there is any play in that joint, flapping happens, and the table feels wobbly. Angle irons don't help much. What would help a great deal is triangulation. Conceptually, fasten a stick to a leg panel on the inside, perhaps half-way down to the floor. Run that stick up at an angle (say 45 degrees) to the table top, and fasten it there. Now you have lots more leverage on the leg panel. Of course, now you have to make it look pretty, and to make it come apart, but it will be sturdy.

[Wayne Morley]

I agree with Jamie about the table being wobbly as designed. Something else to consider is to tilt the legs out at the bottom 10 degrees or so. This will improve longitudinal the stability.

You might also try modifying the joint to something like this. I have made a sawhorse using this method and it is very stable.

[brian gallagher]

thanks for the ideas!
arches and angles. much stronger weight transfers.
brooklyn bridge.
I get it!

actually took me a while to notice the design forum here, so there are lots of threads to browse thru.
much appreciated.


Brian

[John Schreiber]

Wayne, that's a really nice suggestion. I saw that the original design wasn't stable in it's neutral position. It would wobble back and forth, and even if tight at the beginning, it would get loose over time. I couldn't think of a solution that didn't add a lot of complexity, and I could tell the initent was to keep it simple.

This way, it's under tension in it's neutral position and will not wobble.