Introduction: Assistive Table/Desk From Plywood+2x4s
In working with people with disabilities, I often people who need custom furniture, usually in the form of a small table or desk. A disadvantage of mass-produced furniture is that it is based around a "normal" proportions. A desk that was "workable" twenty years ago is now painfully high due to arthritis or osteoporosis. The table that was a good fit now doesn't work because the person now needs a wheelchair. Businesses (sometimes) think about ergonomics in the workplace; in my experience most people quietly resign themselves to ill-fitting home furnishings.
People are not one-size-fits-all. How about we fit the furniture to the people vs the other way round?
Example 1: A man in a power wheelchair needed a table for his computer that was tall enough that he could roll his chair underneath it, as well as being small enough to fit in his very tiny apartment.
Example 2: (shown in the picture) A woman needed a rolling desk for her video magnifier (an enlarging camera and a screen) - she needs it to be sturdy and secure, but size is limited - and for good ergonomics it needs to be shorter than a regular table for her to use
This is a simple plan I have used several times using 2x4s and plywood to create decent sturdy furniture.
The resulting furniture is functional and sturdy, but won't win any woodwoorking competitions.
2x4s (exact number varies based on project, lets say 3-4 for most little tables)
3/4" Plywood (dimensions vary based on project)
Casters (if making a project that is mobile)
Screws (any wood screw of sufficient size is fine, my personal preference are the Grip-Rite #9-3": https://www.lowes.com/pd/Grip-Rite-Primeguard-Plu... because they are self-drilling, coated to prevent corrosion, and easier to drive via star bit than phillips. Not the cheapest screws but worth it)
Paint or Stain based on preference.
Step 1: Calculate the Measurements
We basically need three measurements: the floor to bottom of table height(red), the depth(green), and the width (blue). I always like to have a model conceptually, hence the OpenSCAD model.
If you are using casters, make sure that you remember that casters raise the table up, so account for the caster height.
Width (blue pieces) is how wide it needs to be - make sure it will clear their chair, wheelchair, etc. with at least a three inches to spare on each side. Height(red) needs to clear their knees, again with maybe a couple inches to spare. The depth is also important - most people will not be right up on the furniture, but you want to make sure that the knees are not going to hit the center strut.
The 2x4s are used to form the support structure, so the actual desk top can be bigger than the support structure.For this little desk, the top is 3/4" plywood measured 34.5"x24".
In this example, we are using casters that measure 1.25" tall, and we need 25" from floor to bottom of desk, so the legs will be 23.75". The length of the green (depth) boards is 22", primarily so 2x4 boards are back a little bit from the "user" edge.
(4) - 23.75" (legs)
(3) - 28" (side to side supports)
(4) - 22" (front to back supports)
If using 8' boards, this requires 3 boards:
28" + 28" + 28"
23.75" + 23.75" + 23.75" + 23.75"
22" + 22" + 22" + 22"
I like this cutlist calculator: https://jonathan.overholt.org/projects/cutlist
Step 2: Tack Assembly
Once all the pieces were cut, I cut a 45° bevel on the "knee facing" sides of the front-to-back boards, then went over all edges with a roundover bit on the router.
90° corners and edges are BAD for surfaces that may contact humans. BAD for ouchies, BAD for safety, BAD for clothes, and REALLY BAD if someone trips and falls and hits a corner. Assume Murphy's Law - if someone trips and falls and hits the desk - a rounded edge will leave a bruise and a 90° edge requires stitches.
Notice that the "human facing" sides of the desk top are also beveled, and all top and bottom edges of the desk top were rounded as well.
In this step, we have tack-assembled the top and bottom frames. I like using hot glue to tack the boards together and get everything nice and square, then screw it together later.
I am using some 1/2" plywood triangles as gussets. I do this often enough that small (less than 12") scraps of plywood are often cut into right triangles and stored in their own bin.
Step 3: Ahh, Screw It
Obviously hot glue is not going to be useful long term. I like the self-drilling screws mentioned above for most applications. I clamp everything down to make sure it doesn't shift out of square while attaching the screws. I use at least two screws at every junction.
Once both the top and bottom frame are secured, I set the desk top over the top frame, and then screwed the desktop to the top frame. Flip over and attach the legs - they will butt up against both the frame and the desk top.
Once legs are attached, flip over again (so desktop, top frame, legs) and then attach the bottom frame to the legs.
Step 4: Accessorize
On this model, the client needed it to be mobile, so we are adding four casters.
Pro tip - if an office chair breaks a caster, harvest the remaining casters. Eventually you get enough casters that you can use on small projects.
The other picture is showing the magnifier on the desk. In this particular case, it is the "DaVinci Pro" by Enhanced Vision. Since the unit is top-heavy (due to the camera arm) and costs $4000, it is important that it not tip over, especially if the desk is in motion. I made cleats by cutting a 1/4" rabbet into some scrap plywood that will be enough to hold it securely in place. These cleats will be screwed into the desktop (and into the center strut) for stability.
Step 5: Paint / Stain
Aesthetics matter. In this case (no budget, low skill), they can't be the driving factor, but we can dress up the naked 2x4s a little. In this case I used a stain+polyurethane blend, two coats.
Since the client needed it to be mobile, we added some drawer pulls to the edges.
Step 6: Final Versions
The project is done at this point.
In the other pictures, I show the computer desk listed as an example in the beginning. For safety reasons, his desk was bolted to the stud with a right-angle bracket just in case he hit it while driving his powerchair.
The last example are a set of typing / computer access tables, but the support structure is the same principle.