I'd wanted one of these for quite some time, but never enough to warrant actually buying one because they're ridiculously expensive; the cheapest one I could find anywhere was over $50. Looking at the general design and the materials used in making them, I finally decided to just throw something together to see how I liked it before buying the real deal.
Ninety minutes after trekking to Walmart for the one item I had to purchase (more on that below), I had myself an ergonomic kneeling chair, albeit a very rudimentary one. I see this as a prototype though, so I'm okay with rough around the edges. I definitely won't be buying one...but i will build another for certain.
All of the wood used in this project was reclaimed from various sources. The boards for the seat and knee rest were from a bar stool template I'd made for work. We no longer use those stools so it had become obsolete. The 2x4's were once a sawhorse.
The fabric is also reclaimed material; it was once a canvas style lounge chair. Don't judge the upholstery work, it was my first attempt ever and once cutting the pieces out there were none left large enough for a redo.
It's not that pretty, but for less than $10 invested and less than two hours burned building it, I think it came out alright. I'll be closing with some thoughts on what I plan to change for the next version, (finishing the wood is at the top of that list). Despite the many changes needed and lack of aesthetics, it is surprisingly very comfortable.
Step 1: What You'll Need
Some wood obviously. As I said above, all of it is completely recycled material save the cushion foam. That I got from Walmart at around $7 for four 18x18x1" pieces.
The exact dimensions for everything comes down to preference and your personal physical characteristics. At six feet tall and just over 200lbs, I needed strong enough material to support me, hence the 2x4's which were generously donated by a now leg-less sawhorse (that pretty much makes it just a board now).
The seat, knee rest and base can be made from numerous different sources. I had some 3/4" plywood scrap that worked out pretty well. You could use anything from shelves to old office chairs for these parts and I'd imagine most anyone actually considering building one has something laying around that would work.
I used 3/4" and 3" screws, wood glue, spray adhesive and 6 L shaped brackets (4 corner brackets and 2 from an old curtain rod assembly I think) to tie it all together.
As for tools, it could fairly easily be done using nothing but hand tools, but a miter saw, jig saw, belt sander and cordless drill came in real handy. Good, strong clamps are an absolute must. I also used various marking and measuring devices (tape measure, angle locator, slide square, speed square). Finally you'll need a staple gun for the upholstering part.
Step 2: Building the Frame
The pictures can explain the basic process much better than I can. They are fairly high resolution so you can zoom if needed and I've added notes where I thought they might be helpful. The one thing that was tricky was finding the correct length for the supports and their angles based on my height. I'm sure the mathematicians among you will laugh at my lack of formulae, but I took the easy way out by choosing the angle for the seat support at 20°, rough cut a board a bit long then just sat in my normal desk chair and measured to knee.
After making that first cut, make another just like it. Be sure not to throw away the small angled scraps from your initial cuts; you'll need them for the ends of the seat support (see pictures).
The angle for the top of the seat support is a matter of preference, but it will need to be lesser than that of the bottom. You won't sit very naturally if they're parallel to each other, trust me.
For the knee rest I cut the bottom sandwiched piece at opposite angles to support it. The pictures will explain that a little better.
After dry fitting everything with clamps, I glued and screwed it all together. Pre-drilling pilot holes while you have it clamped is very helpful. You can get away with much less mess by using only screws, but then your chair will be creaky. If you like creaky chairs, enjoy. Otherwise, put glue every place that gets screwed.
This is a good time to add your base board. Mine isn't as wide as the seat but probably should be. Then again, I haven't fallen over yet so...
Step 3: Adding the Seat and Knee Rest
I rounded all the corners on both pieces for the sake of my fabric and I think it looks better. I just eyeballed the radius of the curves, drew it on the boards and went to work with my jigsaw. I followed with a belt sander to refine them.
You'll need to cut 3.5x4.5" (DxW) slot in the knee rest so it fits around the seat support all nice and snug like. Use a couple of L brackets or similar here to keep the board from tilting on the single wide knee support. Two more should be attached closer to the other end as well. Locate the seat with a bias towards the front, see the pictures for a clearer explanation of that.
DO NOT GLUE ANYTHING YET!!
Once you get everything sized and located you'll want to proceed to the next step before permanently attaching anything here.
Step 4: Upholster It
The pictures make it pretty obvious that upholstery isn't one of my best talents. This was in fact the first time I'd ever tried my hand at it, so please, don't judge me too badly.
That being said, the best advice I can give you here is try and keep the creases on the underside. I know, not that helpful. It's not so bad considering, and I'm certain the next will be a vast improvement.
Also, start the front side of the seat and the slot side of the knee rest before attaching them to the base. It will be much easier that way, believe me. Once that's done, glue+screw them to the base (counter sinking the screws is a good idea here) After that I sprayed the tops of the boards with adhesive then carefully placed the oversize foam pads on. Using a sharp pair of scissors I then trimmed them to fit the respective shapes.
From here all that's left is to flip it over and start pulling then stapling the fabric taut. Use lots of staples. Lots.
Step 5: Final Thoughts...
Some improvements for the next build:
- Make it adjustable and collapsible
- High density/thicker foam (the cheap 1" ones I used are a bit hard on the knees)
- More refined base
- Paint it!
- Better upholstering!
Overall this was a quick, easy, and fun project. It could easily be done in under an hour if everything fit correctly from the get-go.
There are no specific dimensions given because people aren't all a specific size. Build it for you.
Feedback and questions are welcome.
I wrote this entire Instructable whilst seated in the chair described.