This is just a summary to help people who want to build an ergonomic DIY kneeling chair – the project is extremely popular judging by the number of hits I have had for the various parts I published. I have listed these below (each link will open the article in question, and you need to follow all of them in sequence to understand what is happening):
- Welding Isn’t Easy! (Introduction)
- Project #1
- Project #1 (Update)
- Project #2
- Project #3
- Project #3 (Update)
- Project #4
Also, someone asked me what size bolts I used. I didn’t include that information in my drawings – I think I assumed that the diameter of the holes was enough, but I should have explained more clearly. In fact, the bolt size doesn’t matter as long as you don’t make your holes so large that the structure is weakened, or use such small bolts that these themselves become the weak point. Mine were two sizes – the ones used to link the struts were about 5/16″ (or 8mm); the ones elsewhere were about 3/16″ (or 4.5mm).
I’ve also been asked if the drawings could be used to make the chair out of wood using 2x2s and 2x3s. The short answer is no – because the strain on the part where the struts join the feet would be so great that the assembly would split (and even wooden ones you buy suffer from this problem, which is why I went for metal if you remember the introductory installment). Also, if you used wooden struts the same size as the steel box section I used here, they would just snap. If you want to build one out of wood you’d need to design it using proper mortices or dovetail joints to get maximum strength. From my own experience with the kits, using cheap wood would also lead to problems – if I ever make a wooden one it will be using a high quality hardwood.
I need to clarify that the kneeling chair I built used three parts left over from ones I had already purchased in kit form, but which had disintegrated with regular use.
The seat (A) and knee pad (B) could easily be built by anyone making this chair to the specifications I have given, and using the foam supplier I linked to in one of the installments.
The raising mechanism (C) would be a little more of a challenge, but still fairly simple to construct. All it consists of is a threaded shaft inside a corresponding threaded socket. When the shaft is turned the overall length of the socket/thread assembly either increases or decreases. Since the ends of this assembly are fixed to the support struts of the chair, the seat (A) rises or falls as the thread is turned. I did look at using a gas-filled system, but these are not as simple as you might expect and require special mounts. You can buy all the parts quite easily, but fitting them is the real problem – they’re designed to fit into office chairs.
There is also no reason at all why the mechanism couldn’t be replaced by a simple t-bar shaft which slotted into preset positions on the lower strut. You could then adjust the seat to any of the preset positions just by lifting it and lowering it again by hand.
EDIT: Hello to Russia and Ukraine! I’m getting a lot of hits from a Russian forum at the moment (Kharkov forum). Someone is looking for a good kneeling chair, and is getting various bits of advice (including the one in my DIY project).
Just a note to reply to the post which says that kneeling chairs start to squeak and creak after a while… yes, they do! That’s because they are beginning to fall apart and the joints work loose. I had exactly the same problem on three chairs, one of which was made of thin metal.
This one I built doesn’t creak, even after four years of heavy use.