The chair is now complete and in use! If anyone has any questions you can email me via the contact form (comments were abused so I turned them off).
First of all, this is the seating section (the seating plate attaches to the top).
To put it together, I used a pair of small G-clamps to hold to spacers (SP2a and SP2b) in the positions I had determined for them on one of the struts (A1). I made a weld along one edge so I could get the clamps out of the way, then finished off the welding in a vice. Then, I used the G-clamps again to hold the other strut (A2) in place – I used a mallet to knock it into position to obtain the correct spacing (so my screw-adjust riser would fit). Note that at this stage I also made sure the curved bottom ends were level with each other so the foot (C1) would be horizontal. Then I made the welds as described above.
I used a pair of powerful welding magnets to hold the foot (C1) in place while I welded it in place.
I made sure the 45º angle cuts were level with each other (just a little filing was needed to get the Seat Plate to sit level), then I used the welding magnets to hold it in place while I welded it.
Once the seat plate was welded in place (see diagram opposite for placement), I was able to slide in the Seat Support Struts (A1a and A2a) – again holding them in place using the magnets. They actually fit almost perfectly, but I did a little trimming to make sure I got the best fit possible. In each case I welded one side so I could get the magnetic clamps out of the way, then finished off the whole weld (all four sides) in a vice. Note that the dotted squares in the diagram show the approximate placing of the struts on the Seat Plate.
Next, the Knee Section. This is a little easier – note that I originally planned to use two spacers on this section, but I didn’t allow for having to slot the Seating Section through it, and a spacer higher up would have got in the way.
I assembled this in more or less the same way as the Seating Section. Initially, I clamped the spacer (SP1a) in place on one strut (B1) and did a single weld, then finished it off in the vice with the G-clamp out of the way. Then I positioned the other strut (B2), making sure the curved cut-out was level with the other one (for the foot) and that the spacing was correct along the whole length. Then I welded it. I welded on the foot as described for the seating section.
I used my angle grinder and a flap wheel to grind down all the welds and to remove spatter.
Next came the test assembly. Omitting the second spacer from the Kneeling Section had the additional benefit of allowing a little flexibility when it came to sliding the Seating Section between the kneeling struts. But I’d got it right and everything fit. I did have to do a little widening of the holes to get the bolts through – with hindsight I would have drilled after welding (unless you are millimetre perfect there is always going to be a slight mis-alignment).
I painted all the parts using Hammerite Metallic Black (from a tin). I inititially tried Hammerite Silver (from aerosol), but apart from the fact it doesn’t fill in imperfections very well, it also looks a bit cheap – too silver, if you ask me! It also makes a bloody mess.
This is the finished stool, fully painted and assembled. You can see how the riser mechanism fits between two sets of holes, and the other set is where the two sections are joined.
You can also see the crappy cushions I am using at the moment – the final stage of this project is going to be to make a decent pair (I’ve found a great company called eFoam who can cut foam to measure).