The layout of the chair’s structure is highlighted in red in this design to show you what we’re testing out.
The measurements for the bench seat framework are 750 x 450 x 750mm (L x W x H). At both ends of the chairs are cupboards/access doors, for both inside and outside access.
In the close up, you’ll notice I’ve used Flexliner’s 15mm winged/flanged extrusion which allows for a 19mm board to be placed flush inside the frame.
Putting it togetherI put in an order for all the connectors I’d need and the special flanged tube. The standard 25 x 25mm tubing for the legs I just sourced locally.
After a few mitre cuts and a rubber mallet on the job, I quickly had the frame up.
I wanted to keep the frame simple at first, to see where it needed reinforcing the most.
Testing it out
The first test was then of course, to sit on it! Hopping on I could tell it had a lot of movement at the joints, obviously some stiffening was needed (& expected). Apart from that though, strength/compression wise, it felt more than up to the task.Next I wanted to see if having the aluminium sheet walls fitted to all sides of the frame would stiffen it up enough.
Since the front & back of the chairs will be covered in sheet metal & riveted on anyway, these would act like large gussets and prevent the frame leaning & twisting (at least on the X axis).
I didn’t have any sheets large enough for this test so I had to make do with using strips of flat steel (& a thousand clamps).
The difference was like night and day! Both my wife and I were quite comfortable on it together and could easily hop on and off as we pleased without the frame leaning or twisting in either direction.
Final tweaksAll that said, we can’t actually have sheet or anything covering the two open ends of the chairs, since these are the cupboard/access doors, but we do need it to be reinforced or it will lean & twist. I figured some corner brackets should do the trick and it was a bonus that they would also act as little door stoppers for the internal cupboard doors. Since I built this, my wife has bought me a 3D Printer (from Winplus) and I have been able to come up with my own printable designs for the corner brackets (& lots of other parts). Here’s a little teaser pic.
Drop a comment below if you want me to tackle a particular part of the build next. Happy building!