Theory -
The third step of the process is to actually take your concept to something that retains your design concept, but also makes it something that will actually work and be comfortable. Although the concept part of the project can be considered art, this next step is also art since you have to balance what you want to see versus what you want to feel - a huge task!!
Throughout my designs, the most important part of a good piece of furniture is to have it function as it is supposed to. For lots of modern furniture, this can be very difficult to achieve since many of the planes and lines of the furniture are so flat or at acute angles. The other neat thing here is that you can size the furniture to fit your size. In my case, I’m about 6′1″, so smallish furniture isn’t really comfortable. I tend to size up chairs and tables to better fit my frame (for example, Chair 00003 is a bit over sized, but fits perfect!).
Lots of the theory you can take from most public furniture, like the library, or from around your house. For Chair 00004, I used our breakfast nook chairs I bought from Pier 1 (obviously before I got into modern furniture design!!). These chairs had great proportions, but didn’t look as nice as I would have liked - but they work.
The other thing to think about is where your body actually touches the chair - the seat, the backrest, the arms, and where your feet will land (unless you like to dangle). The other other thing is what is the chair going to be used for?? There is lots to go into here…
Seat Height - Now think about how the location of the seat to the floor plays a role. If the seat is too close to the floor, your knees are higher, and off the front of the seat, or your legs fold back under the seat. If the seat is to far from the floor, your thighs end up getting cut into by the forward edge of the seat. So in my case, I like a seat high enough so that the length of the seat equally supports the length of my thighs. As a general rule, a seat height of 14″ to 18″ works for me.
Seat Angle - OK, if you were raised like I was, a church pew is nothing comfortable. The seat is perfectly horizontal, and the back is at a right angle (we’ll get into that in a second). The opposite of that is sitting in a folding chair that isn’t locked, so it folds on you. About 5 to 15 degrees from front to rear works just fine depending on what you want the chair used for. If its a dining room chair, generally you sit up pretty straight, so 5 degrees works well. If you’re lounging around, the 15 degree works really well…
Seat Width and Length - I like wide chairs and I cannot lie. No other… ANYWAY, wide chairs give you more sitting options especially on chairs with arms and while using a footrest. My breakfast nook chairs are about 18″ wide, which is ok. Chair 00004 is 20″ wide. The length of the seat is also a pretty big deal - if it is too short, your thighs aren’t supported. Too long, and your back will never touch the back of the chair. I like anywhere from 14″ to 20″.
Back Angle - Like in the church pew example, a right angled seat back is great if you don’t want to be comfortable… An angle of 5 to 15 degrees relative to the seat angle works here too and for the same conditions. So if you want to sit up straight, make the angle 5 degrees relative to the seat angle. Increase the angle for more lougedness.
Back Length - What is the chair going to be used for? If its a lounge chair, or a chair at a bench or bar, a low back is great to leave your upper body free. If you have a high-backed chair, it is more confining, but it also allows you to lean back all the way and be supported. For low backs, 12″ is the max - it is high enough to support the small of your back, but not high enough to hinder movement. For a high backed chair, the ceiling is the limit (unless the chair is used outside). Remember though, your back and head isn’t straight, so if you have a straight back at a steep angle, there’s a chance that your head will always smack the back of the chair as you sit down.
Back Width - I tend to shoot for the same width as the seat - 14″ to 20″
Arms - I’m not good with arms. If they’re too low, you’ll never touch them. If they’re too high, you’re always shrugging. If they’re to far apart, you can’t reach them. If they’re too close together, you fell squeezed in. If the chair is to have arms though, around 8″ high and 3″ wide on a seat with a width of 18″ should work for most.
All in all, I’m no ergonomisist and all of what I just wrote are not any approved dimensions for a “healthy” or “regulated” or “safe” or “registered” chair design, but they work for me just fine.
So we just went through chairs, so you can imagine what its like for things like tables, sofas, bar stools, cabinets, bird houses, bread boxes, etc. Lots to consider. The key is to play around with what you can measure and what feels right to you. Measure lots of stuff and see what it is - then sit in it and see if it feels right.
Your next step is to take your concept and try to get the theory above into your concept. I can’t begin to tell you how hard this is to try to keep the proportions of your concept and push it and pull it until you get some sizes that match what is comfortable. Generally, I use the height of the seat to the floor as the main dimension to drive the rest of the design. If this one is off, you’ll never sit in your chair. If you’re into computers, a CAD system will really help here (I use TurboCAD ). If you’re not into computers, sketch your idea and use a ruler to keep things in the correct size. For example, a 1/8″ on the ruler equals 1″ in real life. Give it a whirl!
If you’re more into hands on stuff, then my suggestion is to mock stuff up in cardboard, but that’s for the next phase - prototypes.
I’m really open for comments on this one. There is so much difficulty in getting a design to something that works!
