Need help designing this chair.

I need some help in the design and manufacture of this chair. I wanted to design a “cute” chair and this is the result. As you can see this is a cardboard model. As you look at the model, envision that the only parts made of wood would be the seat and the chair back. The U shaped leg/arm assembly would be metal tubing. I am thinking a brushed aluminum or copper. Also the part that holds up the back would be metal tubing. I am wondering about bracing. I think I would need to put a metal bar or tube from one front leg to the other sides rear leg right under the chairs seat. By doing this to both sides an X would be right under the chair seat. I would be able to attach the chair seat to this X. Beside the X, I was thinking of putting two horizontal tubes, one slightly above the other between the rear legs. These would be just under the height of the seat. They probably wouldn’t be seen from the front of the chair. The other concern is that as the model is now, it is too small for an adult to sit in. One needs to have rather narrow hips to fit between the arms. Another problem area is the tube that holds up the back. How shall I attach it so that it is strong enough? I thought that I could drill a large hole in the chair seat, large enough for the tube to fit through. If the tube had a flange on the bottom I could attach the flange to the bottom of the seat. I was thinking that a better solution might be to remove the tube as shown in the photo and have a horizontal tube that goes from one rear leg to the other, than I could attach the back to this tube. But this may destroy the look of the chair. Or drop the tube all the way down to the horizontal tubes that go from one back leg to the other and attach it there. Hmmm….
Also I need to figure out the metal work or somehow find someone to do it. How do I find someone who does this kind of work? I am sure that I am missing something here. If you have any thoughts on how to improve the look of the chair or how to make it, I would really appreciate your thoughts. I can also see that if I make the chair tall I would have a bar stool.
Also I must thank John Miliunas for his always generous and freely given assistance with the photo help.
I look forward to any comments, good or bad that you might have.

Pete,

chairs must be comfortable...this design while being symmetrical does not seem to address the rake of the seat...it should be lower in the back and the slope of the arms also lower in the back...
As these 2 importand aspects are added....the design changes and essential is a different design....may be you can take these points and see where it goes. The seat of a dining or upright chair should rake about 1" to 1 3/4"..

Thanks Mark, Just a quick thought here. Maybe if I used a peice of wood that was two inches thick, I could hollow it out so that the back area of the seat was about one and a half inches lower than the front. I would do this instead of tilting the whole seat toward the rear. Is this possible? Now to figure out the arm problem.

Proper ergonomics is set by the rake angle and the coresponding slope fo the back. To simplify the concept...if you imagine making the seat level and then cuttung an inch and a half of the back legs...the rake and slope of the back will occur simultaneously ...I am not saying that it will be comfortable...the only way to know is to make a full size prototype ypu can sit in...from sitting in it you will know what to do. Full scale drawing of all chair parts will help too

Pete --
That's an interesting start on a design. If you haven't named the design already, can I suggest "Lollipop"? :) Here's some comments...

* I like "butt space" in dining or task chairs. By that, I mean I like to have the chair's back support the spine from someplace around the small of the back, and have room for the sitter's butt below that back. I'm pretty sure that if you build the chair like your model, you're going to be running your coccyx into the rod holding up the back, and you won't like it.

* In my opinion, arms on a dining chair are maginally functional. If you make them high enough to actually support the sitter's arms, the chair can't be pushed under the table. Many homeowners really want to be able to do that, so chair designers often make chair arms so short that they really only act as handles when you're scooching your chair up to the table. The result is that you needn't worry about much about the size or shape of the chair arms. They're not arms, they're handles!

* With due respect to Mark Singer, I like less seat rake than he suggests. On my chairs, the rear of the seat is generally 1/2-3/4" lower than the front. However, I strongly agree with Mark that ergonomics is very important. Unfortunately, for me, the only way to evaluate comfort is to build a series of full-scale prototypes. I sit in a prototype, get other folks to sit in it, modify the design, build another prototype, and so on. It takes me lots longer to develop a chair design than, say, a table design.

* You mention making the seat from thicker stock, and carving it out. That's a good approach (see Windsor chair etc). A tractor seat is much more comfortable than a flat plank. Of course, thicker stock and the carving operation cost money, so you have to think about your trade-offs.


Jamie

Jamie,

You are correct on the rake...I measeured my dining chairs and it is 3/4" and sits well....on lounging chairs the rake is greater since it pushes you more against the back..

The other thing to consider is flat is flat. Even at the correct rake. Humans are not flat. This is why you see so many chairs sculpted out of thicker stock. Sure it also has to do with rake but you don't want to sit on a bleacher no matter what angle. One of the magazines that still arrive here (I think FWW) had a pretty good article on the techniques used by Sam Maloof. There is some attention to the seat as well. Might be worth a look.


Keith