Monday, January 16, 2017

Not stools again!

Yes, stools again.  I have become really interested in the design of stools, which are the most basic, and maybe the oldest, form of seating.  Designing stools has allowed me to learn a lot without the additional complexity of a chair.  I am amazed at all the details that go into a well-designed stool.

If you look at my shop stool topic on the right side of this page, you will see my various versions of a bicycle seat shop stool, which were received with understandable skepticism; nevertheless, I am convinced I am on to something.  Over the past year, I have tweaked it repeatedly because I know I am not there yet.

For the shop, I am interested in a type of stool I call "active seating,"  meaning a stool you are going to do physical work from.  It has to let you go about your tasks with agility and power.  Here are some principles I have adopted:
  1. Active stools have basically one leg.  It's really three-legged, but the other two are yours.  The stool itself needs to have three legs, as close as you can come to a single leg and still have a stool that will stand by itself when you aren't sitting on it.  Four legs are bad for an active stool;
  2. Active stools put you into a position where you are almost standing but with your knees slightly bent, a position of power and agility that you see throughout nature and sports.  This position is what lets your legs act as the other two legs of a stool and still take weight off them.
  3. Active stools will move with you to extend your reach.  Tippiness forward and to the sides is good when you are sitting on it and bad when you aren't, because you don't want the stool to fall over when you get up.  In practice, this means that one leg points straight forward while the other two point back.
  4. Active stools have a low center of gravity.  This is what promotes a narrow base for tippiness while still allowing the stool to be stable when you get up.
  5. Active stools have to be either custom fit for a single person, or highly adjustable.  There's a reason bicycle seats are so highly adjustable.
You would be amazed at how comfortable and functional a stool that follows these principles is.  We're used to stools you sit on not with, your legs out of action; this is completely different.

So, after a number of iterations, here is where my efforts stood.  I tweaked the base by tipping the stool forward slightly and adding another block on the rear of the base for stability and to lower the center of gravity.

It does a pretty good job of implementing the principles, but there is a problem:  this is about the ugliest and most ungainly looking stool I can imagine.  In part, that's because the entire thing is made of scraps, but basically it's just ugly.  I have come to think of it as what automotive designers call a development mule.  I want to tweak it yet another time with a new version that addresses some functional issues and hopefully begins to look a little more acceptable.

Because it should be a three-legged stool and because it has a bicycle seat, I settled on a triangular platform for a low base in order to help keep the center of gravity low:

Short legs raise it up to the desired height.  The resulting stool was comfortable and functioned very well but was still unstable when I wasn't sitting on it, having a tendency to tip over if bumped.  I addressed this problem by experimentally adding mass to the base:

Yup, that's a dowel with two 5 lb weights on it.  I did this so I could figure out how much weight to add.   Ten pounds is about right.

Functionally, it was now right, but it was obviously still very much a development mule.  I've learned what I can learn and I am done with it.  The seat is right but I want an entirely different kind of base.  What I have in mind is like an antique, three-legged piano stool with a bicycle seat instead of the traditional round seat.  You can buy a great piece of hardware for this, but I am going to figure out something more economical.

Maybe you are thinking, "Why don't you just build a high piano stool and be done with it?"  It's because woodworking requires much more power than playing a piano.  You have to be in the position I have described and able to use the strength of your legs.  The bicycle seat is what allows you to do that.

In a sense, this project was a failure.  I spent a lot of time and, in the end, I am cutting off the seat and burning the rest.  However, I learned a lot.  More important, though, is that when I am trying to be creative, failure is a part of success.  In business, I used to say to my clients, "I will give you five ideas, four of which are almost certainly stupid, but one of them may be really good.  Problem is, I don't know which is which."  This is a darn good record and the effort to explore is worth it.  Many people don't succeed because they are unwilling to fail.


  1. I can see the bike seat idea and the last stool pic didn't look so ugly. How about a bridle joint (or a M/T) at the bottom of the upright connected to a 'T' with 3 stubby legs? I can't see that upright lasting in the configuration it's in the last pic.

  2. Perhaps you are not so far off on your idea, Google cow milking stool. Dairy farmers used to wear the stool belted on so they didn't have to carry it around. Maybe your one legged stool could be adapted to something like that as well, then you wouldn't have to worry about the base being functional.

  3. Andy: How about a circle for the base, with the seat pedestal set to one side. If the base was 1 1/2 -2" thick you could ease the bottom front to accommodate rolling forward as well as right and left. A dense hardwood might give the weight needed to keep it upright. Small bun or spherical feet are another thought

  4. Andy this is very interesting. First thing that occurs to me is that for comfort and good body mechanics it's always best for seats to tilt slightly downwards. Secondly your triangular base can only tilt forwards, surely, along a side, not at an apex, so the way you have it set up in the photo it would tilt you sideways not forwards, no? Thirdly, why not just use a bike saddle, with the adjustability that comes with it? Fourthly, one thought that's floated into my mind is: use one of those strongly-sprung bars that people struggle to bend in order to increase arm-strength. Shove one end into your weighted base and tother into the bike saddle and hey presto, your flexible friend. Finally, don't dentists have stools along these lines? Good luck with the project anyway.
    John L.

  5. I like the idea of an active stool and hope you haven't discarded the concept with this prototype.

    Jim B

  6. Thank you all for your interesting and worthwhile comments. They are giving me things to think about. As to why I didn't use a bike saddle, I didn't because of cost and aesthetics. Functionally, it would be far superior because of the adjustability. You'd want to use a bicycle seatpost as well to get height and tilt adjustments as well as a secure attachment to the base.

  7. If I knew how to weld, I would get an old bicycle and make the stool from the seat tube, seat post and seat. As I am thinking about it, it occurs to me that I could hacksaw off the top tube, seat stays and bottom bracket and mount it to a wooden base of some kind.

    Regarding the idea of a spring, when I was a kid, it was common for farmers to make a shop stool by welding an old coil spring to a junk wheel and fastening an old cast tractor seat to the top.

  8. The stool does tip forward nicely even with the legs configured this way. Your legs allow you to pivot it forward on the front leg.