I use a standing desk here at the lab, but sometimes I want to sit. So we purchased a nice tall adjustable stool with a comfortable tractor-style seat. The problem is, I'm on the tall side and rather lanky at that, so the desk is really high -- this is so, when I'm typing, my forearms are level with the floor, and my wrists are straight.
The stool was pretty tall, but not quite tall enough for that. It needed about 3 more inches for me to type comfortably while seated. Additionally, the tilt of the seat was the reverse of what my back needed. It slanted back, which encourages back-rounding, which makes my sciatic nerve really grumpy. I wanted it to slant forward, which would allow me to keep my spine in a neutral position, slightly arched.
So I decided to remove the seat and jack it up with a stack of 2x4s (2 x 1.5" = 3"). It turned out that the flange holding the seat on was where most of the seat tilt came from, and it looked like it would be easy to reverse since the four screws fastening it were in a square.
Step 1: Materials
This is how the stool looked when I started. Notice that the bottom of the tractor seat is slanted back. If it wasn't, reversing the seat wouldn't make a difference!
Step 2: Remove the Seat
The screws had some sort of thread-locker on them but I have strong wrists from years of ... Hyperborean knife-fighting, so I just cranked on them until the glue popped and they unscrewed easily. Save the screws! You need at least one for the next step.
Step 3: Get New Screws, and a Drill Bit
Take the bolts to the hardware store. They will have this awesome thing on the wall in the fastener section that has different-sized threaded bores to try the bolt on. This is how you can figure out if it's metric or not. Match the bolt width up, and then look for some bolts the same size, just longer. The original bolts seemed to be half an inch long, so I bought some 3-1/2" bolts. That's 3 inches to get through the wood and a half inch to secure the seat just as well as it was before.
Then I looked in the workshop for the right drill bit. I wanted the long bolts to bite into the wood ever so slightly, so I held up a few drill bits next to my long bolts until I found one that was just a tad narrower.
Step 4: Saw Some Chunks of 2x4
I measured the distance between the centers of the bolt holes in the seat. Then I added 3-1/2" to that, so that my holes would be centered on the 2x4 pieces (*waves hands*). I used a hand saw the first time, but when I had to redo it, I used our possessed radial saw to make nice square cuts. Cut four pieces of 2x4 to length.
Don't worry, it's only possessed around Halloween.
Step 5: Mark the Wood
I arranged the 4 pieces in a stack as pictured. I marked the top pieces and the bottom pieces. The I used a speed square to mark the center lines of each piece and approximately where the holes would go.
But approximate is not good enough! I inverted the stool (sans seat) and lined the holes in the flange up with the center lines on my 2x4s. I centered pieces of wood under the flange as best I would, and then marked the holes on the wood with a pen.
Step 6: Drill Holes!
I mentioned before that I had to redo this. Well, i started off using a hand drill, and those holes were totally not square and didn't really line up and it was totally lame. So you really need a nice gig or best of all a drill press to get this right.
Attach the bit to the drill. Reach for your wood that you have NOT put directly on the opposite side of the very sharp but thankfully, not spinning, drill bit. That way you won't gash your hand open and make canida very happy because she gets to patch you up with super glue (tm).
Now that you've avoided that terrible fate, put on your eye protection, fire up the drill, and make some holes!
Step 7: Attach the Stack to the Flange
Put two of the 2x4s on your work surface. Place the flange (that is, the upside-down stool sans seat) on the wood and line up the holes. place one washer on top of each flange hole. Washers! You will need washers.
Now thread the bolts into the holes using a bolt driver, or pair of pliers, or powerful Cimmerian finger muscles alone. When the bolts get through the first pieces of wood, lift up the whole assembly and put the other two pieces of wood under it, going the other direction. Line the bolt ends up with the holes in those two pieces of wood and keep threading the bolts through.
Step 8: Attach the Seat
Flip your assembly back upright and put 1-3 washers on each bolt end. This is to make up for a little gap between the wood and the seat bottom. Settle the seat on top (and make sure you've reversed it if that makes it more ergonomic for you). Thread the bolts into the seat and tighten them. I found it easier to tighten the bolts with the reassembled stool sitting on the floor upside-down.
Ta-da! Now you have a 3" taller stool with a more ergonomic seat tilt!
Step 9: Sitting Pretty
With the extra 3 inches, my forearms and head are at exactly the same height whether I'm seated or standing. I don't need an adjustable desk, and my monitors can stay put (mostly). As a bonus, pair-programming is easier now that rachel can sit on the stool while I stand.
I want to especially thank fungus amungus for all his tips and encouragement on this Ible.
I hope you're inspired to hack your furniture today!