Herman Miller Aeron Hip Pivot Bushing

The Herman Miller Aeron Chair Hip Pivot Bushing Problem

the top of the hip pivot bushing in one side of my chair sheared off, and, a little later, pulled through the hole.  I was stuck in a too-low folding chair for an unpleasant while.

I'm a big, heavy guy, and this has never failed on my chair before.  I believe I'm out of warranty.

getting a replacement from the US is a pain, and I can't order it locally.  I suspect if I contacted support, the local subsidiary could get me one, but I imagine it would be expensive.

The 3D Printed (temporary??) Solution

I didn't do an extensive search, but I only found one other model for this.  it did not fit.

so I measured the undamaged one from the other side, measured the wreckage of the original after I had clipped it apart to extract the bolt, and modeled this.

I installed it on 2025-07-09, and it's held up since then with no weird noises to suggest that it's near failing.  I hope it'll last a lot longer, but I have a second one ready to go.  I'll update this right away if the current one breaks.

“why is this in two parts, ffs??”

the original is some kind of hard plastic that fits very tightly around a bolt.  the bolt has another, rounded, piece of plastic covering the shank, to create a kind of ball-and-socket joint.  this seems really excessive to me—not to mention a pain to manufacture—but it also means that the bolt and the bushing can only be separated destructively.

printing it in two separate parts means there's no trouble getting the bushing onto the bolt, and the support for the seat is putting pressure on the material straight through to the bolt—as much as possible.

“why print at that weird angle?” and “why the extra material?”

I wanted the loops of the layer lines to be as close as possible to inline with the force.  since the top of the bushing sheared off, in my case, I wanted it to be as strong as possible in that direction.

the extra material both provides a convenient bottom-layer surface, and hopefully distributes the force across more material.

what's next?

I'm waiting for it to break.  once it breaks, I want to see how it breaks, and reinforce that.

the measurements I took were pretty haphazard, tbh, so I want to confirm that the next version fills the space as completely as possible—to transfer the force better to the frame of the chair.

I also didn't really bother to smooth out the edges—I was just quickly copying the unbroken one, the bolt, and even the broken bits of the broken one after I extracted the bolt.  so, I want to make the next version more pleasant, and less at odds with the style of the chair.

once it does break, I'll make the changes here and update it as quickly as possible.

if you print one, and it breaks in normal use in the chair, please, please post pictures with a variety of angles so I can update it.

How To Print

• I used 8 walls.  there's a bit of solid infill, but no sparse infill, which is probably important to durability
• the flat on the wide part needs to be the bottom layer.  Orca auto-orient handled this correctly, so it should be easy
• you have to print two (per side).  each piece is half of the bushing.

How To Install

1. verify that two of these together will fit in the hole in the frame—it's tapered and keyed, so it'll pretty much only go in the right way.  if it doesn't go in, I'd like to know
2. extract the bolt from the broken bushing, and make sure that the bushing parts fit around it
3. insert it, and tighten.
4. carefully sit down?