Good Connection

FRITZ HANSEN Bases and Spacer over the Production Years

Over the years of production Fritz Hansen used different techniques to connect the 3- and 4-legged bases of 31xx series, Ant chair 3101, Grand Prix 3130, Seagull 3108, Munkegaardsstolen 3105, Hammer 3103, Butterfly 3107, and 3207 (/w armrests) with the seat shell.
If, like me, you often turn vintage Fritz Hansen chairs upside down or even need a spare part, you may be surprised of the different attachments for the bases on the shell. So here is a brief overview to clarify.

First Series

On this early base from the early 1950s no cap was used, the screw connection was open visible. The screws are still inch thread.

The spacer was a simple round rubber disc and attached to the shell with a small screw.

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Screws Base to Shell | 31xx | Fritz Hansen | Arne Jacobsen $ 13,32

Late 1950s

In late 1950s Fritz Hansen started to cover the screw connection. First, metal cap was connected with 4 small nails, hard to remove if re-tightening of screw is required.

Also design of spacers first changed to a rectangular design (1.picture), later to triangular design which at the same time allowed the chairs to be stacked without damage. This design is, except material, the same till today.
Left picture shows still rectangular spacers, but already center screwed fixture.
The middle picture shows past version of spacers made from solid rubber, and current version made from plastic.
It is just pushed onto the leg and clamped under the seat, no glue, except when used on dot stool. Stool was glued at some versions.

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Seat Stabilizer Under Seat | Fritz Hansen | Arne Jacobsen | Set of 3 or 4 $ 37,28 – $ 53,74

Early 1960s

In early 1960s Fritz Hansen screw connection changed to one screw in center connection. Metal cap and base was connected with one screw in center.
Picture 1 & 2 show a combination for 3-legged and 4-legged bases, picture 3 for 4-legged only.
Number on tag indicates month and year of production, in this case 1. & 2. picture December 1964 and 3.picture April 1966.

Unfortunately the base was not very strong and broke often.
Last picture shows a version for hall seating, it had no metal cap, just a center cross.

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Screw Base to Shell Metal Cap | 31xx | Fritz Hansen | Arne Jacobsen $ 5,84

Late 1960s

covered

uncovered

In late 1960s Fritz Hansen launched 3-screw connection on a round metal plate, covered with a plastic cap.
The number on cap indicates year of production. This one shows 1967.

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Fritz Hansen | Series 31xx Chair Overhaul Set | Arne Jacobsen $ 101,65 – $ 113,62
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Plastic Cap Cover Under Seat | Fritz Hansen | Arne Jacobsen $ 25,30 – $ 95,66
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Series 07 Chair Glides + – Felt | Fritz Hansen | Arne Jacobsen $ 22,44 – $ 43,40

2003 - 2009

In 2003, Fritz Hansen switched from a wooden mounting board to an ABS plastic board, which sticks poorly and coming loose.
The base sometimes spontaneously detaches.
Sorry, I have no image yet, will follow as soon as I have one…

2009 - Today (2025)

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Office Chair Version

For office chair version another different cap was used, fixed by a wire snap ring.