Replacement of the Big Foot (Five-Star Base or Five-Claw Base) of an Office Chair

The replacement of the big foot (five-star base or five-claw base) of an office chair should be carried out in a standardized step-by-step manner. The core process includes diagnosis, disassembly, selection, installation, and precautions, as detailed below:

I. Diagnosing the Problem and Preparing Tools

1. Identify the Type of Damage: Check the location of the break (such as a single caster wheel, partial or complete breakage of the five-star base) and the extent of the damage to avoid misjudgment leading to incompatible parts.
2. Tool Preparation: Basic tools include screwdrivers, wrenches, and pliers. If replacing the five-star base, additional confirmation is needed regarding the outer diameter of the gas lift (commonly 28mm/32mm/35mm), mounting hole spacing (such as 100mm/110mm), and the type of tilt mechanism interface (snap-on/threaded) to ensure compatibility with the original chair.

II. Disassembling Old Components

1. Caster Wheel Replacement:
   • Threaded type: Rotate counterclockwise to remove the old wheel and clockwise to screw in the new one and tighten it.
   • Insert type: Press and rotate or directly pull out the old wheel and vertically insert the new one until a "click" sound is heard.
2. Overall Replacement of the Five-Star Base:
   • Place the chair on its side or upside down on a soft pad to avoid scratches.
   • Operate according to the connection method: For flat washer snap-ring fixed types, remove the snap ring; for tapered press-fit types, lightly tap to loosen and then pull out the old base.
   • For special models (such as the Sihoo C series), first remove the three fixing screws of the footrest.

III. Selecting New Components

1. Core Parameter Matching: The outer diameter of the gas lift, mounting hole spacing, and tilt interface type should be consistent with the original chair; otherwise, it may lead to unstable installation or a loose chair back.
2. Material and Workmanship:
   • High-quality products use Q345 high-strength steel + triple electroplating (nickel + copper + chromium), with a salt spray test exceeding 48 hours without rusting.
   • Low-priced products often use Q235 cold-rolled steel + ordinary powder coating, which is prone to rusting and breaking.
3. Type Selection:
   • Standard type (carbon steel powder coating) is suitable for ordinary staff chairs.
   • Reinforced type (Q345 steel + electroplating) is suitable for executive chairs or medical chairs.
   • Integrated silent caster wheel type is suitable for open office areas.

IV. Installing New Components

1. Caster Wheels: For threaded types, tighten clockwise; for insert types, ensure the snap-on is in place.
2. Five-Star Base: Align with the bottom interface of the gas lift and complete the installation by securing with a snap ring or lightly tapping for press-fit. After installation, adjust the balance to avoid chair wobbling.

V. Precautions

1. Avoid Misconceptions:
   • Do not just focus on "being able to fit it on"; ensure it is "securely installed." Tolerance differences between different brands may lead to a loose chair back.
   • Black metal claws are not universal; strict parameter matching is required.
2. Service Guarantee: Prioritize suppliers that offer on-site measurement, disassembly of old parts and installation of new ones, balance adjustment, and recycling of old parts to reduce the risks of self-installation (such as gas lift popping out).
3. Emergency Scenarios: Ensure that the supplier can complete the process of "reporting for repair → confirmation → on-site visit → completion" within 4 hours, suitable for emergency repair needs in law firms, etc..

If the chair is inexpensive or severely damaged, it may be more cost-effective and safer to simply replace it with a new one.