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Total Solutions From Design To Manufacturing

Job Description:

Project Name: Core Chair/Stool

The core chair is a functional device with a saddle like seat covered with premium cow leather, and a unique shape of backrest also covered with premium cow leather. The back rest also has the function to rotate independently against the seat. The designed unique mechanism is CNC machined from stainless steel 304 with a brushed finish. This chair is designed to help people to sit properly and reduce the back pain. This product is targeted to very high end markets.

Processes: (Over 50 parts, 26 of them are customized components made from over 12 different manufacturing processes).

Revolve Mechanism: CNC milling, CNC turning, EDM sparking, wire cutting, laser cutting, welding, bending, polishing, leaser engraving and assembly.

Seats: Blow molding, copper inserts, memory foam manufacturing, leather cutting and stitching, gel pad molding, upholstery and assembly.

Backrest: Laser cutting, welding, expand foam molding, leather cutting and stitching, upholstery and assembly.

Standard Components: PU/Nylon wheels, reinforced gas springs, NSK bearings, screws and washers.

Material: Stainless steel 304, cow leather, expanding PU foam, memory foam, polypropylene, copper and aluminum.

Lead-Time: 12 months.

Quantity: 25 core chairs and 35 core stools.

Project Details

David France, a chiropractor and the owner of Chaired Logic from Australia, devoted himself to develop the Core Chair and stool, to improve poor sitting posture and to reduce reoccurring back pain.

Prototype Finder specializes in providing the total solution for big project with very small volume production. We provide varied manufacturing services and design services at a much lower cost compared to costs in western countries.

About Chaired Logic

David France B.Ed.B.Sc.Grad.Dip.M.Chiro

Having gained a masters degree in Chiropractor, with 15 years experience as a chiropractor, and having taught Ergonomics at Macquarie University (Sydney). David France is an authority on the science surrounding workplace ergonomics. Seeing the obvious link between sitting for long periods and back problems, David became passionate about improving how we sit.

David developed the Core Chair to directly attend to the frustrations of patients with reoccurring back pain and poor posture.

Phase 1 (Redesign The Whole Chair, Lead-Time 6 Weeks)

A: Rotating Mechanism Design

The chair needs the backrest function to rotate independently against the seat. It also should combine the functions of a gas spring to smoothly move up and down. The mechanism expected to be designed is: unique, strong, easily assembled, with a lower cost compared to the first design.

  • Changed the shape from rectangle to round to look more uniform.
  • Changed the material to stainless 304 to achieve unique and different finishes with a strong and stable function.
  • Removed the bearing sleeves, nuts and rings, to totally improve the function and assembly way.
  • Changed the bearing assembly method to achieve a more reliable function.
  • Changed the tube material size, and manufacturing method, to achieve high quality.
  • Changed the mechanism assembly way to make it much easier to assemble for end users.

B: Seat Design

   The seat needs higher end cosmetics with a very comfortable feeling for a reasonable price:

  • Changed the seat cover and seat bottom shape and size to get the most suitable size.
  • Changed the way to make the seat from injection mold to blow mold to save cost.
  • Changed the fabric layer to leather layer to improve the cosmetic quality.
  • Changed the foam from standard foam to combination of standard foam, memory foam, and gel pad, to improve the comfort of sitting.

C: Backrest Design

   The back rest needs a perfect position against the seat, with a much higher quality, and better feeling, while being easy to assemble, and at a reasonable cost.

  • Changed the frame of backrest from machined plastic to a stainless steel metal frame to save cost and be more stable.
  • Changed the foam from standard foam to expanding molding foam with higher shore. A required hardness to improve the comfort of back.
  • Changed the fabric layer to leather layer to improve the cosmetic quality.
  • Changed the way to assemble the back rest to improve the efficiency of assembly.

Phase 2 (Prototypes To Evaluate The Design And Manufacturing Possibility, Lead-Time 12 Weeks)

Sourced the high standard wheels, aluminum based and reinforced gas springs, high duty bearing and stainless steel screw, nuts and washers.

A: Made The Mechanism Prototype (15 Customized Stainless Steel Components)

  • CNC milling and turning of stainless steel 303 top housing used for gas lifting purpose and backrest rotating purpose, then welded on the laser cut stainless 304 plates which was used to support the seat.

CNC Milling, Turning and EDM Sparking Stainless Steel with brush finish


  • CNC milling, turning and EDM sparking stainless steel of bottom housing to hold the bearing and CNC turning the inner/invisible gas spring holder. Press to fit the bearing into bottom house with punch machine and fixture.
CNC Milling, Turning and EDM Sparking Stainless Steel with brush finish

CNC Milling, Turning And EDM Sparking Stainless Steel With Brush Finish.

  • CNC turning, laser cutting both stainless steel gas lifter levers and rotating handles and relevant components, then screwed and welding all together.
    Laser cutting, CNC Turning, Bending and Welding of Stainless Steel 304 with brush finish

    Laser Cutting, CNC Turning, Bending And Welding Of Stainless Steel 304 With Brush Finish.


  • Weld top housing and bottom housing together though the invisible gas spring holder.


  • Stainless steel tube was formed to the required section shape and bended with rubber core to final shape, then laser etched the logo and hand polish to brush finish.
    Bending, laser etching and wire cutting the stainless steel tube

    Bending, Laser Etching And Wire Cutting The Stainless Steel Tube.

  • Weld the tube into bottom house and hand polish the whole mechanism to be with brush finish.



B: Made The Seat Prototype (3 Customized Parts Plus Leather Upholstery)

  • Make the blow molding parts from PP material with 4.0mm thickness, also designed the thought holes on the part to improve the strength.
  • Press the designed and copper inserts to base holes on the part. This new design of cooper insert is to avoid the spin issue compared to the traditional way which is to insert co-mold into blow mold.Blow Molded Seat Bottom
  • Glued gel pad, standard foam, memory foam on the seat cover and assembled the leather on the seat cover.Blow Molded Seat Bottom 2
  • Use stainless screws and washers to assemble seat cover and seat bottom.


 C: Made The Backrest Prototype (10 Customized Parts Plus Leather Upholstery)

  • Make the stainless steel 304 frame base on shape of back rest. Laser cutting all tubes and then welded together on the fixtures.
  • Put the metal frame into expanding foam tooling which is made from aluminum.
  • Assemble the leather on the surface of expanding foam.
  • Screwed the bottom stainless plate on the bottom of backrest.



Phase 3 (Blow Mold Tooling, Bending Tooling, Small Volume Production, Lead-Time 32 Weeks)

  • Make further design in improvement based on prototype and design.
  • Create final spec, part list and schedule.
  • Co-ordinate technique, quality issues and delivery schedules with all partners.