Chair Prototyping

On the 21/9 I spent the day working on a basic prototype of my chair with the assistance of Bernie from the Workshop. My aim was to determine the right method, materials and machinery for the manufacture of my chair. We began by removing the plastic shell off the chair and sourcing appropriate steel rods for the frame and shell of the chair. Using coat hanger wire we moulded various profiles of the chairs shell to use as a guide. Using the jig we began hand bending the steel, this process was easy and not physically arduous, however, we discovered using tubular steel would be swifter and make for a lighter frame. Next we arc welded two parallel steel rods to the side profiles to form our seat shell frame. Arc welding is moderately difficult but ensures strong bondage of joins. Our next step was placing the frame on the base to determine how it was to be fixed and also how the inner steel rods that form the seat would be joined. We realised the seat needs to have a degree of flex to be comfortable to seat in which requires rods of a certain diameter and length of span. The seat should also not have a base that interferes with its sagging in weight, hence, our decision to remove the three steel braces off the base with a power saw. What remains to be resolved is how to suspend/fix the rods to the frame and how much flex should be allowed? I have ordered in 6-8 meters of 6mm mild steel rod to test this aspect of my chair design.

Hand bent and welded solid steel frame on existing sled base

Clamps used to hold frame in position while welding temporary legs

Jig used to bend steel rod for frame. A hammer was then used to straighten the rod.

Quick welding job to form an outer frame for the shell of the chair. Tubular steel is proposed for the final prototype.

Basic steel section/profile. To be reused as a guide.

Bernie cutting off the base bracing using an angle grinder.