Upholstered Stool

An upholstered stool for sitting. The stool has a lid to an inner compartment similar to a piano stool. The legs are wood-turned and the upholstery method was studding.

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Brief


Before bed, I like to do a small amount of reading and writing. I dont like sitting in bed so I sit on a small stool beside my bed. Currently, this stool is a plastic IKEA stool.

A plastic stool in a bedroom
The current IKEA stool

It was an adequate solution in the beginning. Now, however, I require more comfort and support from what I'm sitting on. I need a stool that has a larger top and is cushioned.

An upholstered stool
An existing stool design similar to what I was wanting

I put all my books on the floor as I am sick of getting up when I want different books. I want the stool to have a storage compartment so books don't need to be on the floor.

Concept


The guidelines for creating a concept were;

  • The stool must have a storage compartment
  • The stool needs to be low
  • The stool should be cushioned
A wooden upholstered stool
Concept 1

The first idea was to just have a cushioned wooden stool. Focusing on aesthetics and comfort. This would suit my room, however, I would still need to leave books on the floor, or need to get up to get a different book. The design shown is also beyond my capabilities of manufacturing.

A wooden upholstered stool
Concept 2

This design has the comfort and storage but the legs are too long. The stool would need to have stubby or disproportionately short legs to get the desired height. The technique of using studs for the upholstery is one I will use in the design.

A wooden upholstered stool
Concept 3

This design matches the main criteria. Although not using studded upholstery, the leg proportions are correct and the storage compartment is there.

The design of the stool will be based on concept 2 and 3.

Design


The final design criteria were;

  • Stool needs to be strong enough to support stored books and someone sitting
  • Stool needs to be built for longevity
  • Stool needs to have aesthetic value and 'a style'
  • The upholstery must be comfortable to sit on
  • The storage compartment needs to fit multiple books inside
  • Stool should be light so it is easily portable
  • The design should be hand-crafting and not manufactured
  • The craft techniques should be within the workers capabilities

With the design criteria in mind, a mortise a tenon frame was used as the base of the design. Due to the layout of my room, the stool could not extend from the wall more than 35cm. A length and width for the stool was chosen to be 450mm and 350mm respectively. The material I chose for the lid frame left about 250x350mm for the interior storage compartment.

Moving to the legs, I wanted to turn them rather than taper or carve them. I chose a turned pattern of an ogee with 2 beads on either side, and a simple taper on the bottom. I left about 1/3 of the leg as a block for the joints and to hold the bottom of the storage compartment.

Engineering Drawing of Stool Leg
Right Leg Drawing

The storage compartment was given a depth of 10cm. I was going to cut a slit in the legs to sit a sheet of MDF in, however, I decided to have a cut-out in each leg so that the compartment could be fully rectangular. The top of the stool would be another sheet of wood over a frame for the lid. The lid would be attached with some hinges to one of the frame pieces. Some foam and upholstery material would be placed over the sheet and the studs would be inserted into the side of the lid frame.

Engineering Drawing of Stool
Main Assembly Drawing
A exploded view render of a stool
Exploded rendered view of the stool assembly
CAD render of a wooden stool
Final render of the stool adjusted for chosen materials

Build


The tools, joints and material used are outlined below;

Tools Used

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Lathe

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Drill Press

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Ripsaw

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Table Saw

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Bandsaw

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Dropsaw

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Sander

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Chisel

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Carving Chisel

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Mallet

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Glue

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Clamps

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Water-based Walnut Stain

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Water-based Polyurethane

Joints

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Open Mortise & Tenon

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Screw

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Hinge

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Upholstery Stud

Cut List

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4 - 60x60x280mm

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2 - 350x24x70mm

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2 - 450x24x70mm

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2 - 350x50x36mm

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2 - 450x50x36mm

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1 - 250x350x4mm

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1 - 350x450x10mm

All material was sourced from what I had sitting in the garage. I used New Guinea Rosewood for the leg blanks, Radiata Pine for the leg frame pieces, Silky Oak for the lid frame pieces and MDF and plywood for the bottom and top surfaces respectively.

Wood materials
Acquired materials for the stool
Wood planks
Marked out the planks for cutting to size on dropsaw
Wood frame pieces
All framing pieces cut to size
Marked wood pieces
Mortise and tenon joints marked out
Wood pieces with mortise and tenon joints
Mortise and tenon joints cut out on the pieces

The tenons for the lid frame were too large so they were sanded on the disc sander. The sanding couldn't get all the way in so a carving chisel was used to cut the remaining material out.

Plywood sheet
The plywood and MDF sheets were cut to size on the tablesaw
Rectangular wood frame
The lid frame joints were so tight, clamps were not required when gluing
Wood pieces
All components cut to size, ready for the legs to be turned
Plywood glued and clamped together
The plywood sheet and strip were laminated before attaching to the lid frame
Plywood clamped and glued to frame
The plywood sheet finally attached to the oak frame, the excess will be removed with a chisel
A wood turned leg on a lathe
The first leg turned on the lathe
A wood turned leg on a lathe
The leg was sanded and grapeseed oil was applied to finish it
Four wood turned stool legs
All four completed legs, once turned, the leg block excess was sawed off and the edges rounded
Stained pieces of timber
The pine beams for the frame as well as the bottom of the lid frame were stained to match the legs
Two beams in a leg with mortise and tenon joints
Two open mortises and a rebate were made into the leg and the beams test fitted
Three stool legs with two connecting beams
When spaced, the legs don't look as inconsistent
A complete stool frame
The completed stool frame

Although strong, when tested, the joints would not hold over days of use, and the beams would slowly come out of the mortises. A large crack appeared in one of the legs due to a fracture from chiseling, so the frame needed to be glued, however, the joints were strong enough so clamps were not required.

A stool frame connected to another frame by hinges
The hinges and bottom were attached to the stool, completing the woodwork
A stool full of books
The compartment has ample sapce, this test was with five books
A stool with blue cloth laid over it
An upholstery method was not decided, so the fabric remained folded over the cushion
The stool with initial upholstery
The initial upholstery. Rope was sewn onto the sides and the fabric was stapled down
The completed stool with full upholstery
The completed stool, studs were added to achieve the final look as seen in the concepts

Evaluation


Although the stool was manufactured and performed successfully, overall, the stool was fell short. This was due to poor design, minor errors and oversights caused the final result to be less than ideal.

The most major design fault was the placement of the hinges. The legs of the stool protrude from the side beams by about 10mm, which means if the hinges are attached to said beams, the stool lid cannot open. Strips of MDF were added to distance the hinges from the beam, however, the offset meant that the stool lid was now off-center (as can be seen in the final image with the stool legs protruding).

This project has been a lesson in design, especially for furniture and woodwork. As it turns out, the dimensions are far less important than geometric tolerances, manufacturing methods and aesthetic style. In this one project; I switched from manufacturing to hand-crafting, High-Speed-Steel to carbide tooling and relying on glue to relying on the integrity of wood joints. This did not go well, the changes were not inherently bad, but poorly timed.

Specific lessons learned;

  • Never make a major methodology change half-way through a project
  • Don't compartmentalise other elements of the design i.e. upholstery, mechanics and woodwork
  • Consistent wood-turning is difficult when done by hand and without proper measurement
  • Design based on what suits reality and available manufacturing methods, not on what is ideal
  • Open mortise joints are not good to use without glue
  • When designed correctly, a stool compartment can hold much more than anticipated
Criteria Rating
Strength Pass
Longevity Pass
Aesthetic Value Fail
Comfort Pass
Storage Space Pass
Portability Pass
Manufacturing Method Marginal
Ease of Manufacturing Marginal
Design Criteria Evaluation