Helping 3D With 2D

There is one thing I must do before running into the workshop and start cutting up random pieces of wood into lengths that I don't know, I need to draw out a scale drawing and find out the dimensions of my chair

The centre of my chair, the mechanism and my whole project are the cogs and central column. It is crucial that I get that right first! So I cut out a full size cross section of the central column out of thick grey board and from that simply rolled different sized cogs down the side of the column and marking and cutting the teeth I was able to get the correct sized cog!

Something really important that I had failed to realise is that, for the chair to full causing the trap to shut it must be put in a raised position first. This is a problem because if the seat is too hight up the ergonomics would be wrong and the victim wouldn't be able to get onto the stool to then activate the trap. So, I found by having a smaller cog, it would mean I could get the most rotation from the smallest full of the column

I filmed this movement of the column and the rotation of the small optimum cog, which is shown here -

If you have a problem viewing this video, click on the link to see it played in better quality on YouTube, with a killer soundtrack!!

Next I needed to work out the maths behind the different sized consecutive circles that will be cut up to become the cross braces of the pod -

Both of the drawings are drawn half scale but have the full scale measurements on them. The numbers on the rings correspond to the ones of the top drawing. The diameter of ring 1 is 300mm on the outside edge and 220mm on the inside edge. The diameter of ring 2 is 510mm on the outside edge and 430mm on the inside edge. The diameter of ring 3 is 604mm on the outside edge and 524mm on the inside edge. Finally the diameter of ring 4 is 610mm on the outside edge and 530mm on the inside edge

Final Design

I feel I have taken the development of this design far enough to feel relatively happy and confident with my design. With the deadline edging closer it is also time I got in the workshop and starting making this design a reality as I can't really predict how long the manufacturing of my trap will be and also allow time for error

So with the all the research and development behind me I then draw out my final design:

Looking at these drawings I am really excited about making this trap chair!

cross(Brace Yourself)

Now that I have come up with a mechanism that works in theory, I have 5 arms rotating on pivots as the cogs on the them move with the central column that move up and surround the person, I need to make the pod much more enclosed

If you look at my previous sketches, models and SketchUp images the person can easily squeeze between two vertical arms, thus making the trap flawed. So I have come up with the idea of having cross braces between each of the 5 arms, creating a cage-like pod that will totalled Cocoon the victim -

So as you can see each cross brace is attached at one side, but when the arms move in on the victim the other end of the brace should meet perfectly with the other arm giving a seamless pod with consecutive circles

As my ideas and designs develop as to should my model -

I am very happy with this simple effective solution to my trapping pod

Seeing In 3D

With my recent introduction to Google SketchUp I was keen to see my new improved design in 3D so set about creating it -

First making the seat top 400mm by 400mm. Then made the column half the size of my model (200mm diameter) with the thinner part of the column measuring 420mm. Working out the thickness of each layer so that the total hight is ergonomically correct at 450mm

Next I added in the five reduced sized cogs measuring 100mm diameter circle, so with two cogs totally 200mm with the column at 200mm the mechanism should actually sit directly underneath the 4000mm diameter square seat

Next I

added in the base/crochet design that worked well in my original wooden model. It is crucial that the height at which the cogs are suspended and the distance from the column is spot on and identical for all five cogs because if one is off it could jam, flawing the mechanism. Already I can see an improvement in the aesthetics, the proportions, angles and components sit really well together as much more refined piece

Next using the Arc tool in SketchUp I could easily show a rough idea of the five arms that are attached to the five cogs, that curve around the edges of the seat and up to surround the neck of the victim

I really like how my chair trap is looking as is becoming more than just a simply mechanism

New Look

Although time consuming making the full scale model proved very interesting and helpful, I can now see exactly where in my design the aesthetics are lacking. Straight away I can see the cogs are too big and also how they clearly extend further out than the seat, looking back at all the traps I researched they all have one thing in common - they keep the mechanism of the trap hidden and as discrete as possible as to not deter the victim, here is a sketch of an improved design -

As you can see from my annotations, I first halved the width of the central column because it doesn't need to be that big and also reduce weight. I also decreased the size of the cogs so that they 'look' right and so they don't extend outside the width of the seat (staying at 400mm by 400mm) as this is the standard dimensions for a seat

1 Column In An Aesthetically Wrong Pod

When I showed my adapted wooden model with the arms to my tutor, immediately Michelle saw the aesthetics were wrong. The aesthetics of a design is dealing with the nature of beauty, art, and taste, and with the creation and appreciation of beauty, basically it looked wrong - too mechanical. Michelle said there wasn't anything I could about the aesthetics looking at this small model, so the next step was to make a full scale model quickly, with the same proportions as my wooden model -

This is the column made out of 9 layers of hollow grey board discs, the five larger discs measuring 420mm in diameter and 45mm in height and the smaller discs in between measuring 320mm in diameter and 45mm in height, with the top disc at 420mm in diameter and 75mm in height. With a square seat on top measuring 500mm by 500mm and 35mm in height. The total height of the column and seat is 430mm and at the widest point 500mm, I tried to base these measurements on those of a standard school chair for ergonomic reasons

This is the finished full scale model and is blatantly obvious that its looks wrong - the aesthetics need to be improved, it is also interesting to see the scale I am looking at with my chair trap

Ganesha + An Arm...

Now I have a mechanism that is activated by someone sitting down on a suspended column and turning 5 cogs, I need to take this movement and come up with a way that the person is then trapped from this mechanism

It became blatantly obvious that arms should be attached to the cogs in such a way that when they rotate, the arms that are connected on the circumference of the round cogs will move with the rotation and move into a certain position that the user is trapped, confused? here are some sketches of what I mean -

The arms are simply an addition to the previous mechanism. The trap is set with the central column lifted, the cogs in their outward rotated position and arms lay out of the floor. Then as the column falls and cogs turn inwards the arms lift off the floor rotating at the same rate as the cogs. This mechanism will be designed so that then the column meets the floor, the cogs have rotated all they can and the arms are in their upright position all the way round the column with the 5 cogs and attached arms

I then added these arms to my wooden model, using simply foam board so that could quickly and easily see this advance in 3D -