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Spitfire project, day #3: the box blueprints

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Now that I have a nice box prototype made of cardboard, it’s time to make actual blueprints and size calculations, refining the prototype with some ideas.

If you’re new here, and wish to read the whole project, start on day #1 of this project.

The blueprints

As I said above, I made some arrangements to the original prototype. For example, I found a way to hide hinges. Apart from some screws, not too much clutter should be visible from the outside.

The box blueprints

Download blueprints as PDF.

Size calculations

I started on a base control panel size of 20cm width and 15cm height. But to be honest, I don’t really know the required size… At least I have the formulas.

Parameters

height inside = 3cm
panel width = 20cm
panel height = 15cm
panel horizontal border = 2cm
panel vertical border = 3cm
panel angle = pi / 9 
wood thickness = 0.5cm
stiffener thickness = 1.5cm
saw width = 0.1cm

Intermediary products and functions

surface = width * height

panel climb = sin(panel angle) * panel height
            => 5.13cm

base width = panel width
base height = cos(panel angle) * panel height
           => 14.1cm

front height = height inside + wood thickness
back height = front height + panel climb

climb on back stiffener = tan(panel angle) * stiffener thickness
                        => 0.55cm

max(x, y) = if x > y then x else y
min(x, y) = if x < y then x else y

Resulting measurements

Part 1: back vertical stiffener

p1 length = back height - climb on back stiffener - wood thickness
          => 7.58cm

Part 2: front vertical stiffener

p2 length = front height - wood thickness
          => 3cm

Part 3: side stiffener

p3 length = base height - 2 * (stiffener thickness + wood thickness)
          => 10.1cm

Part 4: back stiffener

p4 length = base width - 2 * (stiffener thickness + wood thickness)
          => 16cm

Part 5: side board

p5 width = base height
         => 14.1cm
p5 front height = front height + wood thickness
                => 4cm
p5 back height = height inside + panel climb + wood thickness
               => 8.63cm

Part 6: back board

p6 width = base width - 2 * wood thickness
         => 19cm
p6 height = back height
          => 8.63cm

Part 7: front board

p7 width = base width - 2 * wood thickness
         => 19cm
p7 height = front height
          => 3.5cm

Part 9: bottom board

p9 width = base width - 2 * wood thickness
         => 19cm
p9 height = base height - 2 * wood thickness
          => 13.1cm

Part 10: panel

p10 width = panel width + 2 * panel horizontal border
          => 24cm
p10 height = panel height + 2 * panel vertical border
           => 21cm

Board surface

p5 height diff = p5 back height - p5 front height
               => 4.63cm

p5 surface = p5 width * p5 front height + (p5 width * p5 height diff) / 2
           => 89.01cm^2

p6 surface = p6 width * p6 height
p7 surface = p7 width * p7 height
p9 surface = p9 width * p9 height
p10 surface = p10 width * p10 height

Totals & required material

total stiffener length = p1 length + p2 length + p3 length + p4 length + 3 * saw width
                       => 36.98cm

total board surface = p5 surface + p6 surface + p7 surface + p9 surface + p10 surface
                    => 1072.3cm^2


base board required width = max(base width/cm, min(p10 width/cm, p10 height/cm)) * cm
                          => 21cm
base board required height = p5 front height + p5 back height # the two side plates
                           + p6 height + p7 height + p9 height
                           + max(p10 width/cm, p10 height/cm) * cm
                           + 5 * saw width
                           => 62.36cm

If you find something wrong in here, please tell me :)

Find it on github

As usual, all of this can be found in the github repository of the project. Please note that you’ll need Omnigraffle to open the blueprints. The calculations markdown file can be opened with Calca for better results.

To be continued

The arduino leonardo I needed for this project recently arrived. Next time we’ll try to interface that with War Thunder :)

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