Imperial Units – Mocking Up A Small Workbench in Blender

Description

In this exercise we going to take a look at using Blender to mock-up a simple workbench that’s to be cut from a single 8 foot x 4 foot sheet of 1/2 inch plywood (approx. 2440 x 1220 x 12 mm). First, the grid and units of measurement need to be set to use Imperial with an appropriate scaling for inches. Once this is done it’s then a simple matter to drop and manipulated some mesh primitives, shaping, duplicating and positioning where needed, to form the workbench – inclusion of fasteners and joints (aside from butt for convenience) is optional as the exercise is only to prototype the general design.

Duration: total c. 45 mins (00:45:00).
Info: 1080p.
Suitability: Beginner+.
Source: KatsBits – Imperial Work Bench (c. 250 KB | *.blend).
Product ID: n/a.

Design note: more information to consider when using Blender 3D to mock-up or prototype ‘real world’ objects, i.e. making something that needs a real world representation of Imperial or Metric measurement;

Units vs Grid

The Unit type, Length, used to define the type of unit against which measurements are taken, and the subdivisions of the 3D Viewport grid, are distinct aspects of Blenders overall grid and measurement system that can be changed independently of each other. There’s specific utility behind being able to do this, especially when working with Imperial units as it allows for the grid to be changed relative to the unit while maintaining the overall integrity of Unit set.

For example, using the default scaling so there’s a 1:1 correlation between Unit Scale and the 3D viewports Scale, the grid is automatically subdivided by 12, meaning, major divisions equate to 1′ (Foot) or 12″ (Inches) and minor subdivisions 1″ (Inches). And similarly when using an alternatively Unit set-up where Unit Scale is set to a decimal fraction, e.g. 0.032804 (decimal calculation of one centimetre per foot), the grid will be divided and subdivided based on Feet and Inches.

Aside: the decimal fraction representation of Unit Scale is calculated by dividing a given centimetre distance by 30.48, the number of centimetres in a foot. For example, 1 (cm) divided by 30.48 equals 0.0328084 (1 / 30.48 = 0.0328084), or 2.54 cm (1 inch) equals 0.083333. Using this calculation the grid can be adjusted relative to the ‘virtual’ base unit, i.e. setting up a 6″ (approximately 15 cm) grid is a Unit Scale of 0.492125. In practice what these alternative scale values do is change the perceived dimensions of objects in the scene, i.e. the default cube might 1 x 1 x 1 feet using one Unit Scale value but then read as being 1 x 1 x 1 inches using another (subject to the note below). This can be a useful tool depending on what the unit of measurement represents.

Important: when adjusting Unit Scale [i] and/or optionally grid Scale, once set preference should be not to make any further adjustments because doing so changes the perceived Dimensions [ii] of an object relative to the Unit and the grid, disparities can be introduced that throw out the relationship between the two, grid and unit [iii], requiring all objects in a scene to be readjusted, which in turn will likely thrown them out of alignment and/or positioning.

By not setting up the relationship between the unit of measurement and the grid [i], object size, their dimension [ii], need to be adjusted to (re)match the grid [iii], more so using Imperial due to the way division and subdivisions don’t uniformly break down into numbers with even decimal placement.

Although Length defines the type of units used, Unit Scale [1] establishes the division/subdivision relations with the 3D Viewport grid, itself set using Scale [2], which in turn changes how objects are perceived relative to the Unit set (the default value can be used in most instances).

Unit format

Because Blenders measurement system is expressed through a decimal schematic, i.e. 0.00000, due to the way Imperial units break down into smaller increments, it becomes possible to write or input distances in one of two ways [1], as either/or;

• Decimal
• Sub-unit

In practice this means one and a half inches (1 1/2) can be typed as either/or;

• 1.5″
• 1″ 500 Thou

In either instance Blender will typically (but not always) retain the formatting.

Aside: when Imperial measurement is set to use Feet, the symbols used to delineate units and sub-units is;

• ‘ (apostrophe) = feet.
• “ (quotation) = inches.

Below this;
• Thou = thousandth(s) of an inch.
• Mill = millionth(s) of an inch.

Which may then display as either/or;

• 3′ 3″ 450 Thou
• 3′ 3.450″

Or when an input field is clicked on to be edited, as either/or;

• 3ft 3in 450thou
• 3ft 3.450in

Imperial units can be displayed as decimal fractions or sub-units [1] (requires “Separate Units” be active) in Blender. Using one or the other does not affect accuracy, only the way values are presented.

Object Reset

To ensure measurements are accurate, if objects are (re)scaled or (re)sized in Object Mode, be sure to reset them after adjustment using Apply [2]. This is important as it fixes or resets each objects Scale relative to their dimensions so measurement is then read correctly. To do this, select an object and from the Object menu click Apply, then Rotation & Scale (or alternatively All Transforms) – Object » Apply » Rotation & Scale (or Ctrl + A).

Because distance, scale and size are relational in Blender, when accuracy is required, ensure objects dimensions are ‘reset’ using Apply [2].

Timestamps

Times are approximate;
– 00:00 : Overview & Units Setup.
– 06:00 : Block out & Top.
– 16:00 : Legs.
– 25:00 : Apron.
– 30:00 : Support ribs.
– 32:00 : Stretchers.
– 37:00 : Shelf.