The aim of this app is to perform geometrical calculations that might be useful in the workshop. It consists of six tabs for different shapes or type of calculation.
Fields with a grey background are not user-editable. As a general rule, only fields with a non-zero value are treated as inputs. Values can be entered to any precision but are calculated to 3 decimals.
Press the CALCULATE button to calculate the missing fields based on the supplied data. Press RESET to clear the fields on the current tab.
Circles Tab
This tab calculates aspects of circles, chords and segments.
Required fields: Any one of the first four fields, which refer to the circle.
Optional fields: Any one of the second group of four fields, which refer to a segment of the circle.
Notes on fields:
- Segment height is the distance from the centre of the circle to the centre of the chord
- Chord depth is the distance from the perimeter to the centre of the chord
- Segment area is the area of the triangular part of the segment (centre to chord)
- Chord area is the area between the chord and the perimeter. The total segment area is the sum of these two
Polygons Tab
This section handles regular polygons such as triangles, squares, hexagons, etc.
Required fields: The number of sides (3 or more) and one other value.
Notes on fields:
- Internal angle is the angle between adjacent faces measured at the vertex
- Centre angle is the angle between vertices measured at the centre. This is also the external angle between the extension of one face and the adjacent face
- Inner radius & diameter refer to the inscribed circle that touches the centre of each face. For a shape with an even number of sides, such as a hexagon, the inner diameter is the distance across flats
- Outer radius & diameter refer to the superscribed circle that touches each vertex
- Height is the overall height when one face is horizontal. For an even-numbered polygon it is the same as the inner diameter
Right Triangles Tab
This section deals with triangles containing a right angle. Equilateral triangles are handled by the Polygons section. Scalene triangles are generally the sum or difference of two right triangles and do not have a separate section.
Required fields: Any two fields
Notes on fields:
- The first side is on the opposite side of the triangle to the first angle; likewise with the second side and angle
Rectangles Tab
This section deals with simple rectangles or squares. Squares are also handled by the Polygons section.
Required fields: Any two fields
PCD Tab
This section deals with pitch circle diameters, including the size of the holes.
Required fields: PCD and count or angle
Optional fields: hole size, coordinate reference
Notes on fields:
- Across centres is the distance from one hole centre to the next, as would be set on compasses for marking out
- Across holes is the distance from the edge of one hole to the opposite edge of the next as would be measured when checking
Selecting 'Centre' or 'Corner' makes the app calculate the coordinates of the holes with reference to the specified point:
- Centre - the X and Y distances are from the centre of the PCD circle with the first hole directly above and the angle incrementing clockwise. Negative distances are below or to the left of the centre
- Corner - the X and Y distances are from the top, left corner of the square containing the PCD circle. The first hole is in the middle of the top edge. Angles increment clockwise and are from the centre (not the corner)
Sine Tab
This section is a simplification of the Right Triangles section specifically for sine bars. The height and length do not need to be real lenghts but could be chosen to specify a gradient, such as 1 in 100, etc.
Required fields: Any two fields
Lengths tab
This section converts between millimeters and inches. Inches are entered or displayed in both decimal and fractional form.
Notes on fields:
- Convert millimeters to inches - enter the length in mm. The app calculates the decimal inch equivalent and the nearest fraction (up to 64ths). If the fraction is too low, a positive error is calculated. If it is too high the error is negative. For example, 4mm converts to 0.1575" and is 1.2 thou over 5/32".
- Convert inches to millimeters - enter the decimal inches. The app calculates the equivalent number of millimeters and the fractional inches as above. For example, 1.2" equates to 30.48mm and is 3.1 thou under 1.13/64".
- Convert fractional inches to millimeters - enter whole numbers in all three fields. The app calculates millimeters and decimal inches.