Table of Contents
Can datum targets be on different planes?
Based on ISO, different datum letters must be used in different planes and the numeration of datum targets in each plane starts with 1 [1].
How many datum targets are there?
three datum targets
The primary datum has three datum targets, the secondary two and the tertiary one.
How many datum planes are there?
A typical datum reference frame is made up of three planes.
Can you put a datum on a centerline?
You cannot. So a centerline cannot be a datum. To sum up, a datum can indeed be a centerline, but it is never to be labeled as such on a drawing.
What is the difference between a datum target and a datum feature?
The datum is an imaginary but theoretically perfect surface, line, or points. A datum feature, on the other hand, is the physical representation of datum. Datum targets are specified regions of the datum feature used for locating the part in a fixture.
What are datum targets?
A datum target is either a point, line or area on a workpiece. The datum target is to be the place of contact (supports of the workpiece) for the manufacturing and inspection equipment. When a part has an irregular contour (casting, forging, sheet metal parts etc ) the use of a datum target could be required.
How many types of datum are there?
There are two main datums in the United States. Horizontal datums measure positions (latitude and longitude) on the surface of the Earth, while vertical datums are used to measure land elevations and water depths.
How do you pick a datum?
How To Select Datum Feature In The Order of Precedence. Datum features must be easily identifiable on the part. If parts are symmetrical, or have identical features making identification of datum features impossible, the datums features must be physically identified.
Where do you put the datum?
We can place the datum symbol either on the surface or on one extension line from the surface. For any surface other than a round cylinder, the datum is strictly on the side where the symbol is shown. However, for a round cylinder, the datum is the entire round surface.
Can a datum be an axis?
Datums are theoretically exact points, axes, lines, and planes or a combination thereof that are derived from datum features. A datum feature is the tangible surface or feature of size (comprised of multiple surfaces or revolved surfaces) that is indicated by the datum feature symbol.
Why do we use datum targets?
The datum target is either a point, line or area on a workpiece. The datum target is to be the place of contact (supports of the workpiece) for the manufacturing and inspection equipment. The use of a datum target could be required when a part has an irregular contour (casting, forging, sheet metal parts etc ).
How do I choose a datum?
Datums are important and care must be taken when selecting them. They must be easily identifiable on the part. When parts are symmetrical or have identical features that make identification of Datum Features difficult, the Datum Features should be physically identified.
What are datum planes?
A datum plane is a horizontal or vertical reference point on which surface elevations are based. Though the location of a datum plane is precise, its placement is arbitrary and is determined during the survey stage of a project. Once established, the datum plane will be used for the duration of the project.
What is common datum?
A common datum means a pair of single datums specified to function as one datum. On the other hand, a datum system is a group of datums that is created by combining multiple datums.
Can a datum be on a centerline?
Datum can indeed be a centerline, but it is never to be labeled as such on a drawing. A centerline you can talk about it, but not call it out as a datum on the drawing. A centerline is imaginary and that they should specify the centerline of a feature and then associate other features.
What is aircraft datum?
Datum (reference datum)—an imaginary vertical plane or line from which all measurements of arm are taken. The datum is established by the manufacturer. Once the datum has been selected, all moment arms and the location of CG range are measured from this point.
What is the current horizontal datum commonly used in the US?
North American datum of 1983
The North American datum of 1983 (NAD 83) is the United States horizontal or geometric datum. It provides latitude and longitude and some height information. Unfortunately, NAD 83 is not the only datum you’ll encounter. Before the current datum, cartographers created maps using different starting points.