We have to make some choices when we dimension a block with a notch or cutout.
It is usually best to dimension from a common line or surface.
This can be called the datum line of surface. This eliminates the addition of measurement or machining inaccuracies that would come from "chain" or "series" dimensioning.
A pantograph can be used to trace a drawing by placing a point on the existing drawing and using another point, side by side, on the other paper drawing out the particular drawing. A pantograph looks like a is two rulers in the shape of a "V" that are connected by 4 points. One "V" is inverted.
Silver Point
darker
Addition or removal of features like buildings, roads etc., upheaval or slump in ground levels, change of grid system and datum (point from which levels are compared to).
above ordnance datum!
burnie
1. Question is really vague, it is important to mark out the selected datum, as you just selected that datum? What else are you going to do with It? If you are working from another datum point just ensure that it is a good datum with critical measurements checked otherwise the new datum could throw out al measurements. P.s i wish the selected retards would stop answering with nonsense answers.
Data is the plural, roughly meaning information. Datum is singular and is used someti es to mean a Landmark or starting point, a geodetic Datum point, like in the Grabd Canyon or the Promontory Point in Utah, both recognized landmarks.
burnie
Land-surface datum is a datum plane that is approximately at land surface at each well. If known, the elevation of the land-surface datum above sea level is given... Datum: any level surface, line, or point used as a reference in measuring elevations.
According to ASME Y14.5, a primary dimensioning datum requires at least 3 points of contact to establish the datum plane. Two points of contact are required for the secondary datum and 1 point of contact is required for the tertiary datum.
When utilizing the DAGR, the field that automatically displays the waypoint datum is the "Dat" field, which stands for datum. The datum represents the reference point used to define the location coordinates of the waypoint.
because the datum surface is perpendicular tothe direction of gravity at any point on it.but the horizontal surface is perpendicular to vertical at one point on it :D
A land survey datum (plural datums) is a reference from which measurements are made. The reference in the form of a set of coodinate and a direction. The datum can be arbitary (assumed) or absolute. The arbitary datum point is a point whose coordinate and direction are not known, so an arbitary value is adopted. All other coodinates of the survey project are connected together, but its datum point is not connected to a larger network. The absolute datum is a reference point whose coordinate and direction are already known within a frame of network. So the new survey become part of the network.
To select a suitable datum, consider a stable reference point on the workpiece or surface. Mark the datum clearly and securely. When marking out, ensure all measurements and reference points are taken from this datum to maintain accuracy and consistency. Working from a different datum can lead to incorrect measurements, misalignments, and errors in the final product. It is crucial to avoid this by consistently using the established datum.
hi =) hi =) It is the 0 point, usually the dead centre of the billet
There is a point in Cornwall, in the UK, where there is a hatch in a building and underneath is a mark from which mean sea level for the entire world is calculated. It is in Newlyn, I think. Answer MSL is the average between high and low tides, and is a datum point used to desribe the height of tides, although the actual measurement is quite complex. The Newlyn mentioned above is the datum point for the UK, not the world. Other countries have their own datum point.