Quick Guide to Precision Measuring Instruments

PG25Quick Guide to Measurement4. Error due to inclination of the main scale (column)According to JIS standards, the perpendicularity of the column reference edge to the base reference surface should be better than:This is not a very onerous specication. For example, the perpendicularity limit allowable is 0.61 mm when L is 600 mm. This is because this error factor has a small inuence and does not change the inclination of the slider, unlike a warped column.5. Relationship between accuracy and temperatureHeight gages are made of several materials. Note that some combinations of workpiece material, room temperature, and workpiece temperature may affect measuring accuracy if this effect is not allowed for by performing a correction calculation.6. The tip of a height gage scriber is very sharp and must be handled carefully if personal injury is to be avoided.7. Do not damage a digital height gage scale by engraving an identication number or other information on it with an electric marker pen.8. Carefully handle a height gage so as not to drop it or bump it against anything.3. Lifting of the base from the reference surfaceWhen setting the scriber height from a gauge block stack, or from a workpiece feature, the base may lift from the surface plate if excessive downwards force is used on the slider, and this results in measurement error. For accurate setting, move the slider slowly downwards while moving the scriber tip to and fro over the gauge block surface (or feature). The correct setting is when the scriber is just felt to lightly touch as it moves over the edge of the surface. It is also necessary to make sure that the surface plate and height gage base reference surface are free of dust or burrs before use.0.01+ 1000L( ) mm L indicates the measuring length (unit: mm)Notes on using the height gage1. Keep the column, which guides the slider, clean. If dust or dirt accumulates on it, sliding becomes difcult, leading to errors in setting and measuring.2. When scribing, securely lock the slider in position using the clamping arrangements provided. It is advisable to conrm the setting after clamping because the act of clamping on some height gages can alter the setting slightly. If this is so, allowance must be made when setting to allow for this effect.3. Parallelism between the scriber measuring face and the base reference surface should be 0.01 mm or better.Remove any dust or burrs on the mounting surface when installing the scriber or lever-type dial indicator before measurement. Keep the scriber and other parts securely xed in place during measurement.4. If the main scale of the height gage can be moved, move it as required to set the zero point, and securely tighten the xing nuts.5. Errors due to parallax error are not negligible. When reading a value, always look straight at the graduations.6. Handling after use: Completely wipe away any water and oil. Lightly apply a thin coating of anti-corrosion oil and let dry before storage.7. Notes on storage: Avoid direct sunlight, high temperatures, low temperatures, and high humidity during storage.If a digital height gage will not be used for more than three months, remove the battery before storage.If a protective cover is provided, use the cover during storage to prevent dust from adhering to the column.

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