Gauge blocks are one of the most common forms of dimensional measuring tools. Although they are a simple block of steel or ceramic, while they are actually a highly-engineered price of precision measuring instrument. In this article, we will introduce the gauge blocks grade types, using and precautions.
Gauge Blocks Grade types and their recommended use:
Grade 2: Use in general processes and workshops.
Grade 1: Use for specialized mechanical inspection and calibration of electronic or digital measuring instruments.
Grade 0: Use in the calibration of other blocks or high precision instruments in controlled temperature environments and/or controlled conditions.
Using the gauge blocks:
Gauge blocks are usually available in sets of, from 2 or 3 tens to more than 100 pieces, and in steps of up to a tenth of a micrometer (depending on the degree), that is 0.0001 mm (one ten thousandth of a millimeter). Although one could be tempted to achieve as many steps as models, the most appropriate thing is to verify which are the measures that will be reviewed the most and look for the most flexible combination of pieces to achieve these measures; Find the smallest and largest measure you need and evaluate the number of steps that best approximates the intermediate measures you will use.
In order to achieve intermediate measures, what is done is to join blocks of different measures until the necessary height is achieved. To join the blocks a process referred to as wringing in English is used, which can be translated as " twisting". To join blocks, we first have to select from highest to lowest the blocks that would be needed; For example, to achieve a height of 45.6785mm the following blocks (in mm) would be used: 25 + 17.5 + 1.17 + 1.008 + 1.0005.
How to put gauge blocks together:
Before you begin, take the following considerations: Try to use the minimum amount of block possible.
1. Remember to allow time for thermal stabilization if you are not working in a controlled temperature environment.
2. Clean the measuring faces and check the faces for burrs with an optical plane. If necessary, clean the surfaces with ceraston stone for block maintenance.
3. Apply a small amount of oil on the measuring face and distribute it evenly. Wipe until layer is practically removed; a minimal film will remain on the surface. Use a thin mechanical oil to avoid leaving residue.
4. Gently put the faces of the gauge blocks in contact, with different techniques depending on the size of the gauge blocks:
a) Thick blocks: contact the faces of the blocks perpendicular to each other, then rotate both blocks applying light pressure (you will feel the blocks come together) and finally align the measuring faces.
b) Thick Block with Thin: Place the edge of the thin pattern over one end of the thick pattern, slide the thin pattern over the thick while pressing the surface to align them.
c) Thin blocks: it is important to have first aligned a thin one over another thick one to prevent bending, then repeat the steps as in point b) and finally remove the thick one if you will not use it.
Check the adhesion status with an optical comparator. Repeat the steps as necessary.
Precautions:
1.Remember that master blocks are high precision instruments and as such, they require to be handled by personnel trained in their use.
2.Always store the blocks in their corresponding case and in a dry place and not exposed to the sun.
3.Handle your blocks with cotton gloves or latex gloves to avoid an accumulation of grease and/or sweat on the surfaces of the blocks.
4.To remove dirt from the block surface using compressed air and soft brushes; for tougher items, you can use a cleaning solution such as alcohol solutions, such as those used to clean lenses or optical or electronic items and leave no residue when evaporating, and optical cleaning paper to avoid scratches.
5.Finally, use ceraston stone (alumina stone) to remove burrs and accumulated elements that are not easily removed by other processes, in conjunction with solvent elements.
6.Check with an optical flat lens to check for burrs on the block.
