How to Use a Height Gauge
In precision machining, there are a number of techniques for measuring out precise distances from an edge on the piece being machined. One of the more accurate methods is to employ the use of a height gauge. When used on a surface plate, it can provide highly accurate measurements and be used for highly precise layout purposes.
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Things You'll Need
- Height Gauge
- Surface Plate
- Layout Dye
- Cleaning Supplies
- Soft Cloths
- Mild Solvents
- Workpiece (whatever you're working on)
Instructions
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1
Clean all surfaces of debris before beginning. Using soft cloths and mild solvents, clean the height gauge base and arm, the surface plate and the workpiece. There should be no remaining particulate matter on any surface---the slightest amount can lead to errors up to a thousandth of an inch. Especially important are the surfaces for the height gauge and workpiece, which will lie flat against the surface plate.
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2
Apply layout dye to workpiece. Mark the general region where the workpiece will be machined. The goal behind layout is to use this process to put a thin layer of dye on the workpiece, which will get scratched off later by the height gauge.
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3
Set up the height gauge on the surface plate. Make sure there is solid contact between the gauge and the plate. Set the height of the gauge to the desired position of the line to be marked upon the workpiece. Place the workpiece on the surface plate with the dyed surface facing the height gauge.
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Scribe the layout line by carefully sliding the height gauge across the surface of the workpiece. A very light scratch should be made in the layout dye, revealing the position of where the workpiece will get machined. Only a light touch is needed for the mark to be visible in the layout dye.
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Repeat for all layout lines, setting the height gauge to each height, turning the workpiece as needed, and lightly scribing the lines. Once all the lines are scribed the work piece can be machined before being cleaned up of layout dye.
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Measurement is a similar process, except that no layout dye is used and the height gauge measures the height of the features directly, like a ruler. The gauge is made to point to a reference point---commonly the surface plate---and a measurement taken before pointing to the feature whose relative position is being measured. This is repeated for every feature being measured.
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Tips & Warnings
Take your time and be careful. The more careful you are when making the measurements and scribing the layout lines, the more accurate the final measurement.
