How to Square a Block in an Angle Plate
Machinists have to be precise in their work, otherwise mechanical problems or fitting problems can arise when parts are assembled. Square blocks of metal need to be inspected and tested for proper square dimensions. Squaring a block in an angle plate is generally performed to true-test the block dimensions for proper fitting with other machinery. This process can be accomplished using a surface gauge and a dial test indicator along with a few common machinist tools.
Instructions
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1
Set the block to be squared on the surface plate. Position the surface gauge rod's ball-end in such a manner that it projects out from the base of the surface gauge. Set the reference square adjacent to the angle plate.
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2
Mount the dial test indicator onto the rod. Ensure that the contact point is roughly in the same vertical plane as the outer edge of the ball. Slide the surface gauge onto the surface plate until the ball touches the lower end of a reference square.
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3
Twist the surface gauge in an arc. This action will cause the dial test indicator tip to sweep up to the higher end of the reference square. Mark a high point on the reference square -- no higher than the surface of the angle plate -- that you want to test.
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4
Zero the dial test indicator out. Slide the surface gauge until the ball touches the lower end of the surface point you need to check. Sweep the indicator point as in step 3. Read the deviation from the point on the reference square on the indicator. Continue the process until you've squared the block. Note that by repositioning the ball and the test indicator height points, you can test squareness from different portions of your square block.
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Tips & Warnings
Using a piece of drill rod on a bench vise you can clamp a reference point along the block. This acts as a landmark to check precise measurements of the square.
Always use caution when handling metal.
Wear appropriate safety equipment if cutting or welding metal.
References
- The Home Machinists Handbook; McGraw-Hill; 1984
- Machine Shop Trade Secrets: A Guide to Manufacturing Machine Shop Practices; James A. Harvey; 2005
