Given device can be used to find the center of a round workpiece, as well as for marking circles and radii. It has a simple design and is not difficult to manufacture.
It consists of an aluminum strip and a wooden block.
Assembly fixtures.
First, a rectangle of the desired size and shape is cut out from the wooden blank:
Then a piece of 305 mm long is cut out of a 3x25 aluminum strip. In it, 3 mounting holes for drilling pits, one axial hole and 20 marking holes are drilled. Their size and position are shown in the figure:
When drilling holes in aluminum, burrs may occur at their edges; to eliminate them, it is recommended to sand the workpiece with fine sandpaper.
When attaching an aluminum strip to a wooden block, it is very important to accurately maintain an angle of 90 degrees with respect to its lower edge, the accuracy of the marking will depend on this. This can be done using a square. The edge of the strip should exactly match the top of the triangular cutout in the bar.
After marking, the strip is attached to the bar with 3 screws.
The axial hole is made through.
The fixture is ready!
How to work with the device.
Center finder.
To find the center of a round object, it is necessary to attach a center finder on the top of the workpiece, firmly pressing it to the surface of the measured object. Next, on the workpiece, you need to draw a line along the ruler, rotate the center finder 90 degrees and draw a second line. The points of contact of these lines will be the exact center of the workpiece.
Compass.
Of course, the device is inferior in its functionality to the real compass (since it has a rather large step of marking), but still they can mark circles of a certain radius.
To do this, any sharp object (an awl, a nail, etc.) is inserted into the axial hole of the device. A marker or pencil is inserted into one of the marking holes.
