| 摘要 |
<p>A frame or scaffold has the tubes or rods clamped at the cross over points in a block which is basically a cube, with three 'U' shaped grooves along three edges of the cube. The grooves are at right angles to one another. Three screws mounted in the block, to secure the tubes or rods, are slightly off centre so that the tubes are forced into the groove. Friction prevents axial movement of the tubes, while sideways movement is prevented by the point of the screw. A corner can be machine off the cube to provide a flat by means of which the block can be anchored.</p> |
