Gennady Krivopalov from Kuibyshev offers to make a clamp for the metal line. This device essentially has a new tool, you can use a square to lay parts flat and control immediately in two sizes, one of which is movable into the line – fixed clamping screw. When using this tool the accuracy of the measurements compared to the normal line increases to 0.3 mm. the two halves of a latch it is better to make from durable plastic – the metal is heavier. In the upper half, where there is a line, you need to saw through to her groove; the shank drill the hole and cut it the thread for the clamping screw. On the sloping faces should stick the second the same line.
1 — fitting line, 2 — latch, 3 — clamping screw, 4 — glued to the ruler.