To position the fabric:
Ensure both clamps are up by loosening the each tightening knob and lifting the top until it stays in the open position.
Slide the sample right side down, over the bar and narrow block, under both clamps. Adjust the untested portion over the narrow block.
Lightly fold up the loose ends on either side so that they fit within the stoppers on the clamps.
Ensure the fabric is straight (centered between the clamps) and flat, but not stretched.
Close the clamps carefully without shifting the sample. Hold the two sides of the black toggle plate down while tightening the knob evenly. Check that the needle on the force gauge is in the center.
Do not over-tighten the clamps, as this affects how the material performs.
For older clamps, when using the almond-shaped tightening knob, ensure it is parallel to the clamp edge so that the fixed and movable clamps can come together without the knobs knocking into one another.
For current clamps, when using the black handle tightening knob, make sure it is parallel to the clamp edge by pulling up the spring handle so that the fixed and movable clamps can come together without the knobs knocking into one another.