120-Mesh Sieve: U.S. Standard Sieve No. 120 (Bureau of Standards, 1924)

The standard testing sieve No. 120: plain-woven brass or bronze wire cloth with 0.125 mm (0.0049 in) openings and 0.086 mm (0.0034 in) wire, soldered smoothly into a round frame about 20 cm (8 in) across. Result: a sieve that passes grains under 0.125 mm and holds back larger ones, made to the Bureau of Standards tolerances. Source: Bureau of Standards, Letter Circular 74, Standard Specifications for Sieves (revised 1924). Unknown: the frame metal and the weaving. Picture: the Bureau's table.

中级

Unknown

说明

Weave the wire cloth

Weave plain (not twilled) cloth from brass, bronze or other suitable wire 0.086 mm (0.0034 in) thick, so the openings between adjacent wires are 0.125 mm (0.0049 in) each way, about 120 wires to the inch. Ours: bronze wire. Not given: how it is woven.

此步骤所需材料：

青铜丝1 warp and shoot wires

所需工具：

金属网织机

Make the frame

Make a circular frame about 20 cm (8 in) across, with about 5 cm (2 in), or 2.5 cm (1 in), between its top and the cloth. Ours: brass strip. Not given: the frame metal.

此步骤所需材料：

黄铜条1 frame

所需工具：

铁皮剪

电烙铁

Mount the cloth

Mount the cloth on the frame without distorting it. Fill the joint between cloth and frame smoothly with solder, so the material being sieved cannot catch in it.

此步骤所需材料：

锡铅焊料1 joint

助焊剂1 joint

所需工具：

电烙铁

Check it against the tolerances

Measure the warp and shoot wires separately. Their average opening must be 0.125 mm within ±6 %, their average diameter 0.086 mm within −15 to +35 %, and no opening may exceed 0.125 mm by more than 40 %. Reject a sieve with punctures, loose or wavy cloth, poor soldering, or too many large openings.

所需工具：