52 Machine Trades Print Reading Copyright Goodheart-Willcox Co., Inc. Weight Block When required, the weight block indicates the weight of the manufactured product. Refer to Figure 4-4(H). Actual or estimated values specify the weight. The actual weight is the “true” weight of a fi nished part. The estimated weight is a calculated value that controls the part’s weight during the manufacturing process. The fi rst sheet is the only sheet that shows the weight. Sheet Block The sheet block tells you how many sheets make up the total number of sheets in a drawing and shows the current sheet number for a drawing or a set of drawings. Refer to Figure 4-4(I). Part Number A part number identifi es a specifi c item or part. Refer to Figure 4-4(J). Part numbers are located in the main title block, a parts list, an application block, or separately on a drawing. A part number may or may not be included in a title block. A part number can represent the manufactured part or a distributor’s number for a supplied part. Some companies also use the part number as the drawing number. Drawn By and Date The drawn by area in the title block contains the initials of the drafter who produced the drawing. Refer to Figure 4-4(K). The date area records the starting time or initial completion of the drawing. Checked By and Date The checked by area in the title block contains the initials of the drafting department’s supervisor or manager who checks the prints for clarity and accuracy. The date area records the time of inspection. Refer to Figure 4-4(L). Approved By and Date The approved by area in the title block contains the initials of the drafting department’s supervisor or manager who approves the drawing for use. The date area records the time of approval. Refer to Figure 4-4(M). Material Number Material number is the number assigned by a company to identify the material required for making a part. The number typically refers to a stock number for a specifi ed material. Refer to Figure 4-4(N). Material Description Material description indicates the specifi c type of material required for manufacturing a part. It may also specify the size of stock. Refer to Figure 4-4(O). Material Finish The material fi nish area contains fi nish specifi cations required for manufacturing a part. Refer to Figure 4-4(P). Angle of Projection Block The angle of projection block identifi es whether the drawing is a fi rst-angle or third-angle projection as described in Unit 2—Visualizing Shapes. Refer to Figure 4-4(Q). Tolerance Block Tolerance is the amount of variation permitted in the value of a dimension representing a part or any of its features. The tolerance is the difference between the lowest allowable value and the highest allowable value. A feature is a physical component of a part identifi ed on a drawing such as a surface, hole, slot, edge, or any other described items. The tolerance block indicates the general When reading the dimensions of an object, do not scale (measure) them from the drawing. Scale only reflects the size of the object in relationship to the drawing. It is common for drawings to be printed a different size than the original. When this happens, the scale of the object is no longer accurate. Always use the dimensions listed on the drawing. Dimensions listed on the drawing are always the actual sizes of the object regardless of the scale and size of a drawing. PRO TIP