Steel rule

Steel rules, tapes, and other indicators of length should be checked periodically for wear and damage and although accuracy of greater than 1mm is not normally expected, the loss of material from the end of a rule may result in inaccuracies that affect product quality. 

A hydrophilic polyurethane prepolymer was made according to the procedure taught by Braatz. - The prepolymer was mixed with water at a ratio of 10 parts water to one part prepolymer. The emulsion was poured immediately onto a silicone release liner and allowed to cure for 30 min. It was free of voids and had a density roughly the same as water. For the contraction experiments, the gel was immersed in excess distilled and sterile water for 24 h, tlicii cut with a steel-ruled die into circles 40 mm in diameter. 

Premixed blends of acrylamide and bisacrylamide prepared with varius ratios of monomers were purchased from Eastman Kodak Chemical Company (Rochester, NY). The 37.5 1 and the 19 1 preparations were used for the study. Gels made from these mixtures will be referred to as 2.6% and 5% cross-linked polyacrylamides, respectively. Five grams of each monomer blend were added to 95-g portions of distilled water. Solution was achieved by mixing for 1 h. To each sample was added 1 ml each of a 1% solution of N, N, N, N -tetramethylethylenediamine (Eastman Chemical Co., New Haven, CT) and a 10% solution of ammonium persulfate (Mallinckrodt Laboratory Chemicals, Phillipsburg, N.1). The solutions were poured into an open polyethylene mold and allowed to cure for 12 h at room temperature. The gels were carefully removed and placed in an excess of distilled sterile water for 48 h. The water was replaced several times during the equilibration period. It was felt that this was sufficient to remove unreacted monomers and impurities. The gels were then cut with a steel-ruled die into circles 40 imn in diameter. 

Fig. S. A device used to simplify the calculation of potential energy surfaces. Here the steel rules correspond to a particular atomic configuration occurring in the reaction HCI 4- BrC -> HBr 4- CIC. The carbon atom is bonded to three other atoms which do not enter into the reaction. The scales on the rods give both the interatomic separations in angstroms and the corresponding Morse curve energies for the diatomic molecule in kcal/ mole.

Layout Tools The first step in prototype fabrication is transferring measurements from the drawing and laying them out on the material. Figure 8-13 shows common hand tools—a steel rule and a tape measure—used for measuring and layout. These measuring tools are typically graduated in. 1/16-inch measures. Tri squares or combination squares are used to transfer perpendicular lines to the material. For lumber, the transfer is marked with a pencil. If the material is metal, a scratch awl is used. 

FIGURE 8-13 Common measuring and layout tools (a) a steel rule, (b) a steel tri square, and (c) steel tape. 

The combination set consists of a graduated hardened steel rule on which any of three separate heads - protractor, square or centre head -can be mounted. The rule has a slot in which each head slides and can be locked at any position along its length. 

The surface gauge, also known as a scribing block, is used in conjunction with a scriber to mark out lines on the workpiece parallel with the reference surface. The height of the scriber is adjustable and is set in conjunction with a steel rule. The expected accuracy from this set up will be around 0.3 mm but with care this can be improved. 

Dividers and trammels are both set in conjunction with a steel rule by placing one point in a convenient graduation line and adjusting the other to coincide with the graduation line the correct distance away. 

Use a square on one datum edge and measure the distance from the other datum edge using a precision steel rule. Scribe lines. 

Measure from each long edge and find the centre using a precision steel rule. Scribe the centre line using the edge of the rule as a guide. Find the centre of the small radius by measuring from one end the size... 

Using dividers, set the distance from the centre of the small radius to the centre of the first small hole. Scribe an arc. Repeat for the second small hole and the large radius. Centre dot at the intersection of the centre lines. The dividers are set using the graduations of a precision steel rule. 

Complete the profile by scribing a line tangential to the two radii using the edge of a precision steel rule as a guide. 

Clamp the plate to the face of an angle plate, ensuring that the clamps will not interfere with marking out. Use a scriher in a surface gauge and set the heights in conjunction with a precision steel rule. Scribe the datum line. Scribe each horizontal line the correct distance from the datum. 

Using a precision steel rule measure from two adjacent edges to determine the datum point. Centre dot the datum point. 

Trimming of plastics, if not performed correctly, can be damaging to formed parts and slow down or stop the output. Tools for trimming include shear discs, steel rule dies, and saws. The cutting action can be done with the usual punch press, as well as press brakes and other devices. Punch and... 

The electrical equipment will be identified by graphical symbols on the plan, as described in Chapter 5 and shown in Fig. 5.5. The drawing will be to scale, and if we say the scale was 1 100, then 10 mm or 1cm on the site plan will represent 1 m in the building. The electrician can take measurements from the drawing and transfer these to the building, probably using a retractable steel rule. They can then mark on the walls of the building with a piece of chalk or a marker the final positions of the electrical equipment which is to be installed. 

Blanking (die cutting). The cutting of flat sheet stock to shape by striking it sharply with a punch while it is supported on a mating die. Punch presses are often used for the operation. An alternate method is to make the cut with a thin, sharp-edged, shaped steel blade called a steel-rule die. See also die cutting. 

Die cutters n. Cuts shapes from sheet stock by sharply striking it with a shaped knife-edge, known as steel rule die. 

Steel-rule die n. A sharp-edged knife fashioned from thin steel strip, flexible enough to be shaped to complex outlines. It is used as the cutting element in die cutting. 

A punching press similar to those used in the processing of rigid boards could be used for the blanking of flex circnits. Smaller tons are required to cut thin materials. Steel rule dies are the specialty for flex circuits (see Fig. 63.33). They can be prepared in a few days, and their costs are much smaller than those of hard tools. Their weight is also much smaller than that of hard tools and operators can manage them by hand. A typical cross section is shown in Fig. 63.33(a), a finished steel mle die is shown in Fig. 63.33(b), and some limitations on the configurations that can be used are illustrated in Fig. 63.33(c). Steel rule dies have less dimensional accnracy, lower productivity, and a shorter life than hard tools, and they need maintenance more frequently. 

FIGURE 6333 Steel rule die for blanking flexible circuits (a) A cross section of the configured die, (b) A sample finished die (c) Limitations on shapes that can be designed into a steel rule die. 

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