This American National Standard covers the design, dimensions and tolerances for 2, 3, and 4 post punch press tool die sets referred to in the standard as "die sets." They are in general demand by tool designers and are used by die makers for the mounting of punch press tool details and components. Included in the standard are back post, center post, diagonal post, and rectangular 2, 3, and 4 post all steel die sets. The standard shall be further divided into two categories. Those die sets which would comprise what is generally termed standard die sets consisting of back post, center post, and diagonal post sets in the size range up to 25" × 14" in die area and 4 post rectangular die sets with a die area up to 24" × 16". The range of sizes covered have been carefully selected with a view to meeting the largest volume of present needs of users and, therefore, may be manufactured on a production basis. The second category of this standard shall include sizes which are classified as special. Realistic tolerances which can be readily met with modern equipment have been established that will insure a high grade tool which can be maintained economically in respect to both the component parts and the die set assembly. Die sets covered in this standard are those as stated above and are both heavy and light duty. The die sets shown are of the conventional type with pressed in guide posts and press fit guide post bushings or with demountable guide posts and demountable guide post bushings or any combination thereof. The standard die areas may also apply to die sets with patented mountings for the guide posts and guide post bushings. There are in existence several different types of special guide posts and guide post bushings, some of which are proprietary in nature and therefore are not included in this standard.