A shop detail drawing is a graphic representation in some form of a part or the whole of a structure member like a beam or a column, that gives enough information to fabricate of the parts shown.
Detail drawings should include, but aren’t limited to:
- Sufficient accurate illustrations of the member to be manufactured, giving a clear idea of the arrangement of the parts. This doesn’t mean that the drawing should be equal to a photograph; only that the views should be created that are necessary to give a complete understanding of the make up of the member to be built. Its preferable that the drawings are made to scale, but the scale doesn’t play a very important part in the fabrication. The dimensions are the vital part of a shop detail however.
- Dimensions showing overall sizes, sub dimensions, the location of all rivets, bolts, slopes of members, position and nature of any notches or cuts in the material, gauges in all angles, channels, etc., and any other dimensions that are necessary for laying out the various parts of a piece. Each component part of a fabricated member must be laid out separately in the shop, and for this reason, caution should be used in making shop details to see that enough dimensions are given to permit of this independent laying out. As before stated, dimensions are the most important parts of such drawings. It’s a good practice for the drafter to check over his finished shop details and then ask himself the question “Can I lay out the component parts of this member with the use of the dimensions I’ve given?”
- General notes that include the diameter of the bolts or rivets, the diameter of the holes, the type of paint, the size of washers, if any, the specifications, the type of material, who’s going to inspect it, and any other notes and instruction.
- In the case of girders or beams, a note giving the position of one end or one flange often helps erection and saves turning around in the field. So, the drawing might read “Mark this end ‘South'” or “Mark this flange ‘Up,'” and the words “South” or “Up” would be painted on the proper part before the member left the shop. These are just a few instances of many cases where a little note will help get the job done easily in the steel shop.
- A sketch is often placed on a shop detail, giving a line diagram of the finished structure and showing by heavy line the position of the part detailed on the sheet on which the sketch appears. Thus, if the upper chord of a bridge were detailed on a certain sheet, a small line diagram of the bridge might be made on that sheet and the upper chord made of very heavy line, the remainder being of light lines. This promotes clearness. In case the shop detail on a sheet is that of a complete structure, a small erection diagram is often made on the same sheet. Of large structures, complete erection diagrams are made on independent sheets.
Tim Davis is a veteran general draftsman who has several different drafting courses online at his Online Drafting School at http://draftingschool.net.