Has this ever happened to you? You go to a business establishment and ask for a written estimate for your sheet metal design. They give you a written estimate, but when they present you with the actual bill it’s higher than what was quoted?
- To get the optimum metal usage out of your sheet metal design, plan to use sheets that are 48 or 60 inches wide and 120 inches long. That is the standard for the sheet metal industry.
- A trim cut is required on each side of the sheet to remove the mill edge and get a straight edge – plan to have a usable sheet of 47 x 119 inches.
- Use standard metal types, standard gauge sizes, as well as standard alloys. Exotic is always more expensive.
- Plan how many parts you can get from a sheet based on a single part. This number becomes the Economic Order Quantity Multiple for that part. Example: if you get 56 pieces per sheet, order in multiples of 56 pieces.
- To get a correct part you must convey your design intent to a vendor. This is done with a blueprint or at the very least a sketch. Be sure to include the metal type, metal thickness, metal alloy, tolerances, and finish in the notes section of your sheet metal design.
- In addition to the three standard views (top view, front view, and side view) your drawing should also include any auxiliary views required to clarify any ambiguities. Additionally, your drawing should also have a part name, a drawing number, a revision number, and a date.
- Placing the part name, number, revision and date on your purchase order is your assurance that the vendor will make the correct part to your specifications.
- If you are making items that will bolt together, add some clearance to the hole sizes to allow for minor adjustments or use floating nuts
- Double check your blueprints to ensure the distance between hole centers is the same on mating parts.
- If you are using hardware such as: screws, nuts, bolts, washers, handles, latches, rubber bumpers, grommets, standoffs, etc., then your blueprint should include a bill of materials showing the part name, part number, manufacturer, vendor, and the quantity required to build one unit.
- Make sure that notches, holes, countersinks, counterbores, and embossments are far enough away from any bends so they won’t become distorted during the forming process.
- Listed below there are some excellent on-line resources that can help you with your sheet metal design.
Excellent Hardware Supplier – McMaster Carr
Excellent Hardware Supplier – MSC Direct
Free drafting software – SolidEdge
Free drafting software – Solidworks Blueprint Now
Free drafting software – Google SketchUp
Need a few scraps of metal to live test a design? Check out: Scrap All 2801 E 4th Ave,Tampa,FL, 33605 (813) 247-3619