1. Create the drawing 1. Add “initial release” to the revision description 2. Make sure material is correct 2. Use automatically placed projected views from the drawing template - but if this isn’t satisfactory create three projected views using the default third angle projection and scale if necessary 3. Fourth view isometric and shaded 4. Add all hole callouts 1. 4x prefixes where there are multiple of the same holes 2. Section views for countersunk holes 3. Tapped holes get a “COLD FORMED TAP” callout (make sure drill diameter is correct) 4. For a large number of holes, use a hole table 5. For bores + shafts, choose H7/k6 with the “fit with tolerance” option and 2 decimal places 5. For extrusion, specify the stock profile (e.g. 2040 Extrusion) and a “8x M8x0.8↧20” thread callout 6. Dimension everything you can 1. Reference dimensions in three axes to specify stock size 2. Dimension to datum features where possible 3. Create centerlines between related holes and dimension them to datums 7. If geometric tolerances are required (concentric bores, overconstrained assemblies, etc) 1. Label datums 1. Add flatness, perpendicularity and then surface tolerances to the faces first 2. Attach datums to those callouts 3. For rotationally symmetric parts, choose a surface for the rotational axis datum 2. 0.25 surface profile tolerance with “all over” leader 3. Add geometric tolerances, referencing datums in order of importance 8. Consult table below for low cost cnc tolerances 9. Request review 10. Once approved 1. Final check of materials, holes, key features 2. Create a version and make sure to update all geometry in drawings 3. Release all drawings at once 4. Email manufacturer with BOM and zip file # Low Cost CNC Tolerances | | | | |---|---|---| |Control|Low-Cost Default (mm)|Notes| |General size|ISO 2768-m|| |Flatness, general|0.05|Add 0.05/100mm| |Flatness, bearing surfaces|0.02|Add 0.03/100mm| |Parallelism|0.05|| |Perpendicularity|0.05|| |Concentricity|0.03|Control with position where possible| |Hole Diameters (non-locating)|H10-H11|| |Locating features|H7/h11|| |Locating feature position|Ø0.05 ABC|MMB| |Bolt hole positions|Ø0.15 ABC|Clamping bolts, not location| |Turned shaft diameters|h9 where required|| |Bearing shaft|k6|| |Bearing housings|H7|| |Runout|Circular: 0.02, Total: 0.05|| |Thread class|6H/6g|| |General machined Surface finish|Ra 3.2um|Tighten where required (idlers, sealing surfaces)|