CAD and technical drawing articles

Practical guides for machinists, production and QC engineers, laser-cutting customers and engineering students. Every article can be followed step by step in DXCAD2D Online, which runs free in your browser.

2D drafting and CAD files

• DXCAD2D Online user guide — the complete manual

  Everything in one page — the screen, commands, shortcuts, typed distances, snaps, layers, and opening and exporting files.

• How to open a DXF file online for free — no install

  What a DXF file is, how it differs from DWG, how to open one in the browser, and how to fix wrong units, garbled text and missing parts.

• Exercise: draw a round flange with 6 holes on a PCD, step by step

  Draw a Ø120 flange with a Ø50 bore and six holes on a Ø90 PCD using coordinates and a polar array, then export DXF and PDF.

• First-angle vs third-angle projection: reading and drawing views correctly

  Top view below or above the front view, side view left or right — read the cone symbol and draw views in the right system.

• Drawing paper sizes A4–A0 and common drawing scales

  A4–A0 sizes from ISO 216, choosing a scale from 1:1 to 1:10 or 2:1, and laying out the frame and title block.

• Dimensioning technical drawings to ISO 129-1

  Extension lines, dimension lines, arrowheads and values, the Ø and R symbols, dimensioning each feature once, and chain versus baseline.

• How to convert SVG to DXF at the right size

  SVG to DXF with Inkscape, fixing px-to-mm scale, dealing with Bézier curves, and checking the result before it goes to the shop.

• Free 2D CAD programs that can replace AutoCAD

  LibreCAD, FreeCAD, QCAD CE, nanoCAD Free, DraftSight and DXCAD2D Online compared on licence, commercial use and DWG support.

• Convert a PDF drawing to CAD lines (DXF) for free, at the right scale

  Open a PDF as editable lines, text and tables, scale it from a known dimension, then export a DXF.

• DXF vs DWG: what is the difference, and which should you send?

  Who owns each format, which programs open them, R12 versus newer versions, and which file to send to whom.

• Line types and line weights in technical drawings (ISO 128)

  What each line type means, how to pick standard line weights, and how to set them up correctly from the start.

• Section views and hatching in technical drawings

  When to use each kind of section, cutting planes and labels, 45° hatching, the parts that are never hatched, and how to do it in the program.

Production and documentation

• How to prepare a drawing for laser cutting

  Rules for files a laser shop can cut right away — closed shapes, no doubled lines, kerf, hole size against thickness, separate layers — with a worked example and a checklist.

• General tolerances (ISO 2768) and H7/g6 fits explained

  ISO 2768 tables for classes f, m, c, v, how to state them on a drawing, and H7/g6, H7/h6, H7/k6, H7/p6 fits with example values.

• What a title block needs, and how to control revisions so nobody builds the old version

  The fields every title block needs, a revision table, and the steps to raise a revision after an ECN so the shop floor never works from an old drawing.

• Drawing tapped holes, clearance holes, counterbores and countersinks correctly

  Draw and annotate tapped, clearance, counterbored and countersunk holes, with tap-drill and clearance-hole tables for M3–M12.

• Named dimensions A, B, C and a dimension table on your drawing

  Put letters on the drawing instead of numbers and keep values and tolerances in one table — easy for QC and reusable across sizes.

• Sheet metal flat patterns: bend allowance and K-factor

  Bend allowance, bend deduction and K-factor formulas with a step-by-step example, and how to draw the flat pattern for laser cutting.