The quality of a machining quote depends on the quality of the information behind it. Missing details lead to assumptions, and assumptions lead to back-and-forth emails, revised prices, or parts that are not quite what you needed. Here is how to send a request that a machinist can quote accurately the first time.
The best files to send
- A 3D CAD model in STEP format (.step or .stp). STEP opens in almost every CAD/CAM system and carries exact geometry.
- A 2D drawing as a PDF, and DWG or DXF if you have it. The drawing carries what the 3D model cannot: tolerances, threads, surface finish, and notes.
- Native files (such as SolidWorks .sldprt) are useful as a backup, but STEP plus PDF is the most reliable combination.
What to include on the drawing
- Material grade, for example aluminium 6061, SS 304, EN8, or Delrin, not just 'steel' or 'plastic'.
- Tolerances on critical dimensions, plus a general tolerance note for everything else.
- Thread callouts with size and pitch, for example M8 x 1.25, and whether the thread is internal or external.
- Surface finish requirements where they matter, such as sealing faces or sliding surfaces.
- Any heat treatment, plating, coating, or other finishing.
- Units, a revision number, and a part name or number.
What to put in your message
- Quantity, and whether repeat orders are likely. Price per piece changes a lot between 1, 10, and 100 parts.
- When you need the parts, and whether that date is fixed or flexible.
- What the part does and how it fits with other parts. Context helps the machinist spot problems before cutting metal.
- Delivery location, or whether you will collect.
No drawing? You can still get a quote
Plenty of good parts start without a formal drawing. If you only have a hand sketch, add the key dimensions and note which ones are critical. If you have an old or broken part, a photo next to a ruler or scale, along with its overall size, is a good start. For an accurate quote, the sample part itself is often the best reference of all.
Common mistakes that slow quotes down
- 01Tight tolerances on every dimension instead of only on the features that need them.
- 02Missing material grade, which can change the price significantly.
- 03Mismatched files, where the CAD model and the drawing show different revisions.
- 04Threads modelled as plain holes with no callout on the drawing.
- 05No quantity, so the shop has to guess or quote several options.
A simple checklist
- STEP file and PDF drawing, same revision
- Material grade
- Quantity and required date
- Critical dimensions and tolerances marked
- Threads, finishes, and treatments noted
- A sentence on what the part does
Send what you have, even if some items are missing. A good shop will ask the right questions, and the checklist above simply gets you to a firm price sooner.
Have a part to make?
Send your drawings, CAD files, or a sample part and we'll come back with a straightforward quote.
Related services: Custom Parts Manufacturing · Prototype Machining
