Every machine shop has seen it: a quote request that arrives as a screenshot, a STEP file with no drawing, or a print with no material callout. Each missing detail adds a round of emails, and usually a bit of extra cost, because a shop has to price in the unknowns.
Here’s what we look for at our Murfreesboro shop when a request for quote (RFQ) comes in. Get these right and you’ll get faster quotes, sharper pricing and fewer surprises when parts arrive.
1. Send both a 3D model and a 2D drawing
The 3D model (STEP is the most universal format) tells us the geometry. The 2D drawing (PDF) tells us what matters: tolerances, finishes, threads and notes. One without the other leaves gaps.
- STEP (.stp / .step) for geometry. IGES, Parasolid and native SolidWorks also work.
- PDF drawing with dimensions, tolerances and notes.
- Make sure both files are the same revision.
2. Only tighten what really matters
Tolerances drive cost more than almost anything else. A general title-block tolerance of ±.005″ is achievable on most features at normal speeds. Calling out ±.0005″ on every dimension forces slower machining, more inspection and sometimes extra operations, even on features that don’t touch anything.
Apply tight tolerances to the features that need them: bearing bores, mating surfaces, locating pins. Let everything else fall to the title block. Your quote will reflect it.
3. Call out the material and condition precisely
“Aluminum” or “stainless” isn’t enough to quote accurately. Include the alloy and temper or condition, for example:
- 6061-T6 aluminum, or 7075-T651 if you need the strength (here’s how to choose)
- 304 vs. 316 vs. 17-4 PH stainless
- 4140 pre-hard, or 4140 annealed and heat treated after machining
- Any material certification requirements
4. Use datums and GD&T where it helps
A clear datum structure tells the machinist how the part is located and measured, which removes ambiguity on parts with several critical features. You don’t need GD&T on a simple bracket. But on a precision housing, a few well-chosen position, flatness or perpendicularity callouts communicate intent far better than a pile of plus-and-minus dimensions.
5. Specify finishes, threads and edges
- Surface finish: a default Ra (e.g. 125 µin) plus any tighter callouts on sealing or sliding surfaces.
- Threads: size, class and depth (e.g. 1/4-20 UNC-2B × .50 deep).
- Edges: a general note like “break all sharp edges .005–.015” saves guesswork.
- Coatings and heat treat: anodize type and color, plating, hardness range, and whether dimensions apply before or after.
If your part needs to be ground to final size after heat treat, note it. See when to grind instead of mill.
6. Tell us about quantities and timing
Price per part changes a lot between 5 pieces and 500. Quoting a few quantity breaks (say 10 / 50 / 250) and an annual usage estimate lets us show you where pricing drops. A realistic due date helps us tell you right away whether we can hit it.
7. Add the context a print can’t show
A sentence about what the part does (“this bore takes a pressed bearing,” “this face seals against a gasket”) helps a machinist make good decisions and spot problems early. If there’s a prior supplier issue you’re trying to fix, tell us.
Quick RFQ checklist
- STEP model + PDF drawing, same revision
- Material alloy, temper and certification needs
- Tight tolerances only where they matter
- Surface finish, threads, edge breaks
- Coatings, heat treat and any post-process grinding
- Quantities, annual usage and due date
- A sentence on what the part does
Ready to send yours? Upload your drawing here. We’ll review it with these points in mind and usually reply within one business day.