Hardware buying guide
Shortlist machine shops around the parts you need to make: geometry, materials, tolerances, quantities, and inspection requirements.
Sources reviewed October 5, 2026.
Build a cnc machining brief →03 / Compare
Compare the same drawing revision, material, quantity, finish, and inspection scope. Separate one-time costs from repeat-order pricing.
Compare provider details →Begin with the features that make the part work: mounting interfaces, bearing fits, sealing faces, alignment, or another functional requirement. Tell the shop which features must be inspected and whether the requirement applies before or after finishing. A model describes shape; the quote also needs your material, finish, and acceptance requirements.
Ask for the actual measurement record you need, not simply an assurance that parts are inspected. Protolabs' tolerance guidance describes service-dependent limits and drawing callouts; a published tolerance is useful context but does not confirm that your whole part is accepted for that service.
Use these evidence requests to resolve the project scope before ordering.
On smaller screens, scroll across to read the evidence and open questions.
| Question | Evidence to request | Needs clarification |
|---|---|---|
| Can you manufacture the critical features? | A review of the named drawing revision with feature-specific exceptions. | A generic tolerance claim with no response to the fit requirements. |
| How will you inspect the part? | A sample report and an agreed list of measured features. | Inspection is included, but reporting and sampling are undefined. |
| Who performs finishing? | The finishing scope, supplier responsibility, and dimensions affected. | The quote lists a finish without explaining exclusions or measurement stage. |
Illustrative project: a 20-part aluminum bracket pilot has two alignment holes and a mating face. Send every candidate the same revision and identify those interfaces as critical. Ask whether machining, finishing, and the agreed measurement report are covered. A cheaper quote with no inspection deliverable needs clarification before comparison. Review the pilot's evidence before increasing the order quantity.
It may start the conversation. Supply a drawing or another agreed specification for critical tolerances, threads, finishes, and inspection. Ask the shop to identify anything it cannot determine from the files.
Specify tolerances around the part's functional needs with your engineer. Ask which requirements change the process or inspection cost; do not loosen a critical feature solely to lower the price.
Request a separate quote for the repeat-build quantity and process. Setup, fixtures, material purchasing, and reporting assumptions may change.
Sources provide technical or program context. Checklists and project examples are original editorial guidance. Supplier documents describe that supplier's service; confirm your quoted scope directly.
Documented service scope
These records have an official capability source. Details may cover one service within a provider's wider offering; confirm the process and material combination for your project.
Processes: CNC milling, CNC turning, Five-axis machining, Injection molding, Sheet metal fabrication, Surface finishing
Scope and buying questions: Quote the actual alloy, grade, tolerances, and finish rather than the full catalog. Who approves a suggested design change? Confirm the production location and dimensional evidence, especially for features finished after machining.
Official capability source →Processes: CNC milling, CNC turning, Laser cutting, Waterjet cutting, Injection molding, 3D printing
Scope and buying questions: Confirm that submitted drawings and CAD use the same units and revision. Which tolerances require explicit review? Ask what material, finish, and dimensional evidence are included, and how changes are approved after ordering.
Official capability source →Processes: CNC machining, Design for manufacturability
Scope and buying questions: Ask which location will machine and inspect the part. Specify critical datums, material grade, finish, and inspection records. Are secondary operations included, and which drawing revision controls the quote?
Official capability source →From the directory
3ERP documents CNC milling, turning, and five-axis work within a portfolio that includes molding, sheet metal, casting, and additive manufacturing.
Not documented
Online custom manufacturer for CNC machining, sheet metal, and 3D printing.
United States
On-demand manufacturing services spanning additive manufacturing, CNC machining, injection molding, and sheet metal.
United States
Manufacturing platform for prototypes, tooling, and production parts.
San Francisco, California, United States
These are directory matches, not endorsements. Sponsored placements are labeled. Confirm experience, scope, and availability directly.
