Question 1

What are typical CNC machining tolerances you can achieve at Approved Machining?

Accepted Answer

For high-precision features, we can hold tolerances as tight as ±0.0005 inches, such as for press-fit hardware holes. For more complex features like true position relative to multiple datums, tolerances around ±0.002 inches are typical. In certain cases, even tighter tolerances are possible depending on part geometry and material.

Question 2

How do tight tolerances affect the cost and lead time of machined parts?

Accepted Answer

Tighter tolerances often lead to higher production costs and longer lead times. This is due to increased machining time, added inspection requirements, and a greater risk of scrapping parts. Keeping tolerances only where necessary for fit or function helps manage costs and avoid RFQ surprises.

Question 3

Why is it important to evaluate if a tight tolerance is truly necessary?

Accepted Answer

Unnecessarily tight tolerances can inflate costs and introduce manufacturing challenges without improving functionality. In many cases, relaxing non-critical tolerances leads to more efficient production while still meeting all performance requirements.

Question 4

Can Approved Machining help revise designs to improve manufacturability?

Accepted Answer

Yes. We frequently collaborate with customers to review and adjust tolerances. For example, we recently helped a customer redesign a part that originally required extreme flatness, which was not feasible. Our recommended change resulted in a successful, functional part with shorter lead time and lower cost.

Question 5

When is the best time to talk to your team about tolerances?

Accepted Answer

Upfront! Engaging with us early in the design process allows us to align your design with manufacturability best practices. By understanding your project’s goals, we can offer feedback that keeps your timeline and budget on track.

Machining Tolerances

A Guide to Mastering Tolerances in CNC Machining (Updated for 2025)