---
title: "Custom CNC Machining Services | Metal & Plastic Parts | OpenSpindle"
description: "Get quotes for custom CNC machined parts from independent machine shops. Milling, turning, and 5-axis in metal and plastic. Upload a drawing."
canonical: https://openspindle.com/capabilities/cnc-machining
---

# Custom CNC machining from independent machine shops

Tight-tolerance milled and turned parts in metal and plastic, quoted by independent machine shops. Upload a drawing and hear back from shops that already run the machines your part needs.

## Machining shops on OpenSpindle

Real shops that mill and turn custom parts. See the machines they run and talk to the person making your part.

[Browse all machining shops](https://openspindle.com/manufacturers?capability=CNC%20milling)

## Materials our machining shops run

CNC machining starts from solid billet. If your alloy is not here, ask when you request a quote.

- [Aluminum](https://openspindle.com/materials/aluminum.md) -- 6061 · 7075
- [Stainless steel](https://openspindle.com/materials/stainless-steel.md) -- 304 · 316
- [Carbon steel](https://openspindle.com/materials/carbon-steel.md) -- 1018 · 4140
- [Titanium](https://openspindle.com/materials/titanium.md) -- Grade 5
- [Brass](https://openspindle.com/materials/brass.md) -- C360
- [Copper](https://openspindle.com/materials/copper.md) -- C110
- [Delrin](https://openspindle.com/materials/delrin.md) -- Acetal
- [PEEK](https://openspindle.com/materials/peek.md)
- [Nylon](https://openspindle.com/materials/nylon.md) -- 6/6

## Tolerances

| Feature | With drawing | No callout |
| --- | --- | --- |
| Linear dimension | ±0.005 in | ISO 2768 Medium |
| Hole diameter (not reamed) | ±0.005 in | ISO 2768 Medium |
| Shaft diameter | ±0.002 in | ISO 2768 Medium |
| Surface finish | 125 Ra as-machined | 125 Ra as-machined |

Shops quote to your drawing. Tighter tolerances are available from shops running CMM inspection. Ranges are typical, not guaranteed until a shop quotes your specific part.

## Threads, Inserts & Finishing

Tapped holes, heat-set inserts, press-fit and PEM-style hardware installed before the part ships. Note the callouts on your drawing.

Applied after machining, so each one adds days. As-machined ships fastest; anodize, powder coat, and passivation are common on machined parts.

| Finish | Materials | Adds | Stacks with |
| --- | --- | --- | --- |
| As-machined | All | +0 days | Anything |
| Bead blast | Aluminum, stainless | +1-2 days | Anodize, passivation |
| Powder coat | Aluminum, steel | +3-5 days | Bead blast. Not with anodize. |
| Passivation | Stainless only | +2 days | Bead blast |

Worth knowing: powder coat adds 0.002 to 0.005 in per side. On tight clearances or small holes, account for it or mask them.

## What Makes a Good RFQ

| Instead of | Send |
| --- | --- |
| "CNC part, need a quote" | "6061-T6 bracket, tolerances per drawing, qty 50, as-machined" |
| "Aluminum, tight tolerance" | "6061-T6, ±0.005 in on the two bore centers only" |
| "ASAP" | "Need in hand by the 30th, happy to pay for rush" |

Tolerance drives cost more than any other line on your drawing. Call out only the features that actually need it.

## Industries Served

- Aerospace
- Defense
- Electronics
- Robotics
- Medical devices
- Automotive
- Energy
- Industrial / OEM
- Consumer products

Machine shops on OpenSpindle make parts for regulated and demanding industries, including shops with AS9100 and ITAR registration.

## Frequently Asked Questions

### What tolerances can machining shops hold?

Plus or minus 0.005 in is standard with a drawing, and shops running CMM inspection hold tighter on critical features. Send your drawing when you request a quote and the shop confirms feasibility before cutting.

### Is there a minimum order quantity?

No. Shops quote single prototypes and production runs alike. Expect a one-time setup charge on one-off parts that is reduced on repeat orders.

### Do I need an account to get a quote?

No. Upload a drawing and shops respond. You only create an account if you want to keep the conversation and your files in one place.

### What materials can shops machine?

Metals including aluminum, stainless, carbon and alloy steel, titanium, brass, and copper, plus engineering plastics like Delrin, PEEK, and nylon. If your alloy is not listed, note it in your request and shops will confirm sourcing.

### What file formats should I send?

STEP, STP, IGES, X_T, DWG, DXF, or a PDF drawing. Include material, key tolerances, quantity, and any finish or secondary operations so quotes come back fast and accurate.

### Does my part need milling or turning?

Round or cylindrical parts like shafts, pins, and bushings are turned on a lathe; prismatic parts with pockets, faces, and holes are milled. Many shops do both and will pick the right process from your drawing.

### Can shops do finishing and secondary operations?

Many offer anodizing, powder coating, bead blasting, tapping, and hardware installation. Note what you need in your request so it is built into the lead time and price.

## Other Capabilities

- [CNC Turning](https://openspindle.com/capabilities/cnc-turning.md)
- [Sheet Metal](https://openspindle.com/capabilities/sheet-metal-fabrication.md)
- [Waterjet Cutting](https://openspindle.com/manufacturers?capability=Waterjet%20cutting)
- [Laser Cutting](https://openspindle.com/manufacturers?capability=Laser%20cutting)
- [Welding](https://openspindle.com/manufacturers?capability=Welding)
- [CNC Routing](https://openspindle.com/capabilities/cnc-routing.md)
- [EDM & Wire EDM](https://openspindle.com/manufacturers?capability=EDM)
- [3D Printing](https://openspindle.com/manufacturers?capability=3D%20printing)

## Design Notes That Move Your Price

Not a definition of CNC machining. The design choices that move your price and lead time.

- **Internal corners have a radius:** An end mill cannot cut a sharp internal corner. Design a radius of at least one third the pocket depth, or the shop adds an operation.
- **Deep pockets cost more than wide ones:** Past about four times the tool diameter the shop steps down to a longer tool and slower feeds. Shallow and wide is cheaper.
- **Every tolerance callout is money:** ±0.001 in on a face that does not mate adds inspection time for nothing. Tolerance only the features that function.
- **Thin walls chatter:** Under 0.030 in in metal, walls flex against the cutter. Expect a finish pass, or thicken the wall.

## Get CNC machining quotes

Upload a drawing once and compare quotes from independent machine shops.