CNC Turning Services for Custom Turned Parts

Which CNC turned parts get quoted here?

Turning cuts a rotating workpiece with a nearly stationary tool (source 1), so it suits parts that are round. Round parts with their own pages on the parts hub: shafts and pins, bushings and sleeves, standoffs and spacers, flanges, fittings, weld-in bungs and shaft couplers.

Tapers, grooves and drilled and bored holes are standard lathe operations (source 1), so put each on the drawing with its size: the taper’s angle or end diameters, the groove’s width and depth, the bore’s diameter and depth. A knurl is a serrated pattern pressed into the surface as a hand grip (source 1), which is what makes turned custom knobs and thumb screws easy to turn by hand; call out the pattern and where it goes.

Turned and milled parts: flats, cross-holes, keyways and splines

Most turned parts pick up a milled feature or two: a flat, a cross-hole, a slot. Lathes are often available with live-tooling spindles that mill and cross-drill, so a part can be machined complete in one setup (source 2). The live tools are driven through the turret while the part stays oriented to the main spindle, and polygon machining can produce squares or flats (source 3). Otherwise the milled features are a second operation. Either way you send one model, and the quote prices it as one part.

Keyed and splined shafts are quoted too. For a keyed shaft, dimension the keyway’s width, depth and length; parallel and tapered keyways are cut with end mills or slotting cutters (source 4). For a splined shaft, give the full spline data on the print; external splines can be milled, broached or shaped (source 5).

What does precision CNC turning hold?

On precision turned parts, only the diameters your print marks as critical, such as a bearing fit or a seal diameter, carry the critical-diameter figure in Quick Specs; the rest of the part is quoted to the general tolerance. CNC machining tolerances explains how to choose a band. Position, perpendicularity and runout callouts are quoted from the print. Grinding generally gives a better surface finish and greater dimensional accuracy than hard turning (source 1), and holds roundness and cylindricity more accurately (source 6), so a diameter that needs more than turning gives is quoted through precision grinding on the same order.

A thread is turned with a tool shaped to the thread (source 1). Single-point threading is the usual choice when only a few threads are needed, when the thread is unusual, or when it has to run concentric with features cut in the same setup (source 7), which is why a one-off or an odd pitch suits turned work. For an inch thread, write the diameter, threads per inch, series (UNC coarse or UNF fine) and class on the drawing: class 2A or 2B is the free fit and the most common, and class 3A or 3B is used for closer tolerances (source 8). Threads are quoted to the class on your print, and a screw, bolt or stud with a custom thread is covered on custom fasteners.

Materials for CNC turned parts

6061 aluminum is one of the most common aluminum alloys for general-purpose use (source 9) and the usual default for a light turned part. 7075 is one of the most used alloys for highly stressed structural parts (source 10), so it suits a turned part that carries load.

303 stainless is the free-machining version of the basic 18% chromium, 8% nickel stainless: its sulfur makes it the most readily machined austenitic grade, with significantly less corrosion resistance than 304, and shafts, bushings and fittings are among its typical uses (source 11). Free-cutting C360 brass contains about 3% lead and is the reference alloy, rated 100, on the machinability scale for copper alloys (source 12).

Titanium has the highest tensile-strength-to-density ratio of any metallic element (source 13), for a part that has to be strong and light. Delrin (acetal) is used for precision parts that need stiffness, low friction and dimensional stability, and its bar stock can be turned, milled and drilled with traditional methods (source 14).

Small and micro turned parts

Small-diameter and micro turned parts are quoted too. A Swiss-type lathe suits slender workpieces and large production runs of small-diameter parts (source 15), so if your part and quantity fit Swiss screw machining better, the quote says so. No maximum size is published: for a large part, send the print.

One piece, a small lot, or a production run

Ask for more than one quantity, such as 1, 25 and 100, and the quote shows each. 25 pieces is a good start. At 200, the price per part drops a lot. A production quantity can also be quoted in full and delivered in releases as a blanket order. Price, release schedule and lead time per release are set in the quote.

A finish called out on the print is quoted with the part; the finishing pages cover anodizing and passivation. Rush 1-2 weeks applies to machined parts with no secondary operations. Heat treat, grinding, EDM and finishing add time, and the quote gives the real date. Lead time starts at order approval. Put your need date in the part description and the quote answers it.

Sources

All accessed 27 September 2026. Where a figure here differs from your print, the print governs.

1. Wikipedia, "Turning": en.wikipedia.org/wiki/Turning (a nearly stationary tool cuts a rotating workpiece; taper turning, grooving, drilling, boring, knurling, threading; grinding against hard turning on finish and accuracy).

2. Production Machining, "Horizontal and Vertical Lathes", topic page: productionmachining.com (live-tooling spindles for milling and cross drilling, parts complete in one setup).

3. Preben Hansen, "An Introduction to Live Tooling", Modern Machine Shop, 2 July 2019, updated 1 May 2024: mmsonline.com/articles/an-introduction-to-live-tooling (live tools driven through the turret; polygon machining for squares or flats).

4. Wikipedia, "Key (engineering)": en.wikipedia.org/wiki/Key_(engineering) (what a key does; parallel and tapered keyways cut with end mills or slotting cutters).

5. Wikipedia, "Spline (mechanical)": en.wikipedia.org/wiki/Spline_(mechanical) (spline defined; external splines milled, broached or shaped).

6. Chris Koepfer, "Hard Turning as an Alternative to Grinding", Production Machining, 22 January 2010: productionmachining.com (grinding achieves higher roundness and cylindricity accuracy than hard turning).

7. Wikipedia, "Threading (manufacturing)": en.wikipedia.org/wiki/Threading_(manufacturing) (when single-point threading is used).

8. Wikipedia, "Unified Thread Standard": en.wikipedia.org/wiki/Unified_Thread_Standard (designation, UNC and UNF, thread classes).

9. Wikipedia, "6061 aluminium alloy": en.wikipedia.org/wiki/6061_aluminium_alloy (one of the most common alloys for general-purpose use).

10. Wikipedia, "7075 aluminium alloy": en.wikipedia.org/wiki/7075_aluminium_alloy (highly stressed structural applications).

11. Penn Stainless, "303 Stainless Steel": pennstainless.com/resources/product-information/stainless-grades/300-series/303-stainless-steel/ (free-machining 303; sulfur; corrosion resistance against 304; typical applications).

12. AZoM, "Free Cutting Brass UNS C36000", 12 November 2012: azom.com/article.aspx?ArticleID=6391 (61.5% copper, 3% lead, 35.5% zinc; machinability rated against C36000 = 100).

13. Wikipedia, "Titanium": en.wikipedia.org/wiki/Titanium (tensile-strength-to-density ratio).

14. Wikipedia, "Polyoxymethylene": en.wikipedia.org/wiki/Polyoxymethylene (precision-part properties; bar turned, milled and drilled with traditional methods).

15. Wikipedia, "Metal lathe", section on the Swiss-style lathe: en.wikipedia.org/wiki/Metal_lathe (Swiss-style lathe: guide bushing, slender workpieces, production runs of small-diameter parts).

16. Wikipedia, "Leadscrew": en.wikipedia.org/wiki/Leadscrew (lead is the distance travelled per rotation).