Guides for Buyers of Custom CNC Auto Parts
Written for people who have a part to make and want to know what to ask before they send it out.
Start here
How to Get a Custom Auto Part Machined
The whole job in one page: whether your part should be machined, what it costs, which alloy to ask for, what to send a shop and how to read the quotes you get.
- Buying Guide
Oct 25, 2026Aftermarket Car Parts Trade Shows 2027: Dates and Plan
Aftermarket car parts trade shows for 2027 and 2028: SEMA, PRI, Tokyo Auto Salon, EQUIP AUTO, Essen and Automechanika, with organiser dates and a visit plan.
- Buying Guide
Oct 25, 2026Billet Differential Covers and Rear End Parts: Specs
Billet differential cover guide: bolt pattern, flange flatness, sealing finish, fill and drain ports, bearing cap support and material for rear end parts.
- Process
Oct 22, 2026Press Fits and Bearing Bores in Machined Automotive Parts
How to specify bearing bore tolerance on automotive parts: ISO fit classes, aluminum housings that loosen when hot, bore finish, chamfers and how to inspect.
- Process
Oct 17, 2026AN Ports, Metric Fine and NPT: Thread Specs on Car Parts
AN, metric fine and NPT ports compared for machined car parts: dash sizes, thread callouts, sealing method and what to write on the drawing for fluid ports.
- Materials
Oct 12, 20264130 vs 4140 Chromoly for Machined Automotive Parts
4130 vs 4140 chromoly compared for machined automotive parts: carbon content, strength, weldability, heat treatment, stock forms and which suits which part.
- Materials
Oct 8, 2026Anodizing and Finishes for Billet Car Parts Explained
Clear anodize, color anodize, hard coat, powder coat, plating and bead blast compared on cost, durability and how much each one changes a machined dimension.
- Choosing a Supplier
Sep 24, 2026How to Choose a CNC Machine Shop for Custom Car Parts
Fit matters more than reputation. The shop types, the seven questions worth asking before you send a drawing and the answers that should make you keep looking.
- For Shops
Sep 24, 2026What a Good Automotive Machining RFQ Looks Like to a Shop
For machine shops. How to score an incoming automotive request in two minutes, which gaps are worth a phone call and how to price one off work properly.
- Materials
Sep 23, 20266061 or 7075 Aluminum for Automotive Brackets and Mounts
The two aluminum alloys most billet car parts are cut from, compared on strength, fatigue, corrosion, welding and cost, and when each one is the wrong choice.
- Process
Sep 23, 2026Getting Custom Engine Swap Mounts and Brackets Machined
Swap parts are easy shapes in hard positions. How to define a mount or adapter plate so the first set fits, and where to leave adjustment and where not to.
- Process
Sep 23, 2026Reverse Engineering a Discontinued Car Part for Machining
What a shop needs when the only reference is the broken original: which dimensions to measure, when 3D scanning pays off and what to send with the RFQ.
- Cost
Sep 23, 2026What to Send a Machine Shop So It Can Quote Your Part
Shops price what they can see and pad what they cannot. The files, dimensions and notes that get a firm number, plus a copy and paste RFQ template to send.
- Process
Sep 21, 2026Billet vs Cast Auto Parts: How to Pick the Right One
Machining from solid and casting solve different problems. How the two compare on strength, cost per part, lead time and design freedom, and where they cross.
- Cost
Sep 21, 2026Custom CNC Auto Parts Cost: What Actually Drives It
A breakdown of what you pay for when a shop machines a one off or small batch automotive part, and four changes that bring a quote down without hurting it.