Custom Machined Fixtures Built to Print

What is the difference between a fixture and a jig?

A fixture is a work-holding or support device: a solid base, location elements such as pins, buttons and surfaces, and clamps that hold the work in place (source 1). A jig controls the location or motion of the part or the tool (source 2). On a drill jig, a hardened drill bushing usually lines each hole in the jig plate, guiding the drill and keeping it from damaging the jig (sources 1 and 2). By that line, a check fixture, a weld fixture and an assembly nest are fixtures, and a drill or trim jig is a jig. Custom jigs and fixtures are quoted the same way.

Which fixture page fits the job?

To check a finished part on its datums, several features at once, start with check and inspection fixtures. One hole or one thread is usually a gauge job: a go/no-go gauge checks a feature against its tolerance limits and gives a pass or a fail rather than a measurement (source 3). Custom gauges covers thread, plug, pin and ring gauges, check fixture vs gauge sets out where one ends and the other begins, and who makes custom check fixtures compares the places buyers get them.

A machined end-of-arm tooling plate has its own page; a flat robot mounting plate cut from sheet or thin plate stock is on laser-cut robot mounting plates.

For a fabrication or welding shop, the starting page is weld fixtures and jigs; for an electronics contract builder, test fixtures; for a Tier automotive supplier, check and inspection fixtures; for a lab or university group, CMM holding fixtures. Injection molders and stampers and automation integrators and machine builders have pages of their own, and machined parts for the machines themselves are on custom machinery and robotics and automation.

What does a build-to-print fixture quote cover?

The quote prices the whole print as one order, with one contact, and catalog hardware named on the BOM by part number is priced as listed. Plate work, pockets, and dowel and tapped holes are CNC milling; a ground locating pin or wear pad adds precision grinding. A callout that cannot be made or checked as drawn is listed in the quote, and the print stays as drawn unless you change it. If a part doesn’t match the print, it’s remade or credited. The part the fixture checks or holds can go on the same order, and custom machined parts covers that side. Custom fixture cost explains which callouts move the price.

Questions about paperwork with a fixture are answered in one FAQ on the check and inspection fixtures page. Vendor setup takes a day: W-9, NDA, net terms available. Card by secure link (a processing fee applies), ACH, wire or check.

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. Fixture lead time covers dating fixtures against a program launch, and rush CNC parts covers how a rush job is quoted.

Which materials go into a fixture?

MIC-6 and ATP-5 are both sold for fixture work, and aluminum tooling plate fixtures covers them in full. Alcoa’s MIC-6 brochure lists checking fixtures, gauges and templates among its uses, describes a separate furnace treatment that stress-relieves each plate, and gives 0.005 in as the maximum deviation from flat on plate 3/4 in and thicker (source 4). ATP-5 is Vista Metals’ 5083 plate, homogenized and stress relieved; its data sheet guarantees 0.005 in flatness over 0.500 in thick and names assembly and machining jigs and fixtures among its uses (source 5).

For risers, blocks and other details, the grades have their own pages: 6061-T6 on aluminum 6061, and 1018 and 4140 on steel, with steel fixture details covering where each goes on a fixture. Hudson Tool Steel’s D2 data sheet cites good resistance to wear from sliding contact with other metals (source 6), and its A2 sheet lists dowel pins and gages among A2’s uses (source 7); either goes on pins and wear pads when the print names it. Plastic contact pads in Delrin or UHMW are covered on Delrin and UHMW fixture details. G10 is the older glass-epoxy laminate grade and FR-4 its flame-resistant successor, used as an electrical insulator with considerable mechanical strength (source 8). The test fixtures page lists G10/FR4 for standoffs and insulating details, and G10, FR4 and phenolic details has the rest. Other alloys and plastics quoted on request. Name the grade on the print.

Sources

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

1. Wikipedia, "Fixture (tool)": en.wikipedia.org (a fixture as a work-holding or support device: solid base, locating pins, buttons and surfaces, clamps; drilling fixtures guide the bit through a bushing).

2. Wikipedia, "Jig (tool)": en.wikipedia.org (a jig controls the location or motion of parts or tools; typically a hardened drill bushing lines each hole in a jig plate).

3. Wikipedia, "Go/no-go gauge": en.wikipedia.org (a go/no-go gauge checks a workpiece against its tolerance limits and returns pass or fail, not a measurement).

4. Alcoa, "MIC6 Precision Machined Cast Aluminum Plate" brochure, 2006, hosted by Howard Precision: howardprecision.com/wp-content/uploads/2017/08/Mic-6-brochure-1-1.pdf (listed applications, the separate stress-relief furnace treatment, maximum deviation from flat by thickness).

5. Vista Metals, "ATP-5 Aluminum Tooling Plate" data sheet: public.vistametals.com/products/atp-5-precision-tooling-plate.pdf (AA 5083 alloy, homogenized and stress relieved, guaranteed flatness by thickness, listed applications).

6. Hudson Tool Steel, "D2 Tool Steel": hudsontoolsteel.com/technical-data/steelD2 (good resistance to wear from sliding contact).

7. Hudson Tool Steel, "A2 Tool Steel": hudsontoolsteel.com/technical-data/steelA2 (dowel pins and gages among its typical applications).

8. Wikipedia, "FR-4": en.wikipedia.org (G-10 and FR-4 as glass epoxy laminate grades, G-10 the predecessor without FR-4’s self-extinguishing flammability; FR-4 used as an electrical insulator with considerable mechanical strength).