Laser-Cut Plates, Spacers and Shims

A plate that does its job flat

Most base plates, adapter plates, spacers and washers only need a profile, a hole pattern and a thickness, and a laser cut produces the profile and the holes from one file. An adapter plate that moves a motor bolt pattern onto a gearbox flange, a base under a small machine frame, a spacer that lifts a sensor off a bracket, a set of stainless shims that sets a gap: each is a flat part with holes, and none needs a milled pocket.

The dividing line is what the plate has to hold. A bolt pattern, a clearance slot and a notch come out of the same cut. A thread, a countersink for a flat-head screw or an edge chamfer is called out on the print and quoted with the part, and the tapped and countersunk holes page covers those callouts. A face with a flatness callout, a bore that must accept a dowel pin, or a thickness held tighter than the sheet was rolled to moves the part toward machining, as a second operation on the cut blank or as a fully machined part. Both routes are quoted here as one order; the print decides, not the process.

Materials, and how to call out the thickness

Plates and spacers are typically called out in 6061-T6 or 5052-H32 aluminum, 1008 cold-rolled or A36 hot-rolled steel, 304 stainless, and brass or copper. Name the material and thickness on the print. Thin steel parts are typically called out in 1008 cold-rolled sheet and heavier ones in A36 hot-rolled plate, and A36 is written on the print as the grade ASTM A36/A36M defines (source 1); the steel page covers the split. Other alloys and plastics quoted on request. Name the grade on the print.

Write the steel condition on the print as well. Hot working leaves an oxide scale on steel, pickling removes it, and pickled sheet steel is oiled afterward so it does not rust (source 2), so the print says whether the plate is wanted with its mill scale or pickled and oiled. 304 stainless is used for food-handling equipment and for exterior architectural accents (source 3); the stainless steel page covers the grades, and 304 vs 316 for laser-cut stainless covers when 316 is the better call. The aluminum page covers when 5052-H32 or 6061-T6 suits, and the steel and brass and copper pages carry each material’s edge and finish notes.

When a laser plate is enough, and when it needs machining

A laser-cut plate is enough when the print’s tolerances are the sheet’s tolerances: hole position and profile as cut, thickness as the mill supplied it, and flatness left to the stock. That describes most adapter plates, spacers and washers. It stops being enough when a drawing puts a flatness callout on a face, a reamed or press-fit tolerance on a hole, a counterbore with a controlled depth, or a thickness tighter than the mill supplies. Those features are machined onto the cut blank as a second operation, quoted with the part; the secondary machining page explains how a machined feature is called out on a laser print and how the datums carry over.

Two neighboring part families are machined from the start rather than cut from sheet. Round machined standoffs and spacers are turned parts with threaded or through bores and a controlled length, which a flat cut cannot produce. Fixture plates need a flat, parallel face and a located hole grid, so they are milled from plate, often cast tooling plate, rather than cut from sheet. If your part is a flat plate with a bolt pattern, start here; if it has a controlled face or a turned body, start on those pages. The laser vs waterjet vs CNC page lays out the route decision for a bracket-sized part.

Thickness, flatness and hole position: what a sheet-cut plate holds

Thickness on a laser-cut plate is the mill’s thickness, not a machined dimension, and the quote states the tolerance for the stock chosen. A36 plate falls under ASTM A6/A6M, which lists permitted variations in dimensions for rolled structural plate (source 4), so a print that puts a tight tolerance on the thickness of a cut plate is asking for a machined face, and the quote will say so.

Flatness works the same way. Mill plate is flat only because of the stresses the mill imposed to hold it, and anything that relieves them, cutting the plate into smaller pieces included, is likely to leave a piece less flat than the plate it came from (source 5). A face with a flatness callout is therefore quoted as a machined feature on the cut blank, or the part is milled from tooling plate, and the quote says which. Say on the print whether a shim or a slotted plate must stay flat after cutting.

The holes and the outline are all laser-cut features, so the hole pattern carries the laser’s profile tolerance, and the quote states the tolerance used. A locating hole that has to hold a close tolerance, such as a dowel or press-fit hole, is called out on the print as drilled or reamed after the cut. The laser cut tolerances page covers kerf, taper and how to write the print.

Shim sets, finishes and inspection

Shims are ordered as a graded set rather than one thickness: a print that lists each shim thickness for the same profile, with a quantity per thickness, is quoted as one order, and the print says how the set should be packed. A very thin shim may be cut by a different route, which the quote states rather than substitutes. Name the material on each thickness. Where a shim sets a gap, cold-rolled sheet is the usual call, since cold rolling holds tighter tolerances than hot rolling and improves the surface finish (source 6).

A finish called out on the print is quoted with the part, and the finishing page lists what each finish does to a cut edge. A shim set is inspected thickness by thickness and counted against the print.

What to send for a plate, spacer or shim

Send a DXF of the flat profile or a STEP of the part, plus a PDF print with material and grade (6061-T6, not "aluminum"), thickness as a decimal, quantity per thickness for shim sets, hole sizes with their tolerance if any hole has a close fit, and the finish. Mark any face or hole that needs machining with its own tolerance so it is quoted as a machined feature, not a cut one. The file guide for laser cutting shows what a good drawing includes. With no drawing, send a new sample plate or a dimensioned sketch, with photos next to a ruler; the CAD work is then quoted as its own line, and the quote lists anything missing. A fully dimensioned 2D PDF is quoted without a CAD line.

Adapter and base plates turn up in robotics and automation builds, custom machinery builds and research labs; the robotics and automation plates page covers mounting and adapter plates in more depth. A single plate is a normal order, and there is no minimum: one piece to production runs of 10,000. Ask for more than one quantity, such as 1, 25 and 100, and the quote shows each. Upload the package at the quote form, files first; a person quotes in 24-48 hours, with lead time quoted per job and rush available. Everything under laser-cut parts is quoted the same way: one order, one contact, inspected before it ships.

Sources

All accessed 4 October 2026. Where a figure here differs from your print, the print governs.

1. ASTM International, A36/A36M-19, “Standard Specification for Carbon Structural Steel”: store.astm.org/a0036_a0036m-19.html (Active, last updated 4 July 2019; covers carbon steel shapes, plates and bars of structural quality for riveted, bolted or welded construction of bridges and buildings and for general structural purposes). Referenced, not reproduced.

2. Wikipedia, “Pickling (metal)”: en.wikipedia.org/wiki/Pickling_(metal) (hot working leaves an oxide layer or scale; hot rolled steel is normally passed through a pickling line to remove the scale; pickled sheet steel rusts in humid air, so a thin film of oil is applied as a barrier).

3. Wikipedia, “SAE 304 stainless steel”: en.wikipedia.org/wiki/SAE_304_stainless_steel (304 is used for food handling and processing equipment and for exterior architectural accents).

4. ASTM International, A6/A6M-26a, “Standard Specification for General Requirements for Rolled Structural Steel Bars, Plates, Shapes, and Sheet Piling”: store.astm.org/a0006_a0006m-26a.html (Active, last updated 27 April 2026; scope 1.1 lists A36/A36M among the product specifications it covers; the standard sets permitted variations in dimensions and mass, in Tables 1 to 31 and, in SI units, in Annex A1). Referenced, not reproduced.

5. Rolled Alloys, “Sheet and Plate Flatness”, 6 October 2023: rolledalloys.com/sheet-and-plate-flatness (a finished mill plate is flat because of residual stresses imposed to hold it in place; cutting the plate into smaller sections, among other things, relieves those stresses and can affect flatness; since cutting relieves stress, a cut piece is likely to be less flat). Plain text because the publisher sells plate and sheet.

6. Wikipedia, “Rolling (metalworking)”: en.wikipedia.org/wiki/Rolling_(metalworking) (cold rolling improves the surface finish and holds tighter tolerances than hot rolling; hot-rolled surfaces carry mill scale, usually removed by pickling).