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How a Keyboard Case Is Machined and Finished
A case is two jobs. The machining is measurable and predictable. The finishing is judged by eye, by a hundred people, under their own desk lamps. This page walks through both in the order a shop runs them, with typical figures, so you can read a quote and know what each line is paying for.
We are a matching service, not a machine shop. We match your files with up to 3 shops that already run this route.
The route a case takes
Typical order for an aluminium top and bottom case. Prototypes follow the same route, just once.
Saw and face the billet
6061 or 6063 plate or bar, cut over size. Alloy and temper recorded so a repeat run starts from the same stock.
Rough the inside
Pocketing for the PCB, plate and weight cavities. Most of the metal and most of the cycle time leave here.
Flip and finish
Soft jaws or a fixture plate hold the finished side while the outside is cut. Every flip is a place a witness line can appear.
Deburr and inspect
Edges broken by hand or with a chamfer tool path. Pocket depths, shelf heights and screw positions checked before finishing.
Blast, then colour
Glass bead blast to a stated grit, then anodising or a coating. Tops and bottoms that meet at a seam go in one finishing load.
Mark and pack
Laser engraving after the colour, then a cosmetic check against the golden sample and packing that keeps faces apart.
3 axis and 5 axis milling
A 3 axis mill reaches whatever faces up. Every other face means taking the part out, refixturing it and starting again, and every setup adds time and a chance of a witness line where two tool paths meet.
A 5 axis machine tilts the part, usually locking it at an angle and cutting (3+2), so angled sides, side ports, undercuts and continuous chamfers come out in fewer setups. The saving is in setups and handling, not in the cutting itself. Full comparison: 5 axis vs 3 axis for a keyboard case.
- WorkholdingSoft jaws cut to the case profile, vacuum plates for thin parts, or a sacrificial tab left on the billet and cut off last. Clamping on a cosmetic face marks it.
- Finishing passesSmall step-over ball or bull nose passes on visible curves. The step-over is what you see as faint lines under anodising.
- EdgesChamfers and fillets cut as tool paths rather than by hand, so they stay even all round. Diamond cut edges are a separate pass with a diamond tool for a mirror bright band.
- Long pocketsDeep, wide pockets in a thin case release stress and can bow the part. Roughing both sides before finishing keeps it flat.
Which process makes which feature
Typical results on a stable part. The general tolerance of ±0.1 mm suits most of a case. The shop that quotes confirms what it holds on your geometry.
| Feature | Usual process | Typical tolerance |
|---|---|---|
| Case outside, sides and chamfers | 3 axis with flips, or 5 axis (3+2) in fewer setups | ±0.1 mm general |
| Plate pocket and gasket shelves | Finish pass after roughing, depth probed | ±0.05 mm on the callout |
| Weight pocket | Pocketing in the bottom case, sized after coating on both parts | ±0.05 mm, slip fit |
| Screw holes, countersinks, counterbores | Drill, tap or thread mill, countersink tool | Position ±0.05 to ±0.1 mm |
| USB port and side cutouts | 5 axis, or a side setup on 3 axis | Position to the PCB connector |
| Weights | 3 axis milling of brass, copper or stainless | ±0.05 mm where it seats |
| Plates | Milling for metals, routing or waterjet for FR4 and carbon fibre | Switch cutouts 14.0 mm, flatness stated |
The five dimensions worth a tighter number are listed in drawing callouts.
Weight inserts and screw sinking
A weight is a second part in a second material, often with a second finish and a second vendor. Plan it with the case, not after it.
- Weight pocket fitThe pocket in the bottom case and the weight both get coated. Size the slip fit after finishing on both, or the PVD weight will not go into the anodised pocket.
- RetentionScrews from inside the case, threaded holes in the weight, or adhesive. Press fits into anodised aluminium crack the coating at the edge.
- Flush or proudA weight sunk flush with the bottom face needs both depths held. A proud weight hides small depth variation and costs less.
- Countersinks and counterboresBottom screws sit in countersinks for flat heads or counterbores for socket heads. Depth decides whether the head sits flush after coating, so give it on the drawing.
- ThreadsTapped aluminium threads wear when a board is opened often. Threaded inserts last longer and cost a little more.
Bead blast and coatings
Glass bead blasting before colour sets the texture and evens out tool marks. State the media and grit as a number, not the word matte. Typical film builds below come from public process specifications and coater practice. Your finisher's numbers govern.
| Finish | Typical build | What it means for a case |
|---|---|---|
| Type II anodising | About 5 to 25 µm, roughly half of it growing outward | The default colour finish. Grows from the aluminium itself, so it never chips off. Racking marks are unavoidable, so say where they go. |
| Type III hardcoat | About 25 to 75 µm | Wear resistant and dark. Narrow colour range. Changes tight fits, so design the allowance in. |
| E-coating | Typically 15 to 30 µm | Electrophoretic paint. Deep blacks and true whites that anodising cannot reach, and it hides small surface marks. |
| Cerakote | Typically about 15 to 25 µm | Sprayed ceramic polymer, wide colour range. Masking needed on mating faces. |
| Powder coat | Typically 50 µm and up | Thick and durable. Softens edges and closes small fits. Rare on precision case faces. |
| PVD | Typically under 3 µm | Vacuum deposited metal compound on weights and small parts. Gold, bronze and black that will not patina. Needs a polished or blasted base. |
Anodising types are defined in MIL-A-8625. Colour depends on alloy, blast and dye lot, which is why the materials and finishes index lists them together and why halves that meet at a seam should run in one load.
Laser engraving and marking
Logos, serial numbers and layout text. A fibre laser on anodised aluminium removes or bleaches the dye and leaves a light grey or white mark. On e-coat and cerakote it ablates the coating to bare metal. On brass and stainless it darkens or etches the surface.
- Flat facesCheap and fast. Curved faces need a rotary axis or a focus that follows the surface, so they cost more.
- OrderUsually after colour, so the mark contrasts. Marking bare metal before anodising gives a texture change in the same colour.
- ArtworkSend vector files with line weights. Fine text below about 0.3 mm line width fills in on blasted surfaces.
Questions about the processes
Is a 5 axis case better than a 3 axis case?
Not in itself. A 5 axis machine reaches more faces per setup, which cuts flips, witness lines and handling on cases with angled sides, side ports or undercuts. A plain tray mount case with vertical walls comes out the same on 3 axis and may cost less. The number of setups matters more than the machine.
Do dimensions on my drawing apply before or after anodising?
Say which on the drawing. If you do not, a shop will usually machine to the drawing and finish afterwards, so a coated pocket closes by twice the build. Type II changes fits very little. Hardcoat, e-coat and cerakote change them enough to matter on a plate pocket or weight fit.
Should laser engraving go before or after anodising?
After, in most cases. A fibre laser on anodised aluminium removes or bleaches the dye and leaves a light mark with clean edges. Engraving bare metal before anodising gives a mark the same colour as the case with only a texture change. Brass and stainless weights are engraved bare or after PVD.
Why does the bead blast grit matter if the case is anodised anyway?
Because anodising follows the texture underneath it. The grit sets how the surface feels and how light scatters, which shifts the apparent colour. A repeat run blasted with a different grit will not match the first run even with the same dye.
Guides on machining and finishing
- Cost
Three Axis or Five Axis Machining for a Keyboard Case
Five axis costs more per hour and can still make a case cheaper by collapsing setups. How to tell which side of that line your design sits on before you quote.
- Finishing
Anodising a Keyboard Case, and Why the Colour Shifts
Alloy, blast grit, dye lot and bath time all move anodised colour. What to specify, why top and bottom halves must run together and how to approve a sample.
- Finishing
Anodising or E-Coating: Choosing a Keyboard Finish
Colour range, thickness, durability, cost and the effect on tight fits, set out so you can pick a finishing route before the drawing goes out for quotes.
- Finishing
When PVD, Cerakote or Powder Coating Beats Anodising
PVD on weights, cerakote and powder coat on cases, and what each one adds to the price, the thickness and the number of vendors in your own supply chain.
- Design and Fit
Which Tolerances on a Keyboard Case Actually Matter
A blanket tight tolerance raises the price of every feature on a case. Here are the five or six dimensions worth tightening and the ones that can run loose.
- Finishing
Bead Blasted Keyboard Case: Texture Before Anodising
Bead blasting gives an anodised keyboard case its matte satin surface. What media does, why consistency is hard, and how to specify a blast you can accept.
Files ready?
Every part on a board and the process behind it is on the parts page. Background reading on finishes: anodizing and physical vapour deposition on Wikipedia.