CNC Turned Brass Stepped Spacer Bushing
Stepped spacer bushings turned from C36000 brass, with two or three outer diameters held to ±0.03 mm and concentric to 0.03 mm, shoulders square to 0.02 mm, an H8 bore and overall length within ±0.05 mm. Turned and parted from bar without a second operation.
- Steps Concentric to 0.03 mm
- Shoulders Square to 0.02 mm
- Bore H8, Round to 0.02 mm
- Cut From Bar in One Set-up
*Send the shaft and housing diameters with their tolerances. A spacer sized from nominal will either rattle or need a press, and the step length sets the gap the whole assembly is built around.
Stepped Spacer Bushing Overview
A stepped bushing does two jobs: it sets a gap between two components and it centres one of them. Both depend on the steps being concentric, which is why the part is turned in one chucking rather than in two operations.
Bar is faced, the bore is drilled and bored to H8, the outside steps are turned in sequence from the largest to the smallest, then the part is chamfered and parted off with a square face.
C36000 Brass
C36000 is chosen for spacers because it turns fast, holds a fine finish on a small step and does not gall against a steel shaft. It also looks right in a visible assembly without a coating.
Aluminium 6061 or 303 Stainless
6061 is used where weight matters and the spacer is anodized to match the assembly. 303 is chosen for washdown or food equipment, where brass is not permitted in contact with the product.
Below a 1.5 mm wall the bushing deforms when it is clamped in a fixture or pressed into a housing; the fix is a larger outside diameter, not a harder material.
Brass Spacer Bushing Specifications
Turning data for stepped bushings, with the step, bore and shoulder values that decide whether an assembly closes to the right gap.
| Specification | Machining Data | Specification | Machining Data |
|---|---|---|---|
| Product | Stepped Spacer Bushing / Shoulder Sleeve | Machining Process | CNC Turning, Boring, Parting |
| Material | C36000 Brass | Envelope | Ø 6 – 60 mm, Length 8 – 90 mm |
| Outside Steps | Two or Three Diameters, ±0.03 mm | Step Concentricity | 0.03 mm |
| Shoulders | Square to 0.02 mm | Bore | H8, Roundness 0.02 mm |
| Overall Length | ±0.05 mm | Step Lengths | ±0.05 mm |
| Surface | Ra 1.6 µm, Ra 0.8 µm on a Bearing Bore | Chamfer | 0.3 – 0.5 mm at Every Edge |
| Wall Section | 1.5 mm Minimum | Runout | 0.03 mm to the Bore |
| Customization | Cross Hole, Slot, Knurl, Thread, Flange | Lead Time | 3 – 5 Days Sample, 8 – 12 Days Batch |
| Inspection | Micrometer at Each Step, Bore Plug Gauge, Concentricity on Pins | Packing | Bulk Bag, Boxed by Size |
Key Features of Our Spacer Bushings
One chucking, square shoulders, concentric steps, gauged bore.
All Steps in One Chucking
The bore and every outside diameter are turned without re-chucking, so concentricity holds at 0.03 mm and the bushing centres the shaft in the housing.
Shoulders Faced Square
Each shoulder is faced with a neutral tool in the same set-up, keeping squareness at 0.02 mm so the bushing sits flat and does not cock under clamp load.
Bore Sized to the Shaft
The bore is bored, not just drilled, to H8 with roundness at 0.02 mm, which is what stops a spacer from rattling on a shaft that runs at the low end of its tolerance.
Parted With a Square Face
The parting tool is fed with a slight ramp and the back face is faced afterwards, so the overall length holds ±0.05 mm without a second operation.
Spacer that sets an exact gap?
Surface Finishes for Spacer Bushings
A spacer is usually hidden, but its bore and faces are fits and cannot take plating build.
| Finish | Main Purpose | Finish | Main Purpose |
|---|---|---|---|
| Natural Brass | Conductive and solderable | Nickel Plating | Wear and tarnish resistance |
| Clear Lacquer | Stops tarnish in storage | Tin Plating | Solderable electronics spacer |
| Bead Blasting | Matte decorative look | Passivation | Cleaning before plating |
| Plating Build | 3 – 8 µm, Bores Masked | Ultrasonic Clean | Removes cutting oil |
| Anti-Seize | Where the bushing sits on steel | Colour Match | Nickel satin or bright |
| Salt Spray | 96 h on plated parts | Thread Protection | Caps on threaded variants |
*Nickel at 8 µm closes an H8 bore by 16 µm. Bored spacers are masked or reamed after plating, and every batch is plug gauged before packing.
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Machining Process for Spacer Bushings
Every step is turned in the same chucking, so the shoulders stay square and the bushing seats on its face instead of on the step corner.
01. Fit Review
Check the shaft, the housing bore and the gap the spacer sets, then choose the bore fit and the step lengths from the assembly drawing.
02. Face and Drill
Face the bar, centre drill and drill through with a pilot, keeping the bar in the collet for every following operation.
03. Bore to H8
Bore the through hole to H8 and check roundness with a plug gauge before the outside is turned, since boring can shift the wall.
04. Turn the Steps
Turn the outside diameters from largest to smallest, facing each shoulder square and checking each step with a micrometer as it is cut.
05. Chamfer, Part, Gauge
Chamfer every edge, part off, face the back square, then gauge the bore, the steps and the overall length before bagging.
Send the shaft and housing dimensions, and we will quote a spacer turned in one chucking with every step gauged.
Brass Spacer Bushing FAQs
0.03 mm, because every diameter is turned in the same chucking. A spacer turned in two operations typically shows 0.06 mm, which is visible as a wobble on a fast shaft.
H8 for a slip fit and H7 for a light press. The bore is bored rather than drilled, so it stays round even at a 1.5 mm wall.
Yes, a cross hole or a slot is added after turning on a mill, positioned from the shoulder so it lines up with the mating part rather than the end of the bushing.
It works, but the two should not rub dry. A light grease or an anti-seize film stops the brass from transferring onto the stainless and seizing.
±0.05 mm as standard and ±0.02 mm on request. The length sets a gap in most assemblies, so a 0.1 mm error shows as a rattle or a preload.
Yes, a flanged version is turned from the same bar with the flange concentric to the bore within 0.03 mm, which is the usual way to stop a spacer falling through a hole.
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