CNC Machined Stainless Steel Disc Hub Set
Disc hubs and split clamp rings machined from 304 stainless, with a H7 bore coaxial to the bolt circle within 0.02 mm, a bolt circle at ±0.03 mm, face runout under 0.02 mm and lightening pockets matched within 2 g so the pair balances without weights.
- Bolt Circle Within ±0.03 mm
- Face Runout Under 0.02 mm
- H7 Bore, Bored Not Reamed
- Pockets Milled to Balance
*Give us the shaft fit and the torque you run through the disc. A hub bored H7 on a worn shaft will move 0.03 mm under load, which shows up as a wobble at the rim that no amount of re-tightening fixes.
Stainless Disc Hub Overview
A disc hub carries torque between a shaft and a disc, and it does that through two features only: the bore fit and the bolt circle. Everything else on the part is there to keep those two from moving.
The disc is turned on both faces, the bore is bored with a single-point bar, the bolt circle is interpolated from the bore centre, and the lightening pockets are milled in a mirrored pattern so the part does not need balancing afterwards.
304 Stainless
304 is used where the disc sees washdown or food contact: it does not need coating, and passivation after machining removes the free iron that would otherwise show as rust spots around the bolt holes.
17-4 PH or 316L
17-4 PH in the H1150 condition is chosen when the hub is keyed to a shaft and takes shock torque, and 316L where chlorides are present, at the cost of a softer bore that wears faster on a sliding fit.
A 12 mm disc is the practical minimum under a 260 mm hub; below that the face deflects during boring and the runout comes back after the part is unclamped.
Disc Hub Specifications
Boring and circle data for stainless hubs, with the coaxiality and runout values that keep a disc true at speed.
| Specification | Machining Data | Specification | Machining Data |
|---|---|---|---|
| Product | Disc Hub and Clamp Ring Set | Machining Process | CNC Milling, Boring, Face Turning |
| Material | 304 Stainless, 17-4 PH on Request | Envelope | Ø 120 – 260 mm, 12 – 30 mm Thick |
| Bore | H7, Roundness 0.015 mm | Bore Coaxiality | 0.02 mm to the Bolt Circle |
| Bolt Circle | 4 – 12 Holes, ±0.03 mm | Hole Size | Ø 6.6 / 8.4 / 10.5 mm, Drilled and Reamed |
| Face Runout | 0.02 mm at the Rim | Face Flatness | 0.015 mm Across the Hub |
| Lightening Pockets | Depth ±0.05 mm, Floor Ra 3.2 µm | Balance | Pockets Matched Within 2 g |
| Clamp Ring | Split 4 mm, Two M6 Clamp Screws | Ring Gap | Parallel Within 0.05 mm |
| Customization | Keyway, Taper Bore, Dowel Pattern, Balance Holes | Lead Time | 6 – 8 Days Sample, 14 – 18 Days Batch |
| Inspection | CMM Bolt Circle, Granite Face Check, Bore Air Gauge | Packing | Hub Cap, VCI Bag, Crate |
Key Features of Our Disc Hubs
Bored, not reamed; circle interpolated from the bore; pockets balanced in pairs.
Bore Bored in One Pass
Reaming a 60 mm bore follows the pre-drilled hole, so the bore is single-point bored from the same clamping as the faces and stays within 0.015 mm of round.
Bolt Circle From the Bore
The circle is interpolated about the bored centre rather than from the outside diameter, which is what stops the disc from being pulled off centre when the screws are torqued in sequence.
Pockets Mirrored in Pairs
Lightening pockets are cut in a mirror pattern about the axis, so the imbalance left after milling stays under 2 g and the hub does not need a balance pass.
Split Ring Cut After Boring
The clamp ring is bored first and split afterwards with a 4 mm slitting saw, so the two halves close on the shaft without a step at the split line.
Disc that has to run true at speed?
Surface Finishes for Disc Hubs
Contact faces stay bare, the rim can be finished to match the machine.
| Finish | Main Purpose | Finish | Main Purpose |
|---|---|---|---|
| Passivation | Removes free iron after machining | Bead Blasting | Even matte on non-contact faces |
| Electropolishing | Ra 0.4 µm on a hygienic disc | Mirror Polish | Decorative visible face |
| Masked Bore | Keeps the H7 fit after passivation | Black Oxide | Non-stainless variant only |
| Laser Marking | Bolt circle and balance position | Edge Break | 0.4 mm on both rim edges |
| Bore Plug | Fitted for transit | Face Protection | Peel film on the lapped face |
| Salt Spray | 500 h on 304 after passivation | Roundness Recheck | Measured After Passivation |
*Electropolishing removes 5 to 8 µm and slightly opens the bore; on a H7 fit the bore is masked or bored 0.01 mm under before polishing.
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Machining Sequence for a Disc Hub
The bore is bored in the same clamping as the bolt circle, so the disc runs true on the shaft instead of being pulled off centre by the screws.
01. Fit and Pattern Review
Confirm the shaft tolerance, the torque direction and the bolt pattern, and decide whether the bore runs H7 or a light press.
02. Turn Both Faces
Hold on the outside diameter in soft jaws, turn both faces and the rim in one operation, leaving 0.2 mm on each face for the finish pass.
03. Bore and Check Coaxiality
Bore with a single-point bar, measure roundness in two planes, then interpolate the bolt circle from the same centre without unclamping.
04. Mill Pockets and Split
Cut the lightening pockets in a mirrored pattern, drill the clamp screw holes, then split the ring with a slitting saw and deburr both cut faces.
05. Passivate and Protect
Passivate, rinse and dry, plug the bore, apply peel film to the lapped face and pack with the hub cap fitted.
Send the shaft diameter and the bolt pattern, and we will quote a hub bored and circled in one set-up, with the runout measured before packing.
Disc Hub FAQs
A reamer follows the drilled hole, so on a 60 mm bore the error from the drill stays in the part. Boring corrects position and roundness in the same pass and holds 0.015 mm.
Yes, from a drawing or a sample hub. We measure the pattern on a CMM and cut to the measured centre rather than the nominal, which keeps a replacement disc interchangeable with the old one.
Under 2 g on a 200 mm hub with mirrored pockets. Above that the part is balanced on a mandrel and corrected with drilled holes between the bolt holes.
It removes a few micrometres of free iron but does not change the dimension. Electropolishing does, by 5 to 8 µm, so the bore is masked when the fit is critical.
4 mm for a 200 mm ring, 3 mm below 120 mm. A narrower split will close before the ring grips the shaft, and a wider one leaves the ring oval after clamping.
Yes, and it is the usual way: the disc is faced against the hub face, so the pair is machined and marked together and the runout is checked assembled.
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