Precision couplings
A torque-carrying rotating part: the coaxiality of the two bores matters more than the outside diameter.
Process · Precision components
Precision component machining
These are the parts that hold an assembly together: couplings, stems, small housings, profile sections machined to length. They are rarely complicated shapes, and they are usually the reason an assembly does not fit — because two features that should share an axis do not.
What the job really is
A precision component is defined by its fits, not by its outline. A coupling with a perfect outside diameter but two bores that are 0.03 mm off-axis will destroy the bearing at the far end of the shaft. So the work is planned around the fit: which feature is the datum, which operation finishes it, and how the part is held so the clamp does not distort it.
Tolerance we quote
| Feature | Normal | Achievable on review |
|---|---|---|
| Bore diameter | H7 | H6 with a reamed or bored finish |
| Coaxiality of two bores | 0.02 mm | 0.01 mm when bored in one set-up |
| Concentricity to outside diameter | 0.02 mm | 0.01 mm on a mandrel |
| Length between shoulders | ±0.05 mm | ±0.02 mm |
Part families in this process
Each family has its own page with the machining notes and the checks we run before shipping.
Connecting stems
A slender rod where straightness and the coaxiality of both threaded ends are the two things that decide fit.
Aluminium profile parts
Second-operation work from extrusion or plate, where datum choice and the anodising dimension chain are the risk points.
Earphone housings
Small, thin and curved: cosmetic consistency and the assembly shoulder are where parts usually fail.
Optical light baffles
An optical part: internal matt finish, sharp edges and stray-light control matter more than the outer profile.
What to send for a quote
- The mating part or shaft diameter with its tolerance, not just the bore size
- Which fits actually matter, so the machining sequence can protect them
- Load, speed or pressure, if the part works in motion
- Material certificate requirement, if the part goes into a regulated product
Questions we get
How do you keep a thin ring round?
By not clamping it on the finished surface. Soft jaws are bored to the finished diameter, or the part runs on a mandrel, and the final pass is light enough that the material does not spring back when the clamp is released.
Can you work from a sample instead of a drawing?
We can measure the sample and send a drawing for approval, but the tolerances then become our interpretation of your part. For anything that has to fit another component, a drawing or a mating part is much safer than a sample alone.
Send a drawing, get a price within 24 hours
STEP, IGES, DWG, PDF or a dimensioned sketch — plus material, quantity and finishing. We reply with a price and any questions in one message.