Connecting stems
A slender rod where straightness and the coaxiality of both threaded ends are the two things that decide fit.
Part family · Precision components
Precision couplings
A torque-carrying rotating part: the coaxiality of the two bores matters more than the outside diameter.
What it is, and where it usually goes wrong
A coupling carries torque between two shafts, so the two bores must share an axis. If they do not, the shafts fight each other every revolution and the bearing on the far end takes the load — the coupling itself looks fine.
How we machine it
- Bore both ends from one set-up where length allows; otherwise indicate the part on the finished bore, not on the outside diameter.
- Cut the clamp slit after boring, with a slitting saw thin enough that the clamp still closes on the shaft.
- Deburr inside the bore by hand — a burr at the slit closes the clearance and the coupling will not slide on.
- Mark the balance orientation if the part runs above a few thousand rpm.
Where it is used
Servo-to-ballscrew connections, encoder drives, automation power shafts, test benches.
What we check before it ships
- Coaxiality of the two bores
- Bore diameter and fit against the shaft tolerance
- Slit width and clamp screw engagement
- Perpendicularity of the end face to the bore
Measured against your drawing and written on the inspection sheet that ships with the parts. First article reports are available on request.
What to send for a quote
- Shaft diameters and their tolerances at both ends
- Torque and rpm, so the clamp style and material can be chosen
- Whether a keyway, flat or pure clamp fixing is needed
- Runout allowed at the far end of the driven shaft
A STEP file plus a drawing is ideal; a PDF with tolerances also works. Quantity, material and finishing are enough to give you a real price instead of a range.
Questions we get on this part
Clamp or set screw — which holds better?
A clamp hub grips the shaft around its circumference and does not mark it, which matters on a ground shaft or a servo shaft. A set screw is cheaper and shorter but puts the load on one point; on a small shaft it also raises a burr that makes removal difficult.
Do you balance couplings?
We mark the orientation and keep the slit and screw positions consistent, which is enough for most automation speeds. True two-plane balancing needs the assembled unit and is quoted separately.
Other precision components we machine
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.
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.