Adapters & couplers

Rigid shaft coupler, 5 mm to 8 mm

A rigid coupling that joins a 5 mm motor shaft to an 8 mm lead screw or output shaft in low-torque projects such as small linear stages or slow turntables. It is a 20 mm diameter cylinder 30 mm long with a 5.1 mm bore on one half and an 8.1 mm bore on the other, each with an M3 grub screw hole, and a solid web in the middle so the shafts do not touch. A D-shaped bore option locks onto a flatted motor shaft. Print standing up so the bores stay concentric.

Shaft sizes in hobby motors and screws vary a lot, and SpeakCAD sizes each bore to your measured diameter with the clearance you prefer. Preview free in the browser and ask for a longer body, a flexible slotted design or a D-flat in the chat.

Get it nowGenerate and preview for free, in your browser. A download costs 2 credits.

Create a rigid shaft coupler 20 mm diameter, 30 mm long. One half has a 5.1 mm bore 14 mm deep with a 2 mm D-flat, the other an 8.1 mm bore 14 mm deep. One M3 grub screw hole per bore. 2 mm central web, 0.5 mm chamfers.

Change any number to match what you measured. The AI keeps the rest of the design consistent, and small follow-up edits after a download are free.

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Make your rigid shaft coupler, 5 mm to 8 mm now

Nothing to install and no CAD skills needed. Describe it, watch it render, download the STL or 3MF and print it tonight.

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