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Description: These stainless steel shaft couplers allow you to couple two size shafts together. They can be used for connecting motor shafts to drive shafts, or two different-sized shafts. These shaft couplers have a length of 0.75”, a outer diameter of 0.50”, and couple 1/4” to 5/16"shafts.

Actobotics is a robotics building system based around extruded aluminum channels, gears, precision shafts, and ball bearings. Thanks to the two standardized hole patterns, nearly all Actobotics components can be intuitively connected together. The wide range of components makes building complex electromechanical prototypes or finished projects a reality.


  • Length - 0.75”
  • Diameter - 0.50”
  • Bore A ID - 1/4”
  • Bore B ID - 5/16"


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Customer Comments

Customer Reviews

2 out of 5

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Not quite fitting

I measured the shaft with my calipers (a nice pair of calipers btw), and it was 5/16". I measure the other shaft and it was ¼". So I got this coupler to connect the two. The ¼" connected just fine, but the 5/16" would not go on at all. I measured the inside of the coupler and it was 0.3010", which is a completely irregular size.(fyi 5/16" = 0.3125"). Is it possible that this was intended to be a Standard to Metric adapter? The hardware itself is excellent, the measurements and/or manufacturing tolerances are not.

Hi, I measured a Actobotics shaft and this coupler. Both fit together nicely. And they both measured in at 0.3125". If you would like to have us check out your coupler, please contact us at