key/keyway

[Vulnavia]

Is a 1/4" key/keyway acceptable for the axle [50mm] and hubs? Only size broach set I have.


Thanks
Will

[Jnovak]

1/4" keyways will work if the wall thickness of the axle is thick enough. However all the cars we have built use 8mm pin drive keyways because the wall thickness is too thin to support a regular keyway.

Thanks ... Jay Novak

[LolaT340]

The correct key size for a 44 to 50mm shaft is 14x9mm (to BS4235:Pt 1). Depth of key slot in shaft should be 5.5mm -0/+0.2mm. Depth in the hub should be 3.8mm -0/=0.2mm. Width in hub and shaft should be 14mm N9 in the shaft being +0/-0.043mm, and the hub 14mm Js9 being +/-0.021mm. This will give a normal fit i.e. tap with a hammer (rawhide or other suitable deadblow hammer that will not burr the key!!)

This is the proven theoretically and practically correct sizing developed over many years of engineering.

If you use a 1/4" sq key, then the torque induced by the size of the shaft will damage the key seats in both the hub and shaft.

So if you want a failure, then by all means, use a 1/4" key. If you want something that works, follow good engineering practice.

[Vulnavia]

Thanks Jay,
Is the pin type the same as used on kart axles?

Will