about 20 seconds ...

Interesting concept but a mass of high speed flailing canes will have that arse bleeding in no time at all. I like how the victim is restrained, and on a movable device. It doesn't seem practical as the canes will cut the most prominent flesh. 20 seconds and enough is enough !

A Real Machine ?

A somewhat large and cumbersome contraption. It looks as though it might actually do something but I can't see any venom here. Looks more of a token 'spank' than anything serious.
It also doesn't really satisfy the concept of a machine taking over as someone has to turn a handle.

Springs and Paddles

An old one but good. The restraints are very effective, and the paddles are spring loaded. Not sure if the release mechansim will give the velocity to cause real pain.

Strapping

I can't see how the straps ever recover from the impact ? Mind you the restraints look good.

Spanking Machine

A self propelled approach to a spanking machine. Does it work in real life ? There doesn't seem to be any incentive to pedal