DMB,
When I built my Mk II, I fitted a 1/2 HP motor to it without thinking about the power requirement. The motor itself was a farm sale rescue that had a broken foot mounting but was otherwise a first rate Brook Crompton with ball bearings rather than oilite bushes. Because of the damage the motor was unused and cost me £2
From the experience I have had in nearly 30 years of use, I would consider anything less powerful would rather hold the machine back in its capabilities
Regards Brian.
Edited By Brian Wood on 02/05/2021 10:20:34