My Kennedy hacksaw machine is much modified, it's driven by a single phase 240 volt motor with a built in reduction gear on the end, the saw itself is driven by a 'V' belt, the final speed being in the region of 80 strokes per minute,
I am a firm believer in any machine tool must be fitted with a no volt release starter, that if the power is interrupted it will not restart on it's own.
The original Kennedy had a hoover motor, which had a switch on the end cover that was, by the use of a bit of steel bar hinged and moved by the saw frame decending, flicked this switch to the off position, thereby stopping the motor.
I wanted something better than this arrangement, when the frame of the saw is lifted to put what you intend to cut in the vice, a pivoted vertical bar rests on a stop on the fixed base, to start the saw, a linkage is moved to pivot this bar to allow the saw frame to decend, ( anyone who has a Kennedy will understand this).
As I did not want to have mains power going to any switch actuated by the frame of the saw when it completed it's cut, so I installed a microswitch with it's normally closed contacts, wired in series with the holding coil supply inside the no volt release switch housing.
This micro switch is actuated by the use of a camera shutter release cable held in a bracket directly under the saw fram latch bar, as the frame decends this latch bar pushes the camera shutter release which in turn opens the contacts of the micro switch, interuppting the power to the holding coil of the no volt release switch. and the saw stops.
I have found this saw to be invaluable, for the smaller jobs encountered in the workshop, as time is not an overiding factor, it really does not matter how long it takes to make its cut, I just set it going then do something else.
Digger