But the handles and apparent twin pitch lead of the thread are confusing. Increased pitch reduces power, while speeding up travel.
Screw press also good for straightening, with advance easier to monitor than rack and pinion or hydraulics.
This is how precision barrels are straightened, but screw is from below. The barrel maker looks down the bore 'aimed' at a wire hanging in front near a window or front light. Laid in vee blocks and rotated, the narrow, defined shadow points out ANY deviation from straight; whether curve or kink.