like reference characters indicate like parts throughout the several figures the reference numeral 30 indicates generally the pressure applying apparatus of the instant invention the pressure applying apparatus 30 includes a compressed air bottle 31 or if desired a source of hydraulic fluid under pressure which is controlled by a valve 32 having a hand knob 33 associated therewith a fitting 34 extends upwardly from the valve 32 and has a pressure gauge 35 mounted thereon an elongate handle tube 36 is connected to the fitting 34 and extends to a fitting 37 forming part of a base member 38 the base member 38 is generally cylindrical in cross section and is internally threaded at 39 for reasons to be assigned a hollow cylinder 40 has an externally threaded reduced diameter portion 41 at one end thereof which is threaded into the threads 39 of the base member 38 on each side thereof the hollow cylinder 40 has an internal flange 42 formed at the end thereof opposite the externally threaded reduced diameter portion 41 for reasons to be assigned a piston 43 is mounted for reciprocation in the cylinder 40 and has a shouldered portion 44 which engages the flange 42 to prevent the piston 43.