226 the second frame 260 is guided by the rails penetrating through guide holes 330 332 334 336 formed transversely through side wall blocks 203 of the housing 202 shown in fig1 and 13 the blocks 203 are fastened to the remaining portions of the housing 202 by fasteners 205 the blocks are removable to facilitate assembly disassembly of the cutting assembly 200 brackets 340 342 are fixedly connected to the rails 264 266 within the perimeter of the housing 202 by two clamping arrangements each effected by a fastener 359 shown in fig7 and 13 a pin 360 362 see fig1 extends from each bracket 340 342 into the cam slots 248 250 the pins include plastic rings 363 for reduced friction sliding shown in fig7 and 13 within the cam slots two dual acting cylinders 366 368 act on the rails 264 266 to drive the rails in horizontal reciprocation in this regard a piston not shown is connected to each of the rails within the dual acting cylinders and pneumatic or hydraulic pressure acting on opposite sides of the piston drives the rails into reciprocation the reciprocation of the rails causes the reciprocation of the horizontal longitudinally directed blade 302 and causes vertical reciprocation.