Metal hand Saw machine

Using a carbattery, a lightswitch, a car-window-wiper-motor, and a 3D Printer, i've comprised a simple automatisation for the metal handsaw. For even, straight cuts of INOX 316 & 304 linear rods, electric tools were too violent, and resulted in ugly sawcuts, burr and slivers. This is my 60$ weekend solution to a +300$ slowcutting metalsaw. I figured that, if i added an arm to the wiper motor, i could make a circular motion,into a repetitive, linear one. The next step was the math. If i added an arm with a radius of half the distance the saw needed to back and forward, the complete diameter would bridge that needed distance. The saw had a travel of 137MM from center to M3 pivot-hole at the end is 137mm/2=68.5mm I can saw about 2x 8hrs before the battery tells me to do it myself. So i've searched the web for a simple solartracker ardu sketch, uploaded it to a ArduProMini16mhz, aquired a set of LDR's, fished a servo out of my modelbuilding shoebox, and sketched a solartracker as well. It moves a 18$ aliexpress 18v18w solarpanel. an 8$ solarcharger charges the carbattery. At sunny days, she charges the battery in 4days. Carbattery;50$ Carbattery clamps; 4$ Leads; 2.5mm² copper insulated musicwire Solarcharger; 20A: 8$ Solarpanel 18V18W; 18-22$ Ardu Pro Mini 16Mhz: depends on original or clone, but might i suggest original. the clone producers dont use their income to figure out new things for us. 5-16$ LDR; low sensitivity LDRs. (the cheaper, the less sesitive, but both work with correct resistors) 2-6$ Bearings mr93zz x8: price depends where you source them i guess. As you can see by looking at the files, the assembly has been upgraded since the pics & vid. Its stronger now. 3mm wide plastic bended, and got ripped apart after a while.