Cutting device for cutting of a round

A cutting device for the cutting of a round comprising:

• a transparent substrate arranged on an object to be cut;
• a sleeving tube arranged on said transparent substrate;
• a transverse rod having a first end and a second end and extending to over said object, and said first end of said transverse rod penetrates through said sleeving tube, and a position of said transverse rod in said sleeving tube is adjusted by a locking member;
• a cutting assembly comprising a base and a sliding-ball rod, the base including a cutting member and a bottom of said sliding-ball rod including a ball which touches a surface of said object, wherein the sliding-ball rod is parallel to the cutting member, the sliding-ball rod fixed to said second end of said transverse rod and arranged between said base and said second end of said transverse rod;
• and
• a rotating assembly combined with said transparent substrate and penetrating through said transparent substrate, the rotating assembly and the sleeving tube arranged on the transparent substrate, the rotating assembly and the sleeving tube having spaced-apart vertical axes, and when said rotating assembly is pressed to touch said object and said rotating assembly rotates on said object to rotate said transparent substrate, said transverse rod moves said cutting assembly to perform a round-cutting operation on said object;
• wherein when said base rotates with said transverse rod, said base rotates said sliding-ball rod to roll said ball on said surface of said object, and said sliding-ball rod supports said cutting member.