removed from the razor blade tool 5 when the razor blade carrier 40 is in the scrape position and the lock 50 is in the unlocked position after a new razor blade 71 has been inserted into razor blade carrier 40 and when notch 73 has engaged tab 44 on the razor blade carrier 40 lock 50 is slid into the lock position i e tab 51 now fills notch 58 and becomes part of cam surface 56 which forces engaging element 41 towards the razor blade carrier 40 movement of lock 50 into the lock position causes engagement tab 41 a to engage center hole 74 of the new razor blade 71 the new razor blade 71 is now secured in the razor blade carrier 40 as described supra referring to fig1 rotation of razor blade 71 is now described spring 30 pushes knob insert 25 away from the razor blade carrier 40 force exerted by spring 30 causes positioning protrusion 26 of the knob insert 25 to mate with notch 16 when the razor blade 71 is for example in one of the positions depicted in any of fig1 through 18 this first position i e when positioning protrusion 26 is engaged in a notch 16 prevents rotation of the rotation mechanism knob 10 is attached to housing portion 15 in a manner that allows knob 10 to be rotated and that limits the distance knob 10 can move towards and.