thereof with a single hand while the operator 39 s other hand can screwingly manipulate knob 46 in accordance with the teachings of the invention the cutter wheel 38 is mounted to the outer leg 26 of the lower jaw 14 in a specific way having reference to fig5 and especially to fig6 a and 7 lower jaw leg 26 is shown to consist of two opposite side walls 48 50 and a base web 52 joining the side walls 48 and 50 two partition walls 54 and 56 are further mounted integral to web 52 parallel to side walls 48 and 50 and spaced therefrom and from one another so as to define three cavities 58 60 and 62 fig7 each jaw side wall 48 50 and partition wall 54 56 therefore includes an intermediate transverse through bore 48a 50a 54a and 56a respectively for free lengthwise sliding motion as well as free axial rotational engagement of axle 40 thereabout cavity 62 is not essential it only reduces the weight of tool 10 cavities 58 and 60 are of substantially same dimensions and transversely register with one another each cavity 58 60 define a concave flooring referenced as 58a and 60a cutter wheel 38 is lodged into intermediate cavity 60 being axially engaged around an intermediate section of axle 40 for free rotation thereabout i e that wheel 38 is not fixed to shaft 40 but can rotate around same axle 40 may or may not itself rotate during rotation of cutter 38 this is not critical to the invention but of necessity cutter disk 38 clears the.