vertical when intended for use in cutting cured epoxy tubesheet hollow fiber assemblies the head is fabricated from a 2 steel drill rod and air hardened to a rockwell number of c57 59 before being ground sharpened the manner of fabrication of the tool will be evident from fig1 a and 1b to those knowledgeable in the art fig2 a depicts in 34 exploded 34 view another two part type of tool in which a generally tubular cutting head 20 and a shank 21 are joined by slip fitting and silver soldering the head part of this particular tool is more difficult to fabricate and is sharpened by grinding in such manner that the cutting edge 22 loses its vertical relief after being sharpened only a few times accordingly this tool though fully operable for its intended purpose is a less preferred embodiment of the invention each of the three land portions 23 of the head is much more symmetrical in horizontal cross section than the lands shown in fig1 a and 1b and the u shaped passageways 24 between the lands are relatively narrower the outward extensions of the 34 tooth 34 portions 25 not easily distinguished in fig2 a see 2b of the lands are barely discernible and the cutting radius of the tool is not much larger than the other radii thereof accordingly this trimmer cannot enlarge the bore very much i e has little reaming ability the cutting edges do not extend fully to the bottoms of the intervening passageways by reason of notches 26 made to facilitate outward hot crimping to form the tooth portions toes of the lands each cutting edge is the line of intersection between an inner planar surface 27 which is defined by the vertical portion of.