Perhaps the most frequently used counterbalanced grooving comprises a continuous circumferential groove having the alternate helical and parallel sections machined on tire p。•riphcry of the core in a continuous grooving operation。 However, it is difficult and expensive to ma- chine this continuous combined helical and parallel groovc on tire drum core, and at present it is necessary to install a specially designed Geneva gearing attachment to a lathe in order to properly machine the groove on  the  di um。 This lathe operation is not applicable to the larger sized drum, and as a result, a special attachment  must  be utilized with a vertical milllng machine to ef bciently groove the larger drums。 These  are  expensive  opera- tions, and it is desirable to provide the  combined helical and parallel grooving on the periphery of the drum core without the necessity of the special machine attachments。 The present invention contemplates a novel method of providing the Le Bus counterbalanced grooving  on  the core of a drum in a manner whereby the overall cost thereof is reduced to a minimum。 The novel  groove method comprises the grooving o:I a cylindrical  sleeve with a plurality of parallel grooves, which may be accom- plished in any well known manner, such as with the usual lathe, or usual milling machine,  depending upon  the size of the drum diameter。 The parallel grooved sleeve is then cut in such a manner whereby the arcuate or semi-cylin- drical portions may be severed from the  grooved sleeve and arranged on the outer periphery of the drum core to provide the continuous combined helical and parallel groo-ves。 The segments of the sleeve or “master cylinder” may be bolted or welded to the outer periphery  of  the drum  core。   Of  course, there  are relatively  few segments

to be secured to the drum core, and the attachment thereof requires relatively little time and efl‘ort as compared to the assembly of the plurality of  inpidual  groove  bars, and tlae like。 In addition, the alignment of the relatively few segments is a simple  manner。  The  parallel  grooved sleeve  may  be  cut  in  a  variety  of  patterns  to  provide a

instances, a plurality of inpidual arcuate segments of groove bar are welded to th•< outer periphery of the drum core to provide the desired p•roovin;; pattern therefor。 OF course, a drum core having the  continuous  helical  or spiral  groove  akeady  provided  thereon must  first be ma-

65 variety  of: types of  the counterbalanced  spooling  groove

on a drum core in accordance with the drum size and con- ditions required for the particular cable winding opera- tion。 The novel parallel grooved sleeve may be manu- factured  quickly  and  inexpensively  by  conventional ma-

chined  in  order  to  remove  th>•  groove,  or covered  by  a 60

smooth sleeve, and the groove bars may then be welded to the plain  or  smooth  surface。  This  grooving method has many disadvantages in that some drums are con- structed of hi% carbon steel and cannot be welded。 In addition, the welding of inpidual groove bars onto the outer periphery of  the  drum  core  requires  a  great  deal of time, particularly on large drums such as  used  in mining, and the like。  Even more time must be  expended, of course, when it is necessary to machine off the old grooves, or add a plain sleeve prior to the welding of the groove  bars  on  the  drum  core。    Furthermore, expensive

chining processes,  and may  be  attached  to the drum core