fastener 22 which is shown in fig1 2 as comprising a set screw however those skilled in the appropriate art understand that devices other than or in addition to a set screw may be utilized as fastener 22 depicted in hub 18 is bore 26 defined by collar 28 and designed to receive in use a rotating shaft after such a shaft is received in bore 26 fastener 22 may be tightened to fix the position of the shaft relative to hub 18 one or more openings 30 in hub 18 receive pins 18 pins 18 typically are pressed into openings 30 and maintained therein with a friction fit they need not however be so pressed but instead may be connected to hub 14 in any suitable way or integrally formed therewith also illustrated in hub 14 are one or more clearance holes 34 shown as interspersed radially with openings 30 clearance holes 34 are adapted to receive pins 30 from another hub 14 in the embodiment of hub 14 detailed in fig1 three each of openings 30 and clearance holes 34 are present in the hub 14 with each hole 34 being offset radially from an adjacent opening 30 by sixty degrees fewer or greater numbers of openings 30 and clearance holes 34 may exist however if necessary or desirable pins 18 are shown in fig1 2 as being generally in the form of dowels preferred versions of pins 18 are tapered adjacent their free ends 38 fixed ends 42 by contrast are configured for.