Effective with binders
shipped after 2/1/15, the thread tensioning design has been improved. Tension control is now accomplished with a
cork disc drag mechanism on the spool axis. The sewing machine type tensioners have been eliminated in this new design.
The old design had 2 elements that, in effect, could “control” thread tension: The tension washer assembly plus any tightness of the spool on its mounting post. If the spool was tight on the post, it added to the tension. If it was too loose, it could free-wheel and cause a length of slack thread between the spool and the tension washers. If in loading the spool at the factory, the thread became somewhat untwisted, the loose thread could furl and jamb in the tension washers. Although in most instances it is a manageable situation, the adjustment to keep the spool from free-wheeling and yet not add to the tension is delicate.
The binder operating manual (version 4.2) covers this change.
In the new design the spool is mounted on a spindle that has an acetal brake surface on left end and a thrust bearing on the right end. The bearing housing is threaded and it is tightened against the spool to hold it firmly centered on the spindle.
A 6-32 stainless steel stud is secured to the rotating member of the binder. A cork-faced tension adjustment disc is threaded on this stud.
The spindle with its spool of thread is slid over the 6-32 stud with its brake surface against the cork face. A lock nut and a felt washer is used to tighten the assembly and apply pressure on the brake surface. Thread tension is adjusted by slightly rotating the cork faced disc to change the pressure on the brake surface.
Thread routing is quite simple as shown here
with orange thread for clarity