They make up for errors in alignment while allowing the motor to spin without excessive friction. Unless you can be sure that :
a) motor and driven shaft are perfectly parallel.
b) motor and shaft are aligned about the center
c) whatever you use to couple fits both shafts without slop and it's bores are aligned as above
you will really want to use a coupler.
Or you could waste a bunch of time "making your own", having problems which you can't be sure might be the fault of the couplers, or might be something else. Sometimes $20 (or $60 for three of em) is cheap compared to the headache and frustration they save. |