Author of the “Making the Most of Your Flexshaft” book here, so let
me address your question.
As a side note, there are only 200 copies left from 5000, so if you
want a book, get one soon.
By “pendant” motor, I’m assuming you are referring to a hanging flex
It’s a fair question and honestly, it depends on the work you do.
Personally, I use both. I have a Foredom TX which is very versatile,
allows for a #30 Jacobs chuck for tiny drill bits up to heavy carbide
burs. The TX and the newer SR reversible is great for lower speed,
heavy torque, perfect for stone settings. Why use large and gigantic
carbide burs? Recently I was drilling out acrylic for making a die on
for a hydraulic press. I could have hand filed the whole thing, but
my Foredom TX and a heavy duty cylindrical bur chewed through the
plastic in half the time.
The micromotor on the other hand is another great tool for my bench.
Even in the limitation of the handpiece using 3/32 inch mandrel
(sorry, we are still backwards in the US), the speed needed for
polishing applications, like the radial bristle disks which need
high rpms is quieter and more gentle on my hands. I have the option
of setting the speed once and knowing that with all the polishing
options, the rpm will be high enough for polishing. With this
operation, it doesn’t need the torque. The handpiece is very easy on
the hands, delicate, great for making perfect slices through a bezel
for cabochons using the slim separating discs. Most accessories will
accommodate the micro motor handpiece.
Deciding on which one to buy is sort of like the car you drive. Do
you haul stuff where you need a truck, or can your sedan pretend
it’s a truck and be able to jam stuff into it.
If I had to choose one, I would go with the hanging flexshaft. It’s
cheaper, and you can do everything with the flex shaft that you can
do with the micro motor. However, if you are experienced, set a lot
of stones, then yes, a micro motor will work great.