A lot depends on the type of work you’ll be doing & the number
of times you’ll need to change the tool (bit) you’re using. I’d
suggest you really need 2 hand pieces, a Foredom # 30 & a quick
change hand piece. The # 30 is about 1" in diameter & uses a
Jacob’s chuck that accepts tool bits with shanks up to 5/32"
diameter. It’s draw back is that the time need to change the bits
can add up if you need to change frequently. An advantage is that
there are many accessory tools made that attach to the # 30. It’s
a well made solid tool.
The quick change hand pieces only take tool bits with 3/32"
shanks. The bits are release by twisting or pressing a lever
(depends on hand piece type). On some models the bit can be
released without the tool coming to a complete stop.
One other item I’d recommend for both hand pieces is a ‘duplex
spring’. The ‘duplex spring’ is a very flexible connection that
goes between the hand piece & the relatively stiff flexshaft that
comes from the motor. It makes controlling the hand piece lots
I currently use both a Foredom #30 & # 18 quick change. If I had
it to do over, I’d bypass the # 18 & get a better quality quick
change. I don’t know which quick change I’d get, I haven’t
investigated them thoroughly yet. My complaint with the # 18 is
it gets noisy sometimes, there seems to be a vibration in the
mechanism that opens/closes the collet.