A fire shovel

whose scoop was removed

is tamei

because it is like a hammer (the end of the handle opposite the scoop was wide and heavy, and could be used to crush coals),

these are the words of Rabbi Meir,

and the Sages rule it is tahor (as it was never intended to be used this way).

A saw

whose teeth were removed,

one from in between every two (i.e. every other tooth was removed)

is tahor (as it can no longer function).

If there remains in it

like the size of a sit (some say this is the distance between an outspread thumb and index finger, other from the outspread index finger to the middle finger)

in one spot

it is tamei.

The plane (a tool consisting of a block with a slightly projecting metal blade from its middle, used to smooth a wooden or other surface by paring shavings from it)

and the scalpel,

and the chisel,

and the auger (a hand-drill)

that were damaged (the damage was to the body of these tools, but not their cutting edges)

are tamei;

if their cutting edge (made of a different, harder metal than the body) was removed, they are tahor;

and all of them that were broken into two

are tamei (if a piece of the cutting edge remains attached to each half),

except for the auger (as each half cannot have the cutting edge, it is impossible to function properly once broken in two);

and the plane block alone (without the blade)

is tahor.

פרק יג משנה ה

A needle

whose eye was removed,

or its point,

is tahor.

If prepared for stretching (it was prepared for use as  a pin)

it is tamei.

[The needle] of a sackmaker

whose eye was removed is tamei,

as one writes with it (this was a larger needle, so it could be held and used as a pen),

if its point was removed it is tahor.

[If needle made] for stretching

either way is tamei (as it does not need its eye or point to function properly).

A needle that became rusted

if [the rust] prevents sewing (some say this means even if it can sew, but will leave rust stains)

is tahor,

and if not is tamei.

A hook that has been straightened

is tahor

if one [subsequently] bent it

it returns to its state of tumah.