I recently bought a used ER25 collet set and 1" diameter straight-shank
arbor, aside from missing a few of the larger collets, it seems to be in
good condition. The long taper in the arbor was galled, but not badly.
It looks like someone forgot to tighten the arbor nut enough, and the
collet spun in the arbor when used under power.

If one rotates a collet in the arbor by hand, it catches. The arbor is
hardened, and a file was not successful at cleanup. (The steep taper on
the arbor nut is perfect.)

To repair the arbor, I tore off a strip of 220 grit wet-dry sandpaper,
wetted it, wrapped it around one of the collets with the rough side out,
and gently sanded the inside of the arbor taper. This worked quickly
and well, preferentially removing the galled metal that protruded above
the level of the taper.

The arbor is not marked with a maker's name, but appears well made. The
only markings are "025-EXT" and "100". It was claimed that the set was
made by ETM, and one of the collets is so marked, but I doubt that the
rest of the pieces are by ETM.

Joe Gwinn

Joseph Gwinn wrote:

I recently bought a used ER25 collet set and 1" diameter straight-shank
arbor, aside from missing a few of the larger collets, it seems to be in
good condition. The long taper in the arbor was galled, but not badly.
It looks like someone forgot to tighten the arbor nut enough, and the
collet spun in the arbor when used under power.

I haven't seen that sort of damage but I've seen a number of them where the body was
cracked from excessive tightening. Usually shows up when a long, relative to length,
drill spinning high rpm starts drilling off location.

Wes

In article ,
Wes wrote:

Joseph Gwinn wrote:

I recently bought a used ER25 collet set and 1" diameter straight-shank
arbor, aside from missing a few of the larger collets, it seems to be in
good condition. The long taper in the arbor was galled, but not badly.
It looks like someone forgot to tighten the arbor nut enough, and the
collet spun in the arbor when used under power.

I haven't seen that sort of damage but I've seen a number of them where the
body was cracked from excessive tightening. Usually shows up when a long,
relative to length, drill spinning high rpm starts drilling off location.

In the set I didn't buy, some of the collets had a raised edge that
looked like the tool had been forced sideways in the holder, displacing
the metal. The inside of the collet was not visibly damaged, so I doubt
that the tool was wrenched out of the collet.

Joe Gwinn