Skip to content
AccessoriesMade in USA

ER25-M3

ER Style Integrated Collet and End Mill Extension Holder

ER25 Metric Extension Holder, 3mm Hole Diameter, 10mm Extension Diameter, 25mm Extension Length

ER Style Integrated Collet and End Mill Extension Holder — ER25-M3
Series photo — representative of the ER-M family
Dimension diagram of an ER solid mill extension: body diameter, extension length, and hole diameter
Dimension reference — labels match the specifications below
Speeds & FeedsDialed to this exact tool — free
Free CAD & DataSTEP 3DDXF 2DISO CSVCAM library
Cutaway of a RobbJack ER solid mill extension showing the precision-ground ER taper and triangular set-screw grip

Solid ER-mill extensions

  • Reaches micro tools past fixturing that a standard holder can't clear
  • Holds exceptional runout at extended reach — TIR under .0002″ at full extension
  • Beats deflection and chatter on long, small-diameter work
  • Set screws grip the shank in a triangular arrangement for repeatable accuracy
  • Internal stop adjusts from both ends with a standard hex key
  • Precision-ground ER taper twists and snaps into most standard ER clamping nuts — available ER8 through ER25
  • Coolant-Thru versions available in ER16

From the RobbJack Applications Guide.

About this series

ER Solid ER-Mill Extensions

Reach deep into fixtures without giving up accuracy.

Integrated ER collet-and-extension holders that let miniature and standard end mills clear fixturing and run at extended length while holding exceptional runout — solving the deflection and chatter that come with long, stacked tool assemblies.

  • Precision-ground ER taper — available in ER8, ER11, ER16, ER20 and ER25
  • Internal stop adjusts from both ends of the holder with a standard hex key
  • Set screws clamp the shank in a triangular arrangement for excellent accuracy
  • Coolant-thru versions available for ER16

Twist and snap into most standard ER clamping nuts — RobbJack recommends HiQ® by REGO-FIX for best results.

Headline spec

TIR < .0002" at full extension

Best for

  • Deep-pocket & fixture clearance
  • Micro tools at reach
  • High-accuracy finishing

Specifications

US machining terms with ISO 13399 codes.

Accessory Type
ER Holder
ER Size
ER25
Hole Diameter
0.1181″
Body DiameterDMM
0.3937″
Extension LengthOAL
0.9843″
Series
ER-M — ER Style Integrated Collet and End Mill Extension Holder

See it run

Starting at$421.10

Made & shipped in the USA · lead time confirmed at order. Buy at retail or through your distributor.

Performance guaranteed. Run it against the tool you use today — if it doesn't beat it, we'll make it right.

Adds Uncoated · $421.10 — our pick for your material. Choose another finish below.

Calculate Speeds & Feeds
CADDXF·STEP
Add to Quote
Download ISO 13399 data (.csv)

Proven in the field

See the case studies →

Finishes (1)

  • Uncoated

    ER25-M3

    $421.10

    Available to order

Compare tool coatings →

Starting at

$421.10

Performance guaranteed

More in the ER-M series

Same series, different size — what changes from this tool is shown in red.