Overview

This ER32 collet set pairs an R8 shank collet chuck with 11 metric spring collets (Φ3 mm–Φ20 mm) in one ready-to-install kit. The R8 shank fits directly into Bridgeport-style mill spindles and secures with the standard 7/16"-20 UNF drawbar. Collets cover the full size range a hobbyist or small-shop machinist reaches for most: 3 mm through 20 mm in stepped increments, plus the collet nut and ER32 spanner wrench.

Buying the chuck body and collets as a matched ER32 collet set removes the guesswork of sourcing separate ER32 components. Every piece is pre-confirmed to the ER32 standard before shipping from our Toledo, OH warehouse.

Key Features

• 11-piece collet set: Φ3, Φ4, Φ5, Φ6, Φ8, Φ10, Φ12, Φ14, Φ16, Φ18, Φ20 mm — covers standard metric end mill and drill shank sizes
• R8 shank collet chuck: 7/16"-20 UNF drawbar thread; fits all R8 spindle mills without modification
• ER32 spring collets: 1 mm clamping range per collet; hardened alloy spring steel construction
• Included ER32 spanner wrench: no hunting for the right wrench — collet nut tightening tool ships in the box
• Matched components: chuck body and collets verified to the same ER32 OD and taper spec before packaging
• Drawbar-ready design: R8 taper accepts standard 7/16"-20 drawbar found on all Bridgeport-compatible spindles

Specifications

• Collet system: ER32
• Chuck shank: R8 taper, 7/16"-20 UNF drawbar thread
• Collet set size: 11 pieces
• Collet range: Φ3 mm – Φ20 mm (metric stepped increments)
• Per-collet clamping range: 1 mm
• ER32 collet OD: 33 mm (1.30")
• ER32 collet length: 40 mm (1.57")
• Max ER32 chuck RPM: 8,000 RPM
• Drawbar thread: 7/16"-20 UNF

Compatibility

This kit is designed for milling machines with an R8 spindle taper. Confirmed compatible with:

• Bridgeport Series 1 / J-Head mill
• Grizzly G0704
• Grizzly G0731 / G0758
• Sieg X2 / SX2 / X3
• Autobox MD100930 mini mill
• LittleMachineShop HiTorque mini mill
• Tormach PCNC 440 / 770 / 1100
• Harbor Freight #44991 mini mill
• Precision Matthews PM-25MV / PM-727

Not for lathes or drill presses: R8 is a mill spindle interface. If you need an ER32 chuck for an MT3 headstock, message us — we carry MT3 ER collet chucks separately.

What's in the Box

• 1× ER32 R8 shank collet chuck body (7/16"-20 UNF drawbar thread)
• 11× ER32 metric spring collets: Φ3, Φ4, Φ5, Φ6, Φ8, Φ10, Φ12, Φ14, Φ16, Φ18, Φ20 mm
• 1× ER32 collet nut
• 1× ER32 hook spanner wrench

Frequently Asked Questions

Q: Does this fit my Bridgeport mill?
A: Yes. Bridgeport Series 1 and J-Head mills use an R8 spindle taper with a 7/16"-20 UNF drawbar. This chuck installs the same way as any R8 tooling — insert the taper, thread the drawbar, snug it down.

Q: What collet sizes are included — are they metric or imperial?
A: The 11 collets are metric: Φ3, Φ4, Φ5, Φ6, Φ8, Φ10, Φ12, Φ14, Φ16, Φ18, and Φ20 mm. Each collet clamps a 1 mm range. If you primarily use imperial-shank end mills, see our ER32 imperial collet sets (sold separately).

Q: Do I need anything else to start using this kit?
A: No. The kit includes the chuck body, all 11 collets, the collet nut, and the spanner wrench. You just need a mill with an R8 spindle and the standard 7/16"-20 drawbar (already installed on most R8 mills).

Q: What is the maximum tool shank diameter this system can hold?
A: The largest collet in this set is Φ20 mm, which holds shanks from 19 to 20 mm. ER32 collets cap out at 20 mm maximum. For shanks up to 26 mm you would need an ER40 system.

Q: Can I use this on a drill press or lathe headstock?
A: No. The R8 taper is designed for milling machine spindles and requires a drawbar for secure clamping. Drill presses typically use MT2 or MT3 tapers, and mini lathe headstocks are usually MT3 — neither is compatible with R8.

Why Buy from Autobox

• Ships from Toledo, OH — same or next business day; typical 3-5 day US delivery, no overseas wait
• Pre-matched kit — chuck body and collets are from the same ER32 spec run, so you are not mixing tolerances from two separate orders
• 30-day returns, no restocking fee — if a collet size does not work for your tooling, send it back
• US-based customer support — email us a photo of your machine and we will confirm fit before you order