Overview

This R8 ER32 collet chuck and spanner set gives your Bridgeport-style or mini mill spindle a precise, quick-change tool holding system. Each kit includes the R8-shank collet chuck body and a matched hook spanner wrench — the two items you need to put the ER collet system to work. Available in ER25, ER32, and ER40 to match your tooling diameter range. The R8 shank has a 7/16"-20 UNF drawbar thread for use in standard R8 spindles.

Available Options

• ER25 — R8 Shank: Collet range 1–16 mm (1/32"–5/8"). Fits standard ER25 collets. Includes ER25 hook spanner. Price: $42.95.
• ER32 — R8 Shank: Collet range 2–20 mm (3/32"–3/4"). Fits standard ER32 collets. Includes ER32 hook spanner. Price: $52.95.
• ER40 — R8 Shank: Collet range 3–26 mm (1/8"–1"). Fits standard ER40 collets. Includes ER40 hook spanner. Price: $68.95.

Note: ER collets are not included. Order the collet size that matches your tooling; see our ER collet sets listed separately.

Key Features

• R8 shank with 7/16"-20 UNF drawbar thread — fits standard R8 spindles without modification
• Hook spanner wrench included for each collet size — no separate wrench purchase required
• Hardened and ground collet chuck body for concentricity at the collet seat
• Choice of ER25, ER32, or ER40 to match your end mill and drill bit diameter range
• Drawbar thread engagement verified to standard depth — addresses common fit issues seen with budget alternatives
• Works with any brand of ER-standard collets (ER25, ER32, or ER40 as applicable)

Specifications

• Shank type: R8 taper
• Drawbar thread: 7/16"-20 UNF
• ER25 collet range: 1–16 mm
• ER32 collet range: 2–20 mm
• ER40 collet range: 3–26 mm
• Material: Alloy tool steel, hardened
• Wrench included: Hook spanner matched to collet size (ER25, ER32, or ER40)
• Collets included: None — order separately

Compatibility

Designed for mills with R8 spindle tapers. Confirmed compatible with:

• Bridgeport Series 1 / J-Head (R8 spindle)
• Grizzly G0731 / G0758 (R8 spindle)
• Grizzly G0704 (R8 spindle, mini mill)
• Sieg X2 / SX2 / X3 (R8 spindle)
• Harbor Freight mini mill #44991 (R8 spindle)
• LittleMachineShop HiTorque mini mill (R8 spindle)
• Autobox MD100930 (R8 spindle)
• Precision Matthews PM-25MV / PM-727 (R8 spindle)
• Tormach PCNC 440 / 770 (R8 spindle)

Not for use in lathe tailstocks, drill press spindles, or MT-taper machines. All listed machines confirmed in our compatibility database.

Unsure if this fits your machine? Message us — we'll confirm before you order.

What's in the Box

• 1 × R8-shank ER collet chuck body (ER25, ER32, or ER40 — per variant selected)
• 1 × Hook spanner wrench matched to collet size

ER collets are not included. Sold separately.

Frequently Asked Questions

Q: Do I need to buy collets separately?
A: Yes. This kit includes the R8 collet chuck body and the hook spanner wrench. ER collets (ER25, ER32, or ER40) are sold separately. See our ER collet sets or our ER32 R8 chuck-with-collets bundle if you want everything in one order.

Q: Which ER size should I choose — ER25, ER32, or ER40?
A: Choose based on the largest tool shank diameter you plan to hold. ER25 covers up to 16 mm (5/8"), ER32 covers up to 20 mm (3/4"), and ER40 covers up to 26 mm (1"). Most hobbyists running end mills up to 1/2" do fine with ER25; those running 3/4" shanks or face mills need ER32 or ER40.

Q: What drawbar thread does this R8 shank use?
A: 7/16"-20 UNF — the standard thread for R8 tooling in Bridgeport-style mills. If your drawbar is metric (M12), this chuck will not thread in without an adapter; check your mill's drawbar before ordering.

Q: Will this fit my lathe tailstock?
A: No. This is an R8-shank tool holder for mill spindles only. Lathe tailstocks use MT2 or MT3 tapers, which are physically incompatible with R8 tooling. For lathe tailstock work, see our MT2 or MT3 drill chuck arbors.

Why Buy from Us

• Ships from our US warehouse in Toledo, OH — typical 3–5 business day delivery, no overseas wait
• Spanner wrench included with every collet size — no separate wrench purchase, no sourcing mismatch
• 30-day returns, no restocking fee — if it doesn't fit your machine, return it
• US-based customer support — email us a photo of your spindle, we'll confirm fit before you order