This is a complete round bore collet set for automatic lathes, covering clamping diameters from 15 mm to 52 mm in one CNC machined collection. Each collet holds a guaranteed 0.005
BQUQ CNC Machined Auto Lathe Round Bore Collet Set 15-52 Collection
This is a complete round bore collet set for automatic lathes, covering clamping diameters from 15 mm to 52 mm in one CNC machined collection. Each collet holds a guaranteed 0.005 mm total indicated r
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This is a complete round bore collet set for automatic lathes, covering clamping diameters from 15 mm to 52 mm in one CNC machined collection. Each collet holds a guaranteed 0.005 mm total indicated runout (TIR) at the nose, is hardened to 58–62 HRC for long service life, and ships from our Dongguan factory in 7 working days. You get a full range of precision gripping tools without chasing multiple suppliers, built for production environments that demand repeatable part location.
How Round Bore Collets Differ From Spring Collets in Auto Lathe Spindles
Round bore collets are designed for gripping finished diameters, not raw bar stock. Unlike spring collets that collapse over a wide range, each collet in this 15–52 mm set matches a specific bore size within ±0.005 mm. This means the gripping surface contacts the workpiece evenly around the full circumference, eliminating the three-point distortion common with slotted collets. For auto lathes running secondary operations on turned parts, this uniform pressure protects surface finish and holds concentricity between the spindle axis and the part centerline.
Materials and Heat Treatment We Use for 58–62 HRC Hardness
Every collet starts as 20CrMnTi alloy steel, chosen for its core toughness and case-hardenability. We machine the bore and the external taper in one setup on CNC lathes, holding the taper angle to ±0.002 mm per 50 mm of length. After machining, each collet undergoes carburizing at 920°C followed by oil quenching and low-temperature tempering. The result is a surface hardness of 58–62 HRC with a case depth of 0.8–1.2 mm. This combination resists wear from abrasive workpieces while the tough core absorbs the clamping forces without cracking.
Bore Size Range and Taper Compatibility in the 15–52 mm Set
The collection includes 38 individual collets covering every millimeter from 15 mm to 52 mm. Each collet uses a standard 8° taper angle, matching most Japanese and European auto lathe spindles including Citizen, Star, Tsugami, and Tornos. The external taper is ground after heat treatment to guarantee seating contact of at least 85% against the spindle nose. This ground taper is what delivers the 0.005 mm TIR at the gripping diameter, not just at the taper itself.
Surface Finish and Runout Control on the Gripping Diameter
The round bore surface is ground to Ra 0.2 µm after hardening, which prevents marring of soft aluminum or brass parts during high-speed clamping cycles. Runout is measured on a dedicated fixture that simulates the actual spindle condition, not on a bench block. We check TIR at three positions along the bore length: front, middle, and rear. The maximum deviation across all three points is 0.005 mm, and we record this value on the inspection certificate shipped with every set.
Inspection Before Every Shipment: TIR, Hardness, and Taper Contact
Each collet passes three independent checks before packing. First, a hardness test on the bore surface using a Rockwell tester confirms 58–62 HRC. Second, a taper gauge with a 0.002 mm resolution dial indicator verifies the 8° angle and contact pattern. Third, we mount each collet on a test arbor and measure TIR at the bore with a laser micrometer. Any collet exceeding 0.005 mm TIR is rejected and re-ground. This inspection protocol is why our defect rate on collet shipments is below 0.3% over the last 24 months.
Packaging and Marking for Quick Identification on the Shop Floor
Each collet is laser-marked with its nominal bore size, the BQUQ logo, and the heat treatment batch number. The 38 collets are organized in a compartmentalized steel case with a foam insert that has a labeled slot for every size from 15 mm to 52 mm. This eliminates guesswork when a machinist reaches for a specific bore. The case is sealed with a desiccant pack and wrapped in anti-rust paper, so the collets arrive ready for installation without additional cleaning.
Custom Bore Sizes and Special Taper Options Beyond the Standard Set
If your spindle uses a non-standard taper angle or you need a bore size outside the 15–52 mm range, we can machine custom collets to your drawing. Custom bores down to 3 mm and up to 80 mm are possible with the same 0.005 mm TIR specification. The lead time for a custom collet is 10 working days, and the MOQ is one piece. We also offer metric or inch bore sizes with the same hardness and finish guarantees.
Specification
Value
Product Type
Round Bore Collet Set
Bore Size Range
15 mm to 52 mm (38 pieces)
Material
20CrMnTi Alloy Steel
Hardness
58–62 HRC
Case Depth
0.8–1.2 mm
Bore Tolerance
±0.005 mm
Surface Finish (Bore)
Ra 0.2 µm
Total Indicated Runout
0.005 mm max
Taper Angle
8° standard
Lead Time
7 working days
MOQ
No MOQ, 1 set accepted
What is the minimum order quantity for this collet set?
There is no MOQ — you can order a single 38-piece set or a single custom collet, and we treat both with the same priority.
Can you make custom bore sizes or taper angles for my specific lathe?
Yes, we machine custom bores from 3 mm to 80 mm and non-standard tapers to your drawing within 10 working days, with the same 0.005 mm TIR guarantee.
How do you ensure consistent quality across all 38 collets in the set?
Every collet is individually tested for hardness, taper contact, and TIR on a calibrated fixture, and the results are documented on a certificate that ships with your order.
What is the typical lead time for a standard set and for a custom order?
Standard 15–52 mm sets ship in 7 working days from our Dongguan factory, while custom collets require 10 working days including heat treatment and grinding.
We are a precision manufacturing factory in Dongguan, China, with 20 years of CNC machining experience. Our collets are made in China under ISO 9001 controls, and we export to 14 countries. This round bore collet set is one of our fastest-moving products because it solves the runout problem without the cost of hydraulic chucks. The 0.005 mm TIR is verified, not claimed.
For engineers selecting tooling, review our CNC cutting tool selection guide to understand how collet grip force interacts with cutter geometry. If you are pushing tolerances below 0.01 mm, our CNC machining tolerances guide explains the practical limits of grinding and turning processes.
Send your drawing or your spindle specifications, and we will confirm the taper angle and bore range for your machine. A firm quote is emailed within 12 hours, including shipping cost to your port. Contact us at sc@bquq.com or WhatsApp +86 13713157787. No MOQ, no inquiry fee, no obligation.
