This is a complete ER collet chuck disassembled parts kit: collet nut body, backing nut, and precision-machined taper seat. You get 0.005 mm TIR (total indicated runout) at the nose, surface finish Ra 0.4 µm, and a hardness of HRC 58-60 on the gripping surfaces. Lead time is 15 days for standard sizes, and we ship from Dongguan with no MOQ for first-time engineering samples.
The collet nut body is the critical torque path. When you tighten the nut, the internal 30-degree taper forces the collet segments radially inward. Our nut body threads are cut to ISO 6H tolerance, which means smooth engagement and zero binding even at 40 N·m torque. The taper seat is ground, not just turned, to hold the collet's OD concentric to the spindle axis within 0.003 mm. This is what eliminates tool chatter and gives you that 0.005 mm runout at the cutting edge.
We machine the nut body from 42CrMo4 alloy steel, not cheap 1045. After CNC turning and milling, we carburize the threads and taper to a case depth of 0.8 mm, then harden to HRC 58-60. The outer surface gets black oxide for corrosion resistance, but the taper and thread flanks stay clean for dimensional accuracy. For stainless or aluminum spindle applications, we offer a 17-4PH version at HRC 40-45 on request. Every batch is hardness-tested with a Rockwell tester, and we reject any part below HRC 57.
| Spec | Value | |------|-------| | Product type | ER collet chuck disassembled parts (nut body + backing nut + taper seat) | | Collet range | ER11, ER16, ER20, ER25, ER32, ER40 | | Shank diameter options | 1/8" to 1-1/4" (metric equivalents available) | | Thread type | Metric fine (M12x1.5 to M40x1.5) or inch (UNF) | | Material | 42CrMo4 (standard), 17-4PH (optional) | | Hardness | HRC 58-60 (case hardened) | | Taper angle | 30° per side, ground to ±0.05° | | Runout (TIR) | 0.005 mm at nose, 0.008 mm at 4x diameter | | Surface finish | Ra 0.4 µm on taper, Ra 0.8 µm on threads | | Tolerance | Thread pitch ±0.01 mm, OD ±0.02 mm | | Lead time | 15 days for standard sizes, 20 days for custom | | MOQ | No MOQ for samples, 10 pcs for production | Inspection Before Every Shipment: Runout and Thread Gauging
We do not ship blind. Every collet nut body goes through a thread ring gauge (6H class) and a taper gauge with a dial indicator. Runout is measured on a test arbor with a 0.001 mm resolution indicator. We also check the hardness spot with a portable Rockwell unit and record the values in a batch report. If any part exceeds 0.005 mm TIR, it goes to scrap, not to you. You get a digital inspection report with each shipment, including material certs and heat treatment curves.
Why This Design Works with Your Existing Tooling
The disassembled design lets you replace just the worn nut body or taper seat without buying a whole chuck. That cuts your tooling cost by about 40% compared to a monobloc chuck. The nut body has a knurled surface for a standard spanner wrench, and the backing nut is pre-drilled for balance screws if you run above 15,000 RPM. We match the taper to standard ER collets from any brand—Rego-Fix, Techniks, or generic—because the 30-degree angle is universal.
Custom Sizes and High-Speed Options for Your Spindle
If you run a BT30 or HSK spindle and need a shorter nut body to reduce overhang, we can machine the OD down to 0.5 mm wall thickness without losing thread strength. For high-speed machining above 20,000 RPM, we add balance holes in the nut body and dynamically balance the assembly to G2.5 at 25,000 RPM. Just send your spindle drawing or existing chuck dimensions, and we will give you a CAD model within 48 hours.
Frequently Asked Questions
What is the minimum order quantity for these collet nut bodies?
No MOQ for samples—you can order one piece to test fit and runout, and production orders start at 10 pieces.
Can you customize the thread size or taper angle for my spindle?
Yes, we machine any metric or inch thread and can modify the taper angle by ±0.5 degrees, but we recommend keeping 30 degrees for standard ER collets.
How do you ensure the runout stays at 0.005 mm after heat treatment?
We grind the taper after hardening, not before, and use a live center with 0.002 mm repeatability to eliminate distortion from the case hardening.
What is the lead time for a custom ER collet chuck disassembled set?
Standard sizes ship in 15 days; custom thread or material takes 20 days, and we provide tracking and a firm delivery date on your PO confirmation.
Get a Firm Quote Within 12 Hours
Send your drawing or just the collet size and shank dimension. We will reply within 12 hours with a fixed price, lead time, and a CAD preview. No hidden tooling fees, no MOQ pressure. For engineering samples, we ship via DHL or FedEx at cost. For production runs, we offer FOB Shenzhen or CIF your port.
Email your RFQ to sc@bquq.com or message our WhatsApp +86 13713157787. Include your ER size, shank type, and quantity. We will respond with a quote and a sample drawing for approval.
Before you finalize your tooling, check our CNC cutting tool selection guide to match the collet chuck with the right end mill or drill. And for tighter tolerance requirements, see the CNC machining tolerances guide to confirm your spindle's capability. BQUQ is a precision manufacturing factory in Dongguan, China, with 20 years of CNC machining, stamping, springs, and heat sink production. We are made in China, but our quality reports are world-class. Send us your drawing today.
Related Products
parameter
| Parameter | Capability |
|---|
| Materials | AL6061/7075, SUS303/304/316, 45# steel, T2 copper, H59 brass, POM, PEEK, nylon |
| Tolerance | ±0.005mm standard, ±0.003mm on request |
| Machines | 3/4/5-axis CNC, turn-mill, Swiss lathe |
| Surface | Anodizing, nickel, zinc, passivation, sandblast, polish |
| Size Range | Max 400 x 300 x 200 mm |
| Prototype | 72 hours, no MOQ on samples |
| Inspection | Full report per batch, CMM data on request |
