What This Extended Collet Series Does Differently on Your Auto Lathe This is a CNC machined collet chuck system designed specifically for auto lathes that need extended reach into deep bores or over l
This is a CNC machined collet chuck system designed specifically for auto lathes that need extended reach into deep bores or over long protruding toolholders. The extended nose length grips bar stock or tool shanks up to 30 mm further out than standard ER collets, reducing vibration and deflection at the cutting edge. You get a guaranteed runout of 0.005 mm TIR (measured at the nose), a surface finish of Ra 0.4 on the gripping bore, and a consistent hardness of 58–60 HRC after heat treatment. Lead time is 15 working days for standard sizes, and we ship from our Dongguan factory with no MOQ on any item in this series.
Standard collets lose stiffness when the tool extends beyond the chuck face. Our extended series adds a hardened steel nose sleeve that supports the tool shank over a longer contact length—typically 1.5x the diameter of the collet pocket. This means for a 20 mm shank, you get 30 mm of continuous grip instead of the usual 20 mm. The result is measurable: deflection under a 50 N radial load drops from 0.012 mm (standard ER32) to 0.006 mm with this extended design. That translates directly to better surface finish and longer insert life when you are machining deep pockets or using long reach boring bars.
We machine the collet bodies from 8620 alloy steel, then carburize and quench to reach the 58–60 HRC case hardness. The gripping leaves are ground after heat treatment—never before—so the hardened layer remains intact across the entire clamping surface. The internal threads are cut on a CNC lathe with a tolerance of 6H, which keeps the pull-back action smooth and repeatable. For the spring collets inside the series, we use 65Mn spring steel with a fatigue life tested to 500,000 cycles without losing clamping force beyond 5%. Every batch is verified with a Rockwell hardness test report included in the shipping documents.
We do not ship a single extended collet without a full inspection report. Each unit is checked on a precision test arbor for TIR runout at the nose—the pass criterion is 0.005 mm or better. Surface finish on the gripping bore is measured with a profilometer; we reject anything above Ra 0.4. We also test the clamping force at 80% of max torque to confirm the collet closes evenly across all slots. The report includes the measured runout value, the actual hardness reading, and a photo of the part with the batch number. This is standard practice, not a paid extra.
| Specification | Value / Range |
|---|---|
| Collet Series | ER16, ER20, ER25, ER32, ER40 (extended nose variants) |
| Gripping Range | 1.0 mm – 26.0 mm (depending on series) |
| Extended Nose Length | +10 mm to +30 mm over standard ER collets |
| Body Material | 8620 alloy steel, carburized |
| Spring Material | 65Mn spring steel |
| Hardness (case) | 58–60 HRC |
| Runout (TIR at nose) | 0.005 mm max |
| Surface Finish (gripping bore) | Ra 0.4 μm |
| Thread Tolerance | 6H |
| Lead Time | 15 working days (standard), 7 days (rush, +20% fee) |
| MOQ | No MOQ – order 1 piece or 1000 pieces |
We are a precision manufacturing facility in Dongguan with 20 years of experience in CNC machining, stamping, and springs. Because we control the entire process—from raw bar stock to final grinding—we eliminate the middleman markup you see on European or Japanese collets. The same 0.005 mm runout that costs $80 per unit from a German brand costs $28 from BQUQ for the extended series. And because we make our own springs, we can guarantee cycle life without sourcing delays. If you are comparing quotes, include the cost of import freight and customs clearance; our pricing is EXW or FOB Shenzhen, which typically saves another 10–15%.
This extended series is designed as a drop-in replacement for standard ER collet chucks on most Japanese and Taiwanese auto lathes—Citizen, Star, Tsugami, and Hanwha models are common fits. The external taper and thread pitch match the original chuck nut, so you do not need to modify your spindle. If you are unsure about your machine's interface, send us a drawing or a photo of your current chuck nut, and we will confirm compatibility within 24 hours. We also offer custom bore geometry for special tool shanks—just specify the shank diameter and the required grip length in your inquiry.
Standard ER collets stop at round bores, but our extended series can be machined with hex, square, or stepped bores upon request. The most common custom we run is a stepped bore for a drill with a reduced shank—we machine the back step to 0.01 mm concentricity with the front gripping section. This is done in-house on our CNC lathes, so the added cost is only $15–$25 per unit depending on complexity. For production runs above 200 pieces, we will waive the custom machining setup fee entirely.
There is no MOQ—you can order a single collet for prototype testing or a full production batch, and the unit price remains the same.
Yes, we can extend the nose up to 30 mm beyond standard, and we machine round, hex, square, or stepped bores with 0.01 mm concentricity for the custom section.
Every collet is tested on a precision arbor for TIR runout (0.005 mm max) and checked with a Rockwell hardness tester (58–60 HRC), with the report included in your shipment.
Standard lead time is 15 working days from drawing approval; rush orders are shipped in 7 days with a 20% expedite fee.
For the right toolholder setup, check our CNC cutting tool selection guide to match the collet bore with your end mill or drill. To understand how our 0.005 mm runout fits into your overall part quality, read our CNC machining tolerances guide—it explains what runout means for your final part dimensions.
Send us your drawing or your current collet nut specs, and we will send a firm quote within 12 hours. Email sc@bquq.com or WhatsApp +86 13713157787. We ship worldwide from our Dongguan factory, made in China, with no MOQ and full inspection reports on every piece.
| 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 |
