What This Collet Set Does and Why It Matters on Your Auto Lathe This is a complete set of heavy-duty collets for automatic lathes and CNC turning centers, covering four bore sizes: 50 mm, 52 mm, 55 mm
This is a complete set of heavy-duty collets for automatic lathes and CNC turning centers, covering four bore sizes: 50 mm, 52 mm, 55 mm, and 60 mm. Each collet is CNC machined from 20CrMnTi alloy steel, carburized to a surface hardness of HRC 58-62, and ground to a gripping tolerance of ±0.005 mm. You get a total runout of 0.008 mm or less at the nose, which means your bar stock spins true from the first pass. We ship these sets in 15 days from drawing approval, and we do not force you to buy a full box—no MOQ applies to this CNC machined auto lathe collet set 50 52 55 60 heavy series.
Standard heavy series collets often show 0.02 mm runout after a few hundred cycles. Ours stay under 0.008 mm because we grind the bore and taper in the same setup, on the same machine, without unclamping. That single clamping eliminates the stacking error between the taper and the gripping surface. For your auto lathe, this means less bar deflection, tighter concentricity on turned diameters, and fewer rejected parts when you are holding long, unsupported stock. We also hard-turn the serrated gripping area instead of cutting it, which keeps the tooth sharpness consistent across all four collets in the set.
Most collet sets we see from other factories use 45# steel, which hardens to about HRC 45-50. That is fine for light duty, but it wears fast when you grip 60 mm bar stock at high spindle speeds. We use 20CrMnTi, a low-carbon alloy steel that carburizes deep—0.8 to 1.2 mm case depth—and gives you a tough core with a hard shell. After carburizing, we quench and temper to HRC 58-62 on the surface. The core stays at HRC 35-40, so the collet flexes without cracking when you clamp oversized or slightly out-of-round stock. This combination is why the heavy series set holds up for 200,000+ clamping cycles in real production, not just on a test bench.
The set includes four collets: 50 mm, 52 mm, 55 mm, and 60 mm. Each collet has a grip range of ±0.5 mm from the nominal size, so one collet covers a 1 mm span. The slots are milled with a 0.3 mm width and a 120-degree spacing, which gives you even radial compression without pinching the bar. We also back-taper the bore by 0.02 mm over the gripping length—this means the front of the collet grips slightly tighter than the rear, pulling the bar back against the stop. That detail alone reduces push-back on your auto lathe by up to 30% when cutting with high feed rates.
We grind the taper to an accuracy of 0.005 mm over the full cone length. The bore surface finish is Ra 0.4, and the taper face is Ra 0.2—smooth enough to seat firmly in your spindle without galling. The outside diameter is ground to h6 tolerance, which means a 50 mm collet measures between 49.981 mm and 50.000 mm. This tight OD tolerance ensures the collet seats concentrically in the spindle nose, not just on the taper. If your spindle has a worn taper, the h6 OD lets you compensate by adjusting the drawbar tension slightly without losing grip force.
| Specification | Value |
|---|---|
| Product Type | CNC machined auto lathe collet set, heavy series |
| Available Bore Sizes | 50 mm, 52 mm, 55 mm, 60 mm |
| Material | 20CrMnTi alloy steel (case-hardened) |
| Hardness | Surface HRC 58-62, core HRC 35-40 |
| Grip Tolerance | ±0.005 mm |
| Total Runout | 0.008 mm max at nose |
| Surface Finish (Bore) | Ra 0.4 |
| Surface Finish (Taper) | Ra 0.2 |
| Outside Diameter Tolerance | h6 |
| Lead Time | 15 days after drawing approval |
| MOQ | No MOQ, single set accepted |
We do not ship any collet set without a full inspection report. Each set is checked on a coordinate measuring machine (CMM) for taper angle, bore diameter, and concentricity. Runout is verified by mounting the collet in a test holder with a dial indicator at 50 mm from the nose—this is stricter than the industry standard, which often checks at 25 mm. We also perform a hardness test on the surface and the core for every batch, not just the first piece. The report is included with the shipment, so your incoming quality team can verify our numbers in minutes.
No, we accept orders for a single set of four collets with no MOQ, and the price per set does not increase for small quantities.
Yes, we can bore any collet to a custom diameter between 3 mm and 65 mm, and we can adjust the grip range to ±0.3 mm if you need tighter control for thin-walled tubing.
Every collet is individually measured on a CMM, and the runout test is done on a matched test holder, with the inspection report shipped alongside the set for your records.
We ship standard sets in 15 days from order confirmation, and we can expedite to 10 days if you confirm the drawing and pay a small rush fee.
Buying a set of four collets individually from a distributor usually costs 20-30% more than our direct set price, and you often wait 4-6 weeks because each size is sourced from a different warehouse. With this set, you get matched collets that are ground in the same batch, which means the taper angles are identical to within 0.002 mm across all four. That consistency matters when you switch between 50 mm and 60 mm bar stock on the same machine—you do not have to re-tune the drawbar pressure. Plus, you save on shipping and customs paperwork because it is one box, one invoice, one origin.
If you are still deciding on the right tooling for your spindle, our CNC cutting tool selection guide covers how to match collet grip force to your cutting parameters. For tighter tolerance requirements, our CNC machining tolerances guide explains how runout and surface finish translate into real part dimensions.
Dongguan has been the center of precision manufacturing in China for 20 years, and our factory has been running CNC machines and grinders here since 2005. We are not a trading company; we operate 12 CNC lathes and 4 cylindrical grinders on-site, which is why we can control the heat treatment and grinding in-house. This vertical integration is the reason we can guarantee the 0.008 mm runout and the 15-day lead time. When you source from us, you are buying directly from the shop floor, not through a middleman in Shenzhen or Guangzhou.
Send us your drawing or just specify the bore sizes you need—we will confirm the exact dimensions, hardness, and price within 12 hours. Email your inquiry to sc@bquq.com, or send a WhatsApp message to +86 13713157787. We will reply with a firm quote, a recommended shipping method, and a delivery date. No MOQ, no hidden fees, and the inspection report is free with every order. Send your drawing today and see how fast precision manufacturing in China can respond.
| 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 |
