What This Square Bore Collet Locks Onto This is a CNC machined Auto Lathe 42 Type square bore spring collet. It holds square, rectangular, or hex stock on sliding-head and fixed-
BQUQ CNC Machined Auto Lathe 42 Type Square Bore Spring Collet
What This Square Bore Collet Locks Onto This is a CNC machined Auto Lathe 42 Type square bore spring collet. It holds square, rectangular, or hex stock on sliding-head and fixed-head auto lathes. Th
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This is a CNC machined Auto Lathe 42 Type square bore spring collet. It holds square, rectangular, or hex stock on sliding-head and fixed-head auto lathes. The bore is precision ground to match your exact square dimension, typically from 4 mm to 32 mm across flats. You get 0.005 mm total runout at the nose, which means your turned parts stay within tolerance even at 8,000 RPM spindle speeds. We ship standard sizes in 15 days, custom bores in 20 days.
Why 42 Type Collets Fail on Square Stock
Round collets crush square bars. They only touch the four corners, creating uneven grip and vibration. Our 42 Type square bore collet uses a full-contact design. The bore is wire-cut and then hand-lapped to match your exact square dimensions. This distributes clamping force evenly across all four flats. We guarantee concentricity between the bore and the 42 mm taper cone within 0.003 mm. That is the number that keeps your bar from pushing back during heavy cuts.
Materials and Heat Treatment We Use
We start with 20CrMnTi alloy steel. This is the standard for high-wear collet bodies because it carburizes well. We machine the bore and the 42 mm taper on the same setup to hold geometry. Then we carburize to a case depth of 0.8 to 1.2 mm. The final hardness is HRC 58-60 on the gripping surfaces, but the spring slot area stays at HRC 40-45. That soft back gives the collet the flex it needs without cracking in the slot after 50,000 cycles.
Our Spring Slot Cut Is Not a Straight Line
Most collets fail at the slot root. We cut our spring slot with a 0.3 mm radius at the root, not a sharp corner. This distributes stress and extends life by roughly 40% compared to standard sharp-cut slots. The slot width is 1.5 mm ± 0.05 mm. We measure every slot with a pin gauge before the heat treat step. If the pin does not slide through with a specific drag force, the collet is scrapped. No exceptions.
Inspection Before Every Shipment
Every collet goes through a three-step check. First, we verify the bore dimension with an air gauge—repeatability is 0.001 mm. Second, we mount the collet on a test mandrel and measure runout at 10 mm from the nose using a dial indicator. We reject anything above 0.005 mm. Third, we check the taper angle with a precision comparator. The 42 Type taper is 1:10, and we hold it to ± 0.005 mm over the full length. You get a written inspection report with every order.
How to Order a Custom Square Bore Size
We stock 36 standard square sizes from 4 mm to 32 mm. If your square is non-standard, send us the exact across-flats dimension and corner radius. We will wire-cut the bore to your drawing and hand-lap it to the final size. Custom bore lead time is 20 days from drawing approval. We do not charge a tooling fee for custom bores under 50 pieces. For anything above 50 pieces, the tooling fee is waived entirely. Need to check tolerances for your square stock? Read our CNC machining tolerances guide before you send the drawing.
Packaging and Delivery for Export
Each collet is individually wrapped in VCI paper and sealed in a plastic tube to prevent rust during ocean freight. We pack 20 pieces per carton, with foam inserts that keep the collets from touching each other. Carton dimensions are 40x30x25 cm, weight is 12 kg. For air freight, we use vacuum-sealed bags to reduce volume. We ship from Dongguan via DHL, FedEx, or sea freight to your port. Most clients in the US and EU choose air freight because 15-day production plus 5-day shipping beats local sourcing.
Parameter
Specification
Product Type
CNC Machined Auto Lathe 42 Type Square Bore Spring Collet
Material
20CrMnTi alloy steel (case-hardened)
Hardness (Gripping Area)
HRC 58-60
Hardness (Slot Area)
HRC 40-45
Bore Range (Square)
4 mm to 32 mm across flats
Taper Angle
1:10 (42 Type standard)
Runout (TIR at nose)
0.005 mm max
Bore Tolerance
+0.005 / -0.000 mm
Surface Finish (Bore)
Ra 0.2 µm
Standard Lead Time
15 days
Custom Lead Time
20 days
MOQ
No MOQ (single piece accepted)
What is your minimum order quantity?
Our MOQ is one piece. We accept single-piece orders for prototypes or replacement needs, and we offer tiered pricing starting at 10 pieces.
Can you make a collet for a square size not on your list?
Yes, we can custom machine any square bore from 3 mm to 35 mm, including metric and imperial sizes, with a 20-day lead time from drawing approval.
How do you control quality for high-volume production runs?
We use SPC on every batch—air gauging every 10th piece and full CMM inspection on the first article, with a written report shipped with your order.
What is your lead time for standard and custom orders?
Standard sizes ship in 15 days, custom square bores in 20 days, and both timings are guaranteed in writing on your quotation.
Request a Firm Quote Within 12 Hours
Send us your square bore size, stock tolerance, and quantity. We will reply with a firm price and lead time within 12 hours. For material selection tips, see our CNC cutting tool selection guide to match the collet to your machine. Precision manufacturing is our core—we have run this factory in Dongguan for 20 years, and every collet is made in China with full export documentation. No MOQ, no minimum, no hassle. Email your drawing to sc@bquq.com or WhatsApp +86 13713157787. Get your quote today.
