Wexmar provides custom collet machining for special workholding, fixtures and machine builders that need a collet shape, bore or length not available as a standard. Our Canastota, New York shop produces CNC machined collets, emergency collets, pushers, feed fingers and collet-style clamping sleeves on CNC lathes, Swiss-type machines and horizontal machining centers. As a working machine shop that runs collets every day, we understand what the part has to do on the machine.
What collets do and who buys them
A collet grips a workpiece or tool by closing evenly around it as it is drawn into a taper. Grip force, repeatability and runout all depend on the relationship between the external taper, the gripping bore and the slots. Typical buyers include:
- Machine shops and production plants needing special-bore, stepped or extended-nose collets
- Machine and automation builders with custom clamping mechanisms
- Instrumentation and medical hardware makers using collet-style clamps in their products
- Maintenance buyers replacing obsolete collets for older equipment
How our custom collet machining works
Turning the body, taper and bore
Collet bodies are turned on our Mazak and Doosan lathes. The external taper, the gripping bore and the drawbar thread are finished in the same chucking wherever possible, since their common axis is what sets runout. Small collets and pushers up to 32 mm diameter can run on our Maier MLK-32 Swiss-type machines. See CNC turning.
Slotting
Slots are cut with live tooling on the lathe or on our Mazak horizontal machining centers with 4th-axis indexing, so slot spacing is set by the machine. Slot width and end radius are controlled to give even spring action.
Emergency collets and soft collets
Emergency (soft) collets are supplied with a pilot bore so the customer can bore them in their own machine. We can also finish-bore them to a specified size.
Typical collet materials
- Alloy spring steels and 4140, heat treated for spring temper
- Tool steels for high-wear gripping surfaces
- Brass and aluminum for soft emergency collets and non-marring grip
- Stainless steel for food, medical and corrosive environments
- Engineered plastics for delicate parts
Critical features and how we hold them
- Taper angle and fit: turned to the mating spindle or holder taper and checked with a taper gage and bluing.
- Bore to taper runout: bore and taper are cut in one chucking to keep gripping runout low.
- Slot spacing and width: indexed by machine, with slot width held for even closure.
- Drawbar thread: single-point cut and gaged to class, concentric to the taper.
- Hardened condition: where heat treat is required, stock is left and critical surfaces are finish turned or ground after hardening.
Typical tolerances and finishes
| Feature | Typical tolerance | Tighter on request |
|---|---|---|
| Gripping bore | +/-0.0005 in | +/-0.0002 in |
| Bore to taper runout | 0.0005 in TIR | 0.0003 in TIR |
| Taper angle | +/-0.05 deg | Fit to customer gage |
| Slot width | +/-0.002 in | +/-0.001 in |
| Drawbar thread | Class 2A / 2B | Class 3A / 3B |
| Taper and bore finish | 32 Ra | 16 Ra |
Values are typical for collets in the finished condition. Heat treat distortion and collet size affect what is practical, and the quote confirms each callout.
Design notes
Tell us the machine, spindle or holder the collet fits, and the workpiece size range and material it will grip. For collets that must be hardened, the sequence matters: rough turn, slot, heat treat, then finish the taper and bore. Stepped bores and dead-length designs should show which face is the stop. Serrated or smooth grip, and whether the bore is finished at nominal or with a small undersize for grip, both change how the collet performs.
Secondary operations
Heat treat for spring temper or hardness, black oxide and coatings are completed through qualified outside processors. ID and taper grinding after hardening can be arranged through qualified outside processors when the drawing calls for it. Our in-house surface and centerless grinders handle faces and plain outside diameters where the geometry suits them.
Quantity patterns
Special collets are usually ordered in ones to dozens, with emergency collets and pushers in larger lots of 25 to a few hundred. Programs are retained for repeat orders. See also spindles.
Inspection
Bore, taper and runout are checked with gages, indicators and our Brown and Sharpe CMMs, and slot and thread form on the Mitsubishi optical comparator. FAI in AS9102 format, CMM reports and material certs are available.
Getting a quote
Send the drawing or the collet standard, grip size, material and quantity. You can upload a drawing for an instant estimate, and an estimator will confirm price and lead time. Call (315) 400-2654 with collet questions.