Hi Woodguy,
I'll try to answer and hope I don't add to the confusion.
I use 4 different collet systems in my shop: R8, 5C, MT3 and ER40.
R8: The most common (by far) taper collet used for milling machines in North America. Thus, the tooling is readily available and affordable in the new and second hand markets. I've never seen an R8 taper on anything but a mill. The collets require a draw bar to pull them up tight so they are closed end. The collet is released by backing off the draw bar and tapping it with a dead blow hammer.
5C: Quite common on production sized lathes, this is a self-ejecting pass-through collet. Though similar in appearance to an R8 the body is larger and the taper is slightly sharper and more abrupt. The outside far end of the collet is threaded for a draw tube that is connected to the locking/ejecting mechanism.
MT3/4: These are Morse Taper collets. The taper is rather shallow and locks quite firmly using a draw bar. They are closed end. Releasing the collet is similar to the R8 but may require a rather sharp smack to release as they can grip very tight because of the slight taper.
ER series: All of the ER series are similar in design, the difference is the physical size of the collet and capacity. These are a pass-though and self-ejecting design. The collet itself has two tapers and is shaped somewhat like a truncated diamond. A nut with a ring in it locks into a groove in the collet, the nut screws onto the chuck pressing the collet into the taper. The collets for each "step" (ER11, ER16, ER32, ER40 etc) are not interchangeable with each other.
The R8, 5C and MT collets have very little tolerance for off sized work. Your material/tool must match closely the size of the hole in the collet. The ER series is much more forgiving in this regard allowing as much as a millimeter variance in size.
There are many more collet systems used throughout history and the world but these are the most common, you will be able to find any of these at reasonable cost at any of the major tool vendors or on Craig's List/ebay.
If you want to learn more, please visit our website Ruihan.
Three-jaw chucks are the standard work holding device for most CNC lathe users. It is among the most widely used types of chuck in a variety of turning applications. However, that does not mean it is the best chuck for all jobs. A collet chuck is an alternate work holding device that also uses mechanical forces to hold a workpiece. While a collet chuck does not work with the same wide range of workpiece sizes that a jaw chuck can accommodate, it offers advantages in speed, accuracy, and productivity that may be crucial for certain jobs.
The standard work holding system that comes with most CNC lathes and turning centers consists of a three-jaw power chuck, a hydraulic actuating cylinder, and a drawtube. The hydraulic cylinder is attached to the rear end of the spindle, while the chuck is mounted to the spindle&#;s front or working side. The cylinder and chuck are usually connected via a hollow, steel drawtube that passes through the spindle bore.
Similarly, a CNC collet chuck is mounted to the front of a CNC lathe spindle, using the machine&#;s existing cylinder and drawtube to actuate:
The axial motion of the hydraulic actuator&#;s piston is what causes the collet chuck&#;s jaws to open and close. The drawtube moves in unison with the piston, driving a wedge-shaped plunger within the chuck body as the piston slides back and forth. The plunger, in turn, converts axial motion to radial motion, accomplishing the opening and closing of the jaws. The gripping force of the jaws to a workpiece corresponds directly to the output of the actuator; thus, this force is easily regulated via a pressure valve.
Of course, a collet chuck requires a collet to function. Typically, collets have something like a 0.062&#; gripping range. Collets are readily available for round, hex, and square stock. A collet chuck can handle a fairly wide range of collets (e.g. 3/16&#; all the way through to 2-5/8&#;). Special collet requirements can be accommodated. Most modern collet chucks have a quick (e.g. 10 seconds) change functionality for reduced set-up times.
Contact us to discuss your requirements of Straight Shank Collet Chuck. Our experienced sales team can help you identify the options that best suit your needs.
Our preferred supplier partner for collet chucks is Royal Products. Royal provides a wide range of work holding options, including several lines of collet chucks.
For more information about the benefits of collet chucks and help selecting the right work holding device for your operation, contact us.
Want more information on Straight Shank Er Collet Chuck? Feel free to contact us.