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Collet Questions
  1. Do you sell ER style tapping collets that have the internal square in the back?

    Yes we do.

  2. How much should I torque ER style collets nuts?

    The following torque ratings are for solid ER style collets nuts. Bearings collets nuts are not as strong so reduce these values 15%

    When clamping on shanks 30% smaller than collets maximum capacity, reduce torque value 40%.

    In most cases a light oil film on tool holder thread is adequate. Collet and collet seat should be clean and dry. 

    Below values can be exceeded 5% when using our full round torque wrench adapters. Click to View Torque Wrench Adapters »

    ER8      10-12 FT-LBS 

    ER11     15-25 FT-LBS

    ER11M   15-20 FT-LBS

    ER16     30-45 FT-LBS

    ER16M   20-25 FT-LBS

    ER20     50-55 FT-LBS

    ER20M   40-48 FT-LBS

    ER25     70-80 FT-LBS

    ER25M   50-65 FT-LBS 

    ER32     90-110 FT-LBS

    ER40     100-130 FT-LBS

    ER50     140-150 FT-LBS


  3. How much should I torque SK style collets nuts?

    The following torque ratings are for solid SK High Torque style collets nuts.

    If you are using the standard SK nuts please reduce these values 10-15%.
    In most cases a light oil film on tool holder thread is adequate and recommended. Collet and collet seat should be clean and dry. 

    SK6 HT     20-25 FT-LBS 

    SK10 HT    0-1/8" dia shanks 15-20 ft lbs
               1/8-1/4" shanks 20-30 ft lbs
               1/4-3/8" shanks 30-35 ft lbs
               3/8-higher 35-45 ft lbs

    SK16 HT    0-1/8" dia shanks 20-25 ft lbs
               1/8-1/4" shanks 25-35 ft lbs
               1/4-3/8" shanks 35-50 ft lbs
               3/8-1/2" shanks 50-70 ft lbs
               1/2-higher 70-85 ft lbs 

    SK25 HT    100-120 FT-LBS


  4. If most ER collets have a range of .039" (1mm) , why do you stock ER collets in 64'th increments?

    Even though ER collets have a range of about 1mm accuracy and grip is always reduced the more you collapse the collet. Take a letter "F" drill for example. The shank is .257 inches. Most tooling suppliers would recommend a 9/32 collet. We feel that offering a 17/64 ER collet would be a much better match and help increase grip and reduce runout.

  5. What is the difference between standard collet nuts and bearing collet nuts?

    Bearing nuts have a rotating sleeve that isolate nut rotation from the collet while it is being torqued. This distorts the collet less and allows more torque to be transmitted to the collet. Accuracy is sometimes slightly improved. Bearing nuts are not balanced as well as standard collet nuts. Due to the rotating balls they are not balanced to G2.5 @ 20,000 rpms. Bearing nuts are slightly weaker than standard collet nuts, due to the thinner cross sections and internal ball race. Torque must be reduced 15% compared to standard collet nuts.

  6. Why should I choose the ER Collet System?

    The ER collet system is a very versatile system. MariTool offers ER collet chucks in many gage lengths and profiles. Between ER8, 11, 16,  20, 25, 32, 40 and 50 you can get exactly what you need for your application. We also have ER collet chucks with Mini Nuts (last digit of tool part number will have an M). These Mini Nut style tool holders have slimmer necks and collet nuts for even more clearance. MariTool also offers some ER collet chucks with tapered shanks (designated with a T in the part number). These tapered collet chucks are longer in gage length while still offering great rigidity. With this variety of sizes, gage lengths, and profiles you can get the exact tool holders for the tool shank size you need to hold and clearances you need. Below are the ranges for each collet system.
    ER8 .03-.196
    ER11 .03-.3125
    ER16 .03-.4375
    ER20 .03-.5625
    ER25 .03-.6875
    ER32 .03-.875
    ER40 .125-1.1875
    ER50 .250-1.339
    MariTool stocks one of the most comprehensive catalog of ER collets. We stock metric, English in both standard and coolant sealing styles. We also carry Inch collets in 64'th sizes so you are assured a proper collet is available for any shank size.

  7. My ER collet has an off center groove. Is it broken?

    This is perfectly normal and an essential part of the ER collet design. ER collets have an outside groove towards the front. This groove snaps into the eccentric ring in the collet nut. This allows the nut to remove the collet from the tool holder when changing tools. Snap the collet into the nut. Tilting it helps. If the ring was not eccentric the collet would not be able to snap in.