[Video] Jacobs Chuck Collection


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A prime example of toolholding from the early 1900s, the Jacobs Super Chuck is a staple in machine shops around the world. Used in machines from drill presses to lathes, the Super Chuck features robust tool-holding and durability in an easily accessible package. Our collection features six chucks, an original repair kit, and an antique shipping crate.

While the same design is still made and sold today, with some care an original will last for generations. Watch future vids to see how to rebuild them. Get that feel of a new chuck that Arthur designed over 100 years ago.

To purchase Jacobs Super Chuck Press Rings: http://bit.ly/35fiXHl

Kit Contents

The Kit has a mixture of parts for super chucks and parts for other popular chucks. Sticking with the super chucks here is table regarding the reamers

  • 20N 8-Flute Straight 0.6770 A1944
  • 18N 6-Flute Straight 0.5510 A1943
  • 16N 6-Flute Straight 0.5200 A1942
  • 14N 6-Flute Straight 0.4740 A1941
  • 11N.6-Flute Straight 0.3830 Not Marked but obviously A1940
  • 8-1/2N 6-Flute Straight 0.3290 A1939
  • All are marked as #1700 and have an insignia of the toolmaker CMG with a T though the M

The rings are not complete for the Superchucks, only the 20N, 18N, 16N, 8-1/2N. rings were in the original kit. We are still decoding the others and checking other common chucks to see what fits. So there will probably be another set of rings for the "Non-Super Chucks" in the future.

From our basic research here are the Ball Bearings for each chuck. The race needs to be as full as possible to evenly distribute the load. The quantities for each chuck vary from 29 for the 8-1/2 to 36 for the 20N.

Tight Tolerance ($$$) Probably These ($)
Chuck Ball Bearing Diameter McMaster Number McMaster Number
8 1/2N 1/8" 9528K45
11N 5/32"
14N 3/16"
16N 3/16"
18N 7/32"
20N 1/4"


Chuck Key Number JT Arbor # JT Arbor Dia (in) Force (using 7000# grease)
8 1/2N 30 2 0.559 1300 (no room for zerk)
11N 32 2 0.559 1300
14N 3 3 0.811 3000
16N 4 3 0.811 3000
18N 4 4 1.124 5900
20N 5 5 1.413 9500


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