How To Fix, and Maintain, Your Jacobs Super Chuck

There are lots of reasons to take apart your drill chuck: it’s broken and you want to fix your Jacobs Chuck, it’s starting to wear and you don’t want it to get worse, it’s working fine and you want to keep it that way, you bought it on eBay and you want to put it in tip-top shape, or maybe you’re curious and want to see how it works. Fortunately, the original design is both effective and easy to rebuild with the right tools. For that reason, it hasn’t changed much since it was introduced in 1902.

Jacobs Chuck Repair

Most problems with your Jacobs Chuck can be solved with a good clean and lubrication. For more complicated issues, repair kits offer replacements for all the components in the Jacobs Chuck. The process to remove the sleeve is the same for both, and we found it takes about 10 minutes with our helpful Service Ring.  Replacing parts, cleaning and lubrication may take longer.

Tools

  • Jacobs Chuck Service Ring, to press the sleeve on and off without damage
  • Arbor Press, a dead-blow hammer can work in a pinch, but a press is recommended
  • Dental pick (or similar), to scrape out any dirt or buildup
  • Cleaning agent, most degreasers should work fine
  • NLGI #2 Grease, to keep everything running smoothly
  • Optional: A lunch tray, to keep track of everything and stop the ball bearings from rolling away
  • Optional: Repair kit (depends on the problem)
All 6 Jacobs Super Chucks sitting on Service Rings

How to Rebuild Your Chuck

Here's a basic guide on removing and repairing your Jacobs Chuck. Check out the whole process in our YouTube video Rebuild a Jacobs 14N Super Chuck

  1. Place the Jacobs Chuck (jaws facing up) on the deep side of the Service Ring
  2. Retract the jaws so they’re beneath the face of the chuck. Tip: if the jaws are stuck, put a piece of softer material (wood, plastic, copper, etc.) on top of the jaws to distribute the load
  3. Push the face of the chuck (or soft material) down with the press, until the sleeve slides up and is loose.  It contains the ball bearings so keep it in place.
  4. Transfer the chuck to your workbench. 
  5. Remove the Service Ring, sleeve, and split-nut then use the dental pick to slide the ball bearings out of the slot in the split-nut
  6. Remove the jaws from the face of the chuck
    Tip: mark which jaw came from which spot on the chuck
  7. Clean all of the components, look for anything worn or broken
    Tip: the split-nut is supposed to be in two pieces
  8. Replace the jaws into the same holes on the chuck. If you’re using new jaws (or lost track), the holes in the chuck arbor are marked 1, 2, and 3 and match to jaws 1, 2, and 3. Look at the threads at the base of the jaw, to determine which is which.  The jaw tips should all align when they are installed in the correct order.
  9. Apply grease to the ball bearing track, then insert the ball bearings
    Tip: adding grease first helps keep the balls in place
  10. Make sure the jaws are all equally extended, then hold the split-nut around the threads on the jaws
  11. Keeping the jaws even, slide the sleeve over the chuck and split-nut
  12. Place the Jacobs Chuck (jaws facing down) on the shallow side of the Service Ring and push down with the arbor press

 

 

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