Drill Chuck Maintenance

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UPBOILERMAKER
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Joined: Wed Apr 05, 2023 3:07 pm

Drill Chuck Maintenance

Post by UPBOILERMAKER »

I am new to the Forum. Please forgive me if this procedure has been posted previously.

I have a 1979 vintage Mark V that came with a Jacobs Multi-Craft, Model MC8K26, Capacity 5/64"-1/2", chuck. The chuck had about 10 total hours of use and 44 year's accumulation of dust and dried up factory grease. The chuck was operable, but was difficult to turn by hand. I watched all the videos on YouTube and tried to purchase an alum. ring made by a Calf. company specifically to aid in removing the press-fit, adjustment ring. They only make rings for the Jacobs "Super Chuck" which, I believe, is a much larger, professional machine shop, chuck with ball bearings. In watching a "Super Chuck" Disassembly, Clean and Lube video, the author cautioned the viewer to retract the chuck's three grip fingers below the face of the chuck before pressing the retention ring off. THIS IN INCORRECT FOR THE SHOPSMITH's, JACOBS MULTI-CRAFT CHUCK. If you watch the Non-Ball Bearing Jacobs Chuck YouTube videos, they correctly instruct you to only retract the fingers 1/4-1/2 from the full extension position (for a small diameter drill bit). THIS IS CORRECT OR YOU RISK SHEARING OFF THE THREADS ON THE END OF THE FINGERS INSIDE THE CHUCK.

MATERIALS: Not having access to an arbor press or a bench mounted vise, I went to a hardware store with my chuck in hand and found that a 1", Sch 40, PVC, cement fit, pipe coupling and a 1-1/4", Sch 40, PVC, THREADED, female, pipe coupling fit each end of the chuck, tight enough to allow the removal and re-installation of the press ring. The other items I used were two short pieces of 2"x4" lumber and a 45 oz dead-blow hammer.

DISASSEMBLY: Prepare the chuck by applying your favorite penetrating oil (Kroil, WD-40, Master-Blaster, etc.) to each end of the press ring (the ring that turns and has the notches cut in one end to fit the chuck key). Let the chuck sit for a couple hours to loosen up any dried grease between the chuck and the press ring. Drill a 1/2" diameter hole in the 4" face of one of the 2x4's. Extend the grip fingers to all the way closed (for a small diameter drill bit) and then open (retract) them about 1/4 of the way. Place the 2x4 with the 1/2 hole on a concrete floor or other very sturdy surface. Insert the chuck, fingers-down into the 1/2 hole. Slide the 1-1/4", PVC coupling on the other end of the chuck. Steady the chuck and coupling, then place the 2nd piece of 2x4 on top of the 1-1/4" coupling and strike the 2X4 with the dead-blow hammer. Don't kill it, just strike it sharply and observe movement of the press ring down the chuck toward the extended fingers. Repeat until the press can be removed by hand. DO NOT REMOVE THE PRESS RING OR THE CONTAINED FINGERS YET.

Holding the chuck in one hand and the press ring in the other, gently remove the press ring. NOW THE IMPORTANT PART. Place "witness" marks on the body of the chuck, but NOT on the surface that mates with inside of the press ring. I used I, II and III. First with a Sharpy and then I engraved the marks on the chuck body. NEXT, remove the fingers one at a time and place a corresponding witness mark on the end of each finger. THIS MAKES RE-ASSEMBLY A BREEZE.

CLEANING: Drop all the parts in your favorite solvent (I like odorless mineral spirits). Then go have a cup of coffee or favorite adult beverage. Clean each part, inside and out, with a small brush and a Scotch Brite pad. Remember this is a finely machined tool so don't involve files, sandpaper, grinding wheels, etc. in the cleaning process.

LUBRICATION: Place a very thin layer of grease (multi-purpose, etc.) on the fingers, the threads of the cracked nut, the inside of the press ring and the chuck's surface that the press ring mates with. Use just a light coating of grease.

RE-ASSEMBLY: Insert the witness marked fingers all the way into the corresponding, witness marked holes. Slide the fingers forward until the end of the finger is even with the inside ring of the chuck. This will insure even extension of the fingers and correct installation of the split nut. The grease applied to the fingers should provide enough friction to hold them in place while you install the split nut. Observe the tapered threads on the split nut. The more protruding threads engage the fingers on the end toward the small end of the fingers. You may need to fiddle around with the split-nut, but you will see the split nut fits nicely back into place. Holding the split nut together, gently rotate it clockwise and counter-clockwise. If fitted correctly, it will smoothly and evenly move the fingers in and out. Holding the split-nut in place, gently slide the press ring part way on on to the chuck, just enough to cover the split-nut. Again, test the fit by rotating the press ring. It should move the fingers in and out easily.

RE-INSTALL PRESS RING: With the press ring slid on the chuck as far as possible by hand, again test the fit by rotating the press ring, observing the easy movement of the fingers in and out evenly. Now place one of the 2x4's on the floor. Make sure the fingers are in the 1/4-1/2 opened (retracted) setting just like in the disassembly procedure. Place the chuck on the 2x4, fingers up this time. Now slide the 1" PVC coupling over the fingers end of the chuck, so it rests on the teeth cut in the press ring. Steadying the chuck and the 1" coupling, place the other 2x4 on the coupling and strike the 2x4 with the dead blow hammer. Mine went all the way on with the first blow. Again, don't try to kill it. Just hit the 2x4 hard enough so the greased press ring slides to the milled stop ring on the chuck. If the press ring moves easily and your chuck key engages the teeth properly, the press ring is fully seated and you are done. Unless your chuck had damaged parts, it should operate "buttery" smooth.

If you have a sturdy, bench mounted vice, the disassembly and re-assembly would be a bit easier. The press ring is NOT pressed on with the force and tightness of, say, parts of your automobile's suspension. So, don't be afraid of the dead-blow hammer procedure.

Thanks for listening!

UPBOILERMAKER
1979 Mark V with vintage 4" Jointer and Shaping attachments
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