Jacobs Drill Chuck Repair Info

CadillacSTS was kind enough to make some aluminum tubes for me to press on/off my Jacobs drill chucks.
The photo shows my collection of various tubes in aluminum, steel and brass with some delrin rings that sit on the
nose face to protect it. All non marring. Thank you Cadillac STS. The guys at work provided some of the other rings and tubes.Chuck_Tubes459.jpg
 
One thing I forgot to mention. When you have your drill chucks pressed off, you will notice on the bodies
jaw hole ends that the metal is thin and flaky. There is no way around this when making the chuck holes
because of the angle and thickness. Do not be tempted to "fix" this by filing or Dremel. The metal is very thin
here and not hardened. You can cause the jaw holes to deform.
 
4gsr said:
The Molycoat grease as shown or Texaco with moly grease is what I use when I rebuild drill chucks. A little dab here and there is all you need. Anymore than that and you'll be wearing it when running at high speeds.
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The DC MolyKote grease is a little "stiff" for drill chucks. I only use ChuckEezz now. ChuckEez is very tenacious and doesn't wash out easily, even with grease
cutters and solvents. I only used oil on the balls, no grease.
 
Here are the dimensions for all Jacobs wedges:
#1 Wedge: ID 0.442" Thk. 0.163

#2 Wedge ID 0.585" Thk. 0.167

#6 Wedge ID 0.720 thk. 0.162

#3 Wedge ID 0.850 thk. 0.170 (jt3)

There are no wedge sets for JT6 and JT33 tapers.
These dimensions are not available anywhere on the internet.
 
One other bit of information that I'd like to share for those planning on removing their arbors by using a pin punch to knock them out.
It would be a good idea to protect the chuck inner body where the jaws ride or any metal around any drill chuck when knocking out an arbor with a pin punch.

Try a piece of brass tube cut to size and place it in the chuck, then put your pin punch in to protect the chuck body or jaws.

I would also protect the nose of the chuck with some round brass, aluminum etc.. in case you miss with the hammer and dent the nose of the chuck or other part (if it's an Albrecht i.e.).

I've seen a lot of Jacobs chucks with dents and dings and always wondered, and now it seems that it may have a mis-strike with a hammer.
 
On all of my 14N or larger chucks, I drill a 33/64 hole through the web to the arbor. Once in a while, I'll drill into the arbor a bit to relieve some of the radial stress that is holding the arbor to the chuck. Do this only if the arbor is junk. Next, I take a piece of 1018 CRS bar or equivalent, not a pin punch, about 6" long, drop int the hole. IF the jaws are movable, bring the jaws in and snug by hand against the the CRS drift. Support firmly, hit with a 2 lb engineers hammer. If the first strike doesn't drop the arbor, strike again. After the second or third strike it doesn't come loose, cut off arbor on back side in the saw. Put up in the lathe and drill and bore out whats left. Don't do what I did, bored out too big and took out the taper! I have an older 20N chuck that is threaded internally with a 1"-14 thread for extraction of the arbor.
 
33/64" hole, that is quite large. I only went 2.5mm and just past the web to the arbors center hole. I didn't touch the 1/2" JT3 stub arbor at all! I wanted to save it because I've never seen a hardened 1/2" JT3 stub arbor. It is in perfect shape but no shoulder for wedges. I used a Starrett 1/8" pin punch. Came right out. 3 wacks.
 
EmilioG said:
...snip.... I used a Starrett 1/8" pin punch. Came right out. 3 wacks.
Click to expand...

You were lucky. Several of the one's I have, I would have wadded up a 1/8 punch using it to punch out the arbor. Glad it worked out for you!
 
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