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Sticky Jacobs chuck

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PT Doc

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#1
I now have 2 Jacobs Super Chucks that seem to bind when opening the jaws about 3/4 of the way to fully open by hand. Can get the chuck to fully open but it’s clearly binding. With the key it’s no big deal to fully open. One is a 14n and the other is an 18n. Both are USA made and older. I don’t have an arbor press to separate the chucks. When this happens, what is the likely cause? Thanks in advance for the help.
 

DoogieB

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#2
The grease has turned into stiff, waxy goop. You need to take them apart, clean them and apply new grease. You will need a press.
 

Nogoingback

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#3
Chips and dirt also will get into the chuck over time. DoogieB has it right: they need to be cleaned and re-lubed. If the jaws are badly worn,
this would be a good opportunity to rebuild with new parts while you're at it.
 
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PT Doc

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#4
Ok. Will need to get me an arbor press to get these sorted out. Thank you.
 

ddickey

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#5

Bob Korves

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#6
I have seen that problem with Jacobs chucks where the shell has not been pressed on far enough when it is reassembled after being serviced. Usually the key also binds when it is turned. The shell just needs to be pressed all the way onto its seat. Don't overdo it and damage anything.
 

projectnut

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#7
As mentioned I would bet you have chips in the scroll. This often happens when the drill is used in a vertical position drilling up on the underside of something. It also happens on a lathe when not breaking the chip. The chip will crawl up the flutes and finally break off inside the chuck.

Unless the chucks are very old I doubt a hobbyist will use them often enough to wear out the scroll or jaws. They more likely are full of chips or dried grease. We used to rebuild the chucks in the machine shop about every 10 years or so. Those chucks were drilling hundreds of holes a week and probably over 50,000 holes a year. Unless the quality of the chuck have substantially diminished I doubt they are worn significantly.
 

PT Doc

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#8
The 18n jaws are good and the 14n look brand new. I will watch a few YouTube vids when I get the arbor press and disassemble both and clean them up. Thanks for the help.
 
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