# Jacobs Chuck Key



## hman (Jun 5, 2016)

I was missing the key for one of my Jacobs 6A chucks.  Searching the Jacobs website, 6A doesn't appear at all ... must be an obsolete product.  Some other searching finally led me to the K3 key.  Ordered two of them from Enco on their 25% off/free shipping deal.  As usual, Enco delivered quickly.

But then the fun started!  The chuck was kinda old, and its teeth a bit worn.  So the dad-ratted key would hardly engage the teeth!  I have another 6A chuck.  Its no-name key works well on both the newer and older chucks.  I looked to see what was different.  Turns out that the pinion teeth on the "good" key start out at a significantly larger diameter than those of the K3.

So I pressed out the handle, chucked the key up in the lathe, and cut back the "face" of the pinion with a carbide bit.  Fortunately, the interrupted cut caused by the pinion teeth did not ruin the bit!  After checking the fit on the chuck and shortening the now-too-long pilot pin, I pressed the handle back in.  Works!  The photo shows the (spare) "original" and "modified" chuck keys.

PS - the key is indeed marked as being a Jacobs K3, so I'm confident it's genuine.  But guess what ... it's made in China.


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## DoogieB (Jun 5, 2016)

Jacobs was bought out a few years ago and the state-side factory was cleaned-out so a "genuine" Jacobs key is a bit of a misnomer nowadays unless you are talking about NOS stuff.

To further extend the point, if you look at the Enco catalog page they have the chuck key table split-up between "USA" and "Jacobs".  Maybe the USA key would have worked better and it's cheaper too.

http://www.use-enco.com/CGI/INPDFF?PMPAGE=481&PARTPG=INLMK3&PMITEM=292-6220

I bought one of the USA keys for the drill chuck on my lathe and it fits quite well.


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## Bob Korves (Jun 5, 2016)

3K is the correct key for the Jacobs 6A.

Edit:  I also bought a poorly fitting Jacobs key that was the correct number for the chuck.  I have learned not to buy anything from Jacobs anymore since they sold out, unless it is NOS or good used stuff.  Quality has disappeared but the prices are still high...


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## 4GSR (Jun 5, 2016)

I have several 6A chucks including one that has a knurled OD (old!).  They all use K3 keys just fine.  I agree with Bob, they screwed up bad when it moved overseas. Never be the same.  I'm set good for the next three generations of family using up the NOS/reconditioned Jacobs chucks I've collected over the past 14 years.


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## hman (Jun 5, 2016)

DoogieB said:


> Jacobs was bought out a few years ago and the state-side factory was cleaned-out so a "genuine" Jacobs key is a bit of a misnomer nowadays unless you are talking about NOS stuff.
> 
> To further extend the point, if you look at the Enco catalog page they have the chuck key table split-up between "USA" and "Jacobs".  Maybe the USA key would have worked better and it's cheaper too.
> 
> ...


Thanks for the link.  Durn - even the Rohm key is cheaper than the "Jacobs"!  Guess I'll have to pay closer attention from now on.  Thanks to all for your responses.


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## Andre (Jun 5, 2016)

I bought a Jacobs chuck from Harbor Freight for $10. On the Jacobs cheap line, but the key hardly even engaged with the teeth on the chuck hood! Anything over snug and the key just slips, I need to drill new holed closer to the annular ring.


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