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Jacobs chuck

Emiliano Achaval

Emiliano Achaval

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I got a huge load of Olive wood today. On my way back home I stopped by the shop of club member, to give him some of it, and to just visit for a while. He's a beginner turner. I was showing him how I go about turning an end grain piece. I told him that I usually use a drill bit first. He then shows me a Jacobs chuck... Not sure where he bought it, but it's new. Weird thing is, the Jacobs chuck is on something that looks like a live center. I have never seen one like this. What's the purpose of a jacobs chuck like that? I believe he's an Amazon shopper, several of his tools are Hurricane benjamin brand. I told him I would try to find out what the heck he got. He said he ended up putting a glove and was trying to hold the Jacobs chuck with his hand!
 

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Bill Boehme said:
He should be able to pop the Jacobs chuck off with a drift and hammer and install a MT2 to JT6 or JT33 adapter. The chuck should indicate which Jacobs taper it has.

I believe that I've seen that tool before, but I don't remember what it is used for.
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Thanks for the info Bill. I thought maybe I'm missing something here.
 
Gloves are a no-no around moving machinery. Curious about this chuck. Photo or video of the chuck in action?
 
Is it an actual live center or just a solid piece of steel. Maybe it has an odd adaptor to go from the #2 morse taper to the Jacobs taper.
 
I remember seeing a live center for mounting a scroll chuck for what purpose I don't know, but maybe the jacobs chuck is a similar idea.
To use the chuck temporarily for drilling just put the long end of the chuck key handle into the hole and rest the handle on the tool rest, then with your left hand hold the key in and against the rest and crank with your right hand.
 
Don Wattenhofer said:
I remember seeing a live center for mounting a scroll chuck for what purpose I don't know, but maybe the jacobs chuck is a similar idea.
Click to expand...
That particular adaptor is for mounting a chuck with cole jaws to center segmented rings on a bowl being built on the headstock. Also its valuable for reversing a mounted bowl onto a vacuum chuck to maintain center.
 
That type of revolving chuck is used in metal working to support the end of work that doesn't have a center hole for a conventional live center. The most common usage I've seen is holding/supporting motor armatures.

It has use for it's intended purpose, certainly not holding with your hand.
 
I have no idea what the original intent was, but I concur with Richard and Gary as to possible uses for it. If used to support the outboard end of a slender spindle, it will greatly increase the rigidity of the spindle compared to using a live center. For details, see my posting “An Engineer’s Look at Turning Slender Wood Spindles” in the Tutorials and Tips forum July 31, 2016. Also, I have an adapter made by Oneway that screws onto the Oneway live center and allows me to mount any chuck with a 33 mm thread. I use it often as described by Gary.
 
I have that same jacobs chuck, it was one of many accessories that came with a used lathe I purchased not long ago. I don't know the purpose of a jacobs chuck on a live center but I did use it once. I was working on a piece that needed a little extra support without interfering with my access so I chucked up a 3/8" dowel about 12" long. Worked like a charm. Not sure what else I would use it for.
 
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