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Adapter to mount a Jacobs chuck?

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Sometimes a standard wood lathe chuck is just too large and/or cumbersome to open and close repeatedly for quick operations. I have a Jacobs 1/2 inch chuck mounted on a MT taper, but it only stays in place if there is pressure from the tail stock side. I have been looking for an adapter from 1 x8 or even 3/4 x 16 to 1/2 x 20 so I can mount a keyless chuck to my headstock spindle. I could buy collets, but they are so expensive compared to just a spindle adapter. I found adapters at a place like Graingers, but .I am told their tolerance could leave the center as much as a 32nd out of true center. (which seems pretty sloppy.) I would think others could use such a thing if it were made
.
 

Tom Gall

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Sometimes a standard wood lathe chuck is just too large and/or cumbersome to open and close repeatedly for quick operations. I have a Jacobs 1/2 inch chuck mounted on a MT taper, but it only stays in place if there is pressure from the tail stock side. I have been looking for an adapter from 1 x8 or even 3/4 x 16 to 1/2 x 20 so I can mount a keyless chuck to my headstock spindle. I could buy collets, but they are so expensive compared to just a spindle adapter. I found adapters at a place like Graingers, but .I am told their tolerance could leave the center as much as a 32nd out of true center. (which seems pretty sloppy.) I would think others could use such a thing if it were made
.
Drill and tap the MT for a drawbar to go through the spindle. Some MT's already have it tapped for an all-thread rod.
 

john lucas

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Some chucks come with a threaded end on the morse taper to accept a draw bar. That being said I use a Vicmarc chuck with the 1" extended jaws. They will hold down to 1/4" and are very solid. I'm not sure they still sell the set I have. I think the new jaws have a square hole instead of round when totally closed.
 

Bill Boehme

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Sometimes a standard wood lathe chuck is just too large and/or cumbersome to open and close repeatedly for quick operations. I have a Jacobs 1/2 inch chuck mounted on a MT taper, but it only stays in place if there is pressure from the tail stock side. I have been looking for an adapter from 1 x8 or even 3/4 x 16 to 1/2 x 20 so I can mount a keyless chuck to my headstock spindle. I could buy collets, but they are so expensive compared to just a spindle adapter. I found adapters at a place like Graingers, but .I am told their tolerance could leave the center as much as a 32nd out of true center. (which seems pretty sloppy.) I would think others could use such a thing if it were made
.

It sounds like the Morse taper socket on your spindle might have some damage from galling ... that's what happens when a MT shank spins in the socket and creates rings of smeared metal. The end result is that the shank won't be able to seat securely. What the world needs is a MT2 to JT6 shank with a threaded hole for a drawbar, but I haven't come across one yet. I would suggest using a collet chuck. They aren't as fast as using a keyless chuck, but they are better for holding wood tenons.

Will the tenon be part of the final piece and does it matter if the tenon isn't concentric with the rest of the piece? The potential tolerance build-up of the adapter that you found just means that the axis of rotation is shifted a bit.
 

hockenbery

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Draw bars work great but will will take a bit longer than a threaded Chuck to put on and take off.
But if it’s a put it on and use it for a half hour it’s inconsequential

I have a set of collet jaws for my stronghold Chuck. A good investment.
 
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Lee Valley MT2 to JT arbor.jpg

Sometimes a standard wood lathe chuck is just too large and/or cumbersome to open and close repeatedly for quick operations. I have a Jacobs 1/2 inch chuck mounted on a MT taper, but it only stays in place if there is pressure from the tail stock side. I have been looking for an adapter from 1 x8 or even 3/4 x 16 to 1/2 x 20 so I can mount a keyless chuck to my headstock spindle. I could buy collets, but they are so expensive compared to just a spindle adapter. I found adapters at a place like Graingers, but .I am told their tolerance could leave the center as much as a 32nd out of true center. (which seems pretty sloppy.) I would think others could use such a thing if it were made
.

Perry here is what you need, it is a threaded MT with a JT for the chuck, you need a piece of threaded stock and washer and nut to hold that MT safely into your spindle, free shipping as wel
 
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It sounds like the Morse taper socket on your spindle might have some damage from galling ... that's what happens when a MT shank spins in the socket and creates rings of smeared metal. The end result is that the shank won't be able to seat securely. What the world needs is a MT2 to JT6 shank with a threaded hole for a drawbar, but I haven't come across one yet. I would suggest using a collet chuck. They aren't as fast as using a keyless chuck, but they are better for holding wood tenons.

Will the tenon be part of the final piece and does it matter if the tenon isn't concentric with the rest of the piece? The potential tolerance build-up of the adapter that you found just means that the axis of rotation is shifted a bit.
Like this?
 

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A conventional Jacobs style drill chuck isn't a good way to hold wood if concentricity is your intention. The jaws bite into the wood unevenly because of the narrow jaw face contact with the wood and the varying hardness of the wood due to grain orientation.

A better way is to use a Jacobs armature or commutator chuck. These chucks have a wide contact surface on the jaw faces and tend not to bite into the work. I believe the jaws are brass or bronze.

Here's a video:
View: https://www.youtube.com/watch?v=LZqOr-wi9Ik


I have a couple of these type chucks, I'll post the model number later today.
 
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