For Mill or Bench
Chuck Holder
© Frank Ford, 2004; Photos by FF

Any number of times I've wished I had a lathe chuck mounted on my bench to hold round things vertically. This weekend I decided to make a holder so I could simply use any of my lathe chucks. I figured it might come in handy for working on a item that needed both lathe and milling operations where I'd keep the part in the chuck so I could return it to the lathe for more work. So, I set about making a replica of the Hardinge style tapered spindle nose and a plate on which to mount it.
Looking around the shop, I located a nice scrap of 3/4" CRS. It had a bunch of holes drilled in various places, including a number of threaded holes in the edges. Just for a slightly neater appearance, I poured a bit of thin viscosity cyanoacrylate into the edge holes and drove screws into them, cutting them off flush. Most of the top holes got cut off when I trimmed the plate to size, leaving just two visible.
Clamping the plate in the mill vise, I squared it up.
And, flattened the bottom face that would contact the mill table when in use.
I drilled a pilot hole in the center and followed with a 33/64" drill.
A 1" reamer finished my hole nicely.
Using the Darex online Bolt Circle Solver I spotted, drilled and countersunk a pattern of five holes for 1/4-20 cap screws. Why five? I don't know - it just seemed attractive at the time. This was a mighty casual project, and I made up the rules as I went along.
Seems I can never find my little bottle of layout dye, so I'm always reaching for the Steinway Touchup Kit.
Using the point of my caliper as a scribe, I got neat little locating marks/
First a center drill to spot the hole, then a 33/32" drill to receive 1/2" clamping bolts.
A quick bevel around the edge, and my plate was done.
I had this big (for me) of 3" diameter CRS from which I'd make my new nose. Now, I know you're not supposed to part between centers, but nobody said I couldn't make a really deep groove.
Once I got the center down to about an inch or a bit less, I introduced the bar to Mr. Bandsaw. I just didn't want to stand there all day pushing on this thing, so grooving it saved me a lot of time and effort.
There wasn't a lot of grip to hold my piece back on the lathe, so I took it slow and easy as I faced off my cut end.
Off the lathe, I drilled a center hole in the opposite side, and pressed the faced end up tight into the chuck as I tightened it down. Then, I felt I had a good grip as I turned down the end to make a nice slop-free fit in my base plate's 1" hole.
Switching to a 1" collet, I stuck the turned end in, and center drilled the opposite end. I turned down the diameter of the nose section to the maximum diameter of my lathe's spindle nose, leaving a shoulder at the base for extra stability
Off the lathe, and simply gripped in the milling vise, I located the center, spotted and drilled the (#7) tap holes using the same pattern as the base. That's the Darex calculation I printed out, posted right on the mill.
Here's a little trick I use for hand tapping holes in the milling machine. It's one of those "works for me" kind of things. I use my lathe hand tap handle with its long shank, stick a 1/2" R8 collet on, and push it up into the quill. I don't use the draw bar at all, but simply let the collet ride up into the quill, keeping my tap nice and straight as I go.

OK, time to get "serious." This is the only operation that required any precision, so, in an uncharacteristic move, I took my time with the set up. Sparing no effort, I located the ball of my indicator precisely at center. Then, with about a hundred very light taps with my rawhide mallet as I slowly tightened the lathe compound, I was finally able to get it so there was virtually no needle movement as I ran the slide back and forth.

The setup time paid off (as it always does, for sure) and I was able to turn the nose section to a nice fit on the taper of this face plate. I had done all the turning with the center in place for extra support, of course.
And once I was happy with the fit, I went around to what would be the bottom side of the chuck holder, and took a very light skimming cut at the edge to make certain it would be true to my new taper, just in case.
I stuck the faceplate back on the taper, and screwed the pin down hard into the taper. That left me with a nice mark to locate the end of the slot I'd be milling.
With the tapered nose in my 5C spin index, I knew my setup was far from rigid, so I took impossibly light cuts with a 3/16" end mill to create the slot. I didn't take the trouble to try to figure out how I could cut the angled slot, so I just picked an approximate angle, clamped my spin index at that angle, and milled a really deep slot. At 3/16" the slot is considerably wider than the original, but I didn't think it would matter for a simple fixture as long as the chuck would go on and off appropriately tightly and easily.
I screwed the support to the plate.
Here's the final product. As you can see, I located the mounting holes so they'd line up with table slots.
And, the chuck pops on and off just as it does on the lathe.

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