Trying to add a drive center to my 3/4x16 headstock

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larrystephens

larrystephens

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Arlington, Texas, USA.
I want to use an old CNC lathe to round my blanks but I am having trouble figuring out how to drive the material.

The headstock is 3/4x16 and I have a full set of collets for it. I also have a 3 jaw chuck (not so good for square material)

CSUSA has a spindle adapter to make it 1x8 so I could use my G3 chuck, but that seems really big and I would prefer just a small drive.

Any suggestions are appreciated.
 
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Larry - I ran a 3/4-16 lathe for several years with a one way talon Chuck. G3 is comparable.

Still have the talon but changed the insert. Nova sells a 3/4 -16 insert.
 
Take a piece of round stock ... aluminum or brass or even hardwood ... and put a 60 degree point on it. Use that in your 3-jaw chuck to drive the square stock, just like a dead center.

Once it's round, slip the straight shank out of the chuck and chuck the rounded stock ... cut to length and drill if you wish, the setup would be perfect.
 
I used one of the PSI spur drives in a collet, I want to say the size of the collet was 3/4", but not sure on that. Since the PSI drive was to long, I cut off most of the 2MT taper using a Dremel cutoff blade.
 
Larry -- I noted that you did not specify the collet system. My Taig lathes use ER 16 collects but Beall sells an ER 32 holder

There may be an adapter to ER 25 on the market.
 
Taig makes a 4 jaw scroll chuck for around $80 that will fit 3/4- 16 threads if you want a seperate chuck.
 
larrystephens said:
I want to use an old CNC lathe to round my blanks but I am having trouble figuring out how to drive the material.

The headstock is 3/4x16 and I have a full set of collets for it. I also have a 3 jaw chuck (not so good for square material)

CSUSA has a spindle adapter to make it 1x8 so I could use my G3 chuck, but that seems really big and I would prefer just a small drive.

Any suggestions are appreciated.
Click to expand...
Does the headstock also have a Morse Taper (female)?? Most headstock spindles with 3/4"-16 threaded ODs had a No. 1 Morse Taper (Female). If that's the case you can use a no. 1 Morse Spur Center (male morse taper) or 60 degree dead center (male morse taper) to turn betwween centers.
 
Something to consider is holding a socket from an ordinary socket set in your existing 3-jaw chuck. The larger sizes usually have a 12-sided recess which hold a 4-sided blank, and whilst the smaller ones are only 6-sided, it doesn't take much shaping on the sander to get them to fit. In the past I've done this with blanks from 1" square down to lace bobbin size.

Tony Wells
 
I run into the same issue since my lathe is collet only and I don't have an MT socket in the head stock.

If we are taking about un-drilled blanks I would chuck up some 5/8 drill rod and get a shop smith drive center.. I got one off Ebay for $12. They are made to slip over the 5/8" output shaft on a shopsmith motor.

For drilled I'd turn between centers.

I use the same method to mount my G3 with a shopsmith 5/8 bore insert.
 
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sschering said:
I run into the same issue since my lathe is collet only and I don't have an MT socket in the head stock.

If we are taking about un-drilled blanks I would chuck up some 5/8 drill rod and get a shop smith drive center.. I got one off Ebay for $12. They are made to slip over the 5/8" output shaft on a shopsmith motor.

For drilled I'd turn between centers.

I use the same method to mount my G3 with a shopsmith 5/8 bore insert.
Click to expand...

Hmm ... why couldn't you pick up some 5/8ths brass or aluminum rod and make a 60 degree cone on the end and use it directly as a drive center?

For that matter, 5/8ths stainless isn't SUPER expensive for a fairly short piece .... if you're patient with a decent pattern to follow and some carbide tools, or at the very least some hacksaw blade and a holder, you could make your drive center easily. Just finish it with some sandpaper backed by some hardwood. The more you polish it, the harder glue will find it to stick to.
 
I did make myself a 5/8" dead center from drill rod. It works great for drilled and tubed pieces but for a raw un-drilled blank it takes some pressure to keep it from slipping and I worry about splitting.
Straight shank dead centers are easy to fin.. Straight shank spur drive centers are somewhat difficult to aquire. Almost everything you see is morse taper.

For rounding un-drilled blanks I wanted a spur drive center.. that is where the shop smith drive center comes in.
 
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