Dead Center Help

[BigBoy1]

I have project that requires the use of a lathe dog, however, I do not have a dead center for my spindle and that is the problem. The spindle is a 2MT but the opening diameter is 1.629". I looked in the catalogs and the largest diameter 2MT dead center I found is 0.700". What do I need to get to make it work? Is there some South Bend dead center that I have to get to fit the large diameter hole? I looked at taper adapters thinking that I could get one with an external 2MT and an internal 1MT and then get a 1MT dead center. But couldn't find any information on the outside diameters of the taper adapters. Any help appreciated. Thanks.

Bill

[SGW]

If the spindle hole is 1.629", it ain't a #2 Morse....

What type of SB lathe do you have? I expect you need an adapter sleeve of some variety, which is a fairly common thing to need in this context. If I rmember correctly from previous threads, the internal taper of assorted SB lathes is some proprietary weirdness, so you'll need to get the official SB taper adapter.

If you can't find the proper adapter sleeve, you can always chuck a piece of stock in a collet and turn a 60 degree point on it to be the headstock center. It doesn't need to be hard, since it turns with the work and there is no wear on it.

[ERBenoit]

Chuck It

The taper in the headstock of most South Bend lathes is proprietary. At least mine is. Thus you would need an adapter. Fortunately I have the adapters for M/T and 5-C, so I do not encounter this problem.

I have in the past though, without the adapter SGW is on the right track, I'll just add a bit more rail... SGW suggests turning a 60* center in a collet. The only problem with turning a 60* center from a collet, that I can see is how are you going to drive the dog? Most collet set ups have no means to drive anything. Once the center is turned, it is true to the spindle, thus you do not want to disturb it.

Use a chuck. Once you turn the center as directed, you must not remove it from the chuck. Use one of the chuck jaws to drive your lathe dog. Make note of, and use the same jaw to drive the dog throughout the work process. Make this a habit. If not for your current project, using the same jaw to drive becomes important if you are doing any thread cutting where the work could be removed from the lathe for whatever reason. If you have to remove the turned center, re point the center prior to re-use. If not done, the runout in the chuck, and re-chucking your turned center could affect your turning, resulting in a non-concentric diameter.

Not slamming you SGW, or your suggestion, using a chuck is how I would and have done it with success.

[SGW]

On my 10K, I can put the small drive faceplate on and use a collet too, so in my case it's not a problem. If that's not possible on the lathe in question, driving the dog off a chuck jaw seems like a dandy solution.

[ERBenoit]

Now I think I follow as SGW suggests. Are you using the drive plate in place of the adapter knock out nut? I could do that with mine also, just never even thought about it.

At least SGW didn't blast me for differing with his idea.

[SGW]

The SB 10K has the collet taper built into the spindle, there is no collet adapter needed. A threaded cap is supplied to protect the threads while you're using a collet, but it serves no other purpose. There is no reason not to replace that threaded cap with a faceplate, or chuck, or whatever, while you're using a collet.

[sch]

The 'larger' SB lathes at the CC I took adult ed at were Taiwan made 12x36
and a 14x48 +/- more classical SB both of which had D1-4 chuck mounts and MT5 spindle holes. The MT5-MT3 adapter that came with my D1-4 spindle 12x36 measures 1 23/32 OD at the big end and protrudes perhaps 1/4" beyond the end of the spindle taper. Bigboy might just have an MT5 spindle.

[rvannatta]

The 'larger' SB lathes at the CC I took adult ed at were Taiwan made 12x36
and a 14x48 +/- more classical SB both of which had D1-4 chuck mounts and MT5 spindle holes. The MT5-MT3 adapter that came with my D1-4 spindle 12x36 measures 1 23/32 OD at the big end and protrudes perhaps 1/4" beyond the end of the spindle taper. Bigboy might just have an MT5 spindle.

both of my older large lathes have a #6 MT in the Headstock and a #5 MT in the tail stock. The extra diameter of the spindle bore is always welcome.

[John Garner]

Bill --

Do you have a chuck that fits your lathe's spindle? If so, maybe you should forget about fitting a center to your spindle's taper. Instead, make and use a "chuck center", which can be as simple as a short length of stock chucked tightly and turned to a 60 degree point. Have enough stock sticking out of the chuck to have the dog's tail driven by a chuck jaw.

The simple chuck center as I described above has to resist all of the axial cutting force by the clamping force of the chuck jaws on the stock. Improving the design by adding a thrust face is easy . . . simply turn a reduced diameter on the stock for an inch or two, leaving a square shoulder. Then turn the stock around and grip the reduced-diameter shank in the jaws so that the shoulder butts against the face of the jaws before turning the 60 degree point.

One note of caution, though: If you take the chuck center out of the chuck and reinstall it later, you'll need to take a truing cut on the point.

John