Lathe dog from the scrap bin. Will it work?

[corbinace]

I do not have a proper lathe dog.
I looked in the scrap and found this piece of brass.
It already had a hole just a tad over the proposed work diameter of 1.25" 416SS.
I simply drilled and tapped the side for a 3/8 set screw and the face for a 3/8" drive lug.
Will it likely hold with the diameter being so slose and only one set screw?
Don't worry about hurting my feelings, it is a very short trip back to the scrap bin.

 

[mmcmdl]

Nothing wrong with that ! If it spins , it's serving the purpose .

 

[Shotgun]

Perfect lathe dog. My only question, "Why are you using a lathe dog with a 3jaw chuck?"

 

[Ulma Doctor]

Perfect lathe dog. My only question, "Why are you using a lathe dog with a 3jaw chuck?"

If you turn a 60* taper on a piece in the 3j, it can be used as a center. The dog uses a jaw from the 3j to drive the work.
Since the center was turned in situ, it will be as accurate ( or more ) as a manufactured center installed into the spindle

 

[RaisedByWolves]

Perfect lathe dog. My only question, "Why are you using a lathe dog with a 3jaw chuck?"

Cause the three jaw is holding the precision dead center, duh. (<<<there would be a smiley here but they dont work for me on this board.)

 

[corbinace]

Yes UD and RBW are correct. The chuck center came with the lathe and I have not trued it yet because I do not have any cutters. Once I do recut it I am hoping for it to be a good center.
I was just mocking it up to see if it would work even a tiny bit.

Thank you all for your help and comments.

 

[Jake M]

I do not have a proper lathe dog.

You do now.....

A factory made lathe dog would more than likely have a shape that made it grip harder than a circular hole, in a three point fashion. If that one fails to hold tight enough, a second set screw, 90 degrees from the existing one, that would give you a nice three point grip. I wouldn't sweat that unless it was needed, but if it's needed, it'll be just that simple. If you were doing heavy cuts like that (which you probably wouldn't be...), it wouldn't hurt to move the center back in the chuck, the drive dog closer to the chuck, and shorten the drive bolt, to reduce the lever arm there. But again, unless it's an issue, I wouldn't sweat it. Odds are that piece you just make works out fine.

I'm not sure if you know this, but you will want to re-cut that center. The three jaw chuck will not give you a true centered part. Close, but not quite. They always run out "some". Just dust off that center, a couple of thousandths is fine. Just barely enough that the point has shiny "fresh" metal all the way around. So long as it STAYS mounted in the chuck, after you cut it, the point of that canter will be dead nutz true on the lathe's centerline. Each and every time the center is removed from the chuck, it will need to be cut again in order to be true again. But by doing it that way, it's DEAD true. As true as true is ever going to get.

 

[corbinace]

Thank you for the reply Jake M.

I had wondered about the lack of grip due to the wide bearing surface away form the set screw. And slippery brass at that.

That center came with the lathe and has a smaller shank that actually gets pinched in the jaws. That is the reason it is so long. I read that it is a good thing to have that shoulder up against the face of the jaws, so it does not get set back if your work gets warm and stretches.

I think the previous user may not have known or not cared about perfect centering. because there are many chuck marks and the face of the tool looks like it has not been dressed for a perfect center, as you mention, for ages.

This was just kind of proof of a concept mock-up as I do not own any cutting tools yet. Little baby steps for me.

 

[Ulma Doctor]

If you don’t have any bits yet, i’d be able to grind up a couple HSS general purpose tools for you at no cost to you
Send me a private message if you are interested