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krems
12-30-2006, 03:11 PM
When turning a dead center from scratch or trueing up an existing one should you be cutting towards the point or away from it?... (3 jaw chuck 60deg angle). Mild steel, carbide inserts (60 degree triangle type)

Any secrets to getting a mirror like finish?

Thanks.....Krems

KDuffy
12-30-2006, 05:05 PM
Cutter depends on the material. Some are soft enough to cut with a sharp carbide lathe tool, factory made units are likely hard enough that a tool post grinder must be used. Might be able to use a hand held grinder resting on the tool post to clean up and polish a center if nothing else will touch it. If a file sings and doesn't cut, you are likely to grind. Using your compound and high spindle speeds and light cuts you may have a chance with a carbide tool (don't worry about speeds and feeds that will make the cutter last longer, figure on regrinding when you are done) Light passes and high speeds might make it work. Try both directions to see which your machine will do. I prefer working out to the point, but with your case it may work better the other way. If you work into the spindle tool pressure will keep the center seated. Given that the MT in the spindle is likely to have been knicked over the years and may not be true because of this, always match mark the center after truing.
Just reread and it sounds like you are just trying to make a center to hold in your chuck, in such a case recut it every time you chuck it. I have never saved one when I was done with it, because it takes no time to cut one in mild steel and I rarely ever need one. Wish I had bought some of those bent tail lathe dogs at the surplus store years ago. You can Save Money Till Theres None Left at some of those places.

Tin Falcon
12-30-2006, 06:01 PM
1) cut towards the head stock when cutting the point
2)I would use drill rod to make one
3) HSS is fine a nice radius will help finish also stone the cutter makes a big difference.
Regards
Tin

Carld
12-30-2006, 07:24 PM
Use cold roll, Say 1 1/2" dia. reduce the dia. on one end by 1/2" then flip it around and use a left hand tool and cut toward the spindle with the compound set to 30deg. This gives a shoulder to keep the center from sliding into the chuck as the work is being machined and the large dia. give many trueing cuts before you will have to make a new one. As you reduce the tip remember to leave a 1/4 to 3/8" thick shoulder to keep the center from sliding into the chuck.

krems
12-31-2006, 01:48 AM
Thanks for the tips......I'll make one tomorrow out of some round stock lying around. I like the Idea of leaving a shoulder on the dead center. I may try the HSS cutter tomorrow w/ a stoned tip. All my inserts look like they are shot. I'll have to order new ones.

Kduffy:...what are those bent tail lathe dogs used for. I hear them mentioned once in a while???

Thanks again........Krems

J. Randall
12-31-2006, 04:02 AM
You clamp the lathe dog around you workpiece as close to the end that mate with the center will allow you. Then that bent tail that protrudes toward the chuck or dogplate which is allready mounted on the spindle nose, that bent tail will either caucth on a chuck jaw, or hook in a slot in the dog flate and driver your work piece. James