# When And Why Would I Use A Half Point Dead Center



## tfleming (Dec 12, 2016)

I have used solid dead centers quite a bit.  I also use live centers as well.  While I am somewhere between a rookie and a novice, I would like to understand why and where I would use a 1/2 point dead center.


----------



## RJSakowski (Dec 12, 2016)

When you want to turn close to the tail stock center, the half center allows you to turn to very nearly the center.


----------



## Bill Gruby (Dec 12, 2016)

The half point dead center is used when tool clearance is needed at the start of the cut. It allows you to move further to the right without hitting. You can also make the diameter of your work smaller because of this extra clearance.  It's a handy center to have.

 "Billy G"


----------



## tfleming (Dec 12, 2016)

Thanks RJ and Billy G, that's what I thought, but wanted someone more knowledgeable than myself to confirm that.  most of my work has tolerances around +/- 0.002 and when I need to be close to an end, I usually just chuck it up and make the cuts.  however, I see how leaving the work "on center" would be required on close tolerance pieces.


----------



## mmcmdl (Dec 12, 2016)

Used the half point on cylindrical grinding quite a lot for the stated above reasons . Small diameter shafts require them .


----------



## Big Bore Builder (Dec 12, 2016)

Check your  South Bend  "How To Run A Lathe"  book.  You do have one, right?

Primarily for facing the end of a shaft in the lathe without having to go to another setup or another machine.

A big time saver back in the days of yore when a gent was producing many, many shafts on old style manual machines.

PS the South Bend book is valuable just for the photos of lathes and setups.   And gear charts.   And tool bit grinding.    And on and on!


----------



## brino (Dec 12, 2016)

There are a few different versions of that PDF book available here:

http://www.hobby-machinist.com/resources/sb-how-to-run-a-lathe-1966-27th-edition-56-pdf.2909/
http://www.hobby-machinist.com/resources/how-to-run-a-lathe-20-15th-ed-pdf.532/
http://www.hobby-machinist.com/resources/how-to-run-a-lathe.4/

-brino


----------

