# A "Better" Center Drill For Small Lathe ?



## randyc (Feb 7, 2015)

This is a fairly trivial project but a useful one.  Sometimes when center-drilling in the lathe, I can see the drill wobbling slightly, indicating that the tailstock drill chuck is not well aligned with the spindle axis.  (There is a fix for that, by the way, which I’ll post sometime.)  I decided to attempt to improve the performance as well as shorten the distance between the drill point and the tailstock ram.

  I had a well-used morse taper tailstock center that had seen better days.  I ground off the point, installed the dead center in the headstock using a MT-3 to MT-2 adaptor that came with my Emco lathe.  This was the best way of holding the part since it couldn't easily be secured in a collet or chuck.  This method also provides the best accuracy for alignment with the spindle axis.

  After facing the center with a carbide cutting tool,  I carefully drilled a pilot hole with a carbide drill and then bored it.  (I used a small broken carbide end mill that I’d reground as a boring bar.)  When I was satisfied with the pilot hole diameter, I loctited a center drill into the bore.

  When the drill dulls and I wish to replace it, the tool can be heated on a gas or electric range and the center drill extracted easily.  The new center drilling tool works way better than the drill chuck.  When the drill is introduced to the work piece, there is no discernible wobble.


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## Ulma Doctor (Feb 7, 2015)

Great solution to a common issue, thanks for sharing!
mike)


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## chips&more (Feb 7, 2015)

You may experience center drill wobble if you are trying to center drill say an unfaced end. Like a sawed off cut that has not been faced yet. Since the end to be centered drilled is not perfectly flat and true the center drill will tend to wobble a bit. It’s best to face the end first, then center drill…Good Luck, Dave.


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## 12bolts (Feb 7, 2015)

Neat Randy,
I just cut the MT off an old drill that had been sharpened down to the end of its life. I drilled it for a centre drill but locked it in place with a set screw.

Cheers Phil


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## randyc (Feb 7, 2015)

chips&more said:


> You may experience center drill wobble if you are trying to center drill say an unfaced end. Like a sawed off cut that has not been faced yet. Since the end to be centered drilled is not perfectly flat and true the center drill will tend to wobble a bit. It’s best to face the end first, then center drill…Good Luck, Dave.



Yep, fifty years of experience taught me that


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## randyc (Feb 7, 2015)

12bolts said:


> Neat Randy,
> I just cut the MT off an old drill that had been sharpened down to the end of its life. I drilled it for a centre drill but locked it in place with a set screw.
> 
> Cheers Phil



Sounds good to me !  Simpler than my solution.  No problem with drilling and tapping (hardness) ?


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## 12bolts (Feb 10, 2015)

Nope. Quality P&N drill bit.


randyc said:


> No problem with drilling and tapping (hardness) ?


Drill shanks are usually not hardened so as to allow the holder to get a good grip on the bit. If they were hardened fully the chuck jaws, (on a straight shank) or the female MT would not be able to hang onto the glassy surface.

Cheers Phil


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## Dan_S (Feb 10, 2015)

Randy, are you using long center drills? 

I ask, because that drill looks pretty long for its diameter.


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## randyc (Feb 10, 2015)

Dan_S said:


> Randy, are you using long center drills?
> 
> I ask, because that drill looks pretty long for its diameter.



Yes - I envisioned the possibility of having to center drill a blind bore, for example, requiring some length to the drill.  A better solution would be to tap the dead center for a set screw, as mentioned above.  That would permit adjusting the drill length to any reasonable dimension.  In fact, that is so sensible that I'm going to do it


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## randyc (Feb 10, 2015)

12bolts said:


> Nope. Quality P&N drill bit.
> 
> Drill shanks are usually not hardened so as to allow the holder to get a good grip on the bit. If they were hardened fully the chuck jaws, (on a straight shank) or the female MT would not be able to hang onto the glassy surface.
> 
> Cheers Phil



Yes, of course, but I was referring to the hardness of the dead center and whether you had a problem drilling and (especially) tapping for the set screw.


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## 12bolts (Feb 11, 2015)

I think you misread my post Randy. I used a, (I think), 3/4" bit that had a MT2 shank. Cut the flutes off just at the MT and drilled the shank to take the centre drill

Cheers Phil


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## randyc (Feb 11, 2015)

12bolts said:


> I think you misread my post Randy. I used a, (I think), 3/4" bit that had a MT2 shank. Cut the flutes off just at the MT and drilled the shank to take the centre drill
> 
> Cheers Phil



You're correct, I misread and was thinking of my own implementation, sorry !


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