Question about center drills

[tigtorch]

I need to get a few small center drills as I have lost the only small one I have. Enco has a no limit 10% off and no shipping deal that ends tomorrow (I also want a few other things).

Could someone please enlighten me on the benefits and drawbacks of 60 degree, 82 degree and 90 degree center drills?

 

[November X-ray]

All I can think is if you use the center drill for spotting centers to use mainly with a lathe center (live or dead) then you want to go with 60 degree version, other than that I personally see no advantage/disadvantage to the other angles but I am sure someone can enlighten us.

Good Luck!

 

[george wilson]

If you want to do taper turning,get the bugle shaped center drills. They drill a hole with curved edges. Such a hole maintains 100% contact with the tailstock center when it is set over for tapers. The regular center drill only touches at 2 places during taper turning.

For normal turning,just get the 60º as it fits the tailstock center's angle.

 

[Jeff in Pa]

..................

Could someone please enlighten me on the benefits and drawbacks of 60 degree, 82 degree and 90 degree center drills?

60 degree is used for turning with a center. Some folks like the 60 degree for starting taps.

82 degree is the angle for (most) Inch thread countersunk screws

90 degree is the angler for metric countersink screws.

That's the very abbreviated list.

 

[tigtorch]

Thank you, Jeff. Since I only use center drills to get the hole started at the exact right point, and use othe bits for counter sinking, I will get the 60 degree ones.

 

[DMS]

If you are only using your center drills for spotting holes, you would be better off with a spotting drill, they work much better (and they don't have tiny pilot tips that snap off easily).

 

[Tom Griffin]

Center drills are only available in a 60º angle, although as George pointed out, they can be had with a bugle shape for turning tapers. Their purpose is to drill the end of a part so it can be supported with a 60º center when turning between centers or supporting the end of a long shaft. The are commonly used to start drills on center, but that is not their intended purpose. Countersinks can be had in various angles, such as 82º, 90º or 100º. They are used to prepare an existing hole for a countersunk screw. Any well equipped machine shop will have a good selection of both.

Tom