Will a Stub drill eliminate the need for a center drill?

[martik777]

Sizes 3/16 1/4 and 3/8. I doubt the 3/16 will, but will the others?

 

[benmychree]

Maybe ---

 

[MrWhoopee]

I do it all the time, but it depends on how critical location is.

 

[mmcmdl]

A split point may . Its only a hole .

 

[MyLilMule]

You need a spotting drill. Not just any stub drill. The angle of the point matters.

I use a 120 degree spotting drill for my 118 degree drill bits.

 

[BGHansen]

I have 120 deg. spotting drills but use a 60 deg. center drill also. The lead end of center drills is typically 120 deg., just don't go too deep and it works like a spotting drill.

I'll spot drill if I'm worried about accuracy. If it's a quick throw-together bracket with oversized holes, I'll go right to the stubby drills. I have yet to snap off anything as small as 3/32", so must be good for not walking the bit without spotting.

Bruce

 

[mattthemuppet2]

i've only ever used screw machine drills to start holes, can't say I've had any problems with location that weren't of my own doing. If I need a deeper hole than a stub drill will give me I'll start the hole with a stub/ screw machine drill and then continue it with a mechanics or jobber length drill.

I do have some spotting drills now though, so I'll have to give them a go. One appealing aspect is that if you get the depth/ width right with the spotting drill it can also countersink the hole at the same time which removes one tool change.

 

[mksj]

Depends on the application, the size of the drill and the accuracy required. On the lathe I typically use a center drill to start the hole so that when I follow with a larger drill it will not walk/move off center. On the mill I primarily use stub/mechanics length if drilling into a flat surface, if I am drilling into a curve or angled surface I always start with a short center drill. If I need to drill a deeper hole I will start with a mechanics/screw machine and then switch to a longer drill. I also find that standard length or longer drills will often not produce a straight hole when drilling deep and sometimes will follow with a sized reamer to also address some of the ridging that may occur. Different approaches depending on the machine, application and accuracy.

 

[dirty tools]

General yes
but for special work not really

 

[Shotgun]

I will often just bring the drill down and touch off several times. Just bumping the drill bit against the material. When I have a good dimple, I drill right through. Never seem to have a problem with the bit walking. I know. I'm a terrible person.