Centerdrill vs Drillbit

[Vaino]

I've read numerous times that a centerdrill is used by many to start a center punched hole in either steel or wood in lieu of a small drillbit. Having served a 5 yr. tool & diemaker apprenticeship and an addt'l 11 yrs. "on the bench", I was taught that a centerdrill was only used when the workpiece and spindle are locked down. A lathe, radial arm drill press and a milling machine are some examples where a centerdrill is appropriate. On gun work using a drillpress, whole shooter or hand drill, whether it be stl or wood and where the intended hole is prick punched, a small drill bit, because of it's flexibility, will center on the "dimple". Of course once the drill is started, the drill must be lined up vertically to produce a straight hole. A centerdrill because it lacks flexiblity won't always center on the prick punch and especially in wood, could stray and produce a mislocated hole. This topic is mainly for those having trouble locating drilled holes because misplaced holes are mentioned every so often.....Fred

 

[Roy]

I like to use a centerdrill to start when drilling the pin holes on a pre-shaped fore stock of a kit. A drillbit will flex a bit too much and want to travel down the slope, where the centerdrill will mark the hole square to the barrel allowing the drillbit to drill a perfect hole. :v

 

[Vaino]

I just chisel out a very small flat at every hole for both the bbl lug and pipe locations so as you said...the drill doesn't skate down the slope on a precarved fore end. The flats disappear when the stock is further shaped. Do you use a centerdrill on all the other holes?....Fred

 

[Roy]

Yep some of the times. I guess I should add I use a really small one... not too sure of the size.. :haha: I don't too much care for the large sizes. Mostly I use them in the lathe to mark center.

 

[davy]

Interesting point made by Fred. :hmm: I use a center drill ANYTIME (wood or metal) I want a reasonbly straight hole ... never had one move on me with a centerdrill ... but I will give to his expertise in the matter as I am no machinist! :shake:

I punch a dimple first, THEN use a centerdrill .. has worked everytime for me so far. Others experience may vary :hatsoff:

Davy

 

[Stophel]

I don't even know what a "centerdrill" is....

 

[Roy]

well it should be two words :haha:
http://upload.wikimedia.org/wikipedia/commons/thumb/d/df/CenterDrills123456.jpg/584px-

 

[J.D.]

I use them all the time. I do, however, have a cross slide vise to insure that the dimples are properly aligned with the point of the center drill.

I have found that misdrilled holes occur when the drill bit flexes to "center" on the dimple. Gotta have the dimple and the point of the drill aligned, no matter how the hole is drilled, and a center drill prevents the drill from wandering.

 

[flashpanner]

I use a centerdrill sometimes to "push" a badly placed centerpunch back into position. Yes it is better in a more ridgid set-up like a mill, jigbore machine, lathe, etc., we don't all have that luxury.

 

[Bubba45]

Ha ... I've even misused them(center drill) with success for an endmill cutting an 1/8" slot for a trigger plate , not wanting to drive 40+ miles for an 1/8" endmill . Works well going slow and using lots of coolant. :grin:

 

[Stophel]

The closest thing I'll ever have to a milling machine is my benchtop drill press...