A method for centering a drill

[Ubarch]

I don't know if this isn't already an established method, but I sort of improvised it and found that it worked quite well. I drilled holes for screws that needed to be very slightly widened. I had been trying to align the bit previously by putting the original drill bit in the chuck, lining it up as best as possible in the hole, and then replacing it with the larger drill bit. However, I noticed that small drill bits will flex very, very easily, and I was always off by a few mils. This is an alternate method that I thought I might share:

1.) Put the drill bit you wish to cut metal with in the chuck.
2.) Lower chuck until the cutting edge of the bit, shaped like a cone, is halfway below the existing hole.
3.) Eyeball the alignment in the XY plane as much as possible.
4.) Increase Y until the bit barely touches the metal. In my case, I could hear the bit hitting the iron.
5.) Measure the distance required to traverse from the point located in (4) to the other end of the hole, via the same method.
6.) Backtrack by half.
7.) Repeat for X.

As far as I could tell, this method was quite accurate. It may not be news to everyone, but maybe it's news to someone.

[HuFlungDung]

Good idea to post your methods, Ubarch

Performing such a task frequently, makes a good excuse to buy a set of drill blanks (as if we need excuses to buy more tools ). Then, I leave the part sitting unclamped on the tabletop, and lower the rotating drill blank into the hole, then shut the spindle off. Even quite a small drill blank will pull the part into position on the table. So, while the chuck is still lowered, with the drill blank at rest in the hole, apply a top clamp or two, to the part. Then exchange the drill blank out for the desired drill bit.

[Mcgyver]

what are you drilling with? on a drill press, most of the time you just let it float, ie not clamped to the table and the drill picks up the hole/centre punch/centre drill. large parts are held by hand, small in a drill press vice. Clamping to the table is more for larger holes

you'll quickly get onto what sort of jobs pose a risk - where the torque is greater than your ability to hold - this is why the dill press is the most dangerous machine shop tool. sounds dramatic, but really only applies to larger holes. a simple saftey device is a large piece of angle iron clamped to the table such that it would prevent the work from doing a 360. I hold the work or vice close the angle iron stop with fingers clear of it - sounds worse than it is

[whateg01]

...a simple saftey device is a large piece of angle iron clamped to the table such that it would prevent the work from doing a 360.

Or for longer pieces position the workpiece so that it is near the drill press's column. (Somebody will probably tell me that I should not do this as it poses a potential risk of damage to the column, but it hasn't happened to me yet.)

Dave

[ViperTX]

Hu...has the right approach...the drill bit must be spinning....otherwise you will be off....then there is the better approach....DRO....and then CNC.