Drilling a straight hole

[mofosheee]

Hello Forum

Looking for advice on how to drill a; 0.250" hole, 6" deep in a 1" round steel bar and keeping the bit on center.
At my disposal, I have a mill or lathe and visions of using a 4" long drill bit to make the 1/2 way point then flipping the part in the vice or chuck
to complete the drilling. What say the forum please. Thanks

 

[akjeff]

I'd likely opt for the lathe, and do it all from one end. Face the end off square, and spot drill. Start with a new, sharp, stub length drill as far as it will go, and switch to incrementally longer bits as needed. Plenty of cutting oil, and clear chips frequently.

 

[RJSakowski]

For some reason, a stationary tool and rotating work seems to work better. When drilling on the lathe, I pause the feed when using the center drill to let it find the true center relative the the spindle axis. This will compensate for slight misalignment of the tail stock relative to the spindle. Once the center drill has settled in, I proceed, repeating the pause, if necessary.

If the hole is started off the spindle axis, it will just get worse as drill progresses. Personally, I prefer to drill long holes from either end, if possible. The longer the hole, the greater the chance of deflection of the drill. I start with an undersized drill and drill through until both holes meet. Then I increase he drill size and drill through from either end, repeating until reach my desired diameter.

For maximum straightness, I would bore the hole, followed by an appropriate ream. I believe that Joe Pieczynski did a recent You Tube video on the subject.

 

[mmcmdl]

If your part is 6" long , I would start with 1.062 stock drill and ream thru the entire 6" and turn to size between centers using the holes . The hole might not be perfectly straight but would be true to the OD .

 

[mofosheee]

I'd likely opt for the lathe, and do it all from one end. Face the end off square, and spot drill. Start with a new, sharp, stub length drill as far as it will go, and switch to incrementally longer bits as needed. Plenty of cutting oil, and clear chips frequently.

 

[mofosheee]

For some reason, a stationary tool and rotating work seems to work better. When drilling on the lathe, I pause the feed when using the center drill to let it find the true center relative the the spindle axis. This will compensate for slight misalignment of the tail stock relative to the spindle. Once the center drill has settled in, I proceed, repeating the pause, if necessary.

If the hole is started off the spindle axis, it will just get worse as drill progresses. Personally, I prefer to drill long holes from either end, if possible. The longer the hole, the greater the chance of deflection of the drill. I start with an undersized drill and drill through until both holes meet. Then I increase he drill size and drill through from either end, repeating until reach my desired diameter.

For maximum straightness, I would bore the hole, followed by an appropriate ream. I believe that Joe Pieczynski did a recent You Tube video on the subject.

Just like both you and Joe said! Thanks