How to drill an off center hole on a curved surface

[rogerrabbit]

Dimensions are roughly 1.5" diameter, .5" thickness. The center hole is .25". The hole on top is for a set screw. The 2 rods sticking out are 3/16. Material is Aluminum.

Hi All,
I need to drill a .375" hole through the side of the cylinder. It needs to be offset from the center hole so there is no interference, but as close to the center as possible (see pic)

My initial thought is to mill a flat spot for measuring and a center punch, is there a better(easier) way? The most important thing is that I don't drill into the center hole.

I tried to place the hole in solidworks, but couldnt figure that out either..


Thanks!
Roger

 

[GaryK]

You could mill a flat then while it's still in the vise center drill then just drill the hole.
To miss the center hole you will need to first find the center then move half the distance of the diameter of the hole and then half the distance of your drill diameter.
Then add how ever much distance you want to clear the center hole by.

 

[Syaminab]

Align and hold the part on the mill, locate, previous to the drill bit, use a small endmill to flatten the spot, then use the spot drill, and finally the drill bit followed by the reamer if it is precise. All tools as short as possible and sharp.
regards.

 

[Kevin45]

Mill a flat then use a centerdrill that is equal to or slightly larger than the drill bit you are going to use. If you have a center drill that is considerably larger than your drill bit, only go deep enough to be slightly larger than your drill bit.

 

[Chrispy]

Quick and dirty - put a shaft through the center hole that's a snug fit. Drop the part into your mill vise with the shaft 90 degrees to the jaws. Grab a drill bit ( or shaft) that's your hole size you want to drill plus the clearance (x2) you want between the drilled hole and the center hole. Example - if I wanted a .5" hole and .25 between the hole I drill and the center hole I would grab a 1.0" drill bit or shaft. Put the bit or shaft in your mill and bring it over to just touch the side of the shaft running through your parts center hole. Lock that axis and center the mill on the parts width. Put in an endmill and feed down to make a flat spot. Center drill then drill your hole.
Chrispy