How to drill opposite holes on round stock?

I'm still confused on how the tapatalk - photo upload works. Maybe it works now.

Britt
 
I know this thread is a few years old but why did we need anything other than a collet block here for 180 degrees? The larger aluminum piece (tube) could have been turned out of a piece of stock leaving a 1" dia end for the collet block. Maybe I missed something. As much as I would also like a nice super spacer or expensive rotary chuck something and support, it would rarely get used. I'm not saying they don't have their place, I have just never been able to justify buying one. And who am I talking to? No-one will ever read this... (sigh...)
 
You can make yourself a Rose Index as some have previously alluded. Here is a video of how to use it. Pretty expensive from Lakeshore carbide but simple enough to make out of say 3/4" aluminum plate.

www.lakeshorecarbide.com

ROSE-INDEX

Easily re-position your work piece, rotating at 45, 60 or 90 degree increments, or use angled parallels for one degree increments. Removable during machining
www.lakeshorecarbide.com
 
When faced with that task, I indicated the bottom of a V groove, and drilled a small hole. Drilled one side of the tube, dropped a dowel in the hole. Flip the tube to fall on the dowel, and drill the other side. The V groove forces the tube to center for the first hole. Having drill the dowel hole in place, I know it is centered, and the tube will be centered on that center when it is flipped over.
 
Using your same idea...

1. Lay a piece of flat material slightly narrower in width than the diameter of the tube or bar on the bottom of the mill vise pushed up against the fixed jaw.
2. With just the flat material in the vise, clamp it, indicate off the fixed jaw half the diameter and drill a pin hole in the flat stock.
3. Open the vise, put the round stock in the vise, clamp and drill the pin diameter thru the top wall.
4. Then put the pin in the top hole, flip it over and put the pin into the hole in the flat stock in the bottom of the vise.
5. Now you can close the vise on the tube while you drill or ream it again.

Minimal set up. What's wrong with that idea?
 
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