Drill or mill??

[Peacons]

Have a .75 aluminum round, .5 inch long and it needs a .5 inch hole thru.
Better to drill or mill?

 

[mikey]

Depends on your requirements. If it's just a simple through hole then drill it. If the ID has to be precise and/or if the finish is important then you can ream it or bore it. If the walls of the hole must be precisely straight, bore it.

 

[mmcmdl]

Guhring drill .

 

[Peacons]

After fooling with a Chinese boring bar set for half an hour and getting crappy results, I finished it with a 1/2 in drill in the lathe tail stock and the results were very good.
Did a second one by progressively drilling a larger hole after starting with a center drill and that went smoothly as well.

 

[mikey]

If I were you I would go back to the lathe and learn to use those boring bars. There will come a day when only a boring bar will work.

 

[JimDawson]

After fooling with a Chinese boring bar set for half an hour and getting crappy results

The Chinese boring bars that I bought all needed to be reground to the correct shape. None of them were right. No clearance on the cutting edges.

 

[Peacons]

Believe that is the problem with these.
But they're carbide tips so what do you use to reshape? Dremel??

 

[JimDawson]

I have used a Dremel with a diamond wheel. Harbor Freight sells the diamond wheels at a fraction of the cost of the Dremel ones. https://www.harborfreight.com/diamond-rotary-cutting-discs-5-pk-69657.html

I see that Harbor Freight also has some larger diamond wheels with what looks like 1/4'' shank. https://www.harborfreight.com/large-diamond-rotary-grinding-wheel-set-4-pc-69658.html

But I normally just use my bench grinder.

 

[Peacons]

I have used a Dremel with a diamond wheel. Harbor Freight sells the diamond wheels at a fraction of the cost of the Dremel ones. https://www.harborfreight.com/diamond-rotary-cutting-discs-5-pk-69657.html

I see that Harbor Freight also has some larger diamond wheels with what looks like 1/4'' shank. https://www.harborfreight.com/large-diamond-rotary-grinding-wheel-set-4-pc-69658.html

But I normally just use my bench grinder.

Bench grinder with the normal wheels?

 

[JimDawson]

Bench grinder with the normal wheels?

Yes. They will work. Especially good for the roughing out process, gets the steel shank out of the way so you don't damage the diamond with the steel. But I just normally use the tool without finishing with a diamond. You do have to push a bit harder to get the normal wheel to cut the carbide. Keep moving across the wheel so you don't wear a groove in one spot.