Roughing out a Bore with a Drill

[wrustle]

That's right...... 1.00" drill to depth, and rough to 3.345" dia. with the same tool. 

Sounds impossible, but not with the right tooling............

Here's my Haas ST20 all loaded up to make some aluminum sleeves. 

Material size = 3.750" Dia. cut 2.00" lg.










Here's the tool. 1.00" Center-Dex Inserted Drill.





The drill drills to depth, or in this case (due to total depth being longer than flute length) drills .500" deep then roughs dia to 3.345".

After drilling .500" deep drill moves over in the "X" axis .250" to open the bore .500" in steps until 3.345" Dia. This repeats in .500" deep increments until final depth of 1.500".

Here you can see the piece has been completely roughed out and is ready to be finished bored to 3.375" +.0015"/-.0000".


We also rough turn the OD before finishing the ID.




Here we are all finish bored and OD finish turned to 3.625" dia. I use a .500" dia. solid carbide boring bar with aluminum specific inserts on the ID and OD to achieve the finish and hold size without issue, always using Walter inserts of course.

Now to part off 1.500" lg.




Before and after.









And that my friends is how you drill and bore with one tool.

Later,
Russ