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

[DaveH]

Now that is good  
 
DaveH

[stevec]

Disgustingly good!
thanks russ!

[Mayhem]

Hi Russ - the centre dex drill is static in that carousel isn't it?

[wrustle]

(11-15-2014, 08:51 PM)Mayhem Wrote: Hi Russ - the centre dex drill is static in that carousel isn't it?

Hi Darren,

If you mean fixed or stationary, then yes.  

Best Regards,
Russ

[Mayhem]

Hi Russ - yes, that is what I meant. I'm not totally familiar with the world of CNC machining but I know some machines have live tooling.

So in this application, you are using the centre dex drill to plunge the hole and then (effectively) using it as a boring bar. Is that correct? If this is the case then I guess the tool has to be indexed appropriately.

So given the same tool, I could do this on a manual machine. However, I doubt I could do it with a standard drill.

[PixMan]

You are correct Darren.

Using the CenterDex to drill then bore is just a matter of making the first plunge with the tool "on center", then using the outboard insert (aligned with X travel) to step over.

Because the tool has no side clearance angle (square inserts), it's not good as a finish tool but a fantastic rougher.