Drilling Square Holes in Roll Formed Aluminum

Perhaps CNC plasma cut in a custom rig? Plasma consumables may be cheaper than rotary broaching cutters and drills for the pilot hole. Plasma would also be faster.

Yeah, that's it. I don't know what they do when you can't rotate the workpiece, but my understanding is that they have a solution for that.

Otherwise, if the radius will allow it, the best thing I can think of is milling. I might consider horizontal milling with a short cylindrical cutter, but that probably would cause some awful burr problems.

A final possibility is drilling a round hole and then going in with a corner pull broach -- one tooth -- after slapping on an external fixture that will hold the aluminum tube down but which would allow room for the pull-broach cutter. But that's custom tooling.

Unknown... Plus, I'm trying to sell them a machine to do it so I don't want to give them *that* good of an idea.

Regards, Joe Agro, Jr. (800) 871-5022 x113

01.908.542.0244 Flagship Site: / Pneumatic Drills: Spindle Drills: Tapping:

V8013-R

Rotary broaching it is then... You'll sell more machines since it's a two step process of drilling a pilot hole and rotary broaching it square... You'll sell even more machines since they'll need parallel production lines to handle the volume...

You know this already, but if there's _really_ a better solution out there that doesn't involve your machine, you'll earn a whole lot of good will by pointing them to it.

Hmm ... I thought that I remembered the aluminum as being square tubing, which is why I did not suggest broaching or punching.

The Unistrut is mostly U-shaped steel, so it could be some kind of rolling punch to do the holes in a continuous process -- before forming to the 'U' shape or after.

But if you have to reach into the middle of a length of square tubing, it is hard to get the die end of a punch and die in position for the operation. So the tri-flute square drill bits (and all the fixturing which they involve) seem to be the way to do it.

Enjoy, DoN.

Check out , and look for the "DROPBOX" click bar. Note that if this file is from 2008, it is likely to be in one of the "archive" subdirectories. And without a file name, you are at the mercy of recognizing what the uploader may have called the files.

Someone needs to make a "machinist's phrases" dictionary web page. (Though "cool beans" may not be metalworking related -- just a local phrase from somewhere.

Enjoy, DoN.

Absolutely. That's the way we work. Thus the "" at the end of my post.

My personal stance, and one I try to encourage throughout the entire company is to do the right thing, all the time, every time... Regardless of cost and time. It all pays off in the end.

I guess I gave only the details I thought were necessary.

It is a square profile outside, but if you look at it from the end, the interior actually shows it started as a flat bent into a square with some of the material going "inside" the square as a supportive profile. To oversimplify the interior clearance issue, imagine the "do not enter" sign or the "universal no slash" going from the upper right corner to the lower left corner of a square. That's close to what they have inside the profile even though it does not need to be drilled out.

This seems to suggest that the best approach is punching the holes before the forming is done. That diagonal (assuming that the square hole gets that deep may cause problems -- though since I have never used such a square hole drill, I don't know for sure.) Of course, the drill (if still made) would be a better match to your equipment. If it is not still made, could you start making it again? Is the patent expired, or can you find someone to license it from?

Good Luck, DoN.