How can I automatically tap 500 holes in 5/16-18 thread size using a hand drill or drill press?

You're tapping the ends. How long are the pieces? Short enough to fit between the base of your drill press and the end of a tap in a tapping head?

A *hand* drill? Yes -- you are pretty likely to break them that way. They are quite brittle, and it is difficult to avoid putting side stress on the tap/drill when working that way.

And if you are drilling and tapping the *ends* of these extrusions, I suspect that these are not through holes. The drill/tap combinations are made for use in through holes as far as I can tell. The drill tip has to clear the far side of the workpiece before the tapping part starts working.

So -- you want a drill (in a drill chuck) followed by a spiral flute tap to get the chips out -- or even better a rolling tap (thread forming tap) which generates no chips -- but requires a slightly larger hole. (Look it up and order the right size drill bits at the same time. It is likely to be a Metric size. Look up the proper size in _Machinery's Handbook_.

This would still be better done in a drill press if the workpiece is short enough. If your drill press table will tilt to the side, rotate it 90 degrees, and bolt a chuck onto it to hold (and position) the workpieces. Drill them all, then change out the drill chuck for the tapping head and go back through tapping under power. Be sure to get the proper lubricant for the roll taps. But they will form stronger threads in your aluminum than the standard thread cutting taps will.

Now if you consider the drill/taps expensive, you *won't* like the new price of a tapping head. But they can be found somewhat more affordably on eBay -- given patience and luck. I got the smaller of mine (TapMatic) from eBay -- and the larger from someone else at a local metalworking club meeting.

You have my opinions above. Now to see what others have suggested.

Good luck, DoN.

William and Don thanks for the tips about ebay and using a drill press. I can't believe how helpful this forum is! I'll try to post a few complete photos when I am done with my project so everyone can give themselves a pat on the back for helping me out.

If I understand your project you want to use the extruded holes in the ends of the material to fasten them together with 5/16 18 screws.

If the hole is an appropriate size or you can enlarge it to the correct size you can buy thread cutting screws that you can skip the tapping process altogether.

Mc Master sells these in 5/16 18. Mow all you need is a socket on the end of a hand drill with a clutch and you are in business.

JUst crank the quill(shaft the chuck is on) down---there should be a slot in the side of it, into which you insert a tapered wedge& tap gently with a hammer.forcing the chuck out. if you don't have the tapered wedge, better buy one, you'll use it a lot. Jerry

Forget taps and use the appropriate Rivnut.

Vaughn

--EEEEeeewww! Evil! Make sign of crossed wrenches! I hate it when those things start to spin! I switched to Formdrill; no regrets (well not as many!)

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Called a "drill drift". If it is an old one of US origin, it will be forged steel, not stamped steel, and rounded on the top edge to match the end of the slot in the spindle.

You may have to rotate the chuck (or the pulley on top) to line up the slot in the spindle with the slot in the outer quill. On my drill press, it is typically once every five or six changes that I actually have to rotate it. The rest of the time, it is close enough to get started, and the drift will rotate the spindle enough to fully match.

There is even a semi-fancy tool which has a drift welded to the end of a shaft with a slide hammer on it -- a little easier to use when you want to devote one hand to catching the chuck or tapping head. :-)

Given the length of the workpiece (which I think that I read in another branch of this thread late last nigh) -- it sounds as though you might (if a not too heavy import drill press like mine from Taiwan) want to lay it down on the floor, with the base rotated to one side (and probably some 4x4 stacks supporting the column near the head) so you can drill something longer than the column. The trick of the vise on the tilted drilling table still should work.

Good Luck, DoN.

Roger, Vaughn, and Steamer, this aluminum profile is heavy duty there is no way you could use self tapping bolts, rivenuts or Formdrill on it. My friend jokingly says the aluminum has steel in it. It is that heavy.

--I never did get the wall thickness. It *is* 'tube', yes?

He's tapping the ends of 80/20 extrusion, so they have a small hole in the center of the extrusion shape.

right in the middle of the photo on the front page of their catalog, you'll see two side views and the end view.

Nope. Different brand, but like this...

You can use self tapping screws on steel. The only time you will have an issue is if the hole is not the appropriate size for the screw, otherwise they will work just fine.

Riv-nuts are great for putting threads into thin sections but if I understand the OP's project correctly, he needs to have threads in the end so there will be nothing for the riv-nut to grab on to.

Right. As I understand it, Rivnuts are really for things like sheet metal where you need a threaded fastener but the material is too thin to get adequate thread engagement,

Yes. Sheet metal or metal otherwise too thin for the thread pitch in question to offer sufficient strength.

And as for the spinning in the hole -- there are Rivnuts with a key under the flange, and a tool for notching the hole to accept the key.

There are also Rivnuts with a hex body.

Enjoy, DoN.

And if it's too late and you have a spinning Rivnut you don't want to totally replace, you can drill a hole at the perimeter and put in a small Pop Rivet as a lock.

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