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Drilling holes and drilling heads off Pop Rivets
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hemi354az
Posted 2018-11-25 1:03 PM (#6087)
Subject: Drilling holes and drilling heads off Pop Rivets


Extreme Veteran

50025
Location: Scottsdale, Aridzona
We have all used two flute drills that some how make a triangular shaped hole, especially in thin material. The hole often is not really where wanted but slightly "out of position". That is because the item was moving around, and/or, the drill tip was moving around skidding and cutting small pieces and then not cutting until the drill finally advances far enough to start making a continuous cut. Putting a DRILL STARTER HOLE CENTER in the item prevents the drill from skidding around and/or the item flexing/moving at the start. If you get a good center started, then the drill will always "drill" where that "center" is. CENTER DRILLS make that "centered hole".
Center Drills are always used in lathes, and they can also be used in a drill press and in your electric or air powered hand drill.

https://www.google.com/search?rlz=1C1CHBF_enUS782US782&ei=6NX6W9r4OI...

They come in numbered sizes and lengths.
Don't buy cheap ones as they will dull quickly. Keo is a good brand . . . but a .99¢ center drill probably won't last long.
There are carbide and other specialty metals/coatings center drills, but they are for exotic metals and VERY expensive.
Just "regular" center drills are needed for most common metals and for the heads of aluminum pop rivets. You can buy single Center Drills or Sets. Various lengths are available as single items as well.
A good on line selection is available at MSC, Grainger, ENCO, McMaster-Carr. If you are in a City . . . most Machine Tool "Stores" will also have them.

If you use a hammer punched center location or a spring loaded center punch -

https://www.google.com/search?q=spring+loaded+center+punch&rlz=1C1CH... -

right where you want a hole, then use a center drill to enlarge that center punch, and then a good drill . . . you will have a good hole RIGHT WHERE YOU WANT IT.

If you don't hold the item too tightly on the drill press table , the Center Drill will pull the item (Drill press has to be "ON") into the Center PUNCHED hole CENTER . . . then you can raise the Center Drill and firmly clamp the item to the table, and then finish the Center Drill starter hole, and then the hole using a regular drill. That "loose" technique sometimes also works on a hand drill letting the Center Drill "seek" the Center PUNCHED hole CENTER . . . then once "centered" . . . grip the drill firmly and put a Center Drill starter hole in the item . . . then finish the hole with a regular drill.

CENTER DRILLS are the easy way to drill the heads off aluminum pop rivets. They sometimes work on steel head rivets too.
The heads of most common rivets used in fiberglass and sheet metal can be removed with a #3 or #4 center drill. I would buy one or two #3's in the regular length, one in the #4 regular length, and maybe one 4 or 6 inch long #3, for "reaching" into those few places that you can't get the electric drill or air drill into. You may also consider a "set" of No. 1 thru 5, but still get one of the longer #3's as well.
Of course, after you drill the head off . . . you may have to use a pin punch to drive the pin out of the "barrel" of the pop rivet.

Sometimes the pin does not break off down in the barrel but breaks off right at the top of the rivet head. If the pop rivet had a steel pin . . . you are then trying to drill a fractured pin that is just barely snug up at the top of the rivet. The Center Drill wants to move "off Center" because the steel pin is pushing it one way or another. There is no real good solution in this case. If you can get in position to put both hands firmly on the hand drill, and can really see what is happening at the rivet, then you might be able to direct the Center Drill to kind of move in a SLOW circle around the steel pin as it chips away at the rivet head. Pe prepare for the Center Drill to suddenly JUMP/PULL OFF CENTER into the softer aluminum head and the fiber glass or sheet metal, making a bigger hole that is not where the original rivet was. A Center Drill sometimes works on a steel pop rivet. The rivet will tell you whether the Center Drill will work. Otherwise . . . careful grinding. Flush rivets can be drilled with a Center Drill if you Center Punch . . . but remember that a Center Drill has a 60º angle. Aircraft rivets are usually 100º. Other "flush" rivets are ??? angle. Many of the frame to body structure rivets on the FMC are "Cherry" rivets that are NOT like common Pop Rivets. They take "special" tooling that pulls the rivet tight , then the pin breaks. They should be replaced by those special type rivets.

If you have never drilled the heads off common Pop Rivets or used a center drill . . . get some scrap material . . . Center Punch and then drill some starter holes with the Center Drill . . . to see how the Center Punch and the Center Drill work, and how a good Center Punched location will pull the Center Drill into the center that you marked. Then Pop Rivet some pieces together and practice drilling off the HEADS.

Drill ON ! Lou #120

Edited by hemi354az 2018-11-25 1:05 PM
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