Drilling out pop rivets

[PC Paul]

Gold 'coloured'.

[Duncan Wood]

I know....

[Mike G]

I know text books talk about different included angles for different materials, but in practice, engineers in jobbing shops just grind a drill by hand so it cuts. Maybe variations when drilling plastics , resin bonded materials etc, otherwise they're all ground the same. TBH, unless used on a production m/c I see little point in using TiN coated drills, as once they need sharpening any cutting advantage is lost, and they will need sharpening, especially if used in hand held electric drills. A set of HSS drills will last for years. Just needing the occasional sharpening to keep them in a serviceable condition. The HSS drill sets I have at work are at least 15 years old. A few bits have been replaced through breakage or loss, but the majority came with the set when purchased. Mike.

[cerberus]

The biggest problem with with 'pop' rivets is whether they are open or closed. An open rivet is relatively easy to drill out.....it's just a matter of knocking the 'mandrel' out (the piece that expands the rivet) & then drilling the head off, then the shank can be 'knocked through' with a centre punch!

A 'closed' rivet is a different kettle of fish, normally the mandrel cannot be knocked back...it's a matter of drilling the 'head' off & then knocking back with a punch and expanding the origional hole.

[cerberus]

When is a pop rivet not a pop rivet?

When it's a monobolt

[meow2222]

Gold coloured drill bits are tough low friction titanium alloy coated, TiN or TiAlN.

NT

[meow2222]

well I'll take your word for it. I thought ali tended to stick to hss at higher speeds.

NT

[meow2222]

AIUI the advantage is that Ti coated bits have longer life to first resharpen, thus for a DIYer that means less time out of service. The other plus is that since most DIYers dont resharpen bits, the Ti coated ones will last longer, easily justifying the extra cost. Probably all DIYers should resharpen bits, but IRL most dont.

NT

[Dave Plowman (News)]

Wish there was a decent drill sharpener on the market. I have two and they're both near useless on anything other than large drills. Which even I can do as well on a grinder by eye.

[Mike G]

That's the way all real engineers sharpen drill bits. :-)

Seriously though, a proper drill sharpener is an expensive precision piece of equipment, and not worth buying for sharpening the odd drill. Mike.

[Mike G]

I disagree. TiN coated drills don't last well in hand held grinders. In that application I doubt they last much longer than plain HSS ones.

I suspect most DIYers have facilities for grinding drills, even if it's only an angle grinder. If they can't sharpen a drill, they should learn how to. Far cheaper than buying a new drill bit when it becomes blunt. Mike.

[Clint Sharp]

In message , Mike G writes

Trigger's Broom springs to mind...

My dad was a lathe operator in a small engineering firm, he had drill bits and tools from his apprenticeship that he still used daily, had to be over 40 yrs old.

[Mike G]

Not really. 75% of them are the originals. Most of those replaced have been under 5mm in diameter. Small drills, especially the very small sizes are easily lost or broken. And I also have boxes of miscellaneous drills. Many of which date back to my early years in engineering.

Prexactly. Mike.

[Dave]

And once ground, will only stop aluminium from sticking to the flutes of the drill.

At this point, I should add that most pop rivets are made from monel metal. The aluminium ones are usually bought from the local pound shop. I suspect the original question was about a monel metal rivet that was spinning round. Tilt the drill to about 30 degrees and you will drill off the head, just stop drilling before you go all the way through and try a punch to break what is left of the head. If it does not easily break the head of the rivet, drill again at 30 degrees.

You and I know that. Try telling those that can't ;-)

I once had a job trying to drill through some umpteen thousand ton steel, using a D 200 drill of 2.5 mm. I spent more time walking to the grind stone than drilling. The twist drill showed nothing wrong, but it wouldn't drill any more. Grind it and it would drill another three holes and so it went on for a few weeks. Umpteen holes in this job :-(

The Italians, who were responsible for the job we were doing came round to see how we were doing. One of the lads that was opening up the holes to full size had turned the epoxy primer, around one hole, to a light blue colour. The Italian rep turned round and said 'your drill is too blunt'. The lad turned round and said 'your steel is too hard'.

The Italian turned back to him and said 'The designer, we should take him around the corner and keel him'. Made me laugh when he told me though

Dave

[Dave]

Pop rivets can be divided into 3 types.

The first 2 types are made from monel metal and the third from crappy aluminium.

The monel metal ones can be sub devided into break head and break stem.

A break stem retains the lower part of the manderl that is used to expand the rivet on the blind side. This is done, so that there are no loose items left on the blind side. This stem can ususally be removed, providing the structure it has been set in is firm and not bouncy, by a small punch with a 'quick' bang by a small hammer.

Break head, as the name sugeusts, is designied to let the pulled head of the rivet to fall into the void of where the rivet was pulled. If this void is capable of being cleaned out, everything is OK. If it isn't, then some form of sealant has to be injected into it to prevent the dross from harming the void. This pruduct is usually a bonding agent.

Dave

[Dave]

You don't need a drill sharpener. It is a bit late in the night to describe the method. But if I have not gat back to you within 24 hours. Feel free to poke the e mail address.

Dave

[Dave]

Only supersoft crappy alli.

Dave

[Mike G]

If drilled or machined dry, ally tends to stick to any cutting tool. Applying a lttle parrafin occasionally, is usually all that's needed to stop it happening. Mike

[John Rumm]

Fancy posting your method here:

like it could be useful for reference later.

[Duncan Wood]

Well there's always the trick of milling the head off with a handheld router :-)