countersinking

The best way would be to use a 'countersink bit' but it also depends to some extent on how thick the material is and how 'professional' do you want it to look.

For most situation it will be best to use a slower speed than what you drilled with.

Hope this will help you.

Lewis.

*****

If you want the countersink to fit anything then you need to use a countersink bit, which also has more then two cutting edges and in addition to cutting the correct angle is more likely to make a smooth cut.

By the way, wood screws have an included angle on the head of 82 degrees, machine screws have an included angle of 82 degrees, but rivets have a 78 or 100 degree included angle. You will need to match the countersink to the fastener used. Cheers,

Bruce (bruceinbangkokatgmaildotcom)

IIRC the 82 degree coutnersink angle is used for unified screws, metric and BSF, BSW use 90 degree countersinks so the OP needs to check what is being used.

Also note that metric countersunk screws have an included angle of 90 degrees upto and including M20 thereafter 60 degrees! (Source Unbrako Eng guide) I must admit that until fairly recently I did not appreciate that UNC UNF etc were 82 degree inc angle not 90.

Richard

Many, many different angles but none of them are the 118 degrees of a standard drill bit..... :-) Cheers,

Bruce (bruceinbangkokatgmaildotcom)

Low speed works best for me.

Just to add a little more complexity:

I have been countersinking holes with a standard drill bit that's about

3 times the diameter of the hole. This works for me because I am using (mostly) 1/16" diameter mild steel rivets in the holes and manually riveting them in place. So, I am forming the material to fit the countersunk hole as I go. In this application, I don't need a lot of strength so the thin head that results from the 118° angle isn't a problem.

You can see this application at:

As the other posters have said, go buy a set of appropriate countersinks. They will last a long time and will eventually add to the value of the estate sale.

Pete Stanaitis

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Find one that is rated for steel, not just wood.

jw.

And hold the piece of steel very very securely. Preferably with a clamp on a drill press.

The problem with using a larger bit to countersink..and we all do it..is if the metal workpiece is too thin..its easy to blow right through if the drill bit gets a good bite and screws itself through the metal. With a drill press, you can control the "bite", as long as the metal is held down so its not pulled into the drill bit.

If all you have is a hand drill motor...brace yourself well and go Slow! when applying pressure, and turn the bit slower.

My $,02USD worth of opinion

Gunner

"First Law of Leftist Debate The more you present a leftist with factual evidence that is counter to his preconceived world view and the more difficult it becomes for him to refute it without losing face the chance of him calling you a racist, bigot, homophobe approaches infinity.

This is despite the thread you are in having not mentioned race or sexual preference in any way that is relevant to the subject." Grey Ghost

The best countersinks I've ever used are the "through hole" style. /Never/ any chatter.

of the page.

Bob

Thanks heaps for the information. Looks like I need to find a suitable countersink bit for a 5mm bolt.

Buy more tools. Oh the horror!

Hrm... why, when I have had way too much time on my hands for the last

3 weeks do I need to find a bit, some 5mm Nyloks, and some ethernet cable (not related, but still required) in a window of around 2 hours on Saturday morning?

Zebee

snip----------

WRONG!!! - machine screws are available with 90 or 82 degree angle, the 90 deg is used for thinner material

Not to dispute you but I'll bet if you stroll over to either Walmart or Harbour Freight, as so many on this group apparently do, you will get 82 degree heads.... Cheers,

Bruce (bruceinbangkokatgmaildotcom)

use a slocombe drill of the appropriate size in a drill press.

you 'merkins will probably swear blind that they are called centre drills.

Stealth Pilot

huuuuuuuuunnneeeeeeeeyyyyyyy its been 3 weeks now and my widget still isnt fixed. no nookies for you until it gets fixed.

:-)

Stealth Pilot

Don't you get chatter from the two flutes? I get the best results with a single flute cs. I've ever had much luck with multiple flute ones. RR

No Harbour Freight in reach, and I don't patronize Walmart, but I would not expect anything but the most basic screws there.

I know that I have some 90 degree and some 82 degree screws, and probably some other angles as well. Granted that some of these were left-overs from a job building flight simulators with standard aviation style hardware.

It was where I learned about Clecos and Rivnuts, among other things.

Enjoy, DoN.

Well ... center drills (we would never spell them "*centre* drills") have a 60 degree angle, to match the angle on lathe centers. And I would not normally consider them for countersinking screws.

I've got the 82 degree and the 90 degree countersinks in several styles and sizes -- as well as 180 degree ones (normally called "counterbores". :-)

Enjoy, DoN.

The multi-flute ones like the Severance ones (with slightly staggered flutes) I find it best to bring the drill press spindle and countersink down into firm contact with the workpiece before switching on the motor.

Enjoy, DoN.