Countersink bits for metal

[Eddo Rogue]

I'm tired of using crappy countersink bits. My craftsman set dulled out this week, I had to struggle and break a drill to finish a hot job. Looking for a good set that is intended for metal. I will be using them mostly on hot and cold rolled steel, sometimes cast iron or aluminum.... wood on rare occasions.

First off it seems I want carbide instead of HSS...

I found a few: Sun Pro, Ultra tools, and the Irwin set (which I ordered)

I am assuming 6 flute is better for metal?

Also noticed there are varying degrees. I would think 60 or even 82 is fine, 100 might be a little much. I will be setting in various flat screws: drywall, machine, brass, etc...

The above mentioned companies seem legit and based out of Huntington Beach, CA....Which I know has a pretty robust manufacturing/industrial district.

Anyways, just looking for some input and opinions on brands, flutes and angles...

 

[Dirtman]

You do not want carbide unless you are working entirely in a press with clamped material. Carbide is extremely brittle and you will destroy it if you try to use a hand drill or let the material move at all.

If you're using them for screws/bolts you want 82 degree for sae, 90 degree for metric, though 90 works fine for both.

Flute count has more to do with the RPM range than the ability to cut well. The best countersinks I use are single flute. Less flutes means less chatter.

These are the two styles I use. The thru-hole style makes the smoothest cuts.

 

[cbxer55]

Aviation quality kit. We use these at Tinker AFB. I have my own set at home. I've used them on titanium a few times, but that's a whole nother story. Titanium is a biotch to work with.

9 Piece Countersink Cage & Cutter Kit | Brown Aviation & Aircraft Tools

Fortunately for me, the place I linked to is five miles from my front door.

 

[cbxer55]

If you've never used a set like that before, you put the bit in the cage. The cage has a large range of adjustment. Once you get it set for the depth of countersink you desire, you can repeat it over and over again. I use them on an almost daily basis.

 

[Eddo Rogue]

So is less flutes is for higher speed or vice versa?

Most of my countersinking will be done w/ a 3/8" cordless hand drill into mild steel.

The aviation ones seem badass...

I found these Weldon zero flute has some rave reviews.

 

[MikeG]

No. ONE flute will have no chatter. More than one flute.... may or may not have chatter. Depends on a lot of things, not the least of which is nit-pickly differences in the spacing of the flutes. Speed has nothing to do with it.

Cutting oil is your friend, here, if you are working with steel.

 

[Eddo Rogue]

I dont care about chatter, nor need it to be exceptionally clean, I pretty much just need the hardware to sit flush, or just past it.

What does speed have to do with then? What speed do I want?

Yes, agreed, I use tapmagic and it makes a big difference. Still, eventually I am pushing the drill and it is doing nothing...

 

[Eddo Rogue]

I have had the least luck with single flute styles, maybe I'm using cheapo ones or not doing it right...

 

[Dirtman]

The faster you run a 4 or 6 flute bit the more they chatter, they work better at low RPM. Single flute bits don't care what speed they are going for the most part.

 

[sgtsandman]

Aviation quality kit. We use these at Tinker AFB. I have my own set at home. I've used them on titanium a few times, but that's a whole nother story. Titanium is a biotch to work with.

9 Piece Countersink Cage & Cutter Kit | Brown Aviation & Aircraft Tools

Fortunately for me, the place I linked to is five miles from my front door.

That is not a bad price for that kit at all.

 

[MikeG]

Then you are using cheap bits, if having problems. Quality bits and decent cutting fluid; we wouldn't be having this discussion......

 

[sgtsandman]

I never had a problem with my standard counter sunk bits until I started working with aluminum. The stuff Lowes and The Home Depot sell is soft, clogs up the flutes, and chatter is hit or miss. I believe most of the stuff they sell is made from recycled aluminum and isn't not mixed/blended very well. There are are hard and soft spots all through the metal piece. They serve my purpose and the price was right. If they were for structural pieces, I wouldn't trust them but for making protective edges on wood, they work well enough. The above kit would have been real handy but the work is done now.

 

[Eddo Rogue]

its for clearance. the screw is going outward from inside a window frame to catch a locking hinge arm, it has to clear the glass thats dropping into the frame. Its a #3 phillips 2/4"x20. I wasted a 5/8" and 3/4" bit getting it done. It was one of those days everything thought it was stainless. this was into the side of regular old 1/8" thick 1" angle....Anyways I had to sink it flush or below to clear the glass that was gonna drop in.

 

[Eddo Rogue]

whats the dowside of chatter besides a rough finish and irritation? I dont care if it chatters or farts as long as the glass clears my screw. I'm quite used to hearing and smelling farts.

 

[Dirtman]

It wont look as nice or have as precise a fit... and chatter wears the bit faster.