Countersinks for metal ?

[semenza]

I am looking for some countersinks for steel. To use in drill press or hand held drill. They don't need to awesome quality but not junky either.  I see lots of them and most have good reviews. But one of the common bad comments is that they chatter and leave uneven / rippled edges on the holes. This is with ones that are five or six flute.

Recommendations?

Seth

 

[Svar]

... But one of the common bad comments is that they chatter and leave uneven / rippled edges on the holes.

Use zero-flute countersink.
Alternatively use carbide one with multiple (15-20) fine cutting edges. They look like die grinder burr, work best on stainless, etc. Need stopping often to clear the chips.
Also, burr type will produce cone perfectly concentric with the hole, while zero-flute often shifts when used aggressively on softer metals.

 

[rvieceli]

Seth - I like zero flute countersinks for everything. I find KEO carbide ones to be good value and performance. Here's a selection from MSC:
https://www.mscdirect.com/browse/tn/?searchterm=keo+zero+flute&hdrsrh=true

Watch your angles when ordering. Most common for flat head screws are 82 and 90 degrees. Check the material you will be using.

Countersinks are also a good method for de-burring holes for screws and bolts as well. Just take a bit of the edge. if actually countersinking I like to use them in a press to get a  consistent depth. I usually only do handheld if de-burring.

What are planning on doing? There are other methods besides flat head screws.

Ron

 

[afish]

I spent many a year working in a metal fab shop. Zero flute is the way to go.  THey come both piloted and no pilot. zero flute will give you the cleanest chaterfree hole.

 

[kevinculle]

I find a stepped drill gives best results in sheet metal, clean holes and nicely chamfered edges.

 

[semenza]

Current use is in 1/4" thick mild steel for 1/4 x 20 flat head machine screws. This, or similar, comes up every once in a while and I am tired of finding work arounds.

Seth

 

[Cheese]

Where to start...this can be a complicated subject.  [big grin]

For mild steel I'd go with the traditional single flute Ford style countersink. Slow the speed down and use plenty of cutting oil. Make sure you take a bite, .001"-.002", don't try to just skim the surface because that can cause chatter and once it starts it's tough to get rid of it. You can peck a countersink much like pecking a deep hole. Go in, take a bite & get out...repeat until you've hit the right dimension.
When using a countersink the diameter is constantly increasing that's the reason the slower speed is critical. You run a 3/8" drill bit slower than a 1/4" drill bit. If you have any more than 2-3 of these to do, I'd definitely run them on the drill press. Once the first one is done to your satisfaction, be sure to set the quill stop to ensure they will all have the same diameter/depth. For this application I'd prefer using a vise to hold the metal strap and then securing the vise to the drill press table.

For steel here are my go-to countersinks. L to R: Severance, Ford, Ford, Ford with TiN coating, Severance & finally a KEO solid carbide 6 flute. All are 82º even though Severance uses 41º nomenclature. The 6 flute is also known as a chatter less, however that's not necessarily the case.  [crying]

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Another method I've been using lately for aluminum and I think this would also be viable in ferrous materials is a spotting drill. Here are some Hertel 82º carbide spotting drills.
https://www.mscdirect.com/product/details/59918953

Like others mentioned, I love the zero flute countersinks and they are my favorite for aluminum, plastics & wood, but not for steel unless it's just a quick deburring issue. Even though the KEO are machined from cobalt, they will dull quickly when used on ferrous metal products and that's because of the thin wall on the cutting edge.

Here's a shot of the 82º zero flute countersinks I use: Norseman, KEO, KEO, KEO, KEO, Festool & Festool. The KEO are cobalt while the Festool are HSS. It's best to use the KEO in plastics and aluminum and save the Festools for wood. I've used the small Festool in aluminum before and after 3-4 holes the Festool was toast. Again if using the KEO in non-ferrous materials use a lubricant it helps a ton. I prefer to use IPA if there will not be any sparks generated. It evaporates quickly and is cleaner than anything else.

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[semenza]

  IPA = Isopropyl alcohol?

      Or India Pale Ale?  [big grin]

Seth

 

[Cheese]

  IPA = Isopropyl alcohol?

      Or India Pale Ale?  [big grin]

Seth

Both...one is for the tooling and one is for the operator.  [poke]

 

[Svar]

Once Cheese was on the topic I expected nothing less than an illustrated anthology of countersinking.  [thumbs up]

I was eyeing M.A. Ford for a while. Does it stay concentric with the hole? Something I have a problem with using a sharp zero-flute. Once it bites to initiate a spiral shaving it shifts and it's hard to get it back on center. Probably has something to do with angle of attack, too aggressive.
I have one-flute by Bigboxstore and it's not good.

 

[WastedP]

I had never used a zero flute countersink until about a month ago.  It changed my life.  I don't know what brand it was, just a HSS one from Fastenal.  I had to countersink holes in an aluminum geared hinge, and the difference vs a cheap six-flute bit was amazing.  I could pour T-9 on the six-flute all day and it would struggle to do a sloppy job, at best.

 

[Michael Kellough]

Excellent depiction of the choices Cheese!

I get best results with a zero flute countersink, in softer materials.
You can sneak up on the size sink wanted with this bit with good results at every stage.

Next best are single flute bits. Needed for steel.
Almost as good as zero flute but often leave a small radial step when feed pressure is withdrawn.

I’ve seldom had good results from multi flute countersinks except when used in a milling machine.
If there is any slack in the feed pressure on a multi flute bit there will be vertical chatter resulting in a radial washboard pattern instead of nice conical sink.

 

[Cheese]

Well just to give you a visual confirmation of what I claimed yesterday. Only use the HSS Festool c'sk for wood and soft plastics.

Here is a closeup of 2 Festool (492520) c'sks, the RH one has only been used for wood projects, while the LH one has been used to c'sk 3 holes in 1/2" 6061-T6 aluminum, because I was too lazy to go downstairs and grab the KEO c'sk. For the 1st hole everything went smoothly, for the 2nd hole I had to increase the drill pressure noticeably and by the 3rd hole I was leaning into it as much as I could. You can see how the leading edge (far side) is no longer sharp and has started to roll over.

I still use this c'sk for soft woods as it really doesn't like to cut hard woods and leaves tracks in hard woods.

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Here's a closeup of 2 KEO cobalt c'sks. The RH one is fairly new while the LH one has been used for probably a good 100 holes in 6061-T6 aluminum. Again, even though this is cobalt, you can still see that the leading edge is starting to roll over. It still works fairly well, especially in a drill press where you have more leveraged force.

I've read that these zero flute c'sks can be resharpened by stoning the thru-hole with a medium slip until the sharp edge reappears. I've not tried it yet.  [smile]

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[Julie]

Having tried many countersinks, I also prefer zero flute. I bought this set a while back and have been happy with them.https://www.amazon.com/gp/product/B00Q5INRUQ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
As others have said, run them slow.