Over in our tool forum, in the What Tools Did You Use This Weekend thread, bdoell88 made mention of Keo countersink bits, which are zero-flute bits designed to chamfer and countersink holes in a variety of materials.
I also own these bits in a range of sizes, and they definitely do provide great results. I have found that they chatter less than fluted countersink bits, and that they leave smooth edges.
They’re available in different angles, depending on what you want to use them for. You can buy them in 60°, 82°, 90°, and 100° angles, and a range of sizes, usually from 5/16″ to 1-1/4″.
To start, for basic hole chamfering of for countersinking a hole for flathead screws, a 1/2″ countersink with 82° angle is a good way to go. This size, model no. 53512 (more info), can make a minimum cut of 5/32″ and maximum of 29/64″. It has a 5/16″ shank.
Keo countersink bits are made from M-35 cobalt steel, for great wear resistance and use in many different materials, including metals that are typically tough to work with.
They’re available uncoated or with TiN finish, but I’ve mainly seen them uncoated. If you don’t know whether a TiN coating will work for you, stick with the uncoated bright finish style.
If your zero flute bits get dull with use, and they eventually will, you should be able to sharpen and refresh the edge with a small grinding wheel. You should be able to use a Dremel rotary tool, or something similar, with a fine-grit sharpening burr inside the cross hole.
Zero flute countersinks cut slower than other countersink styles, such as single flute or multi-flute ones.
These bits are somewhat pricey. The aforementioned 1/2″ in-between size is $22 at Amazon. For some reason, the 5/8″ size is a little cheaper, at $19, but I feel 1/2″ might be a better general purpose size to start with, unless you know you need one larger or smaller.
Buy Now(via Amazon)
Buy Now(Other sizes)
I plan to eventually talk more about the differences between popular countersink bit styles, but the post idea has been on my to-do list for a few years now.
What’s your take on zero flute countersinks, from Keo or another brand?
Thanks to bdoell88 for mentioning this on the forum! If you haven’t checked out the forum yet, now’s a good time.
I use the Festool version, super high quality and I am really happy with it. The standard style countersink bits leave a very rough hole and are challenging to get a consistent depth, although they are much faster.
To get constant depth a cage is a must have, set it once and countersink everything you have
Certainly, but that’s really a different product.
I’ve learned to prefer single flute countersinks. They work in most materials, don’t chatter and they’re dirt cheap.
Forgot to mention that I’ve used both MA Ford and the really cheap Interstate ‘import’ ones from Enco. Either way, the Interstate ones can be had for a few bucks during one of Enco’s free shipping sales and they work great in metal, wood and plastics.
mike aka Fazzman
As a machinist I gotta say these types are terrible for metals,not really designed for that. These excel in soft materials Plastics,Composites,woods,etc. Hence good for woodworkers.
We use M.A. Fords single fluters for metals out in the shop,if your using them by hand the trick is to go slow speed.Been using these for years. Example – http://www.mscdirect.com/product/details/01051325
mike aka Fazzman
Forgot to mention KEO is a great brand,been using their center drills for ages.
I agree, they’re good for deburring, but on metals they’re not the best solution.
As a machinist I find zero-flute bits work great on copper.
I use single flute for aluminum.
hmmmm, never heard of these. Since I HATE most countersinks I’ve tried due to the chatter, I’m going to give these a try.
I’ve been using this style ( 82 degree) from Weldon – with and without pilots for many years. For sume tasks the piloted bits are better – but can burn the wood hole. If I want to drill and countersink in one motion, I also have some of the Amana / Timberline No-Mar bits you picture – that I like better than some other brands I tried.
I’ve been using this style ( 82 degree) from Weldon – with and without pilots for many years. For some tasks the piloted bits are better – but can burn the wood hole. If I want to drill and countersink in one motion, I also have some of the Amana / Timberline No-Mar bits you picture – that I like better than some other brands I tried.
mike aka Fazzman
ive only had good luck with piloted ones in sheetmetal,but that was when i was doing aircraft work using a microstop style.
mike aka Fazzman
Low and slow when it comes to countersinks is a good rule of thumb. In a hand drill ive never had an issue on speed 1 and you dont have to put alot of pressure on them. Alot of times HSS tools can be too sharp and that will cause chatter issues hit em lightly with a stone and they tone down a bit.
I haven’t used these but I do have two Festool counter sink bits very similar to this. I love them.
The camel says it was $15 last week and then shot up to $22. I’ll wait for it to go back down.
As a retired tool crib machinist at large scale manufacturing facilities, i’ve sharpened thousands of countersinks including this type. They were very easy to do on a Hybco relief grinder. With the correct cam and radial relief set, they’re a breeze. We’ve had these up to 3″ diameter. Mike was correct, low and slow. Don’t force them. The bearing surface does wonders to reduce chatter. Just a word of caution if you try to resharpen them by hand. Try best to match the relief angle. If I remember correctly, there isn’t much more than .015″ clearance.
We should have hired you. When we bought our metal fabrication shop, there was a Seneca Falls grinding station that we sold off for lack of the skill to use it (actually we were downsizing and changing over/ re-purposing the shop.)
Been using this type for years, great in wood.
Regarding chatter with a traditional countersink with a hand drill, use a heavier drill, it does help.
Does anyone have a good resource on how to choose and use countersinks for different materials? I have such a difficult time with countersinks in my shop. For years I have successfully used the tapered drill w/countersink combo bits first by DeWalt then later stepped up to a set by Fuller. They work great on soft wood and plywood used in just a cordless drill. But recently when I had a project that integrated differing hardwoods, steel and brass I found that my knowledge of countersinks was greatly lacking. The tapered drill bits and countersink combo bits clogged and burnt in the hard oak, ash, and maple. Multi flute countersink bits chattered and created terrible looking holes in hardwood, and often the steel and brass. Single flute cutters would sometimes wander or other times such as in the thin brass sheets would severely pucker the backside. Sometimes I got better results using a drill press other times I would have to begin in the drill press then ‘tune up’ using a cordless drill. Often, even new bits seemed to produce more heat than chips. Results were commonly less than expected. In short, the whole project made me feel quite ignorant specifically towards the proper selection and use of such a seemingly simple aspect of fabrication. Are there any ‘all encompassing’ references out there to educate someone like me who often works in ‘multi-media’ fabrications?
If you search around, there’s plenty of advice for metalworking applications, and for woodworking applications. Unfortunately, there’s not a lot out there that cover those who work with multiple materials like yourself.
Here are a couple of recent countersink posts that focus on woodworking applications:
If you’re burning wood, then I would think that perhaps your speed or pressure might be off, or the bits might not be dull. Although, I wouldn’t think Fuller countersinks would dull with just some use in soft wood. Plywood is harsh on all tools, though.
More heat than chips means too much friction – too much rubbing.
I’m sorry that I cannot do it right now, but in a few weeks I can try to pick up a few different styles of countersinks and see how well they work on various materials.
I recently started using a Keo zero-flute countersink (#53513, 5/8” head diameter). Countersinking mild steel at the recommended speed & feed with cutting oil it worked great for about 20 holes then got dull and now won’t cut. I tried sharpening with a circular diamond file inside the hole cutting edge to no avail. Any suggestions?
I’m not sure what the cause could be – you might want to contact Keo or the supplier you bought it from. I don’t believe it should not be dull and worn out after just 20 holes in mild steel.