This numbering system chart from the Kennametal Innovations catalogprovides a guide to the company’s extensive assortment of turning inserts. Other manufacturers offer similar guidelines.

Millinginsertspecification

Create an account today for access to all the great features Kennametal.com has to offer including My Account features, Quick Order, & Collaboration Space.

Thanks, Ben. That's one awesome router "bit" you made! This explains how to avoid climb cuts with a handheld router. Next, you should explain what happens with a climb cut on a router table.

We have created these special content collections organized to give you a deep dive into a range of topics that matter.

ISOcarbide Insert chart

When it comes to cutting tool selection, machinists have three basic choices: brazed carbide tool bits, indexable tooling with carbide inserts, and solid tools made of carbide or high-speed steel (HSS). This article will explain why the middle choice—indexable turning, milling, and drilling tools—is often the best choice for productive, cost-effective machining.

Fine Woodworking receives a commission for items purchased through links on this site, including Amazon Associates and other affiliate advertising programs.

Many of these are tailor-made for specific materials or material groups. For instance, a shop making aerospace components can greatly increase efficiency by purchasing carbide inserts designed for tough, heat-resistant superalloys (HRSA) such as Inconel and Hastelloy. The same is true for medical shops, which tend to cut corrosion-resistant, biocompatible materials like 316 stainless steel, cobalt chrome alloy, and titanium. Automakers can dial in their processes by using inserts optimized for cast iron and low carbon steel, while oil and gas producers benefit from tooling that excels in duplex steel.

Carbide insertidentificationchartPDF

Kennametal's KCS10B turning grade provides easy wear identification. It's ideal for medium machining and finishing operations of nickel-based (S3), cobalt-based (S2), and iron-based (S1) high-temperature alloys.  The extremely hard, wear-resistant carbide substrate allows for longer tool life, while the ultra-fine-grain carbide substrate and smoother coating reduces friction.

HSS tool bits present a similar story. They’ve been around even longer than brazed carbide. They’re much less expensive than carbide and there’s no need for brazing—just sharpen the tip however you want and get cutting. Sadly, you won’t be cutting very long or very quickly because HSS boasts a cutting speed of just one-fourth that of tungsten carbide, and even less compared to some of the newer, coated grades. HSS might be fine for hobbyists with loads of time on their hands, but carbide is the first choice for professional machine shops.

ANSIinsertnomenclature

Very nice video, Ben. A humble suggestion if you are explaining this again would be to use that Sharpie to draw an arrow on the top of your router to show the direction the bit is ALWAYS spinning. I very much appreciate the advice to use a top-bearing bit in one direction, and a bottom bearing bit in the other direction. I'd have just climb-cut and scared myself!

Probably not. Just as there’s no shortage of indexable carbide tooling optimized for certain materials, there’s also no shortage of excellent general-purpose cutting tools. These represent a middle ground between performance and the tool crib bloat just mentioned. That said, the decision to go the material-specific route is a delicate balancing act—if a job’s going to be in the machine for more than a few days or is sure to come around again in a month or two, it almost always makes sense to buy carbide inserts designed for that material.

Where machinists and toolmakers once had to grind special shapes into their brazed or solid carbide tools, they now have the option of buying off-the-shelf indexable inserts in a huge variety of geometries and styles. Need to cut a 1/16” wide groove in a shaft? How about an Acme thread, or a 45-degree chamfer around a part periphery? These and other insert shapes are readily available, no grinding necessary.

I have a router with that arrow embossed on the top of it. The problem is some aren't sure if that means the bit is spinning that way or if it is the direction you should move the router. Early on, I thought it was hinting at the direction.

Last but not least is the whole topic of insert nomenclature. It’s a deep subject, one filled with exceptions and cutting tool-specific rules. Regardless, most manufacturers follow the ANSI or ISO tool identification system (and sometimes both). We won’t get into the details here except to say that it uses an alphanumeric code to specifies an insert’s shape (round, square, triangular, etc.), clearance angle (neutral to positive), tolerance (some inserts are pressed to size, while others are ground), the size of the locating hole (if any) and clamping method, its size and thickness, corner radii, and various other defining features (see the chart above for an example).

ISOinsert chart

There are some concepts in woodworking that are incredibly difficult to understand. Right at the top of that list is what happens as a router bit interacts with the wood you’re cutting. This doesn’t seem like a big deal, but this interaction informs so many aspects of routing—most importantly, which direction to push the router. If you get it wrong, you might wander into a dangerous climb cut.

The Mill 16™ series is a perfect fit for most cast iron face milling requirements with high feed rates to boost productivity and reduce cycle time.

TurninginsertIdentificationchart

. Please enter the desired qty for the material(s) you want to include in your promotion or Proceed Without Promotion and only your base materials will be added to the cart.

Thanks Ben. Apparently size does matter!! Your visual aids were excellent and finally drove home for me what was really happening at the point of contact: bit to wood. Keep up the great work. regards, Mike Strange

Web applications like Kennametal’s NOVO system not only guide users through the cutting tool selection process, but also help with job management and provide numerous video tutorials.

Insertnomenclaturechart

Get instant access to over 100 digital plans available only to UNLIMITED members. Start your 14-day FREE trial - and get building!

Indexable cutting tools are especially important on CNC machinery, where the need to keep spindles turning at all times is critical. Here, machinists rely on indexable drills—often with coolant running through them—to make holes quickly, followed by indexable boring bars to finish machine them. Indexable face mills true up large flat surfaces; indexable end mills rough out pockets and cut slots; indexable profiling tools trace complex part shapes. There’s very little that can’t be machined with indexable cutting tools.

Clear explanation, handy way of identifying non-climb cuts, amazing giant visual aid, and a way to avoid a climb cut when you think you might have to do one.

For as long as there’s been tungsten carbide (which is roughly nine decades), machinists have been brazing small hunks of it to steel shanks and then grinding a sharp edge on the result. These brazed carbide tool bits and boring bars are easy to make, customizable to the application, and inexpensive. Unfortunately, their effectiveness depends on the machinist’s brazing and grinding skills. And since the tool must be removed from the mill or lathe for sharpening, they also lead to significant and costly machine downtime.

Simply put, if there’s an alloy out there, the chances are excellent that a material-specific carbide grade is available to cut it. However, some shops machine aluminum one day, iron the next, and titanium the day after that, often in low quantities. Does this mean they need to bloat their tool crib with dozens upon dozens of different carbide insert grades and geometries, many of which will only be used occasionally?

Long story short, carbide insert selection is much easier than it once was, even though the number of cutting tool options has grown exponentially since the days of brazed carbide and HSS tool bits. Download a catalog, log in to NOVO, or give your local cutting tool representative a call. You’ll be making chips in no time.

That leads us to indexable carbide inserts, the workhorses of the machining industry. As with old-fashioned brazed tools, indexables also utilize small bits of carbide. The difference is how they’re attached. Rather than a permanent braze, indexable tooling relies on a screw or clamp to secure the carbide insert to the tool body. When the edge becomes worn, swapping it out only takes seconds. More importantly, there’s no loss of position or need to “touch off” the tool. Just remove the old insert, stick in a fresh one, and get to work.

Ben nice job on the enlarged visual and the visual cue of the direction of cut on outside and inside cuts. As pointed out in the linked articles, climb cutting is not inherently "dangerous" however and is a preferred technique for certain situations. Also grain direction when template routing doesn't really have anything to do with climb cutting. You did a nice job explaining why on a single board edge you will need to route from different directions and with different bits to avoid tearout.

ISOinsertnomenclature pdf

Become an UNLIMITED member and get it all: searchable online archive of every issue, how-to videos, Complete Illustrated Guide to Woodworking digital series, print magazine, e-newsletter, and more.

With its graceful curves, cabriole legs, and ornamental back splat, a Queen Anne side chair is a bucket list build for many woodworkers. Dan Faia had a very specific Queen…

But how do you know what carbide inserts and cutter bodies to buy? And why are there so many different grades of carbide inserts out there? Good questions; we’ll start with the second one first. Unlike a few decades ago, when machinists had just a few grades to choose from, there are now dozens of inserts grades, coatings, and chip-breakers available.

There are tricks to figuring out which direction to cut. And sure, some may get away with doing it by feel. I haven’t struggled with direction in quite some time, but that doesn’t mean I fully understood what was happening. Considering how much time I spend wielding a router, it’s probably best for me to fully understand what is happening. I know I’m not alone. I’ve had the discussion with some of the biggest names in woodworking, and I’m not sure many of them really understood what is really happening when bit hits wood. The problem is that a router bit is tiny, and it’s spinning faster than we can fully comprehend. So for this video I created a model of a 5-inch router bit (you read that right) and using this unbelievably scaled up router bit, the interactions between bit and wood become pretty apparent. You’ll see!

That statement extends to HSS rotary tool bits such as end mills, drills, and reamers, all of which are used daily throughout the manufacturing industry. That’s a shame. Yes, these tools are less expensive than their solid carbide alternatives, but as mentioned, they’re also far less wear-resistant, predictable, and productive. These factors explain why leading cutting tool manufacturers emphasize the importance of carbide tooling to their customers and why many have stopped offering HSS cutting tools altogether.

Our biweekly podcast allows editors, authors, and special guests to answer your woodworking questions and connect with the online woodworking community.

Complex naming systems aside, however, choosing the right insert for your machining application isn’t as difficult as it might appear. That’s because cutting tool manufacturers have developed online tool advisors that walk machinists and programmers through the tool selection process. For example, Kennametal’s NOVO prompts users to answer questions about the metal removal process (milling, turning, or holemaking), the machine tool that will be used, workpiece material and removal amount, and expected depths of cut. It then generates a machining strategy along with insert and toolholder suggestions, ordering information, product availability, feed and speed recommendations, and more.