Everything you need to know about grinding woodworking tools on a bench grinder

Tool sharpening is a huge topic, some of you have your favorite techniques whether they are with stones, diamonds, sandpaper, belts or machines, others rarely sharpen and have no idea how easy and fun it would be to create them if you learned to do it correctly. So we've created a series of free tutorials for all sides of the issue below this video. I will link to many of those resources. I hope you take advantage of them. You will learn a lot today, we will expand. The topic talking about sharpening straight edged

tools

such as chisels and simple irons on a

bench

grinder

, this is a process that is only done occasionally, usually you have to repair a damaged tool or reshape a bevel that has been altered after of many polishings of its stones.

Of course, you can use a coarse diamond or water stone to grind a bevel by hand, but it would be a slow and tedious process - that's what

bench

grinder

s are for - but with speed comes danger. A bench grinder can be an aggressive machine, you can easily overheat the steel. or remove too much and end up with a crooked edge. There is a lot to learn about bench grinder equipment and techniques, so this will be a pretty comprehensive tutorial. I encourage you to watch it in its entirety even if you think you

know

everything

about it.

I guarantee you. You'll get some useful tips that you may have never considered before. We'll break this topic into several parts, starting with the

grinding

machines and accessories themselves and then moving on to the basics of bevel and

grinding

techniques, including edge dulling and facet monitoring. It's going to be a pretty comprehensive tutorial that's free for you because Woodturners Wonders has picked up the tab, so let's give it 15 seconds before we get started. Some people are a pleasure to work with, like Ken Rizzo on Wood Turner's Wonders. Calm is where I get my turning things like sanding supplies and cbn wheels for my grinder, seriously if you haven't seen what cbn wheels can do for you you are missing out.

I'll put a link below this video, use it and tell Ken I sent you my first bench grinder. it was a 6 inch high speed model with a shitty tool stand and terrible wheels, much like this one, we'll talk about wheels and break in a bit, let's focus on grinders for a minute. You can buy one of these small grinders as long as you understand the limitations and are safe for them, for once the high speed produces a lot of heat, you

need

to be careful not to overheat the tool, which means dipping it in water every few seconds, don't neglect this because it can turn blue and ruin an edge sooner.

You'll find out later in this video, we'll discuss some other techniques that will help you avoid overheating, but a low speed grinder will make this much easier. These operate at approximately one thousand seven hundred and fifty rpm, about half the speed of a normal grinder. overheat a tool at seventeen hundred and fifty rpm if you use regular wheels instead of the CBN wheels I use on mine, so have water on hand, but with a low speed grinder you will be submerged in water a lot less and the heat is a lot it's less likely to get away from you and simply ruin your bezel before you

know

it.

These grinders are also larger with eight-inch wheels. We'll talk about hollow grinders later, but wheel size affects the angle of your bevel that produces a six-inch wheel. a more concave shape with a thinner cutting edge than an eight inch wheel again, you can get by with a small grinder but bigger is better, power is good too but I think it's a smaller factor than many People think this grinder offers maybe a quarter horsepower, but I never felt like I was lacking power when I was grinding

tools

because I rarely remove a large amount of steel at once.

Aggressive grinding is a good way to overheat a tool, as you will learn shortly, light passes are the way to Wow, not much power is really necessary for this type of work, where I do notice that the difference in power is the time that It takes larger grinders with heavier wheels to get up to speed. This one horsepower grinder goes a long way. much faster than the half-horsepower grinder, you may not care about that, but if you get into woodturning and start touching up your tools frequently on a grinder, those extra few seconds can become an irritation, for example. which, while any grinder will work for sharpening

woodworking

tools like chisels and simple irons, I prefer a slower speed, a larger wheel, and a motor of at least half a horsepower if you think you could get into it now or even later.

When wood turning or CBN wheels work at full power now so you're prepared for the future. A final note. My 8 inch grinders don't have wheel covers because CBN wheels don't explode and kill me, but my smaller grinder with traditional wheels does have covers installed and, Scioscia jurors, it's nice to have these plastic guards too, esp. if your grinder doesn't have them. They have spark deflectors on the top of the wheel covers but they are no substitute for safety glasses, trust me you don't want a piece of steel pulled out of your eye and while we're talking safety wear hearing protection when using your grinder and a dust mask, especially if you are dressing the grinder wheels, can affect the speed and quality of the grind, as well as the heat generated, so don't just take the cheapest one and think it will be as good as whichever one you get.

What you pay generally falls into four categories: silicon carbide, aluminum oxide, ceramic and CBN. Silicon carbide is the least expensive. They are the gray wheels that come on many bench grinders. They work well for daily grinding, but they generate heat quickly. and are a poor choice for tool steel. Aluminum oxide wheels are sometimes gray, but higher quality versions are usually white or pink. They break down better and expose new sharp particles as you work to cut quickly and reduce glazing that can overheat your tool. The white wheels are good. For most tools, pink is a little harder, so it's useful for turning tools like dimples that can leave grooves on the edges of white wheels.

Ceramic wheels contain aluminum oxide and are often blue in color and more durable than white ones. or pink wheels while providing fast cutting action, but are expensive for consumable wheels, up to half the price of an entry level CBN wheel that will last longer than many ceramic wheels. CBN wheels are best for grinding and sharpening tools for a large quantity. There are many reasons why they last almost forever, they don't wear out, they don't get smaller or change shape, they never

need

fixing and they are much less likely to overheat. your tools. If you want to learn more about CBN wheels, I will leave you some links.

Below this video are the ones I use in a full tutorial on why I think they are the best option. If you choose not to use a CBN wheel, you will need a grinding tool because non-CBN wheels need regular maintenance as they are ground. The surface of the stone will be filled with metal particles and glazed. The rate at which this happens depends on the type of wheel you are using, but all non-CBN wheels will need regular maintenance. This involves pressing the routing tool firmly against the edge of the wheel while grinding. is underway, you are removing the outer surface of the wheel, exposing fresh sharp sand, it is a complicated process and I recommend wearing a protective mask when you do it because you don't want fine aluminum oxide or silicon carbide dust in your lungs, some People like to use the honing tool to remove sharp edges from the wheel and others prefer to form a slight crown or rounded edge profile.

They believe this helps them reshape crooked bezels because they can use the crown in the center of the wheel to focus on specific parts. For a rim tool, there are videos online specifically on how to dress your wheels, some people seem to make an art out of it. I don't dress cvn wheels so I'll check it out on youtube for more info on that because a bench grinder can be an aggressive tool you should avoid very coarse grits, you can ruin a tool quickly with a sixty grit. I wouldn't use anything coarser than an 80 grit to sharpen a tool and I would still be careful and use a light touch until I felt comfortable, as with many things in life there is a trade-off when it comes to wheel grits.

Coarser grits build up heat more slowly and get the job done faster, but like I said, they can eat through your tool quickly, so more skill is needed. -To obtain a consistent bevel with a coarse grain, finer grains are easier to control, but run slower and heat up faster. If you are new to the world of polishing tools, you can experiment with three or four different grits between 80 and 220 for normal wheels until you find what you are comfortable with, of course, if you plan to invest in CBN wheels for life, the cost will discourage too much experimentation in that case, if you could only get maybe two wheels I recommend an 80 grit and a 350 grit because those are the most versatile and long lasting for

woodworking

when you start out use your 350 grit disc for Do all the polishing of your tools as you feel more comfortable, you can start with the 80 grit disc for the heaviest, perhaps most important material removal.

The feature of a grinder that you want to use for sharpening tools is the tool holder. Some grinders have built-in supports, even close to adequate ones. You would really benefit from a great adjustable platform, especially if you are not yet a tool grinder expert. This gives your tool plenty of support, making it much easier to form a consistent bevel, but the large steel surface acts as a heat sink to keep your tool cool. Years ago I made some wooden tool stands. We have plans for them on our website. All linked below, these are not as convenient or as sturdy as the aftermarket steel stands and do not help with cooling, but they are inexpensive so you can invest your money first in a good grinder or better yet, onto a CBN wheel and then onto the tool holder.

You will want to upgrade to a good tool holder later on, and when you do, I recommend getting one that is part of a larger sharpening system, such as the Wolverine system or the Kodiak system. I have both. I say this because eventually you will want to use your grinder for lathe tools and it really pays to have a rest that you can quickly remove and replace with other sharpening accessories and the rests on both systems can be moved from wheel to wheel quickly, plus these rests They are also large, easily adjustable and durable. Wolverine footrests are the most resistant.

It's rock solid, but I prefer the Kodiak footrest because it's nearly solid and equipped with a simple but clever sliding system that keeps the tool square to the wheel as you move it. side to side is very useful, especially when you are starting out, they even have sliders, angled clamping tools for skew bevels, the Kodiak mount also rotates in a way that maintains its distance from the wheel at all angles, while others brackets require repositioning while you adjust the angle and finally the Kodiak bracket includes a set of positive angle stops that are primarily used for turning tools whose angles are measured differently than woodworking tools, so the stops do not They're just as relevant to planes and chisels, but they're part of the overall Kodiak system, which I think is superior to the Wolverine.

If you are a turner or think you might be one in the future, before grinding you should be aware of the differences between the primary bevels and the micro bevels that a grinder is used to make. Form a primary bevel usually around 25 degrees. A micro bezel, if you use one, is formed by hand with water or diamond stones at a steeper angle than a primary bezel, perhaps about 30 degrees. The purpose of microbubbles is to restrict your daily life. Daily sharpening in that small area along the cutting edge because it is much faster to sharpen just that part of the bevel instead of the whole thing;

However, over time, that more pronounced micro-bevel will become wider as you hone more and more of the primary bevel and the hand honing process will gradually become less efficient until you return to the grinder and restore your original primary bevel. The bench grinder is not an all-in-one tool sharpener, it is for periodic resharpening of the primary bevel so that it cansharpen the micro bevel. by hand, the exception to this of course is our turning tools, which can be used straight from the grinder, but this is a tutorial for woodworking planes and chisels, so we'll stick to those, in addition to the speed provided by a grinder, the concave shape and the round grinding.

The wheel it creates is called hollow grinding and this is advantageous for woodworkers who hone their tools freehand. We will discuss this in our freehand sharpening tutorial which I will link to below this video. Most chisels and irons are ground to a primary angle of 25 degrees. bevel which is not the final working angle, it is just a rough shallow angle that removes most of the steel so you can easily use stones to create a micro bevel at any angle you want to work with except the hollow surface or created concave. with a round grinding wheel complicates things a bit, while the facets in this drawing are exaggerated, it illustrates how a hollow bevel is made up of many angles from heel to edge, this can make setting up your tool holder a bit complicated.

You won't waste time with all the geometry and math. The simple fact is that the higher the contact point on the rim of the wheel, the shallower that part of the bevel will be, so you need to take the thickness of the tool into account when setting it up. your tool holder, a 25 degree setting for a simple iron, will not be the same as a 25 degree setting for a chisel because the chisel is a thicker tool, which is why I don't like fixed angle tool holders. Some people consider the differences to be arbitrary or close enough, but This is the angle for a simple iron and this is the angle for a thick chisel.

It's more than five degrees, although both produce a twenty-five degree bevel on their respective tools. If you sharpen your single iron with the same setting as the coarse chisel, you'll end up with a bevel closer to 30 degrees on your single iron or more, which means you can't hone a 30-degree micro-bevel on the cutting edge, so I like to adjust my tool holder for the tool I'm grinding rather than using just one setting for all tools, the adjustment process is pretty simple if you're simply renewing or repairing an already set primary bevel with the grinder off so you can turn the wheel by hand, adjust the tool holder until it leaves scratches in the center of the existing bevel if you resharpen the tool with the rest in that position it will double the original primary bevel angle on that tool, very easy.

You can also use this scratch test technique to make adjustments to the primary bevel angle. This is especially useful if your micro bezel has become as wide as the original primary bezel. has virtually disappeared instead of doubling the steeper micro-bevel angle. Tilt the tool. The rest of the scratches are closer to the heel than the cutting edge. This will create a shallower bevel on the tool. On the other hand, if you want a steeper angle, adjust the rest so that the scratches are more pronounced. a little closer to the cutting edge, of course, these are arbitrary angles, but there is no rule that says the primary bevel of a tool should be ground at 25 degrees.

With this process, you can refine and adjust the angle little by little to suit your needs. preference, but if you bought an old chisel that someone honed to 45 degrees or some crazy angle and now you have to completely redo it, how do you set up your tool holder for that? You could just look at it and start grinding back on the bead checking every once in a while with a protractor or angle gauge until you get close to what you need or you can find another tool that is similar in thickness and is already ground to the angle of bevel you're looking for, use the scratch test on that new tool and then set up your tool holder and you're done, it's also worth noting that you can make setup jigs by placing a small block of wood on the back of a tool that you have already ground to the angle you want, cut out most of the shape. on the band saw and then let the wheel finish shaping the wood.

These setting blocks will help you quickly reset your tool holder to double that angle later, but they will only work with tools of the same thickness and if your wheel becomes smaller due to wear and dressing the jig will be useless and you will have to do another, so I think they are best suited for CBN wheels that don't get smaller, where the basic tool grinding technique seems relatively simple but there is more than meets the eye. The condition of the tool is an important factor, of course, if you are just restoring the original primary bevel angle, there is no need to remove a lot of steel; in fact, you must be careful to especially rub the surface of the wheel.

If your grate is relatively thick so as not to remove too much steel and get a crooked edge, I recommend a fine disc for routine polishing between 220 and 350, you can use an 80 or 120 grit disc if you are using your standard discs. but use a light touch so you don't remove too much steel at once and end up with a crooked edge, of course if you have to polish a lot of material to repair a tool then 80 or 120 will be much faster. touch the tool with the wheel and then move it sideways, instead enter the cut with the tool already moving sideways, brush it across the wheel and keep it moving as you exit the cut, remove it at the end of each pass and restart it for another if you keep the tool on the stone and just move it from side to side you run the risk of grinding unevenly during that split second pause every time you change direction again press lightly but even with light pressure, you may drag the rear corner when exiting at the end. of each blow because the resistance decreases as most of the tool leaves the stone avoid dragging that corner try to maintain your blows even remember that heat is your enemy but you also have several ways to combat that the type of wheel that you are using is thick.

Grit is how you hold your wheel The size and material your tool rests on is made with a light touch and dipping it in water as needed All of these things add up to protect your tool from overheating Keep your fingers close to the cutting edge so you can feel the temperature rise as long as you can touch the steel it is not too hot if you can't touch it submerge it in water the danger zone when it comes to overheating is the cutting edge of the tool where the steel is thinnest when When you start restoring a primary bezel you will first just work on curing, the cutting edge will not be in the stone, but after a few passes the primary bevel will get closer to that cutting edge so keep an eye on the width of the bevel.

Don't grind the old micro bevel completely, leave a little bit in place, this will help prevent that fragile edge from overheating in the stone and by staying away from the edge you will also ensure it stays square, whereas if you had to do it. grind to the edge of the tool, you may discover how easy it is to grind a crooked tool with an aggressive wheel, while the primary use of a tool sharpening grinder is to restore a primary bevel with light strokes, sometimes you may have to do this. . Do some extra work to completely reshape the tool, such as re-squaring the crooked edge or removing a chip, if the edge is slightly out of square you can pay special attention to the high side of the bevel, it will still fit into the cut. with the tool moving, but start the pass near the low side, then the next pass a little further from that side and so on as you smooth the bevel back, checking frequently with your square.

The key to smoothing a bevel is Make light passes while always keeping your tool moving when in contact with the stone, this takes some practice but is not that difficult when the edge is square again, make two or three light passes across the entire bezel to ensure that fit well and even when grinding a completely new bevel, whether to repair a warped edge or remove a chip or other significant damage you run the risk of overheating the thinnest part of the steel right along that cutting edge you may not even know that overheated it, you're just wondering if it didn't stay sharp for long, some choose to avoid risking it altogether by intentionally dulling your edge, this may seem counterproductive, but it produces some distinct advantages, for one, this is the quickest way When squaring a tool or even honing a bend, a radius profile and the flat facet it creates on the edge can become a guide to help you make sure you keep the edge square if you tilt the tool holder and start honing the tool. bezel again.

Keep an eye on that flat facet as you work, of course it will get tighter, but as long as it stays, even you know it is. Don't remove too much material from one side or the other if it quickly becomes wider on one side, you are grinding the tool crooked and need to remove more material from the wider side to even it out, continue forming the new bevel until it blunts. The facet is barely visible, but don't grind it completely, as it will thin the steel too much and risk overheating it. A small blunt facet on the end can be easily removed when creating the micro bevel on the stones later if you want more information.

For how to sharpen with stones, including creating micro bevels using straps and jigs and

everything

in between, check out the links to additional resources below this video. Wait, don't go yet. If you're new here, sign up and remember to ring the bell. I really appreciate you giving us a thumbs up or, better yet, leaving us a comment. I always read them and be sure to check out the latest issue of Stumpy Nubs Woodworking Journal. It's always packed with tips, tricks, and tutorials designed to make you a better woodworker.