Sharpening: Chisels and Gouges II

Chisels Part II

With long blade chisels out of the way, I thought I'd also take a look at small chisels (palm chisels, micro chisels, etc.) that are more commonly used for detail carving. Because of the length, they will not fit in a jig, and they really do not need one. That is to say, jigs in general are not necessary, but here they are highly impractical.

First step, as always is preparing your stones, whatever sort they may be. My water stones do not need to be soaked, so running them under the tap for a few seconds is sufficient.

The chisels that I will be sharpening in the next three posts are significantly harder (65 Rc) than normal chisels, which is both an advantage and a drawback. While they hold an edge far longer, they also chip very easily. As a result, I need to make use of the very coarse stone to bring the edge back into a line. From there, it is the same grit progression as I would use on an already shaped edge.

For these smaller chisels, I set a lower angle on the bevel, in this case around 20 degrees. I would prefer around 25, but from the manufacturer they came lower, and I have taken it up only to 20. This in part is a cause of the fragility and tendency to chip, so for such hardness I will be taking it up another 5 degrees over time. 

Once you have a feel for the angle on your chisel, try and keep your arms/hands as locked in place as possible to minimize any rolling of the flat edge. 

When I sharpen, I take the chisel to stone at a slight skew angle, applying downward force on the forward stroke (as though 'carving' the stone) and relieve force on the pull stroke. 

Assuming you have already surfaced the back when the chisels were new (shown in Chisels Part I), the only time you need to touch the back to the stone is when you begin to feel a burr rolling over thee edge. On the lower grit stones, I often do not do this at all, and on the highest only one or two quick passes to remove it. Holding the back flat against the stone, again at a slight skew angle. I prefer to push rather than pull, as this mitigates the chance of rolling the burr back to the other side, but it is just personal preference.

After the final stone I turn to the leather strop. Treating it just as the final stone, I polish first polish the bevel, then the back with one quick pass flat against the surface.

For a final stage, I take the edge and (left to right in the above picture) slide it across a corner on the piece of wood holding my strop. A very slight pressure is all it takes to remove that remaining minuscule burr.

Although this is something that should be done throughout the process, I periodically check to ensure that the bevel is square to the blade of the chisel. For a straight chisel, that is. For a skew, this obviously doesn't matter. It should be noted that I treat skew chisels exactly the same way as straight, only that the edge is at an angle to the length of the chisel. 

With these low temper chisels it takes a little longer, as the rough stones need more work to repair chips and the higher stones do not cut as quickly, so it takes between 5 and 10 minutes depending on the extent of the damage. If I am simply honing them back to a sharp edge, it will take a fraction of that. 

Sharpening: Chisels and Gouges I

Of the various types of chisels and gouges, there are some that present a more formidable challenge (to me) than others. Here, I will demonstrate how I personally sharpen straight chisels (which is fundamentally the same as skew), curved gouges, and V gouges. Again, there are countless practises and techniques for sharpening just about everything, but this is what works best for me.

Before we begin, here are the tools I will be sharpening (rather, using for photos) and the things I use to sharpen them. On the left is a leather strop saturated with 3-in-1 oil, although fine jeweller's rouge works well. I would, however, opt to use a grit substantially higher than the highest grit stone I have, somewhere around 12,000 mesh or equivalent. Next are four stones, a #220 for very rough shaping, then #1000, #5000, and #8000 for the sharpening. Only the worst of the tools see the #220, and for a previously established edge, even #1000 is a bit rough. There are dozens of types of stones out there, ranging from the India and Arkansas to Ceramic and Diamond plate, but they all work as long as you understand how to use them.

I also brought out two needle files, one double-half round and one triangular. These help push the burr back over on the gouges, although I would recommend a slipstone instead for the inner surfaces. The only reason these work on my smaller chisels is because the chisels are extremely hard and are not shaped by the files. Rather, the files safely push the burr to the outside where I can remove it with the stones.

On the bottom right is an angle measure (not something I actually use while sharpening, but for illustrative purposes) and a honing guide. The guide is not ideal for the long chisels, as it has a difficult time holding them securely, but it is another option that I will show for those interested.

The chisels themselves are a collection of various shapes. The longer ones are a pair of straight and a pair of round gouges. The smaller are two gouges, one low number and one high, a V gouge, a straight and finally skew chisel. The skew and low number gouge (so small it was difficult to photograph) are effectively the same as the straight and high number gouge respectively.

Chisels part I

First, I will show how I sharpen the long chisels. Whether mortising chisels, paring, firmer, or edge bevel, the theory is exactly the same. Mine are firmer (have a singly bevel on the edge, with square sides), and extremely old. While they will take some time to get back to working condition, these are the steps to repair the edge and sharpen it.

Foremost, it is important to establish a flat back. Whether new or old, this is the first thing I do to them. Out of the factory it will be close, but not perfect, and certainly not polished. At a slight angle to the stone, I keep as much of the chisel in contact as possible, while still having room to pass it over the surface. A chisel this long does not need to be surfaced all the way back to the tang, so I concentrate on the first 3~4" from the edge. When the entirety of the surface is uniformly ground, move onto the next grit, repeating to the highest, in this case #8000.

To demonstrate the honing guide, I set it to an angle of 35 degrees. Some prefer it lower at around 30, but generally, the higher the angle, the more robust the edge. As this will be used for heavier carving, I keep it a little higher. 

When sharpening any edge, I put pressure down on the forward stroke (as though the chisel is 'cutting' the stone) and relieve it when pulling back. This operation minimizes the burr and keeps it from rolling excessively back onto the flat side of the chisel, although it will be removed later.

Again, I move progressively through the grits until reaching the finest. Unlike plane irons, I keep as even a pressure along the width of the edge as possible so that the two corners are sharp. A good way to check the edge consistency is to, when establishing the rough bevel, measure it with a pair of callipers to see if it is an even thickness from end to end. With a honing guide, this is a bit easier, as it takes a lot of the side to side rolling out of the stroke. 

Once I have a clean, even edge to the highest grit stone, I remove the honing guide and gently polish the back once more on the #8000 stone. This removes the burr and ensures that the polish of the chisel back extends fully to the edge. Keeping contact with the length of the chisel prevents a microbevel from forming on the side opposite the primary bevel.

Now the stones have done all they can. Turning to the strop, I treat it as though it is itself a stone. Keeping a consistent angle with the chisel to match the ground angle, I pull (instead of push) the blade with a firm downward pressure. Between 20~30 strokes, periodically checking the polish and burr formation, is all it takes. 

As with the stones, I also turn it over and strop the back, keeping the angle low so as to prevent a convex microbevel and rolling of the burr back to the other side. Having a skew angle to the strop (or perpendicular, but that often leaves cuts in the leather if I am not careful) will pull the burr off instead of rolling it over. 5~10 passes and the chisel is usually done. Feel for a burr and inspect the quality of the edge. At worst, there may be a few indications that the finest grit did not fully reach the edge, in which case it is simple enough to return to the stones, then finish again with the strop. 

With this procedure, I can return a dull chisel to shaving sharpness in about 5 minutes at most. If it is still somewhat sharp, I can start with a #5000 stone and have it honed back in far less. Speed, however, is not the objective. Slow, deliberate strokes will be much more effective in the end than quick, inconsistent ones. 

Sharpening: An Introduction

100 years ago, people simply did not have dull tools. At least, not as we know them today. It has become a standard to buy new instead of fixing what we have, a practise which has led to cheaper and lower quality, perpetuating the need to continue buying. While it would be preposterous to claim that certain things, like chisels and gouges, plane irons and drawknives are tossed when they lose their edge, others such as saws and drill bits are rarely saved. Yet, with only a few simple hand tools, I can re-sharpen almost any tool I own. By that alone, it becomes less of a matter of availability, but more a lack of knowledge or care to put forth the time to repair what we already have. It is with the intent to change that mentality that I have decided to share the process I use for sharpening my hand tools, of which most are at least twice as old as I am (and work better than most of the newly made ones at that).

10 simple tools. That is it. With these (and a few have very specific purposes which are only needed for one or two jobs), I can sharpen anything I own. Yes, certain things will make sharpening easier, such as electric grinders and belt sanders, those fancy gadgets and useless gizmos, but they are not necessary.

First up are the files. I only really need the three (and really only need two).

The farthest left is a flat, medium cut Nicholson (from the manufacturer online, NOT the hardware store). I use it for establishing rough edges on things a stone will take too long to fix. More specifically, however, I use it to prepare the edge of a card scraper before burnishing. In a pinch, it can also be used on splitting mauls and wedges, and to re-face hammer heads.

The second file a smaller half round file, but with a tapered point. I also use it for card scrapers, but on curved surfaces where a flat file will not do. The flat side is perfect for taking care of most drill, auger, countersink, and assorted other bits for drills and braces.

Last is a triangular needle file, which I use exclusively for saws. The slim profile allows for sharpening the angle of the tooth without reverse-sharpening the adjacent tooth.

In the same category (far left) is a file card. While this does not technically sharpen anything, it keeps the file teeth clean.

To the right of the files lies a burnishing tool. I use this solely for card scrapers, although it can also be used creatively for other things which I will not delve into now. It is a double-half round piece of hardened steel that tapers to a fine point. This is used on a square edge of a card scraper to roll a burr, which does the actual cutting. The curves and taper allow for raising a bur on tightly curved surfaces, and the hardness prevents it from losing its smooth surfaces. An alternative to a burnishing tool is the back of a low number (small) gouge. It is hard enough to take the edge of the card scraper, but is a little trickier to use on a French curve.

Below the burnishing tool is a honing guide. This is not strictly necessary, but helps maintain consistency with edge geometry. It was very cheap for what it is worth (around $12) and will last a lifetime. There are two sets of jaws, one to hold chisels, and the other for plane irons. It keeps a constant angle of the blade and helps with minimizing roll side to side, and thus perpendicular edge.

Next are the water stones. Or you can use oil stones, diamond stones, whatever suits your fancy. I also have a few low grit stones for really aggressive shaping, but the file may also work for that depending on what it is you will be sharpening. To repair an edge or hone it back to its cutting sharpness, I start at 1000# until a consistent, straight edge is established. I then move to 5000# and 8000# respectively. These are Shapton ceramic water stones, and wear extremely slowly and evenly, as well as do not need to be soaked for long periods of time before use. The stones are what I use most often, sharpening chisels, gouges, plane irons, draw knives, regular knives, spoke shaves, etc.

Lastly is a leather strop. Mine happens to be glued to a piece of wood, but it does not need to be. Half the time I just use my shop apron and it does the job. On a board, however, it is easier to maintain consistency as well as dedicate a surface to various polishing compounds. Jeweller's rouge works well with the leather fibres, but I use 3-in-1 oil for this one. A strop does not sharpen, but rather hones an edge and helps remove a burr. It also polishes slightly, which for certain blade types is important for cutting ability.

Throughout the course of several short posts, I will cover how to sharpen the following (and maybe more!)-
-Plane irons and Spoke Shaves
-Draw Knives
-Hand Saws (rip and cross cut)
-Chisels and Gouges
-Auger bits and Countersink Bits