When less is more

A recent release from Woodpeckers, this new square is of significant size.

Woodpeckers Mini Square

Significantly small that is!  When so many other items work to convince you that bigger is better, this goes the other way and proclaims “less is more”

As with other Woodpeckers squares, this is guaranteed square (and to stay square for the gauge’s lifetime) to 0.001″

You may notice inside the stylish container, that Woodpeckers products are made in the USA, and that not only being small, it has decent width.  One use of the gauge is for checking that a sharpened chisel is square to the sides, and that width makes it easier to align the gauge with the chisel edge.

Checking a chisel is square

This is not the only use for this gauge, as given its small size it can easily get into small spaces (such as a small box or drawer), and check for square.  That ability to fit into small spaces isn’t something to undervalue – resorting to folding a piece of paper to create a makeshift square will not achieve 0.001″ accuracy!

Available in Oz from Professional Woodworkers Supplies for under $40.

 

The Taming of the Skew

O monstrous beast! how like a swine it lies!
Grim death, how foul and loathsome is thine image!
Sirs, I will practise on this unwitting log.

The Shew Chisel is much maligned by inexperienced wood turners, and yet the experts regularly say it is probably the most powerful tool at a woodturner’s disposal.

I’ve had a number of surprisingly aggressive kickbacks from the skew in the past – encouraging me to quietly put it aside, and I doubt I am the only one!

However, after covering a number of other tools, we got to the skew at Robbo’s, and other than when he deliberately demonstrated a particular user failure (which resulted in a small ‘explosive’ catch, and managed to draw blood), I found myself wondering why the tool was so disliked. It is flexible (both rapid stock removal, as well as finessing beads, forming tenons, and decorative work (particularly when working from square to round cross sections.)

I was surprised how easy the skew was to use!

I don’t remember all the terms, but slicing at 45 degrees, rolling beads, paring away huge amounts of materials. Without being unusually careful either. Sure, catches are definitely achievable (had a few myself, often when I touched the workpiece before properly engaging the rest), and skew catches are often more violent than with gouges, but at the end of the day I was impressed how functional the skew can be.

Robbo has also lent me a DVD; The Skew Chisel with Alan Batty. Interesting that Alan seems to use the skew more with the tip leading, but otherwise the approach is similar, and although it looks so easy when watching it, at the end of the day it can also be that easy in practice, so long as you understand what you are seeing. That is the real benefit of one on one instruction. Even then, I had to pay very close attention to just what part of the skew was doing the actual cutting. What looked like the tip doing all the work was actually a mm or so further up the blade in many cases.

I might have to write a more detailed article (once I understand the tool better), but still would feel like a bit of a knob doing so, when compared to all the real experts out there. On the other hand, that is the real benefit of this website- I have to understand what is happening to be able to write the article/produce the video, and you get dragged along on my journey.

Related articles

• On the first day of Christmas (stusshed.com)
• Learn to Turn (stusshed.wordpress.com)

Tormek Sharpening

A few years ago, I watched a master turner demonstrating his craft, and if you know the name Ian “Robbo” Robinson, or have heard of his monster lathe you will know who I mean. At the time he would touch his tools up freehand on a high speed grinder and continue turning.  When turning powerpoles (he literally can turn powerpoles on his lathe), or bollards, he apparently employs a couple of workers with shovels to try to keep up with the amount of sawdust he generates.  That’d be a sight!  He also can turn a very fine goblet (one I have in my cabinet at home), so that really covers either end of the spectrum.

It bothered me that I was interested in slowly rotating water cooled sharpeners as a way of achieving a fine edge, and yet it didn’t appeal to professional turners.  After all, copying those more experienced than you are is a great mentoring method of learning.

However more recently it turns out that even Robbo has been sold on a Tormek T7, and now swears by it, and considers it to be no slower than his old technique, yet with the advantage that the shape of the tip is duplicatable time and time again.  This is especially important when hosting a class – you don’t want good steel being sparked away, or burnt blue.  This was a real revelation for me.  Not only does the whole concept of watercooled, slow speed wetstone sharpening appeal to me where I don’t have time to learn the finesse required to produce a perfect edge, but it is also being used by the experts in the field.  Who am I to contradict that?!

Square Edge Jig

When using the folded steel standard jig on the Triton, I found it very easy to end up with a skew chisel without meaning to, caused by an uneven tightening, and because the reference edge was at the bottom, which for a chisel is the narrow face, and thus makes it easier to cause the chisel to rotate slightly in the mount.  Tormek have had this problem as well, and so developed this new Square Edge Jig, with the reference being the top edge, and it is tightened against this face instead.  To the right side in the photo, you can also see the corner which is the edge that the tool is mounted against, keeping it perpendicular to the stone.

The discolouring of the stone should be ignored btw – I didn’t want to redress the stone just because of the colour – wasting good stone!  I imagine it is some steel that has become embedded in the surface that has rusted.

Plane Blade

A mounted blade with an edge being formed.

Using the Reference Material

The T7 comes with a full reference manual, and this is worth a lot when you are learning how to set up each tool, including who would use the specific profile choices and that is a real relief not having to guess.  It lists all the variables, and so setup is quick and accurate.

Turning Tool Setter

The support arm is set the required distance from the wheel and locked down.

Setting the angle

The angle of the gouge jig is set – in this case to the #2 position.

Setting tool extension

Next, the amount of extension is set and locked in, so sharpening is ready to go.  Once experienced with these steps, they are very straight-forward.

Recording the settings for repeatability

Finally, the settings used are recorded on a slip which is wrapped around the tool, so there is no guesswork involved in maintaining the tool profile.

Ready, Set, Sharpen

The gouge jig set, ready to go.

Perfect Shape

Rolling the angles

Rolling the tool from side to side, and moving it over the surface of the sharpener to get the perfect edge.

If it looks really simple, and hard to get wrong, you’d be right.  It is a great system, and completely repeatable which is important for speedy retouching the tip to maintain the edge once the tool has been shaped to the desired profile.

The combination of the large, wide wheel that is very smooth during operation and that is very hard to stall, the superb collection of jigs results in a top-shelf tool that is a pleasure to use, and delivers results.  It may be an expensive wetstone grinder, but you can absolutely tell where your money has gone, and like many other purchases, that becomes a distant memory long before the tool itself needs to be retired.

If you’ve never used a Tormek, be careful.  Once you use one (especially if you’ve experienced other grinders/sharpeners), you will find it very hard to walk away from it!  Check them out at Carrolls Woodcraft Supplies, either at their Drysdale store, or at one of the wood shows.

Steel

Steel. Perhaps a strange topic for a woodworking site, but then, so many of our tools, and particularly the sharp edges that actually work the wood are made from it, so it is useful to know a bit about it. In the near future, I will be doing an exposé on all things sharpening, so getting to know steel is really the start of that process.

(I will be pretty general in the descriptions, so don’t be surprised if you can drive a bus through my definitions!)

There are many, many versions of steel. Steel is not an element, but a compound of Iron (Fe) and Carbon (C) (and is actually called an interstitial solid solution, as the carbon atoms fit into the gaps in the Iron atom structure). In addition, you can add other metals into the one material, which is called alloying, and there are a huge variety of steel alloys out there with all sorts of different properties. I’m going to pretty much ignore the alloys at this point, and just focus on carbon steel.

Now carbon steel is just not a bunch of Fe atoms in a grid, with the carbon atoms in some of the gaps throughout the material. If this were the case, the concept of heat treating, tempering, quenching etc wouldn’t have any effect. What there is in fact, are areas of pure Iron (called a-iron or ferrite) then others which are a combination of Fe and C, which is iron carbide (also known as cementite), and is not a discrete molecule, but a crystal lattice containing iron and carbon atoms in a ratio of 3:1, written Fe₃C.

If you have a huge amount of carbon, then you have massive amounts of cementite and ferrite (pearlite – see below), and even areas of pure carbon, and this is where we get into cast iron, which is not used for making sharp tools (very hard, and way too brittle!)

Back to steel. Carbide, as we experience it as woodworkers is generally tungsten carbide, a very brittle, very hard material that is used for producing durable cutting surfaces. Iron carbide (cementite) is similar, hard, but brittle, and if in the right amount gives steel a real edge over pure iron (sorry about the pun).

So what happens when we take our molten steel, and cool it to form our chisel or plane blade? If we let it cool slowly, it will have time to form the normal structures, and will be our basic steel – machinable, hard, but nothing special. It will have (and this depends on the % of carbon) grains of pure ferrite, then others that are a mixture of ferrite and iron carbide. It is these grains that are a mixture that give steel its ability to be heat treated (ok, gross generalisation). As these grains form, they produce a lamellar (plate-like) mixture of ferrite, and carbide, known as pearlite. The steel at this point can be cut, ground etc, to form the desired shape for the plane blade, chisel etc. The steel is ok, but not tough enough or hard enough to be used for a cutting edge. That’s where heat treatment comes in.

Pearlite

White areas are ferrite (Fe) , ‘worms’ are platelets of cementite (iron carbide, Fe₃C)

The steel is then reheated, but not to melting point, held at the required temperature, and then cooled quickly. If you cool it slowly, you form coarse pearlite, which isn’t very hard, and therefore not useful (for us). Cool it quicker, and you get finer pearlite (ie smaller, thinner, and more platelets of carbide). This is harder and stronger material. If you cool it even faster (quenching), you form a new structure, called martensite. Martensite is supersaturated with carbon, and the change to the iron lattice means the atoms can’t slip over one another easily so the material is very brittle and very hard. The faster you can cool the steel, the more martensite is formed (and the smaller the individual grains). Although this transition to martensite happens very quickly, not all the material can get there in time, and retains the original structure. To force more of this to martensite, we need to cool the steel even further, well below room temperature, and is called cryogenic treatment. So now we have an extremely hard, brittle tool steel. (Yeah, I’ve generalised heaps here, but you get the jist). The structure is good – we have a very fine grain structure, but we need to ensure that there is sufficient ductility in the steel, so it can survive being pounded by a hammer into hard wood! (In other words, we want it hard, but also tough).

Martensite

This is done by tempering – reheating the steel until we get just the right combination of ductility and hardness, and the result is called tempered martensite, an ideal combination of toughness and hardness in our resulting tool. The brittle martensite is transformed into a fine dispersion of iron carbide particles in a tough ferrite matrix. The carbide stops dislocations and slips in the structure (so the material can’t shear and fail, ie making the material hard (and is not unlike how the atoms of an alloying material help make a material hard)), and the ductile ferrite can deform locally, arresting any cracks that try to form in the structure (so the material is less brittle).

Thus we have a blade, hard and tough, with a very fine grain, ready to be sharpened to a mirror finish (and if you have 2 surfaces that are so flat as to be mirror-like, meeting at an edge, that edge will be razor sharp).

***Update*** Here are a couple of articles about the practical side of heat treating blades, and are definitely worthwhile getting to see this done in practice, as well as the theory above***

http://villagecarpenter.blogspot.com/2008/02/heat-treating-tempering-blade.html

http://www.hocktools.com/diyht.htm

Tool of-the-Month (February 08)

The tool for this month is the Veritas MkII Honing Guide. Veritas are well known for producing quality jigs and tools, and the MkII Honing Guide is no exception.

The MkII is a significant development on the original jig and although it has been available for a while now, it still justifies being highlighted. It is used in setting and maintaining the bevel angle for edge cutting tools (such as chisels and plane blades).

It consists of 2 main components – the black component is the blade holder, and once the blade position is set, holds it in that position during the grinding/honing process. The other component (silver) (the registration jig) is used to set the blade position so it is honed to the correct angle. Once the blade position is set, this component is removed.

There are a number of advantages of the MkII. First and foremost is the accuracy and repeatability of setting the honing angle. The guide can be used on waterstones, oilstones, diamond stones, and sandpaper (commonly called the “Scary Sharp” technique). It has a large brass eccentric roller which can be set to a secondary position for creating a microbevel.

The setting jig not only controls the amount of protrusion of the blade (ie distance from the roller, which dictates the angle of the bevel), but also keeps the blade square so that an undesired skew is not created.

Here you can see the stop which is dictating the blade protrusion, but also the far side has a fence which the blade is resting against, ensuring that it is square to the roller. The blade in this case is one of my HNT Gordon plane blades (which as you might be able to see, already has a mirror finish).

Once the blade position is set, the registration jig is removed, and you are ready to start honing the blade. I’m going to be doing a separate article/video on various sharpening techniques in the near future, so won’t go into details here.

More recently, extra jigs and modifications have become available for the MkII guide, including a Skew Registration Jig for deliberately (accurately and repeatably) setting a skew angle if so desired.

The Veritas MkII Honing Guide and Skew Registration Jig has been supplied by Carbatec, and continues to prove to be their most popular honing guide.  I’ve had my MkII Guide for quite a while now, and it has proven to be an invaluable tool where it comes to sharpening.  I had the MkI before it, and although it was a good jig, the MkII has proven to be exceptional, and I’ve never regretted upgrading.