Ax Head Geometry

[Steve Tall]

[Written by Peter Vido]

Keen Kutter with high-centerline "convex-sided" geometry:

Gransfors Bruks with "flat-sided" geometry:

[above photos courtesy of killa_concept]


An ax is a tool with a rather more complex geometry than meets the uninitiated eye, where curved lines of different angles blend into each other. Those angles are not easily measured, and in practice they rarely were...

In fairness to the multitude of past and present ax makers, I wish to emphasize at the start that I appreciate all axes. The ones I evaluate critically are simply those I like less than some others – and I will attempt to substantiate my prejudices. It may also seem that this essay is at once an “American Ax Promo” as well as “an attack” on the Gransfors products, but that is not quite how I intend it to come across. I selected the Gransfors as the reference “to pick on” because among the contemporary quality axes they are so well-known. Besides, many of their enthusiasts can (and no doubt will) come to the rescue of their image.

Selecting tools on the basis of the maker’s reputation has become a less dependable guide than it used to be. In many instances, the quality of the same brands has gone through changes, often not for the better. A new Collins ax – to use an example of a well-known old name still on the market today – is a far cry from one made 50 years ago. This is not to say that all new tools are less good than they once were; advancements in metallurgy have partially off-set the universal “need for economizing”. Good axes are still being made, while truly good pitchforks, for instance, are completely extinct...

Considering all of this, I prefer many tools, including axes, that were made decades ago -- even if I can only find them in used condition. Because such purchases usually take place at flea markets, auctions, etc., I have an opportunity to inspect the design of the tool in question. (Steel quality and edge retention can also be tested, but this article focuses on design.)

The factors that influence the outcome of my initial (visual) judgment of an ax are:

(a) the size/weight of the face relative to the size of the poll -- which determines the potential BALANCE of an ax

(b) the outline of the face when viewed from the side -- which affects the VERSATILITY, or conversely, the specialization of a model

(c) the thickness profile of its fore-section -- which also affects the VERSATILITY (discussed below)

The balance issue appears to have received plenty of attention on the ax forums, though (in the sections that I managed to read) I have not yet found a comprehensive explanation of the pertinent points such that newcomers on the ax-scene would likely grasp the principles easily and quickly. There are plenty of poorly balanced axes on the market -- some of them otherwise very well made, others less so -- which people keep purchasing on the basis of “reputation”, because they don’t have anything else of substance to go by.

Among the well-known old trademarks readily available in North America, the larger felling models from Ox-Head (with head weights over 2 lbs) are clearly exemplars of unbalanced axes. So is (or was?) the Hudson Bay pattern – at least when it was still made in USA. The version now outsourced (by Snow & Neally) appears in catalogues to have a larger poll, which might be a compensation -- as far as balance alone is concerned. (However -- in line with the pattern’s tradition -- the face remains too long... well, too long for my liking.) The more recent creation by American Tomahawk (Cold Steel) -- the China-made “Trail Boss” -- is another example of poorly balanced design, one based more on “coolness” than practicality. It may do for some re-enactments games... though I would reject it for both a trail or homestead because it fails on all three counts (a, b, c) listed above.

The sideways profile has been discussed on the ax forums, albeit sparingly. It presents a less straightforward “mixture of concepts”, and as such lends itself to more room in terms of personal likes or dislikes. What I mean is that it's hard to imagine anyone with actual preference for a decidedly unbalanced ax head. But a face which is very narrow, or conversely, one that is extremely wide can rightly be chosen as best for a specific task.

To avoid getting into muddy waters (by trying to suggest some “ideal” shape of the head), let me just say that I endorse the notions on this issue presented by Dudley Cook in his Ax Book.

The aspect of ax geometry that, to my knowledge, has remained mostly un-discussed is the thickness profile of the fore-section -- which is why the following segment focuses on it.

As previously stated, an ax is a tool with a rather more complex geometry than meets the uninitiated eye, where curved lines of different angles blend into each other. Those angles are not easily measured, and in practice they rarely were. (Ask an old-timer what angle he sharpened his ax – and he will likely give you a blank stare. Put the same question to one of the fussy people among the contemporary tool users -- who will know the exact bevel angles of his chisels -- and he will probably bumble for an answer. Don’t blame him, though, it's not an easy thing to explain.)

However, all ax-makers no doubt agree that if an ax is to effectively penetrate into the material to be cut, its wedge-like profile should not be excessively thick. Yet to define “excessive” and how this general principle translates into functionality of axes is somewhat more complicated, because other factors (such as the tool’s minimum required strength, its necessary wedging action, etc.) enter the equation...

Representing the variations of models still produced today, there seem to be two (rather contradictory) schools of thought regarding both the overall thickness of an ax’s working end, and exactly how it should be shaped initially -- under the hammer in the factory.

The European tradition took the notion of “the thinner [the face] the better” to the extreme. Thus, the Lee Valley Tools catalogue description for the 2½ lb German-made Ox-Head can state that “two inches back of the face the blade is still only ¼ inch thick... (which) gives excellent penetration by minimizing wedging action”. Hmm... in theory Leonard Lee (the author of that well-meant ad) was correct. But did the Americans and the Japanese have some other objectives in mind? Or did they not dare make this tool typically subjected to such stress quite as thin? In any event, the American and Japanese ax faces are notably thicker, in many instances twice as thick.

To categorically state that if one of these schools of thought is right, the other must be wrong, would be silly. However, I am also not willing to simply swallow the worn maxim of “different strokes for different folks”, and leave it at that.

A little background related to the theme at hand :

Between 1975 and 1977 – as a greenhorn in the field -- I bought five new axes. Three of them were brands made in Sweden (the small “Sandvik” previously discussed was one of them), and two were the “Iltis/Ox-Head” brand from Germany. I was not looking specifically for imports; these were simply the axes then readily available in Eastern Canada’s stores. My objective was to have a somewhat diverse group of head weights and handle lengths which those five examples provided. What I did not yet know was that such level of diversity was only a small beginning of my (still ongoing) ax-related education...

Sometime thereafter I learned that a rather large variety of axes was still easily found at local garage sales, flea-markets and antique stores, sometimes at pitifully low prices ($2 to $20). Thus followed three decades of mostly used additions, many of them beaten-up and rusty, with an occasional one in very good condition. Beside some Banko/Sater and several more Ox-Heads, the bulk of them were made in USA or Canada. I brought a few more back from Europe, both used and new.

About two years ago, we bought the Wetterlings “Camp/Small Forest Ax”, and a year later their “Large Forest Ax” (2 lb head on 26 inch handle). It was out of curiosity rather than a need for still more axes. You see, while every ax-nut I know has a Gransfors (or several of them), nobody around these parts had a Wetterlings – another “hand-forged" Swedish product, but at half the price (back then) -- for me to look at. Meanwhile, more old relics continue finding their way into our hands, as gifts from generous friends or as irresistible bargains stumbled upon here and there...

Oddly enough, there still is not a Gransfors Bruks product among the now fairly sizable heap... Yet, for perhaps 30 years -- during which time they steadily grew in popularity -- I knew of these Swedish axes, initially through the catalogue of the Smith & Hawkens company (which may have introduced them to North America). Eventually Lee Valley Tools (which probably sold more of them to date than any other retailer on this continent) added them to their product line and, as an old customer, I have since read their up-beat description many times.

Considering how partial I am to anything “hand-made”, the Gransfors axes could win my heart just with their “story of origin”... as they probably did for thousands of owners worldwide. But by the time I first held one (belonging to a friend) in my hands to closely inspect its head geometry, I was already convinced that the profile principles of North American axes were very sound... and they were noticeably different from the Gransfors.

Quite likely, if I found a used Gransfors for the price that good quality old axes typically bring on the street, I’d be tempted to get it just the same. But to spend the required chunk of cash on a new Gransfors is not for me... Nor would I advise it to an ax-less friend who has no extra money to pay for a famous name, or who needs an ax which is somewhat multi-purpose. What appear to be the most popular of the Gransfors models – the two versions of “forest” ax -- are both, in my view, less versatile in application than other less known and less costly alternatives, including some new axes and many of the remaining relics from the heyday of the North American ax industry.

Before explaining what I mean by “less versatile”, it may be helpful to briefly review how the first axes brought from Europe gradually evolved into this continent’s prevalent design. The two principle features that istinguish the contemporary North American ax from the initial imports are the increase in the weight of the poll and the decrease in the length of the bit. This has been discussed by numerous authors and documented in drawings and photographs of museum collections. But there is an additional feature or “touch”, actually two touches, which I never found specifically mentioned in writing. The first is the "high-centerline" convex-ness of the face in the to-and-fro direction (meaning parallel to the edge direction, or perpendicular to the eye-to-bit direction). I see this feature in every single specimen of old North American felling/all-purpose ax head that we’ve collected. The Swedish-made axes sold on this continent in the past also had this feature, and some (the Wetterlings, Husqvarna, Agdor, and perhaps others) still do.

The second touch is the relative thickness of the face between the edge and the eye, which, in a way, makes the "high centerline" convex-ness I’m talking about possible, or let’s just say “realistically useful”. An alternative way to put this: if the “mid-blade hollow” of an ax is as thin as it is on the regular Ox-Head or the Gransfors “Forest” models, shaping it so as to incorporate the "high centerline" convex-ness may be a bit futile, because such an ax will remain less efficient for splitting much of anything, nor excel at serious felling -- the tasks the North American everyman’s ax versions were, after decades of changes/evolution, eventually designed for.

In any event, it appears that while most of Europe, including the UK and perhaps parts of Scandinavia, stubbornly adhered to the somewhat medieval tradition in ax design, at least some Swedish companies were more creative. (I speculate that they may have been influenced by the developments in American ax design, because for more than a century some North American companies sub-contracted to have a portion of their axes made to their specifications in Sweden.)

Well, the Gransfors Bruks axes seem to have never “graduated” or departed from the initial European tradition, or they later broke away from what I think of (perhaps wrongly) as the “Swedish/American style” regarding the face geometry, and thereby lost my full endorsement.

This is not to imply that Gransfors axes are “bad” -- and to prevent an attack by an army of their sharp-edged owners, I hasten to state a positive thing or two about this widely beloved baby:

Regarding the most obvious of the fundamental design features, the regular product line from Gransfors is better than anything I have seen (which, admittedly, is but a fraction of the total) made in continental Europe or the British Isles. Namely -- in relation to the fore-section’s weight -- the poll is more or less of adequate size, and the distance from center of eye to the bit is about “the right length” (meaning not excessively long). The company is obviously using better steel than is commonly chosen for much of the global ax production these days, or else they would not dare to heat treat their edges to such high RC hardness. (Depending on circumstances, however, an excessively hard edge can be both blessing or a curse...but more on this in a future article.)

If only there was more of that good material in a certain area of its face, I’d think of the Gransfors “Large Forest” model as a fine option for extended “walkabouts”. But the material is not there, and the face is flat – a duo of features typically found together. Consequently, if I wanted an “all purpose” light ax, I would choose another one instead.

The photos below are an attempt to show the difference between the two schools of thought on head geometry:

[immediately continued in next post]

 

[Steve Tall]

The photos below are an attempt to show the difference between the two schools of thought on head geometry:

In group “A” (above) are two old American felling axes, along with the very model of Plumb’s Scout hatchet that Peter McLaren supposedly threw 42 feet to split a woodchip, plus our little Sandvik. Now, if a straight edge is laid across the fore-section of their heads (parallel to the ax’s edge) it will be noted that the center is higher than the top and bottom of the face. In some models the difference is very substantial, in others less so, but it is always there.

Group “B” are European axes -- Rinaldi from Italy, Ox-Head from Germany and the Gransfors forest ax. They all lack the “high centerline” feature. (This specific example from Gransfors actually has a slight hollow on one side of its face...)

“So what?”, some of you may now ask; “Is this a big deal?” To me it is a big deal; just exactly how big depends on the intended use for the ax in question...

In the discussion below I will refer to the two head styles as “flat-sided” and “convex-sided” (terms I just invented). A flat-sided ax is fine for limbing small to mid-sized limbs, cutting saplings the size severed in about one to three strokes, for dressing timber (i.e. carpentry work), and making kindling out of small dimension round stock or scraps of boards. In other words, for all tasks where the ax is not sunk so deep into material that will then exert significant side-pressure upon its face.

For felling and bucking larger than, say, 4” diameter trees, and for serious splitting of firewood, a flat-sided ax is, in my view, inferior to one which is convex-sided. (Assuming, of course, other parameters like head weight, overall thickness and width of face, as well as state of sharpness being equal.)

Why is this so? Well, a suitable chopping ax should not only sink into wood with relative ease, but also release itself from the cut sort of “automatically”. By this I mean that just a slight tug will bring it back to starting position without disturbing the “chi” of chopping. (I am not talking of splitting right now, though the principle is the same). The “high centerline" convex-ness of a fuller-faced ax helps in this regard because the wood has less surface to “grab onto/squeeze/hold” than if the sunk portion of the ax face is flat.

I noticed this years ago (and before I read much ax-related “how to”) when I first began using the double-bitted Ox-Head to fell green poplar trees. In spite of a very positive initial expectation for this famous “ringing” ax, I eventually concluded that a plain old American model was easier to use. In any event, I could cut more wood in a mornings-worth of chopping with the latter, regardless of whether it was a Plumb, Collins, Walters, Campbell, etc., or for that matter the Swedish axes made for the North American market in the past. The Wetterlings would fit into that category as well, because its (“full”) face is convex-sided. I might add that our impressive-looking Ox-Head double-bit has been collecting dust for many years...

That said, for the kind of weekend adventures during which no sizable trees need to be cut nor volumes of firewood split (in order to keep your butt adequately warm on a relatively cold night without the aid of state-of-the-art camping gear), the Gransfors “forest” model is a fine enough ax. However, if my livelihood in a northern climate was dependent on only one ax, I would give decided preference to a Wetterlings (of appropriate head weight) or any of the older North American models. I emphasize “older” because at some point in the insidious phenomena of globalization, many once-reputable ax manufacturers (Collins, Snow & Neally, etc.) transformed themselves into mere distributors and began to out-source their ax production to Mexico, Brazil or somewhere in the “East”.

It has been a gradual process, and it would take a committed, knowledgeable detective to ferret out the pertinent information as to when each make/brand underwent what changes, and how much of what had previously earned them the deserved reputation still remains. If, as the result of this investigation, a comprehensive directory was made readily available to aspiring ax-users, we’d be a needed step further along the path of being adequately informed.

As it is – and it bears repeating -- choices are often based on the assumption that the store owners have (as they commonly claim) customers’ satisfaction in mind, or (in case of mail-order purchases) on catalogue descriptions alone. Those assumptions are sometimes wrong -- many store clerks haven’t a clue about the axes they sell, nor do many of those writing catalogues -- and the unsuspecting buyers frequently end up with less than they hoped for. In addition they may not come to realize it for years...

Steel quality aside for now, many of the contemporary reproductions (still sporting labels with the famous old names) no longer have the efficient shape of a classic American ax. Many now have what I call “flat faces”, and make neither good wood-splitting nor tree-felling tools. What on this continent was once referred to as a "swamping ax” could normally be used for a whole range of jobs with appreciably better results. I believe that some version of it is the tool to be acquired by a serious homesteader as his/her first or only ax.

Provided a new owner understands the principles of ax-head shaping, many of the worn old leftovers can be re-conditioned and most of the readily available “utility” versions somewhat improved. In both case it involves a considerable amount of hand filing or careful electric grinding. Unfortunately, the otherwise finely-forged Gransfors “forest ax”, or for that matter the “felling” models of Ox-Head do not provide that opportunity, because (as already mentioned) they are missing material in certain critical places.

Paradoxically, we may be witnessing an example where the attainment of one goal seems to have brought about a shortcoming of another. You see, it is the trademark of skillful workmanship to forge an ax very thin and yet strong enough to withstand years of repeated beating. In this respect the European ax makers have done very well indeed; in relation to their surface area the faces are often extremely thin. At least some of them are also remarkably tough. (See the photos below as an example.)

[immediately continued in next post below]

 

[Steve Tall]

When I found this ax head (above) in a used tool shop many years ago, I bought it for $2 as a kind of souvenir, and with the notion that one day I’ll learn how to reshape and then re-temper axes in my forge...

I have seen many examples of abuse, but this one is unique. Namely, an average ax of good quality -- if that thin in the face -- would likely break before it bent this much. There was no sign that it may have gone through a fire (like a burning building). Its mangled edge was somewhat mushroomed over most of its length ( I had back then filed away the sideways-protruding metal), and there were couple of small chips but no cracks.

Interestingly, the poll showed hardly any signs of being beaten upon with anything harder than it (i.e. a sledge hammer). I suspect that this ax may have been used to chop ice on a road and driven (frantically, or stupidly) against rocks or concrete.

In any case, if I didn’t know its maker I’d think that it was some cheaply-made and uncommonly soft version of an ax. But we’ve used the Ox-Heads enough to know first hand that metallurgically speaking they are first class axes, neither soft nor exceedingly hard. (I never read how hard exactly, but guess them to be approximately 50- 52 RC.) So if anything, this bent-up ax head can rightly be considered a piece of advertising for the Ox-Head company.

But the goal of wood chopping is the least energy expended for the volume of wood in one’s firebox. Wood begins its journey into that box as a standing tree which must first be felled. Here the extremely thin cheeks just “don’t cut the cake”. Well, for cutting a cake they would be OK; in green wood they stick, and they also do not “throw a chip” as well as a “cheekier” ax can do it. Same goes for cutting sizable limbs or bucking the trunk into pieces. To split the billets into stove-sized pieces is, of course, a job for an even cheekier ax . If,
however, a splitting ax is not owned, then an old ax made in Canada or USA should be up to the task -- especially if the user learns how to not drive the ax straight through the block, but instead give it a sideways twist just as it enters the wood...

To sum up the above thin-versus-thick discussion -- for many of the tasks expected of an average ax, an extremely thin face may be a case of “too much of a good thing”.

Interestingly, the Champion model from Ox-Head (currently sold in the USA) is a radical departure from their traditional felling and general purpose models. I haven’t seen it in real life, but from the photo it appears that (although the poll remains starving/crying for more heft) this famous company finally borrowed a page from an old American ax-makers’ guide on head geometry...

The relatively recent "American Felling Axe” (3 lb) model from Gransfors may also be a move in that direction. (Again, I have so far only seen it in the two-dimensional electronic form.) If this indeed is the case, that ax as delivered to a new customer can probably be thought of as the old “swamping” version, fit more or less for some splitting as well as felling, limbing etc. Whichever of these tasks the owner has more use for, he/she can, by means of a good file, shape-shift the ax head in either direction.


To be continued... some day, perhaps.


-- Peter Vido

(an expanded version of this post appears in Peter's blog "Axe Connected", Notes on Ax Head Geometry)

 

[Pipeman]

Thanks for posting this fantastic article Steve. So much of todays purchasing is done based on the hype of the seller and the buyers perception of "quality". When you compare axes to knives the same can be said. Old makers like William Scagel and modern makers like Ed Fowler knew and know the huge value of a blend of convex lines in the performance knife. IMO the best place to shop for GREAT axes and hatchets is yard sales, junk shops and old barns. Thanks again for posting great article.

Best regards

Robin

 

[abcdef]

Quite an article! The flat vs. convex principle to “grab onto/squeeze/hold” is the same as for knives. It just seems logical.

 

[Ed Fowler]

A breath of fresh air! Nice job and great photos, your experiments, comparisons, discussion and insight are very welcome. Mother nature made a lot of convex and complex convex shapes for a reason. I believe you have found insight into why.

 

[Pipeman]

Mention complex convex shapes and the Master arrives ;-))) It's an honour to have you drop by the axe forum Ed.

Very best regards

Robin

 

[Ed Fowler]

Thank you: the pleasure is all mine! It looks like this is a place where the tools we make actually get used, known to some as the real world.
I dearly wish more custom knives would be used by people like Steve, it would make a huge difference in the blade and handle designs of the knife community.

 

[Pipeman]

Thank you: the pleasure is all mine! It looks like this is a place where the tools we make actually get used, known to some as the real world.
I dearly wish more custom knives would be used by people like Steve, it would make a huge difference in the blade and handle designs of the knife community.

This is a great forum Ed, lots of knowledgable people here all willing to share in their knowledge. Not too many safe queens here.

Best regards

Robin

 

[sumoj275]

What a great read. Thanks for posting this up.

 

[M3mphis]

Great article! Thanks for posting. I'm really liking this forum...

 

[rg598]

As always, a very well thought out and lengthy article. I do however think that making a distinction between American and European axes creates a bit of a misnomer. Most often when we discuss European vs. American designs, it is in the pre 1800s time frame, before the changes occurred in the American designs. You can see my interpretation of it here. Specifically, when speaking of the tapered cheeks (the convex parallel to the bit) I am not sure exactly at what point it became so prominent among American manufacturers, but if we look at European axes from the early 1900s, we see the same pattern. For example, the Hults Bruk axes have the exact same convexity, which disappears on their current designs, much like it did for Collins and other manufacturers. So, once we get past the 1800s, and the changes that occurred to axe designs (larger poll, narrower/triangular eye) I am not sure there is much of a distinction in “traditions” between Europe and America. Keep in mind, the Gransfors Bruks and Wetterlings designs with which we are familiar today originated not in European traditions, but were rather created in the 1990s.

I fully agree with the balance problems with the Ox Head axes due to the minimal poll, and I am also not aware of any benefit to that design. I don't know of any other European Manuracturers that use such a design.

With respect to the benefits of the tapered cheeks (convex parallel to the bit), I think the theory is correct, that it is supposed to limit sticking of the bit in the wood, allowing for easier withdrawal. I am not sure by how much it increases efficiency in reality, but the theory is sound, particularly in soft wood. I personally have not been able to tell a difference between my GB American Felling axe and an old True Temper or Plumb of the same size, but that doesn’t mean there isn’t any. I have noticed a much more pronounced difference resulting from the thickness of the bit however. In fact on many of the old axes I have, the taper (the convex parallel to the bit) has been all but filed away in an attempt to thin out the bit by the prior owner. The "crescent" filing technique is a direct result of this tapering, and often serves to eliminate it from the first two inches of the axe head. That is not to say that the tapered cheeks do not offer a benefit, I am just not sure how large it is.

I think there is a much more important issue when it comes to the grind than the tapered cheeks (other than the thin bit). Paul put it better in his article than I can. You can see it here. From my axe use, I’ve seen a much greater increase in performance from these particular grind changes than from the tapered cheeks. In fact, I think many American axe manufacturers (I’m sure in an attempt to keep up with the trends of the time) created such large taper, that it completely destroys the rest of the head geometry (some of the smaller True Temper and Stiletto axes in particular).

I certainly like the tapered cheeks. I am not sure how much they help. Much like the phantom bevels that became trendy at one point, they certainly make sense in theory. In my opinion, there are much more important considerations when it comes to axe head geometry. I am sorry if I missed the discussion of those characteristics, but it was a lengthy article for sure. Thanks for posting it.

Ross
http://woodtrekker.blogspot.com/

 

[BRab]

Excellent article! In general I think that most axe patterns evolved from trial and error based on local wood varieties and the purpose the user had with the axe. The majority of the old American axes had the convex head geometry as shown by the OP because they were designed for use on hardwood. Gransfors, and similar style axes, are designed for softer wood. Where I live, the old American axes work the best because all of the trees are hardwoods (mostly Black Locust, and some Oak). If I were to live in another part of the world my tool choice may differ, but the best axes for my use are the ones designed to be most efficient in the environment I'm in.

 

[rg598]

Excellent article! In general I think that most axe patterns evolved from trial and error based on local wood varieties and the purpose the user had with the axe. The majority of the old American axes had the convex head geometry as shown by the OP because they were designed for use on hardwood. Gransfors, and similar style axes, are designed for softer wood. Where I live, the old American axes work the best because all of the trees are hardwoods (mostly Black Locust, and some Oak). If I were to live in another part of the world my tool choice may differ, but the best axes for my use are the ones designed to be most efficient in the environment I'm in.

I think that you are right in that the ideal grind will depend at least in part ont he type of wood you have. Here is some information of different grinds for different types of wood put out by Tuatahi for their racing axes: http://www.tuatahiaxes.com/racingaxes.html It was pointed out to me by a member on another forum. I have no idea how exact those designs are, but as a well known manufacturer of racing axes they are probably more or less on the money.

http://woodtrekker.blogspot.com/

 

[thunderstick]

In addition to the parallel convex a strictly felling and splitting axe will typically have a 1/4 moon edge so that that center is forward of the edges. This works in conjunction with the convex to keep the axe from sticking. When the axe is used for shaping/flattening/hewing work, then a Jersey type head with a shallow parallel convex and a very small 1/8 moon on the edge is better for shaving/hewing a consistent surface. A lot depends on how versatile the axe is intended to be. We tend to think chopping vs. splitting as the two axe uses, but in old times hewing or crafting shapes also came into play in head design geometry.

 

[rg598]

Here is something I posted on another forum with respect to this discussion. I'll cross post part of it here. The pics are not the best, but I hope they help:

As far as the proper axe geometry, I certainly agree that the tapered cheeks are beneficial, as they reduce the contact area with the wood, at least in theory limiting binding. My main point on this issue is that this is an incomplete discussion of axe head geometry. There is another aspect which I find much more controlling when it comes to head binding and ability to throw chips, which I don't believe was mentioned. It is the geometry consideration that Paul discussed in the article to which I linked. Here is an axe that I would consider to have good overall geometry. It is a Plumb 1.5 lb head:

It certainly has the characteristic that is discussed by Peter. It also has a proper poll, etc (no argument there). However, it also has the other important (IMO) geometrican characteristic:

You can see the transitions explained in detain by Paul. Now, here is another example (a 1.75 lb head by True Temper) where the taper of the cheeks was too large, and the prior owner had the file down the bit in order to get it to the right thickness. As an unfortunate result, the geometry along the length of the head gets distorted, creating an elongated contact spot between the head and the wood (between the 1 inch and 2.5 inch mark). This will significantly increase binding.

Here is an even more extreme example of a 1.75 lb Stiletto axe head. Here the taper (beneficial in some cases) was so significant that the owner had to grind the bit down to a point where the axe has taken the chape of a wedge. This will significantly increase binding even though there is a significant taper of the cheeks.

The geometrical characteristic that Peter discusses is an important one. To what extend it helps, will largely depend on the task you are performing. I can't tell a difference in most tasks, but then again, I'm not the most skilled person with an axe. My point is that the discussion misses an important consideration, which depending on the case may have a much larger impact on the performance of the axe.

http://woodtrekker.blogspot.com/

 

[bearhunter]

wow! that is some great info from all sides. thanks guys!

 

[Steve Tall]

Thanks, guys, for all the feedback; and thanks to Ross for the additional info (from a different angle ).

As far as the geometry goes, a "flat-sided" axe head (like the Gransfors) with the curvature that Ross talks about will make a line contact with the wood, parallel to the edge on both sides of the head. Adding the "high centerline" convex-ness that Peter advocates would result in a point contact.

Yes, axe heads sometimes need to be reprofiled, usually after countless resharpenings when an old head gets shorter and the remaining edge portion is thicker. Filing down the high centerline "convex-ness" to result in a flat portion seems to be an incomplete reprofiling.

 

[rg598]

Thanks, guys, for all the feedback; and thanks to Ross for the additional info (from a different angle ).

As far as the geometry goes, a "flat-sided" axe head (like the Gransfors) with the curvature that Ross talks about will make a line contact with the wood, parallel to the edge on both sides of the head. Adding the "high centerline" convex-ness that Peter advocates would result in a point contact.

I think you are 100% right. I didn't want it to sound like I was saying Peter was wrong. The point he makes is a very valid one. What I wanted to point out is that there is more that goes into axe head geometry, and that if we do not consider those factors, we can get a worse performing axe even with highely convexed cheeks as you can see from some of the examples. The ideal axe would take into account both of those factors (and a few other minor ones). I have personally found greater performance increases from the bit geometry than the convexness of the cheeks, but that's just me. Even though the Gransfors provides for a line contact, the rest of its geometry eliminates a large amount of other contact points. An axe like the True Temper one that I show above fails in that respect, and provides a much larger binding area than the GB would despite its highely convexed cheeks.

As far as filing down the high convexness, many people actually consider it to be the proper way to file down such an axe. You should not have to re-convex the cheeks after sharpening, and much more importantly, you should not have to regrind the whole cheeks behind the bit. That is why convex cheeks alone are not enough to provide proper head geometry. You should be able to follow the crescent pattern that you see in book illustrations without ruining the overall geometry of the axe (going back from the bit).

http://woodtrekker.blogspot.com/

 

[Briarbrow]

Hi Guys.

I'm not sure I understand the purpose of reprofiling. To be honest I would feel alot better about it if the "half moon" bevel was prevalent on forum axes. I hardly ever see it. rg, it's not really a matter of following a pattern in a book. It happens naturally by filing a swelled center at a consistent bevel. Whatever angle is needed for that bevel will depend on what you cut. hardwoods can be soft and softwoods can be hard, frozen? green? dead? I think increasing/ or decreasing the bevel will solve sticking, chipping issues. Or, perhaps choosing a more suitable handle length for a given head. Put a long handle on an ax meant for a short one and all the sudden it will stick since it can be driven so much harder.

Often a given maker would simply duplicate their design for hatchets-Exactly why I don't know- I really think the swelled center is a specialized feature of a felling/notching axe. I'm not an expert. I can count the number of large (16-24 inch diameter is a Large tree to me. 70's vintage DB collins) on one hand that I have felled. Notching for hewing is something I don't get to do. As a dedicated splitter-the felling axe is not the tool. Better than a thin wedge, but still not a splitting ax.

As a hatchet/small ax I feel the swedish ax is a better wilderness tool than say an american boys ax or hatchet with convex heavily swelled center. Because that design is not well suited to the number of tasks one may wish to undertake-bowls, spoon, paddles,- complex shaping beyond pointing stakes. imho if you cannot split your bucks billets with your chosen tool -then they are too long. Most species in my area are typically small, twisted, knotty.

fwiw I feel very uncomfortable with a Boys Ax handle length. I'd much rather be at 19 or less, or 28-30