Thread: Axe talk

Originally Posted by Robson Valley

Those forestry hammers are used here by timber cruisers (measurement job for stumpage surcharges).
The heads are custom cast/carved and government registered, as are cattle/livestock brands.
The ones I've seen have the general appearance of a 3kg post maul.

Same here, with regard to government registration. We call it a "crowning hammer", and it used to be compulsory when purchasing logs from the government (the crown) to mark both the stump and the butt of the log with the cutters hammer. I am unsure why we don't do it that way anymore, but now we have an individual cutter number for the feller which we must mark onto both the stump and the butt end of any log and we can just use crayon or paint rather then having a hammer. One less thing to hump out into the weeds dont generate complaints from me.

Originally Posted by rsser

In my casual axe tests I was looking at three aspects: penetration, chip ejection and edge retention.

Clearly in bit geometry the design has to achieve an appropriate trade-off between these three. You could get a high degree of penetration at the risk of the bit sticking or the edge chipping out or even bending. And vice versa: low penetration and high edge retention. (By bit I mean that part of the bit from the cutting edge back to the point that doesn't enter the wood.)

Chip ejection influences are exercising me at the moment. You can have a so-called chisel bit (flat bevel) or the traditional convex bit with greater or lesser included angles and varying convexity.

I can see why a convex bit might be better at chip ejection since as it penetrates it also pushes more in a sideways direction helping to break fibre adhesion to form and push out a chip.

In terms of the rough tests mentioned in #144 and later however, I don't see much evidence in practice that there's a simple correlation.

It may be a matter of how the edge is presented. There must be a more restricted range of effective angle of approach. Outside of this you're either going too square-on or else the bevel contacts the wood first and bounces sideways.

What does the brains trust think?

Chip ejection has more to do with the back of the grind then it does with the angles at the pointy end. It's a dynamic relationship because the angle of the grind and the length of the face determines penetration which effects chip size... and we need to look at the interaction of all these things together... but to simplify it we grind the front of the axe to get the most penetration we can get away with (grind angle) while holding enough strength (shoulder shape and placement) to prevent the edge being damaged during the job at hand. Soft timber - irrespective of grain - we can use a sharp front on because there is little resistance to penetration. Hardwoods require edge support, either a thicker angle for medium hard type timber through to a full rolled edge for an iron bark type timber.

Then we play with the mid portion of the axe... the overall body shape and hollow grind... to enhance chip ejection. Chip ejection is mostly a "nature of the grain " thing. Long straight grained timbers will just about fall out the cut. Short curly grained woods tend to hang up. More hollow grind will enhance chip ejection and reduce the chance of binding... but it also removes shoulder support meaning the axe body may fail behind the shoulder.

This is why there are so many different axe shapes out there... because an axe that will survive Ironbark would be a slow cutter due to lack of penetration in soft wood. Conversly the axe that will penetrate best into ironbark (a softwood axe) will have a damaged edge and not cut after a couple of blows. A fast cutting straight grained tropical hardwood likes a medium grind with the shoulder set well back to give decent penetration but impart strength to the edge, and a long face and exaggerated hollow grind to enhance chip ejection because of the nature of the grain, That exaggerated hollow grind is not ideal for softwoods because there we want more of a wedge shape to bust the chip out. But a wedge shaped axe that would work well in a softwood of similar density to the tropical hardwoods would cause the axe to bind.

The order is always to keep the axe intact first... which is shoulder placement to support the edge.
Then grind angle to allow penetration. There are degrees of difference in performance between a half rolled edge on a set back shoulder and a straight bevel to a close shoulder even though they both offer similar degrees of edge support.
Then overall shape and amount of hollow grind to enhance chip removal/reduce binding.

You gotta make the chip first before you worry about getting rid of it.

Can you unpack some of your terms John to help me grasp what you're getting at? What are you referring to with 'back of the grind', 'face', 'front of the axe', 'shoulder'?

How do they map onto this:

axe.jpg

Some of this is probably localised jargon (shoulder for instance in america refers to the area behind the eye but here that area is called the butt (england its poll) or just "the back of the axe) but most of it is just more specialised terminology then your diagram shows.

When an axe is manufactured the first step is to manufacture what is called a "blank", which is a roughly axe shaped lump of steel with an eye hole in it.
Blanks are either forged (mass market axes but also Tuatahi), cast (Keech axes -keech/ aussie speed/ keesteel) or at the artisinal level (Osbourne, Langdon) now often they start life as a solid lump of tool steel which is then shaped to suit, often by CNC machinery).

From there the blank is machined or ground to a finished shape either in the factory or by the end user. The shape the axe takes from the blank is referred to as "the grind" . An axe blank will have certain dimensions to it in terms of length, width, weight, general shape but its a very unfinished item, which means that it can be ground to a wide range of shapes from the initial starting point to suit a variety of woods or meet the needs of a given individual.

The "face" of the axe is the tip to tip width of the cutting edge, (straight line not around the edge). Its how wide the axe can bite into the wood.

The bevel is the area directly behind the edge that is ground (straight taper/ variable taper/ round or half round or a mix of these) to give a penetrating edge.

Where the bevel finishes is the "shoulder". On some axes it is a definite shoulder because the area behind it will be hollow ground to reduce surface tension related sticking.

"Cheeks" are the area behind the shoulder but forward of the eye

"Hollow grind" is meat removed from the cheeks to reduce sticking.

"Wings" are the top/bottom areas of the cheeks that are often significantly ground out. This is often related to balancing the axe headm but on an axe with a big face this is also to reduce the weight.

The "pin" is what most production axes lack, which is a steel roll pin from one side of the axe head to the other through the handle in addition to the normal handle wedges. It's compulsory on a racing axe because no-one really wants to just depend on wedges to hold a 6lb razor blade to a handle when some big dude is swinging it right beside you. Pretty much all my axes have pins, because its a cheap and easy safety enhancement in case a wedge comes loose unexpectedly which happens rarely but it does happen. Its not a replacement for a wedge and you still check your wedges and adjust as required - it's more a "last chance to keep your foot attached"

Sorry I cant draw well.

axe head.pdf

Thanks.

I've been checking chip thicknesses - my own and those of the woodchopping comp guys at one event. Their chips, of green Eucy, weren't more than half an inch thick. My own, from dry hardwood, don't get over 3/8ths. That leaves me wondering about the role of any part of the head behind the bevels. To the extent that these guys had bevels, they were in the order of half an inch, but many of them had no distinct bevel - just a taper.

Let's say to get a chip you need an edge and a wedge. The edge servers the fibres crossways, the wedge breaks the lengthways bond between the fibres and pops the chip out. Given the chip thicknesses mentioned clearly it doesn't need much depth of wedging to work (though the edge goes in a bit deeper than the chip that's loosened). If the outside of the bit slides down the existing cut face of the log we would expect more wedging effect and here's one role for the bit behind the bevel.

The comp guys maximise bit ejection by ensuring that in the top and bottom cuts of the log the heel and toe respectively extend out of the wood. The head inertia is thus concentrated on less of the edge allowing greater penetration and of course greater wedging. It also means obviously that one long side of the chip is bonding to nothing more than air.

Ever wonder at the speed those comp axemen can get through a log? Well, apart from the tool and the skill, the wood is green - it's dropped, trued, wrapped and delivered sopping wet.

https://www.facebook.com/HallAxeman/...8786497958557/

...and we pick them (woodchopping blocks) with care: no knots/holes/bends/cranky grain. By rights they're supposed to be consecutive blocks off the same tree to keep it fair. Even then "luck of the draw" still plays a part... all it takes is one knot in the wrong place to give you a real bad day, or at least a couple of evenings grinding out the chip and turning a big axe into a slightly smaller axe.

Even then, more then the nature of the blocks, and more then the tools... it's mostly about skill and practice. I know guys with the skill who never do well because they wont practice. I know little guys that cut a block with half the effort of some big guys because they don't miss a blow. Mind, being a big bastard definately helps but big alone won't win any races.

It's all about skill, if you go back to look at your picture in post #144 your cut angles are uneven and too steep. The axe should enter the wood at 45 degrees, it gives the maximum mix of penetration and chip removal. Even the best competitive axemen in the world draw lines on their block in a ring to show where the axe needs to go (not that they always get followed, but next time you go to play mark out a couple of lines to follow)
Cutting clean matters... if the old chip is still held in place when you take the next blow you loose power to re severing the same piece of wood rather then it sinking into uncut fibres. Cutting beside the old cut rather then into it means you work twice as hard to shift half as much. Ideally each cut should follow the same plane so its a smooth cut - its about moving the maximum amount of wood with each blow (or usually 4 blows - 2 each side to get the chip to fall free.)
And theres a mindset to cutting seriously: part of it is confidence from practice and skill, but how an axeman looks at a woodchop block is a bit different. Most people chop at a block of wood, a skilled axeman slices through it. Most people chop until a chip falls out... a skilled axeman expects the chip to bust free. There's a whole lot of pressure applied when an axe is swung correctly and in straight grained timber that shock loading parallel to the grain is what causes chips to fly.

You can learn a lot from watching good axemen. Some of it doesn't translate real well to the bush or the wood heap... but most of it does.

Thanks for sharing your experience JG.

Yeah, I took an underhand lesson recently and learned a lot.

So this is the next exploration, a Husky Carpenter's Axe. Forumites will know that Husqvarna have them made by a Swede, possibly Hultafors.

20" handle, 4" edge, quite heavy. It came at c. 20 degrees but cleaning up the edge it crept up to nearly 25. I'll correct that after a play if necessary. It came with the toe chipped and I decided to round it and the heel a little for safety's sake.

It's quite a substantial tool and will take a bit of training to use. I note that when Robin Woods roughs out a spoon he uses a hatchet that's a good deal smaller.

It's used with the hand under the head, in that notch, and pushed down. That's reasonably comfortable.

Husky carpenter 2.jpgHusky carpenter 1.jpg

I did have a close look at the Husky Carpenter's Axe a while back. I like what I could see of it from online sources, but decided in the end that it was too much of an overlapped between my small Hults Bruk hatchet and my Japanese carpenter's axe. The latter has the same feature as the Husky in that you can hold the handle right up behind the axe head, which is ideal for fine trimming work.

I will be interested to read what you have to say about it, Ern.

Well, it's kinda crude but effective!

I'm practising on 5/8" pine boards - drawing a line, swinging the axe to put in a set of notches to that line, and then choking up on the head and pushing down. That splits the segments out and does a bit of planing.

The edge hasn't come out of it all that well, after about a metre. Your antecedents might have an explanation Neil. Isn't it the case that the surface of hardened steel doesn't get much hardening? If that hasn't been ground away in the shaping of the bit the edge might well get pushed around to begin with.

It's also damn hard on the hand.

Ern, I'm thinking about the ends of your edge that came chipped and what that might say about the temper on this axe. I would expect the edge on a carpenter's axe to typically have less temper (leaving it harder and more brittle) than most other types of axes, which have to be sufficiently tempered down to withstand the impact of heavy chopping. Since carpenter's axes are as much a chisel as a chopper, I would think they would be left with a harder and more brittle temper, thus the chipping off at the ends of your edge.

We know that some tools come new with surface de-tempering due to insufficient attention to that process, leaving the surface steel softer than the deeper steel. Grinding the softer surface steel away can expose the lower down harder temper. However, given the chipping on the edge ends of this axe, I'm not sure that is the problem or the solution.

Before I got into any regrinding I would be inclined to do some sharpness testing: how sharp can you get it (I like the cigarette paper cutting test) and how long does that sharp edge last.

As for antecedents, Ern, I may be descended from Welsh blacksmiths that go back four centuries, but I failed to ask the questions I would now like to know the answer to from the last of them, my great uncle. I spent a lot of time in the smithy as a child watching the process, but you don't interrupt the smith or the striker with questions while the hot metal is being swung from forge to anvil and rhythmically hammered into shape, then quickly plunged into oil or water.

On another sub-topic, I was at a friends place this morning who showed me a book that he got for Xmas, titled Norwegian Wood; it covered all aspects of firewood getting, storage and use in Norway. I loved the photos of their wood stacks. The relevance here is that it includes a section on axes. Of course, their wood is primarily softwood, so only partly applicable to our hardwoods here.

IMG_20170108_115401.jpg

Stay sharp!

Neil

That looks like an interesting title Neil. And could make a good song title.

Yes, I see your point about the temper.

The edge started hair popping and ended dulled with a little wave in it. To be fair, I hadn't put a microbevel on it.

Also it had copped a solid blow on the toe in handling - enough to cut half an inch length through the sheath.

Well, it's just taken a few passes on the green crayoned leather belt to restore the edge and maybe I should whack that microbevel on it too.

Now my vision is destroyed of the Strongs debating water v brine cooling around the dinner table ;-)

Originally Posted by rsser

It's also damn hard on the hand.

Ive only ever seen Robin Wood,Jojo Wood, Ben Orford , Jogge Sunqvist and Willie Sunqvist use green timber which would be hand friendly...

Pete Von Trott and Jeff Doone (spoonsmith.com) both use green Australian hardwoods to make spoons. Jeff if I recall uses a robin wood axe or a Hultafors and Pete a granfors Bruks Swedish Carving axe.