Thread: Australian timbers and tool steels

Originally Posted by derekcohen

Wikipedia notes, Laterite is a soil and rock type rich in iron and aluminium, and is commonly considered to have formed in hot and wet tropical areas. Nearly all laterites are of rusty-red coloration, because of high iron oxide content.

There is still plenty of silicon in the residual clay minerals and even pure silica.

There are heaps of references to silica in timber.

This one shows and electron microscope picture of SiO2 grains in wood.
A Tale of Three Timbers - ScienceWise - ANU

12 of 36 brazilian timbers in this study were found to have detectable Si.
https://www.degruyter.com/view/j/hfs...-2011-0240.xml

Page 46 of this article shows Si content in the ash of ~30 NSW trees.
http://www.dpi.nsw.gov.au/__data/ass...ee-Species.pdf
Also shown is the SG of the timber - you might like to examine any correlation of SiO2 content with the SG and then hardness?

That's probably enough for the moment.

Something else to bear in mind is the Janka hardness quoted in most cases is some kind of an average value.
In some species, not including sap or heartwood, the hardness can vary by +/- ~10% on the same tree and +/- 20% across different trees. If you happen to be given two pieces of wood from different species and base your experience on those pieces you could be up to 40% away from the averages

What about anisotropy?

Originally Posted by ian

Another approach would be to go through old issues of Australian Wood Review -- dating back to around 1995 -- where workability and edge retention was discussed, explored in the context of plane blades (in particular Paul William's M2 blades).

Originally Posted by derekcohen

Ian, thanks again. I tried to find any Australian Wood Review articles without luck.

Hi Derek

I'm not sure how far back your collection of Australian Wood Review extends ...

Issue 33, page 70 Richard Vaughan has an article "Different strokes" reporting on a plane blade trial he conducted -- this is the one I was thinking of

Issue 17, page 70 has an article titled "Plane blades, carbon steel, HSS steel, Japanese steel blades"

From my experience, the worst 3 timbers i have used for high silica and fast blunting of blades (including an expensive King Resaw CT blade) are; Tasmanian Blackwood (my favourite firewood), Turpentine and Brush box. I avoid all 3 now - like the plague.
Softwood Sheddie 😎

Originally Posted by BobL

Something else to bear in mind is the Janka hardness quoted in most cases is some kind of an average value.
In some species, not including sap or heartwood, the hardness can vary by +/- ~10% on the same tree and +/- 20% across different trees. If you happen to be given two pieces of wood from different species and base your experience on those pieces you could be up to 40% away from the averages

Correction that should be "40% difference between two pieces of wood from two different trees of the same species"

About a decade ago a number of Qld box street trees were dying around Perth due to a lack of water and a few ended up at the tree loppers yard where I milled them into slabs. They were still green but rock hard and lots of silica. Milling these later into the early evening in the shade I noticed a LOT of sparks. They are now quite dry and recently I cut up and put a couple of the slabs through my small thicknesser and it knocked the stuffing out of the blades.

Originally Posted by rob streeper

What about anisotropy?

Rob wins.

Originally Posted by derekcohen

...... He seems to think that I make it all up (that our timbers are hard on tools). Anyway, I did a little research, and was surprised that Jarrah was not abrasive due to high silica, as I had supposed. Obviously there is "something else", and I was wondering if it was more than just hardness.....

Derek, the bloke you are referring to has obviously not encountered too many of our more notorious hard woods! I'll send 'im some of the leftover bits of Bluegum Luke's bench is made from, if you like. It had all the ingredients; Janka hardess, interlocked & rowed grain, plus silica, in abundance. It also had an extra vice: despite frequent applications of wax, a gummy residue quickly built-up on the plane sole, making it harder still to push, & generally adding to our misery. Even for someone used to our hard woods, that particular tree had a few surprises! The River Red gum we made some of the parts from was like cedar, by comparison.

BTW, silica isn't the only blade-dulling mineral in wood, there are a number of calcium salts, plus a few other ingredients I can't remember atm, that can also be very hard on cutting edges. And if termites have been into your tree before you, there will be lots of little sand grains (which are mostly SiO2) that can do a right number on chainsaw teeth, and also get into cracks & crevices in the sawn wood to make life miserable for hand-tool users down the track!

Siliceous salts are definitely major ingredients responsible for edge-dulling. Silica is the second most abundant element on our little planet, so it's just taken as a given that any soil on earth contains plenty of it, & it's there to be accumulated in some form or other in those plants that are disposed to taking it up. How much gets incorporated into wood cells is a function of availability (solubility of particular salts, soil pH, etc.,) but very importantly, the genetic make-up of the plant, some species having a much greater affinity for it. Even within species, there can be much individual variation. We have the dubious distinction of having the most siliceous wood in the world in "Qld Walnut" (Cryptocarya palmerstonii, formerly Endiandra sp.), by a large margin. It's also an excellent example of how much variation there can be within a species as this recent thread demonstrates. People who have been lucky enough to strike good stuff (probably from younger trees) wonder what all the fuss is about, but older trees in particular are lethal to steel edges, and this has been well-known to millers and woodworkers where I come from, for well over a century. In his book on rainforest woods, Morris Lake devotes a paragraph or two to relating how some Qld W'nut he'd had made into doors for his kitchen virtually destroyed the joinery's cutters!

But there are obviously other factors that promote edge-wear to your planes & chisels. My bench-top is hard Maple from southern Ontario, and although not quite in the same league as any of our Eucalypts or Corymbias or dry-country Acacias & their allies, the particular tree my bench came from was a tough old nut! I thought it may have been my lesser experience & maybe not as sharp blades as I achieve now that caused me so much effort levelling it up when I first made it (~1984), but I re-surfaced it a couple of years ago, & was surprised again at how often I had to stop & re-sharpen. However, having worked with most of their 'standard' woods, I would agree with Luke that Nth. Americans don't know how lucky they are. Even the ones they consider challenging certainly don't compare with the majority of open-forest & dry-country hardwoods we deal with.

To really sort out the factors which contribute to edge-dulling in any given wood, & in what proportions, I think you'd need input from physicists, engineers, chemists, botanists, electron microscopists, and of course, a skilled woodworker or two. Aren't many of us here who could claim competency in all of those fields, so we need to put a good team together.....

Cheers,

I think its important to highlight that the generally higher Janka timbers indigenous to WA do not on their own reflect the vast range of Janka, both in softwood and Hardwood form, that are also available from other states of Australia. Tasmanian being a prime example. On top of that, Australia does import a vast array of non indigenous timber from other parts of the globe including the USA, PNG, and Indonesia. Oregon, Merbua, Meranti, American Cedar, to name a few. As to the type of steel to use, my personal preference is 01 steel, as its quick to re-sharpen and shape to camber on the type of oil and water-stones I prefer to work with. But that's a personal choice I have made, and should have no sway on what other types of tool steel others choose to use. Having a drawn out discussion on why some timbers are far more abrasive than others, regardless of Janka rating and density, is beyond the scope of most woodworkers understanding, and is best left to the scientists and botanists to ponder over. My 2c worth.

Originally Posted by Luke Maddux

Rob wins.

My comment above was based on my experience with one of our native high-silica species, mesquite. It cuts on the lathe with TC tooling very nicely when cutting or scraping perpendicular to the grain but is extremely destructive to sharp tool edges when cutting into the end grain as one encounters when hollowing bowls for instance.

The scholarly literature suggests that tool wear arises from several characteristics of the wood including silicia, ash (non volatiles and inorganics) and corrosive factors including tannins. Tool geometry is of course very important suggesting that high-silica/high abrasive species might best be mechanically milled with tooling intended for cutting Hardie board type products.

THE IMPORTANCE OF EXTRACTIVES AND ABRASIVES IN WOOD MATERIALS ON THE WEARING OF CUTTING TOOLS | Darmawan | BioResources

https://www.deepdyve.com/lp/de-gruyt...ies-ok9QIRSQrl

Page not found | SNS...

iopscience.iop.org/article/10.1088/1757-899X/142/1/012088/pd...

https://link.springer.com/article/10...107-005-0015-6

Interesting that you mention ash Rob, as regular bushfires are sure to be part of the history of many of our forest trees.

I think the authors above mean ashing in this sense: ANALYSIS OF ASH AND MINERALS
Similar but not the same as burning.

Right. Total minerals v specific mineral content. I was way off!

As Australian woodworkers, we tend to bang on about the impact our timbers have on tool steel, whether this is in plane blades, chisels (both lathe and bench), and machine blades. Over the years we have seen the introduction of HSS (M2), A2, recently PM-V11, and even M4 replacing the O1 and high carbon steels commonly used by Stanley and many other manufacturers.

Cant wait for the discussion to move onto the benefits of using LV tool steel.

Originally Posted by Fergiz01

Right. Total minerals v specific mineral content. I was way off!

One of the authors finds that the corrosive compounds in the various species tested are more important than the mineral content. How the corrosives degrade cutting edges in use isn't discussed.
Another finds that the calcium content plays a significant role. In my home area we have very alkaline soils with high calcium which is also likely a significant contributor to the dulling effect of mesquite.
Unfortunately a lot of the studies are pay-walled so it's difficult to get a good grasp of what the state of the art is but there is apparently a lot more going on than just silica.