# Milling a Silky Oak



## BobL (Jan 7, 2012)

On the menu today was a Silk Oak. It's not an oak but you will see why it is called an oak in the pictures. The species name is Grevillea robusta and in it's natural setting it is a a medium sized (up to 60 ft) hardwood, native to the coastal rainforest from northern NSW and south-east Queensland but is planted all over the world (including Hawaii) as a plantation timber. Interestingly it only grows to a decent height in mixed plantations because it produces growth inhibitors on other trees of its own species. Hardness is similar to yellow birch so for me it's a softwood and I really enjoyed cutting it up.

This is the first one of any decent size I have milled and has ~36 ft of millable trunk divided into 4 sections.
I started with the base section which is about 26" wide at the base and about 20" at the other end.














The tree lopers yard where I mill is next door to a limestone block factory which is not ideal - when the morning easterly blows it sends a white smog of concrete dust over onto the logs which is why you will see a hose in some pictures which I use to wash the logs down. The big logs behind the silky oak are Queensland Kauri Pines which should make interesting milling





Some close ups in the next post.


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## BobL (Jan 7, 2012)

*Silky Oak Part II*

The 880 and the BIL mill were a pleasure to use on this log and only touching up the chain on every 3rd cut (probably could have made 6 cuts) made a change from the usual once per cut. I measured the cutting speed mid-log and was getting around 0.28 to 0.31 "/s (cutting width ranging from 20 to 26") without optimizing all the cutting variables - I was using an 8 pin drive sprocket.

The grain is very interesting. I'll let the pictures tell the story.
This is the rift sawn section of the log so we are looking a the ends of the medullary rays.
I was really pleased with the finish I was obtaining with this chain and could have probably reduced the slab thickness to get one more slab out of the trunk





More grain shots





Here we are looking and the quarter sawn section showing the medullary rays in all their glory - I can look at the grain on this timber all day.









And my fave.





You can see why fine furniture folk and people that make jewelry boxes etc drool over this stuff.

Now to think there are 3 more logs and one interesting crotch to play with!


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## Mill_wannabe (Jan 7, 2012)

Wow! That is fantastic grain!!! Thanks for posting that.


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## BobL (Jan 7, 2012)

*powerhead temps while milling*

Because the silky oak was so easy to mill I had time while milling to record some temp data.

My temp gauge has the sensor in the fin gap just above the exhaust port - what it measures in reality is the temp of the cooling air that has already picked up heat from the power. 
What I do is every now and then write down the temp reading direct onto the slab and then when I'm done with the cut go back and measure the distance from the start of the cut and record distance and temp. Using the tacho I tried to keep as stead a revs as possible (~9k rpm)

Anyway here is an example




The starting temp is higher than ambient (it was 75F) because the saw is still warm from the previous cut.

You can see that in a 24" wide piece of wood it takes about 6 ft of cut for the saw to get up to a steady temp. On really hard wood the temp continues to rise right the way thru logs as long as 14 ft because the cutters get blunt quickly.

Then killing the saw immediately (ie no fan) the temp goes up to 300F and drops slowly from there

Usually I leave the saw idling until the temp drops to 140F and then stop the engine. Immediately the Temp now shoots up to over 220 but comes down much quicker than the previpus method


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## mtngun (Jan 7, 2012)

Good to see you milling again, BobL. 

3 passes before sharpening ? Wow, what a radical change for you. 

Thanks for the data and the pics.


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## woodenvisions (Jan 7, 2012)

*Itchy wood*

Are you itchy yet? Its beautiful wood but I learned the hard way that many people are extremely allergic to the dust. It's like poison oak and it took a huge dose of steroid pills to get it to go down!


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## cjk (Jan 7, 2012)

Nice looking wood. 

That temp chart is interesting. I would have guessed it would rise faster. How long do you idle the saw to get to 140 for shutdown?


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## BobL (Jan 7, 2012)

mtngun said:


> Good to see you milling again, BobL.
> 
> 3 passes before sharpening ? Wow, what a radical change for you.
> 
> Thanks for the data and the pics.



Cheers mtngun. I had to go cold turkey on the sharpening.



woodenvisions said:


> Are you itchy yet? Its beautiful wood but I learned the hard way that many people are extremely allergic to the dust. It's like poison oak and it took a huge dose of steroid pills to get it to go down!



In it depends what you mean by the terms "extremely" and "many". I know some people who are allergic to breathing the dust but still work with it without any PPE using a high volume/speed dust extraction system, some who wear an air face/shield, and some who cannot even touch the stuff. The most common problem seems to arise for users who work in high dust level generation activities like wood turning without appropriate dust extraction situations. Interestingly the bible on Australian Forest Trees does not even mention the potential of the dust for allergic reaction.

I have worked with it before and no itch for me, but knowing it can cause problems I oriented myself so the stiff easterly in the morning blowing the dust away from me and in the afternoon the Fremantle Doctor (sea breeze) came in from the west and I had to change milling direction. Then, still being green its not so bad as when it is dry and my saw was throwing nice chips and not much dust. In my home shop I have an industrial grade dust extractor with 6" ducting so hopefully I will be OK there too.


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## BIG JAKE (Jan 7, 2012)

Interesting info Bob. That is some nice looking wood too. Good to see ya pullin' the trigger again. How are your fingers holding up?


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## 820wards (Jan 8, 2012)

Bob,

Glad you are back at it again, and the wood is very beautiful. So where are you warehousing all these slabs of wood when you mill them? 

jerry-


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## BobL (Jan 8, 2012)

820wards said:


> Bob,
> Glad you are back at it again, and the wood is very beautiful. So where are you warehousing all these slabs of wood when you mill them?
> jerry-



They were inside the tree loppers garage but he went and bought several more trucks so now most are outside. They really do need sorting, most are dry enough to stand upright.



BIG JAKE said:


> Interesting info Bob. That is some nice looking wood too. Good to see ya pullin' the trigger again. How are your fingers holding up?


Fingers are definitely weaker than they were before they got crushed so I have to look for different strategies for doing things. The most annoying thing is I can't hold small objects tightly for twisting and turning with my left hand. For some reason my knees and legs have suddenly become a lot weaker. For example even up to a year ago I use to be able to do repetitive deep knee bends without much effort but now I do one and I'm stuffed! 



cjk said:


> Nice looking wood.
> That temp chart is interesting. I would have guessed it would rise faster. How long do you idle the saw to get to 140 for shutdown?


My guess is its 3-4 minutes. I'll measure it next time I do some more milling.


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## qbilder (Jan 8, 2012)

A friend of mine from NZ sent me a piece of silky oak. I can attest to the wild grain. It's almost like lacewood. Stunning. Nice pics, Bob.


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## 820wards (Jan 8, 2012)

BobL said:


> For some reason my knees and legs have suddenly become a lot weaker. For example even up to a year ago I use to be able to do repetitive deep knee bends without much effort but now I do one and I'm stuffed!



Bob,

Being Type 2, I have found that my legs just aren't as strong as they used to be either, and I still get muscle cramps if I don't keep hydrated when I do strenuous activities. It's heck getting older, 60 this year....

jerry-


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## Old Blue (Jan 8, 2012)

Thanks for the pics Bob. Good to see you back at it. 

I never would have guessed that a sildy oak's wood would look like that ! I'll have to put those on my list for wanted to mill. Thanks for the look at another species.

Old Blue
rapacious taxation for the benefit of the falconcrest aristocracy in...
Kali-bone-ya


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