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Author Topic: wood cutting  (Read 4244 times)

boatmadman

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wood cutting
« on: June 11, 2009, 09:23:14 AM »

I had a couple of Lime trees cut down a couple of years ago, I kept the good straight sections of trunk in the garage since.

I think its now time to have these cut into boards.

Now, the question is, what is the best or most appropriate way to do this? I have heard mention of quartering, what is this? why do it?

Thanks in advance.

Ian
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andrewh

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Re: wood cutting
« Reply #1 on: June 11, 2009, 09:55:54 AM »

Ian

Quartering gets you quarter-grain wood!  but wastes lots of wedge-shaped bits.
Quarter-grain  - also known as "C" grain is a plank cut radially from the trunk so the rings are across the thickness of the plank.

Depending on what you are planning to do with the wood, I venture to suggest that you probably do not need quarter grain planks. It is the cut that makes the stiffest planks (wing spars are quarter grain) and hence is the very worst for bending - for example for boat-planking.
Explanation of the different cuts here:
 http://pldaniels.com/flying/balsa/balsa-properties.html
BTW,and for amusement the way that Quarter grain crosses the growth rings shows as a "speckled" pattern (Latin: Lagopus) on the face of the wood - hence Balsa is Ochroma Lagopus (according to some authorities, Ochroma pyramidalis to others)
Lime and beech show this speckling really well, too

andrew
 
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andrewh

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Re: wood cutting
« Reply #2 on: June 11, 2009, 10:40:41 AM »

Well what a coincidence - a friend has just sent me a picture of his sawbench with an excellent example of tangent (A grain) (on the left) and quarter grain (C-grain) cuts

This is what they look like - imagine how the Tangent cut will warp as it dries or takes on moisture
Wood is almost certainly American (White) oak
rgds
andrew
 
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boatmadman

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Re: wood cutting
« Reply #3 on: June 11, 2009, 12:47:44 PM »

Great example and well explained, thanks.

Now, what cut is best for use in boat planking?

Ian
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andrewh

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Re: wood cutting
« Reply #4 on: October 08, 2009, 12:53:39 PM »

Ian

"Best" is a kinda loaded word, but here is my view:

Plank with anything but "C" grain aka quarter grain.
Reason:  although this is the stiffest grain is is also (for the same reason) the least happy to bend and twist.
Planking most hulls bending and twisting are just what is required

Also as a further frustration quarter grain splits most easily iif you attempt to pin, nail or put screws in it

If you are going to slice up your log in the way that gets best usage out of it - all the planks you get will be rather mixed grain (but NOT quarter grain)
Say the planks you cut were 10mm thick, you season them for a while,  bring them indfoors and let them stabilise then maybe slice than into 2 or 3 mm thick strips for planking a boat
OOOOAH - by doing this  - some of the little strips you cut are quarter grain (any through the heartwood)

But its not a problem - you would have ckecked each strip as you used it for suitability anyway, wouldn't you?
My little mind has been running on, and I realise there is a happy relationship here which will keep a boat very well balanced, planking-wise
I am about to sketch my idea but will post this cos i will run out of my allowed (by employer) 30 mins
andrew

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andrewh

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Re: wood cutting
« Reply #5 on: October 09, 2009, 12:59:48 PM »

Eventually managed to get self, picture and lunch 1/2 hour together

I have attempted to sketch below how the second cut (to make a strip out of a plank) varies from "c" grain (in the middle) to "A" grain at the edges - and it does so gradually and progressively



SO - it makes sense to use the C grain (if you are not going to use it as a wing spar) for the planks which bend and twist least - these are generally at deck level down to the "turn of the bilge"

Then the planks get progressively more "shaped":- bent and twisted so it makes some sense to use the planks in sequence from the middle outward as you plank down the hull -

Also the advice is to use, as far as possible, matching planks on each side of the hull.  What better way to do that than by using two strips from the same (big) plank, and with a similar grain pattern
Sorry - I'm rambling again
andrew
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derekwarner

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Re: wood cutting
« Reply #6 on: October 09, 2009, 01:34:11 PM »

Andrew says...........'also the advice is to use, as far as possible, matching planks on each side of the hull.  What better way to do that than by using two strips from the same (big) plank, and with a similar grain pattern' - Sorry - I'm rambling again andrew'

Don't be sorry Andrew....I am sure many Mayhem members appreciate the understanding & explanation on timber  & timber cutting........

I recently purchased a length ....1800 mm x 250 mm x 12 mm of Tazzie Oak [super fine grain]......I understand ~~~~possibly 400 years old & I will rip this into 3.25 mm planks on my new Proxxon table saw......it may seem sacrilege .....but I will paint both sides with 'black board paint'  prior to the ripping down...................Derek
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Derek Warner

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tigertiger

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Re: wood cutting
« Reply #7 on: October 09, 2009, 03:05:32 PM »

...but I will paint both sides with 'black board paint'  prior to the ripping down.

Is this to simulate caulking? If so, good tip.

If not, what is the purpose please?
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andrewh

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Re: wood cutting
« Reply #8 on: October 09, 2009, 08:42:00 PM »

Derek

If you love the wood, and are creating something with care, it appreciates that :}

I am still jealous of Ian's Lime tree - its a lovely wood with a sweet and kind grain. 
Americans, bless them, call their variety of lime (tilia americana) "Bass" which is light and tough and bendable

Good thinking with the blackboard paint  - I have heard of people pasting black cartridge paper to one side for the same reason

Great minds, eh?
andrew
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derekwarner

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Re: wood cutting
« Reply #9 on: October 09, 2009, 10:56:25 PM »

tt & Andrew....yes...a liberal coating of common old blackboard paint offers a good simulation of tar caulking  O0 ........Derek

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Derek Warner

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Illawarra Live Steamers Co-op
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