Thursday, March 26, 2009

Timbering, Part IV -- Scoring

Scoring is the removal of significant amounts of wood from one side of a log, as the first step in squaring the log into a flat-sided timber. I finally began scoring my maple workbench slab-top a few days ago. But alas, other demands on my time are destined to keep this a background project. However, I am long overdue for a blog update, and thought a short article describing the scoring process might be welcomed by those who are interested.

The scoring process essentially consists of cutting a sequence of notches along each side of the log that you intend to square. If you can imagine these first three notches continuing all the way down the length of the log, you get the basic idea:

The intent is to cut the notches to the depth of the layout lines running along the sides of the log. In other words, each notch just about touches the lines on either side of the log, while the bottom of each notch is just deep enough to meet the plane intersecting the two lines.

Of course, in practice, you can never cut them that precisely -- they either go a little too deep, resulting in axe marks in the timber face that you might need to smooth later on (e.g. using an adze), or they don't go quite deeply enough, so you have that much more wood to remove when you subsequently hew (square) the timber face with your broad axe. When I took the photos above, I had not yet finished cutting these notches all the way down to the lines.

Once the notches are cut, the next step is to remove the wood between them. Usually, this is accomplished by taking relatively horizontal strikes at the wood chunks between the notches, using the felling axe. However, because this is such a large log, I'll first split the chunks with a maul, and then clear the broken-up material with my felling axe.

Traditionally, scoring is done while standing atop the log, with the side being scored positioned vertically, as the gentleman in this photograph is doing:

Standing on the log actually makes quite a bit of sense. If you were out in the forest doing this, you could avoid standing on wet, muddy, or uneven ground. Furthermore, you could allow the weight of the axe to do most of the work, while you simply guide it to the target. However, in my case, the maple trunk is too large and too irregularly shaped to make this a comfortable position. Furthermore, the breadth of the trunk also makes it that much more difficult to gauge where the axe is striking, relative to the layout lines.

So, I have chosen instead to keep the face of the log horizontal while I score it. And with my ultra-simple and highly flexible hewing/bucking cradle, there is an advantage to doing it this way, since I can readily rotate the log to any angular position, and then securely lock it in place.

This means that I can begin cutting a notch on the horizontal face, rotate the log slightly toward me, and then continue cutting the notch toward the far side, while generally being able to see how close I am to the line. I can then rotate the log the other way to cut to the line on the near side of the log. All this can be accomplished while standing in the same position, and consistently moving the axe with the same basic motion, striking at about a 45 degree angle, toward the butt-end of the log:

For example, in the photograph below, I had already started the first notch, and then wanted to cut down to the line on the far side. So I tilted the log to the left and secured it...

...and then continued my cut toward the far line:

And, yes, I admit it -- I cut just a little too far on this one, striking just below the line at one point. But this is precisely why I allowed myself a 2" margin between the lines and the final slab surface.

In the photo below-left, I've released the movable supports and used a peavey to rotate the log in the other direction (away from me), so I can continue cutting the notch toward the near line. The below-right photo shows the log locked in place:

You can see that I got a cleaner cut this time -- just about as close to the line as I wanted it:

I'll post more photos as soon I finish cutting the remaining notches on this face of the log. In the mean time, I'll keep swinging and striking, while those crows keep a-cawing and a-mocking... :-)

[ The weight of an ax-head poised aloft, The grip of earth on outspread feet - Robert Frost ]


Shellmo said...

Those crows are singing words of encouragement to you! :-)

John Poole said...

Thanks, Shelley! They sure keep my spirits up -- they're out there everyday, entertaining me with their banter!

Cassie said...

Just read the article on the Roubo. That is quite a workbench you are working on! When it is completed are you going to charge admission to see it?he he. It's going to be a lovely piece John.

John Poole said...

Thanks very much, Cassie! It's going to take about 10 friends to help me carry into my basement when its finished. Wanna come over and help? I bet that darn thing ends up getting dropped on my foot. Let's just wait and see! :-)

Bud said...

Very interesting John. If I were closer, I would come help carry.

SandyVTW said...

this is cool stuff careful!

John Poole said...

Bud & Sandy -- Thanks for your comments, and yes, I will try to be very careful! If you guys ever find yourselves heading down this way, you're more than welcomed to come by and view the progress first hand. :-)

Have a great weekend!


John said...

hmmm... you're having to make cuts across the grain which require much more work than cutting with the grain.

I'd think something like cutting really wide V's whose legs are about 20 degrees from the horizon(instead of a normal "V" where the legs are approximately 75 degrees from the horizon, would be more efficient?

Or better yet, just sawing scores and then using an ax swinging close to parallel to the grain popping those puppies clumps of wood off.

John Poole said...

John -- I cut the first three notches with a rather deep V because I wanted to experiment with splitting the remaining wood to clear it out, something I never tried before, and felt that splitting those chunks might be more effective if the notch walls were steeper.

But you're absolutely right: a very shallow V is much more efficient to cut. I cut the remaining notches with very shallow V's. I will try splitting some of those, too. And if none of that seems satisfactory, then I'll just revert to taking strokes parallel to the grain.

My rationale for splitting when the wood is deep is that I can trade-off many parallel strokes for a very small number of vertical splitting stokes. In the end, I may not be saving myself an effort at all, maybe even generating more work for myself. But I wanted to try it.

I also thought about sawing the notches, as you suggested, but decided to stick with an axe for this particular project.

Thanks very much for your comments! Please stop by again.

- John

John Poole said...

Oh, one additional thought: Although cutting shallow scores is easier / more efficient, it requires you to remove more wood. Since this log is rather large, it seemed reasonable to cut deeper V's and take a shorter path to the line (harder to cut, but less distance and less wood removed). Then rely on splitting the remaining chunks to facilitate bulk removal. That was part of the reasoning for trying the first three scores that way, anyhow. :-)

Paul Bunyon said...

Don't be tempted to use other tools, stick with the ax!

John Poole said...

Thanks, Paul! My regards to Babe...

Cassie said...

hehehehehe. I don't know how to write a chuckle, but that's what I'm doing after reading your last comment. ;<) You're funny!

John Poole said...

Heh! You don't need to write a chuckle. I can hear you and BRD chuckling all the way from AZ! :-D

Glad you enjoyed the post!