further riving details

I got another note from Drew Langsner this morning; here it is.

riving shingles in Japan

Hi Peter,

Here’s more on riving. This photo is of a gentleman who demonstrates riving shingles at Hida Folk Museum, near Takayama City in the Japan Alps. You can easily see that he’s been doing this for hundreds of years. He is riving chestnut.

  It’s not shown in this photo but he will often rive a billet into thirds. Here’s the technique. He starts a split 1/3 of the way across the width. Shortly after the froe enters the billet he removes the froe. He then drives it half way in the remaining two-thirds of the billet. Immediately the froe is removed, replaced into the first opening, and driven down some. Then removed and replaced back into the second split. This continues until one of the side boards pops off. Then he finishes riving the other piece into halves. Very neat trick. I think the chestnut makes this somewhat easier than other woods because it is more bendy and therefore doesn’t pop apart as fast as a wood like red oak.

  Also note his riving brake. I’ve been riving wood for shingles, chairs, fencing for 40 years now but had never seen anything like this. The brake not only holds the wood in place. It also puts pressure (tension) on the outer side of the curve and this causes the fibers along the curve to come apart as the split opens up. 

  

One other trick. The master warms the wood over a small fire before riving. In winter this defrosts it. But I think that all year around it makes the wood a bit more bendy.

  

The froe is almost identical to the ones we use. 

    

(Photo by Drew Langsner from the 2010 Country Workshops Japan Craft Tour)

Thanks, Drew. We’ll see more about the CW froe soon.

 

surface textures & tool marks

I have been meaning to shoot photos in the shop of tool marks; and how they are made. I have not got to the pictures yet, but recently a reader asked about some difficulty he’d been having with tear-out in white oak. Some tear-out is common, especially in white oak that is near the juvenile wood (the section of a board nearest the center of the tree).

What is acceptable, and where it falls in a piece of furniture varies widely. Here’s some examples of just a few tool marks; mostly riving, hewing and some planing. We have seen some of these photos here before, but a review never hurts. First, one of my favorite shots; the bottom boards of a joined chest, Dedham MA c. 1640-1670. Here we have a lot to see. Riven material, never touched by anything other than a wedges and a froe for some of the bottom boards. Others have hatchet work. Iron/tannic acid staining where the nails secure the bottom boards to the rear rail. this staining also needs moisture present to occur. The sawmarks where the joiner trimmed the floor boards at the back of the chest. His saw ran against the outside rear rail, scratched it to a fare-thee-well. So, an extreme case where close-enough is good enough. but none of this shows on the finished piece.

joined chest, rear view of bottom

 

Here is a view of a joined stool showing the contrast between the surface that shows and those that don’t – the molding on the upper rail, and in the background, hatceht work on the inner faces of the adjacent upper rails.

joined stool detail

 

 Here’s some plane chatter (or scratch stock tear-out) in the moldings on this English cupboard (Lakes District, 1691) flatsawn wood, another culprit.

torn-up moldings on cupboard door panel, 1691

 Torn-up grain, mostly from riving, inside the till space on a joined chest from Ispwich, MA. (till is missing, of course)

inside till space, Ipswich chest

 How about tear-out on the front of a piece? See the background (i.e. the panel) on this chest with drawer, Salem MA. 1630s-1690s.

tear-out on panel etc

 Inside a Plymouth Colony chest with drawers, (from a slide, so not the best shot)

interior Ply Colony chest w drawers

That’s enough to get us started. Soon I’ll do one with photos of really first-rate work. It exists, even in New England.

Most of these surfaces I showed tonight result from the riving process, but some of them are from planing. The causes for these torn-up surfaces from a plane can be many; wood that’s too wet/green; It needs to lose some moisture before you can “finish” plane it. Twisted stuff near the heart of the tree;  this juvenile wood is fibrous and tough. It often is wavy also, not as straight at that stuff our neared the bark. Plane irons that need honing will also effect the surface you produce.

 

some birds, some woodworking

Took a few days off at Christmas…hung around the house most of the time. Here on the Jones River, December is a great time for birds. We see more ducks in winter than in summer by far. This week there’s been a flock of about 10 or 12 hooded mergansers, but they are quite skittish. I had to go back to a few years to find a decent photo of one, I had more time then to chase them down for pictures:

hooded merganser

 

We saw lots of hawks and herons too, this cooper’s hawk sat right up for its picture:

cooper's hawk

 

But today I got back to the shop today for a bit. I decided to repair the riving brake I have been using for a few years. It was built just a little different from what I wanted; so today I tore off the cross-pieces and re-did them. I like the upper piece to sit behind the leg on my left, and in front of the leg on my right. I think this arrangement provides a greater range of holding possibilities.

repaired riving brake

 

Once I got the brake straightened out, I split a section of red oak, just to make sure that it was tight enough. In the photo above you see I have a 45″ bolt of oak standing up with its upper end jutting out between the rails of the brake. I drive the froe into the end grain, then lift the oak up and wedge it between the rails, but lying just about horizontally. This allows great leverage when you are trying to direct the split this way or that…

driving froe to start split

 

froe & riving brake

 

While I was working out in the woodpile to fix this brake, a red-tailed hawk showed up & stayed for about half an hour. Dove at a squirrel, but missed. He stayed quite low in the trees, and was not at all bothered by me with a camera. So, I tried to get some woodworking in this post, but it’s mostly birds. Maybe next time.

juvenile red-tailed hawk

 

start at the beginning

The stock for most of my work is riven, or split, from a freshly-cut, or “green” log, usually oak. To get wide panels used in joinery, a large diameter log is best – I like them at least 2 feet in diameter. Here, the split is begun by driving two steel wedges into the end of the log. 

wedges splitting white oak

Once the split is open enough, a large wooden wedge is driven into the split – this really does much of the work of opening up the log.

driving a wooden wedge

 

 After splitting the log in half, one half is again split into quarters, then eights & so on. These are then worked into boards in the shop. This radial splitting results in the width of the board being along the medullary rays of the log. This gives a board that is very stable, there is minimal shrinkage across the width of these boards.

eighths and sixteenths of white oak

Wider stuff is split the thinnest, and used for panels or parts for carved boxes. These splits are done with a froe & club. The froe is wedge-shaped, but not sharpened. Once it’s embedded in the stock the handle is twisted to advance the split.

I hold larger stock in a “brake” – in this case, a wooden tripod. The brake serves two functions; it traps the workpiece at a convenient height to work from, and also allows me to exert pressure this way or that to manipulate the split if need be. If the split is going astray, I flip the stock in the brake, and apply downward pressure to the heavier half.  This will often bring the split back on track – when you have a good quality log, and things are going well.

using froe to split panel stock

So these are the first steps I take to get the stock into workable sections that I then take into the shop to work with a hatchet and various planes. I try to only work one quarter of a big log at a time. This leaves the remaining stock in as large a section as possible, which helps keep it from drying too fast.

riving brake