Thursday, September 10, 2009

First Light XLIII

43rd installment, must...gasp!...complete....project....

For previous episodes, please take a look to the Blog Archive at the right of the page.

Lots of links in the post for you today folks - if you see something underlined, it's a link. I'm nearly there (something I've been saying every day the last week) with this lantern build. A few months back, a Japanese gardening specialist on a certain forum shared with me his opinion that I should try to meet a price point for a garden lantern of about $129. How close have I come? Let's see, materials have run about $500 altogether, so....

Anyway, enough crazy talk. I've got a few new photos of progress to show, today's topic being 'fixing pins'. The word for 'pin' (here, not in the sense of a sewing pin) is sen 栓. This character, if I might explain just to fill out the picture a bit, is composed of the radical, or identifier of 'tree', '木', compressed on the left side of the character, and then the part on the right: '全'. Given the radical, the character clearly has something to do with wood or trees. The part on the right, '全', was originally composed of jewel、'玉' , with a cover, '八' on the top of it. The meaning of '全' was a covered container filled with jewels. This came to have the modern meaning of fill. The character sen 栓, means a wooden plug, stopper, or bar. It does not however mean 'plug' in the sense of a repair patch, often called (pejoratively, it seems to me) a 'dutchman' - this type of plug is however given a different term in Japanese, and I'll cover that some other time.

So, I was working on some sen, of various types. You might say I was coming to my sen-ses (couldn't resist), the first of which I will describe are the hi-uchi sen, or 'flint' bars that fit into the lantern housing wall plate. The mortising for these was described a dozen or so posts back. The sen I made out of Bloodwood, and here's one half of a pair slid into place in the corresponding oblique mortises, the pins themselves traveling along a double, or compound slope:

Then the other one slides in alongside the first:

The sliding of one wedging pin against the other gives rise to the term of 'flint' for these types of pin, given that a flint is struck with sideways glancing motion. That's my theory and I'm stickin' with it.

Here, the second one is now driven up tight:

The inside corner view:

All four corners complete, save for trimming the pin ends a bit more neatly, which can wait a bit for the time-being:

Another task on the list was chamfering the corners of the main post - I removed 90% off of the material using the router, then applied my 45˚ chamfer plane:

And then time to make the central drawbar sen. After making various pieces, I have been finding the Bloodwood a little prone to fracturing, to I thought to use something even tougher for these important pins, since they serve lock the lantern housing down to the supporting bracket complex and the support post. I therefore went extreme (uh-oh!), getting out some lignum vitae, the hardest and densest wood on the planet. Wonder Twins, activate!:

This wood is now banned for trade (due to habitat destruction) and is generally unavailable. When it is for sale in North America it is therefore a pre-ban import (or an impostor from Argentina), and it is often sold by weight, instead of board measure. Yes, that means that it is a tad pricey. I bought some 30-year old stock up in Canada, 4 pieces, about 10 years ago and have been hoarding it in, ahem, an undisclosed location, well-fortified and guarded by highly-trained commandos.

'Lignum Vitae' translates from the Latin into 'wood of life' (a reference to the medicinal properties of the tree's resin)- however the botanical name is Guaiacum officinale (the National flower of Jamaica) or Guaiacum sanctum (the National tree of the Bahamas). This tree is a member of the Creosote Bush family and has beautiful flowers with pentagonally-arranged petals. In the JANKA hardness rating system, where the relative hardness of various woods are ascertained by the means of measuring how much pressure it takes to force a 0.444" metal ball halfway down into the surface, Lignum Vitae comes out at the top of the list, at some 4500 lbs-force (lbf). By comparison, Red Oak rates only about 1300 lbf. That's right, it's more than 3 times harder than oak. The only wood even remotely close to lignum vitae is Ipê (tabebuia spp.), a wood from an overlapping geographic region to lignum vitae, which comes in at a mere 3600 lbf.

The two species of Lignum Vitae are similar in working properties, however the officinale variety is called 'true' lignum vitae, while the sanctum is termed 'bastard' lignum vitae. The only difference between them is in colour, the 'bastard' being a dark muddy green with dark brown tones, while the 'true' is a more pure green hue. The stuff I have is the 'bastard' variety. I'm SO illegitimate here folks -it's really embarrassing!

So, here's a picture you likely won't come across very often - lignum vitae being planed:

Most pieces of worked Lignum Vitae I have seen have been turned on a lathe - goblets, cups, balls, bed posts, and so forth - not planed or joined.

Len Brackett at Eastwind told me once that he took a block of Lignum Vitae along with a plane blade to a local dai-ya san (plane block maker). When he came back a week later to retrieve the competed plane, the dai-ya san told him, in reference to the wood, "never again". Hmm, sounds like the dai-ya must have had some fun chopping the mortise for that blade....

Here's the shavings of lignum vitae:

The resulting surface was pretty reasonable, however do note the characteristic rowed (interlocked) grain:

So was my plan to dimension this wood by hand plane? Not on your life. It's akin to planing stone. I was going to work it with carbide and my router. I thought it would be educational to have a go at planing it, but let me tell you, this stuff is very very very hard. As soon as the plane gets a little bit dull, the blade wants to ride up over the surface. I think the way to deal with it would be with a plane set to around a 60˚ bedding angle, along with a lot of scraping. I have a wide enough piece of Lignum Vitae -about 12" - in my small collection that I could conceivably make a small frame and panel cabinet out of it. It would be a piece that would literally last forever.

Lignum Vitae is very high in resin, and has self-lubricating properties as a wood. It was used historically for applications where conditions are wet and there's lots of wear and tear. Places like sailing ship belaying pins, sheaves, rubbing plates - even early nuclear submarines had this wood, employed as guide blocks for the propeller shaft. Apparently it outlasts bronze 3 to 1 in such applications. It also finds use in hydroelectric dams for guiding turbine shafts, and even in some early air conditioning equipment as a fan blade bearing material. That's how it was used - of course, in an area of manufacturing excellence such as we live in nowadays, where planned obsolescence is the mantra, such materials are undesirable. The rational product designer of today certainly wouldn't want to employ materials that outlast 'x' by 3 to 1 - good god, no! That's completely wrong. You would want a material that looked like material 'x' but only lasted until 5 minutes after the warranty expired. And preferably made somewhere with the absolute cheapest labor.

Anyhow, I'll try to stay off my soapbox for the moment - however I do encourage readers to check out the link above - I was especially struck by the following comment:

"Packard divided planned obsolescence into two sub categories: obsolescence of desirability and obsolescence of function. "Obsolescence of desirability", also called "psychological obsolescence", referred to marketers' attempts to wear out a product in the owner's mind. Packard quoted industrial designer George Nelson who wrote: "Design... is an attempt to make a contribution through change. When no contribution is made or can be made, the only process available for giving the illusion of change is 'styling!.'"


Just for fun, I thought I would try a ripping cut with my ryoba:

I got about 2cm into the piece and then thought better of the idea. Saws must have nightmares about such torture. Leads me to wonder how this wood was worked from the log in the 1800's....

So, onto the part where I regain my sen-ses - I worked the lignum with a spiral carbide bit in my router table, first bringing each piece carefully to dimension:

I found the wood worked very well with the solid carbide spiral router bit, no burning or chipping, and it's very stable - it didn't move at all as I removed more than half the material from each blank. A 0.5" square section of this wood is incredibly stiff - I can barely bend it at all!

A short while later I had my two pins cut out:

I found the fine shavings my router bit produced, when alighting upon my skin, resulted in a mild rash:

Note taken for future reference.

Here's the head of one of the sen:

I radiused the neck of the pin's head so as to reduce the opportunity for a crack-precipitating stress riser. Probably over-kill, I know.

Well, folks, I've reached my self-imposed limit of 15 pictures per posting, so I'll conclude this look at making sen in my next post. Thanks for visiting.


  1. I only got 10 pictures out here in Idaho. Another great post Chris

  2. Hi Charlie,

    hmm, only 10 pictures you say? Were there blank spaces then for the other 5? Would re-loading the page help?

    Oh, and by the way, have you had any luck at getting your computer to read the Japanese characters I sprinkle around my postings? Is it time for a newer computer Charlie?

    Glad you enjoyed the read.



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