Wood: trestles

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On Sunday I borrowed a friend’s woodworking shop to produce a couple of trestles for a table. They sort of look like sawhorses, but they’re not. They’re intended for lighter duty than that. I still have to produce the top of the table, which will have two bars or cleats on the bottom to help lock the table and the trestle together.

These are based on a medieval design produced by the St. Thomas Guild, a medieval reconstruction group in the Netherlands. They are pretty modern, though. I’m trying to decide if I want to add in the fancy carving and tracery work to them. I know how to do that work, I just don’t know if it will be worth it in DIY shop pine.

Some things to think about —

  • Adding a second board across the bottom for stability would help these trestles be less wobbly.
  • Adding a wedged mortise to the top cross-board would also make them less wobbly
  • Adding a cut-out to make the triangles more like a pair of legs would add stability, as well.
  • The table-top will have to have two cleats or bars on them, to slot into spaces at the top of each trestle.
  • Adding some pegs to the bottom of the table top; or to the top board, that slot into the table top, would also improve stability, generally.

There’s a lot of things to think about.

In general, though, I like this idea.  The trestle table has some serious advantages for me, in that I can take the table up or down as needed, and have the flat surface or not as I need.

Additionally, in reviewing the St. Thomas Guild website, I see that I can design this table top to do many things that may help it be quite portable or adjustable.

Table Top DesignMy initial thinking resembles something like this — a kind of construction known as “frame and panel” (which I’d like to learn), with four types of members:

  1. Dark green outer frames, with one groove and three mortises.
  2. Internal ribs, with a tenon on each end and a groove on each side (purple)
  3. four panels (mottled blue) with a tongue carved all the way around them.
  4. Two internal frames, with three slots and a groove (light green)
  5. Four outer frames (yellow) with tenons on each end and a groove on one side.

The blue panels thus fit into the groove on each side.  A quartet of hinges join the two inner frames to one another, so the table can fold flat and store more easily;  or be arranged to provide a wide or narrow table as needed.

I may have to rebuild the trestles to accommodate the larger table surface. But my understanding is that panel and frame construction is fairly lightweight, and this might do quite well for my general needs.

Dimensions of the surface still need to be worked out.

 

Magic: chops

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Owl chop

I recently read Benebell Wen’s brilliant book The Tao of Craft after hearing her on Gordon’s show.

One of the things that really caught my attention in the book was the idea that a Fu sigil or talisman should really be signed and sealed — that is, in the same way that a decree from the emperor would be signed and sealed, a Fu sigil carries the authority and mark of the creator. I explained this idea to my partner, who thought it was equally interesting. And so I decided to make a chop — a seal stick — for her, in part as practice for making my own. Which is part of the reason I made that captive ball a few days ago: I want to get better at wood carving, because it’s a useful skill to pair with woodworking generally, and because it will be a nice fit with the automata work I intend to do when the woodworking shop is up and functional again.

My partner frequently uses an owl as her emblem, so I went online and searched for how to carve an owl. This isn’t the one that I used, but it’s close enough — a series of photos of an owl carving.  I used basswood, because I don’t carve jade or soapstone (slightly different and sharper tools, more patience and care required); and I had the tools for this already. It’s a fairly simple procedure to carve an owl. It was also fairly simple to reverse and cut the runic-style emblem my partner uses for her magical sign, into the base of the chop. Except, I still screwed it up — and I’m going to have plane the bottom of her chop flat, and then cut it again.  I don’t have the tools out to do that yet, butI can certainly do something else while I wait to make that set of tools available.

img_3232From there, it was fairly simple to find a procedure for carving a bear. His advice about frequent sharpening is good — I sharpened my cutting tools about six times in the course of carving the bear, and I still wound up using too much force and chipping his right arm off.   I chose to do a statue against a pillar for my bear, because I want to have a place to practice chip carving, on the back of his pedestal; I already completed the small chip-carvings around the base, and I cut my own version of an emblem into the bottom of this seal.  I still think this won’t be my final seal, for me — the missing arm is a bummer.

So here we have an object that shares kinship with a magical-scribal-calligraphic tool from Chinese Taoist magic: a seal. But it’s carved in a Western style, with a Western character sign that indicates a person. And it could be used in western magic to do the same thing it does in Taoist magic: sign and authenticate and command the results in the name of the practitioner.

Is it cultural appropriation — Or cultural inspiration— to draw on the techniques and tools of other traditions to add to and build to the existing Western tradition? Ironically, I think this is part of the reason why I broke my bear at the last possible moment… because the character on the base of my chop is one I chose for myself from Chinese characters a decade or more ago.  But it’s not my emblem to use, nor my tradition. And so, this one is broken, and I’ll have to make it again.

But I still think it showcases what’s possible, what’s within the realm of workability.  The folk tradition of carving already exists in the West; the tradition of ‘enlivening’ statues and statuettes has been part of Western magic since Egypt; the idea of a personal seal to accompany a signature has fallen out of favor in the last two hundred years, but there are still signet rings in the Middle Ages, the Renaissance and early Enlightenment periods… and we have evidence of signets or seals all the way back into Babylon and Sumer, at least.

Maybe it’s time to re-awaken the idea of a personal seal.

Wood: captive ball

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Stage two unlocked!

One of the basic exercises for woodcarvers is the creation of the Captive Ball, or Ball in a Cage.  Usually carved of a relatively soft wood like this basswood at first, then moving up to more complicated materials, the idea is to improve both knife and safety skills.

I only managed to get one small cut on the tip of my index finger while making this.  No bleeding — just a nip of the blade and a small pain.  When woodcarving, it’s difficult to aim the blade away from oneself the whole time; therefore the blade needs to be extra sharp so that you avoid trying to force it.  Chip Barton, the master woodcarver, explains in his book that you should sharpen your woodcarving tools at a fairly steep angle, first of all; and second that you should use a coarse stone, a fine stone, and then sandpaper mounted to paint stirrer-sticks at 800 grit, 1500 grit, 2000 grit, and 2500 grit if you can find it.  I made a set of sticks like that, and it was awe-inspiring how sharp I could get my blades; with practice, I’m sure I can get them even sharper.

Sharp tools are scary to some people, and I suppose with good reason. The assumption is that you’re at greater risk from a sharp tool, because it will cut deeper into the person holding it during an accident. But dull tools put one in the mindset that more force needs to be applied… and so there’s this Catch-22 (as in the novel by Joseph Heller) — a dull tool inspires its user to apply more force, which increases the likelihood that the tool will break or slip, and cause an injury; a sharp tool cuts more cleanly and carefully, and so less force needs to be applied… BUT, of course, the act of using a very sharp tool gradually dulls it. Which means that as the user gets tired, the tool is also getting ‘tired’, and the chances of an accident rises with the length of time one works with hand tools.

Glue failure

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I went into the woodshop the other day to find that the boards on which I’d lavished so much attention cutting dovetails, had light showing through where they’d been glued.

Broken


Either the change in weather summer to autumn, or the change in humidity, or the failure to move this project along at a fair clip, or something like that (maybe my failure to use biscuits or pegs?) has split several boards along the glue lines. 
Argh. 

A few quick tests revealed that all of the boards’ glue seams were problematic. Either the boards were warping or the glue hadn’t properly dried or the glue had taken on extra moisture or … I don’t know. Lots of potential difficulties here. 

So, I disassembled the boards. Later I’ll cut off the dovetails and pins, sand the edges smooth and try again. 

Cutting Mortises

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This morning I cut mortises. I broke my last coping saw blade for wood while cutting dovetails last night, so i shifted over to work on a shelf for my reference books for woodworking — partly so all the books I have (and borrow) stay in one place, and partly so I don’t buy more books than I need (like that will stop me!).

Each shelf will be held in place by a pair of mortise and tenon joints. You can see in this first picture where I’ve drilled out the holes for the mortises. I wound up cutting six mortises today, much more cleanly and square than you see here.

mortise is a hole in a piece of wood, designed to be square (or at least the right shape to accept) to a matched tenon, or integral peg, in another piece of wood.  In furniture making, mortise and tenon joints are usually used in furniture intended to be collapsed for travel; it’s very common in medieval furniture where kings went on progress between manors, for example; and a lot of modern furniture built for the Society of Creative Anachronism (SCA) is similarly mortised and tenoned.  A secondary mortise is usually cut in the tenon, as well, to hold a wedge-shaped peg.  I plan to do that, too.

I had initially planned to cut all six mortises on each shelf upright, and the four on each of the three shelves, by hand.  But one took an hour, and so I drilled the other five out on one shelf with a powered drill press.  I plan to cut the other six mortises with not-just-a-drill-press but also a Forstner bit, to remove more of the waste material much more cleanly and faster.  The shelf panels are 3/4″ wide board which is nominally 1″x10″ (really 3/4″ x 9 1/2″-ish… even the 1/2″ isn’t accurate over the length of the board.)

The design of this bookshelf is pretty easy, really: it is three shelves with tenons— a tall shelf on the bottom for tradesman’s paperbacks and Popular Woodworking hardcovers; the middle shelf serves for hardcovers and trade paperbacks; and an open shelf on top for whatever happens to come my way. The three shelves are each half of a 6′-long board, and the verticals are also each a half of a 6′-long board.  The pegs in the tenons are going to be bits of 1″x 1″ square doweling cut and shaped to fit the holes; I may drill in screws or nails to hold bits of brass chain to hold the pegs, so the pegs don’t get separated from the uprights during transportation.  I plan to cut the tops of the uprights into a gothic arch, and maybe in the long run add some decorative carving — both to improve the look of a simple pine bookcase, and to reduce the overall weight of the parts.

I think my biggest challenge is going to be getting the mortises on the second upright cut so that the shelves lie mostly parallel to the floor and square.  Cutting the mortises in the shelf tenons will be relatively easy — I can drill out the waste and then use a chisel to make them mostly-square; the use of a peg there will help hold the shelf together, but so will the weight of the books on the shelf itself, as will the tension and pressure provided by the pegs.  I may have to add a secondary diagonal brace of some kind, but I have some ideas on how to do that; but most shelf designs like this don’t seem to need them — the three shelves themselves help keep things tight and square.

I did cut one end of one of the shelf boards with the tenons, and managed to fit them into the shelf mortises. They fit, but my tendency, I see, is to cut the mortises too wide and not high/tall enough.  I’ll have to correct this in future iterations.

Yarn winder

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The devil is always in the details.


Here we have the yarn winder, mostly sorta but not really working. We’re like, 77% of the way to working. But the act of trying to get to 100% operational is breaking the machine down even as it stumbles toward completion. 

It’s possible that both the first and second Death Stars in Star Wars blew up, not because of the actions of a brace squadron of resistance fighters — but because they were overdesigned technical marvels that failed at their first test firing. Even an empire as vast as a galaxy — especially an empire as vast as a galaxy — can build a non-functional superweapon that destroys itself on ignition. All the other empires so far that have built superweapons have done the same; why not assume the same of the Galactic Empire?

How do I extrapolate that from a yarn winder?

Simple. Gears are required — by the laws of nature, mind you — to be a particular shape. Why are the teeth of a gear on a Colonial or US Civil War-era mill so exact, so huge, so regular? They were ground that way by the first six months or so of operation. The engineers who built them over-engineered them, and then let nature do what nature does — which is grind down and wear away things that are even slightly unfit for their environment. 

And so, as I test and shape the gears of my yarn winder, the plywood chips away and the teeth get narrower and the profile of the gears gets sloppier. In time one of the teeth will break and I’ll build the whole thing anew. 

When designing, especially for the long haul, the needs of the design must take into account the question of lifespan. In a school program, maybe that’s a week or even two days — the length of the project. But in a machine, it’s hundreds of hours of use.  Maybe thousands. Even as I build this machine, it’s breaking down so that parts will need replacement and repair. 

And it occurs to me that maybe the Sith masters knew this. They derived as much satisfaction and peace of mind from the deaths of millions of life forms on a planet, as on a space station. The ability to destroy planets or planetoids though quality design, or space stations through bad design, equally serves the Dark Side. 

Yarn winder step five

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As I said in the last post, we’re inching toward a working machine.  The photo below shows the machine assembled completely. From left to right across the photo: the yarn feeder arm and wire feed assembly, then the spindle on the 12P gear, then the central wheel, then the crank wheel. Above the machine are two c-clamps used for fixing the machine in place while you wind a ball of yarn. And at the top of the photo are the feet of the yarn swift that will hold the skein of yarn that is being wound into a ball or cake. 

The challenge I’m facing at the moment is that the stem of wooden disks that supports the spindle has to be able to turn freely without being loose. Looseness introduces sloppiness into the yarn ball. Tightness results in the internal arbor catching on a bit of unshaped or misshapen glue inside the tube… and snapping the disks with shearing force. Every single disk has failed now and the column is increasingly made of glue rather than wood.   

I have a variety of options at this point. 1) I can drill and sand out the shaft by hand. 2) I can recut all the disks and sand them individually before reglueing the stack. 3) I can buy a speciality drill bit which is something like 21/64″. 4) I can find a friend who can grind the 5/16″ steel arbor down to 4.85/16 radially/lathe-like. Option 3 is probably best, but I may have to do 2 anyway. 

Sanding the gears is also needful. But my friend and family member Lynn has pointed out that wooden gears over time are often self sanding. Work them long enough and they grind themselves to the optimal shape. Who knew?

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