Wednesday, January 23, 2013

Wooden clock: crossing out. wheels

I am getting used to clockspeak. Gears are wheels. Almost. Big gears are wheels. Little gears are pinions. Axles are arbors. Sometimes arbours, depending on the brand of English you speak. Bearings are pivots. What horrifies me is that I have learned both the Italian and German equivalents to these terms. And so we come to crossing out. For a clock to work, we have to have minimum mass on all the wheels. This makes it easier for the weight, or spring depending on your clock, to drive the stupid thing! So it is a time-hallowed practice, dating from the 16th century at least, to remove as much material as feasible from the wheels. In fact we make spoked wheels. To do this we cannot use a bandsaw. The blade of a bandsaw is continuous and we cannot stick it inside the wheels without breaking it. So I used my faithful jigsaw. I got this contraption at a thrift store for $10. A best buy to be sure.

What you do is drill four holes inside the area to be crossed out. Then you unship the jigsaw blade. You then insert the blade through the hole you have drilled. You then hook up the blade again. This is not as easy as all that. You cannot see what you are doing and must sort of guess where the blade goes. But it is doable. Then you ever so carefully saw out the wheel. You could do this with a fretsaw. But it is an awful lot of work by hand. Above, a wheel all crossed out. Approximately. It still needs to be sanded down to the line. Another wheel on the saw. the escape wheel to be specific. I now have all the wheels crossed out.

The whole thing about sanding down the various wheels and pinions is problematic. John Wilding found a linishing belt for his bandsaw. Good luck with that. Never even heard of one till I read the book. No such nimal at Home Depot (or Lowe's, pr even AHI). So I am now in improvise mode. I am making a linisher. This is a low-profile belt sander. Stay tuned.

Thursday, January 17, 2013

Clocking with plywood

Long ago now, while I was in Juneau, I bought a book by John Wilding, FBHI entitled The Construction of a Wooden Clock. You may google on it. It seems like an auspicious project for the new year. I really want to make a clock; I had the book. It seemed like a nice way to break into the business. It came with full-size templates for absolutely everything. You can, in fact, make the thing out of plywood. You do not even need power tools. You can cut everything out with a coping saw, even. But, after some experience, I would not advise it. There is awful lot of cutting to do, and for once power tools are indicated. Either a bandsaw or a scroll saw or even both,  and even then it is a bit of a via crucis.

So here goes. There are many useful videos on YouTube that will amplify my directions. Look under "wooden clock". The general order of work is this: first, you make copies of the plans that came with the book. Absolutely necessary. If you make a mistake you have not only ruined your piece, you cannot get back to it. Lots of places these days will make copies for you, even in Alaska.

So far I am following Mr Wilding's directions to the letter. He has made more clocks, as we used to say in the Air Force, than I have passed telephone poles. So you find a suitable sheet of plywood. Here I am limited to what I can find at Home Depot/Lowes. We will see how it works out. Then you glue the templates on to the plywood with contact spray. Then you cut the stuff out on the bandsaw. I have no scroll saw.

I began with the plates. These are the frame of the clock. Above, fresh off the bandsaw. This is the front plate. The back plate is identical, but has no holes cut in it. The purpose of the holes is to display the works. The clock would work just as well without them. But if you're building a clock, might as well watch all the gears go round. So we cut the holes in the front plate.

I  used a circle cuttter on the drill press and it was awful. We will either figure out how to fix it or re-make the front plate. Next we smooth
 things with our faithful Dremel.
 Now we have something resembling a front plate. Do the same thing for the back plate. Now we have the pillars to make. This is lathe work. I used dowels and the Taig lathe.
This is relatively simple work. The key points are that the plates have a separation of 135mm and that must be exact. Second, the ends of the pillars must fit through a half-inch (say 12mm) hole in the plates. I decorated the pillars a bit by turning a groove in them. I may get around to making them fancy later.

Next part, and by far the hardest, is to cut the gears. Now clockmakers call these things "wheels" and not gears. So let us use clockspeak. We cut these wheels out on the bandsaw.
This is mind-bending work. It is very finicky. If you did not know what a bandsaw can do, by the end of this clock you will be a bandsaw expert. Mr Wilding gives you very clear instructions on how to do it. Also see numerous YouTube videos. At the end of the day, we have a pile of wheels.
As you can see, I have a lot of wheels done and two to go. The hard part is the teeth, of course. One slip and you have lost the wheel. Or the pinion as the case may be. A "pinion" is a small-radius gear, and that is clockspeak too.

So at this point I have all done but two wheels. Then I have to "cross out" the main wheels. That is clockspeak again, meaning I have to saw out all but the spokes of the wheels. Then I have to sand them. And there is much more, but it will have to wait.

However I am quite pleased with progress so far. I find this bandsaw business quite tedious. But it works. Stay, as they say in the TV biz, tuned.

Thursday, January 10, 2013

A Knife for John

So we continue to catch up with our Christmas projects, which can now be revealed. I made a knife for John. It is a big step. I am going from hacksaw blades (or even a cut-up circualr saw blade) to an old file as raw material. As I found out, there are some bumps in the road, although the principles are exactly the same.

 I started out with a worn-out file. It was annealed overnight in the woodstove. In retrospect it was not enough! But OK, live and learn. I have, since I did this, gotten a book as a Christmas present. It is a book entitled Hardening, Tempering and Heat Tratment by one Tubal Cain, a pen name for the late T.D. Walshaw. You can google on it faster than than I can type in a long ISBN. Priceless. Anyway, I started with this semi-annealed file.
I then ground down the blade to what I thought was a nice shape. I also gave the thing a few touches with a file. This is a full-tang knife. So to handle it I will have to drill holes in the tang to accept the handle. The handle is a more or less straightforward piece of woodworking. I happen to have a few priceless pieces of applewood. I turned them inside out, pith outward, because it looks much prettier.

Now we have to attach the handle to the blade. For this kind of thing we want rivets. I happen to have a bunch of brass rods which are intended for welding (actually brazing) . But I use them for rivets. You cut them a bit longer than they need to be, say 1mm longer, and then whale the daylights out of them with a hammer. They will spread out and hold your handle firmly. Needless to say you have drilled matching holes in tang and handle. These brass rods may reappear again in another role. Stay tuned.

The rest of the knife is the business of honing.  I've been before there on this blog! Try the "sharpening" label. And we must, of course, apply linseed oil to the handle.

Main lesson learned from this project. As if I didn't know it theoretically. The bigger the mass the more heat it needs to work it.  Tempering this thing was a bear. From the book I cited above, I now see what I should have done. However, ignorance is bliss. I got away with it, and it is a very nice knife indeed.

Friday, January 4, 2013

A Christmas Carol, I mean Ulu.

Now all may be revealed. Christmas is over. I have to catch up on my Christmas projects. The first one to appear will be KZ's Ulu. Now an Ulu is a Northern Native knife. I am appalled that I can't give you a label, but I have posted on it before. I now have an "ulu" label. I make my ulus out of old circular saw blades. I will have to repeat some pictures of the manufacturing process. I take an old circular saw blade and cut it into fourths, first removing the teeth. For this I use a circular saw with an abrasive cutoff blade. I cut the saw into quarters, much like a pie.

Now we have to grind the edge on the thing. For this, I use my wet grinder and my homemade ulu-grinding jig.

The jig allows me to rotate the proto-ulu pie slice. If you did not do that, you would simply grind a flat ulu. Not at all what you want. So grind and rotate. Use the angulometer to get the bevel angle, in my case 25 degrees.

Next problem is heat-treating. Circular saw blades are built to take abuse, since that is the fate of a mass-produced saw blade. But as a result they are almost impossible to sharpen. Not what we want. We want to put a real edge on these things. So what we want to do is soften it up a bit. My usual procedure is a propane torch. But an ulu is much too large for this treatment. So I used the kitchen stove instead. A lot more BTU than a propane torch.

Here, I hold the edge of the ulu in the convenient circular shape of the stove burner. Aluminum foil helps keep the heat away from the body of the ulu. I want it to blue, but not to anneal. Tougher that way, you see. I want to temper the edge to "straw" as the books put it. Straw indeed. Looks golden yellow to me. When it gets to the desired color, you quench it in a butter tub full of water. The ulu is still held in its grinding jig. This makeshift arrangement actually worked. I got a tempered edge and a blue body.

Next step is to put on a handle.
In KZ's case, there is a totem pole handle carved from an oddly-shaped birch sapling. I created her totem pole. This was a straightforward piece of carving;  I enjoyed it as a big change from all this metalworking stuff. Note the edge protector. Very important to have an edge protector.

The last step is honing the thing. I use my Lee Valley diamond hone for this job. It may be tedious but it is necessary. A dull tool is dangerous, period. I was very pleased with the bluing on the upper part of the ulu. Exactly what I wanted.

I made a similiar ulu for Fluffy, but I did a turned handle for it. I turned it on Polecat, my trusty pole (bungee) lathe which I documented before. Fun. Lovely turning, too. I forgot to take a picture. I think making ulus is a great game. Furthermore ulus are useful. I chop almost everything with a ulu except when I emulate Jaques Pepin. Then I use a 30 cm chef's knife. That is a better slicer, but the ulu is a better chopper any day. Those Inuits know what they are doing. In Point Barrow they flense whales with ulus; only much bigger than mine.

By the way, the pattern I use is the so-called "Fish River" pattern. I do it because it is less work than other patterns. If you google on ulus you will find various learned works on ulus. Happy ulu new year!