Farewell, Greenhouse 1.x

The old greenhouse collapsed this winter. It was not entirely a surprise, and I am astounded that it lasted as long as it did. So I finished it off today.
When you have what I call a direct-plant greenhouse -- that is, you plant directly into the soil inside the greenhouse -- you must rotate the location periodically. If you don't, the soil gets exhausted no matter how well you fertilize. There is something about fresh air, or maybe simply the pull of the seasons. See Eliot Coleman's invaluable books. Last year the greenhouse did not do well. It was an old sandbox, built by the previous owners of Chalupy acres. The rotation was overdue. So I have a new design in mind, Greenhouse 2.0, but I refuse to comment on it until I get it built. There is a Venezuelan expression for this: pava. This unique expression (means litererally "female turkey") means something like bad luck, jinx, hex. So it is pavoso to comment before the thing is up and running. Me, superstitious? Never! As an old friend of mine used to say, of course there is no such thing as witches. But nevertheless they fly (las brujas no existen, pero de que vuelan, vuelan!). Thanks, Kotic.

Anyhow I tried to dig postholes for GH 2.0 but the ground is frozen 10 cm down. I amused myself and indeed got some work done with my new toy, the grape hoe. But that is another post.

Bare Ground!

Readers in more temperate climates may wonder what the big deal is. But up here in Willow, this is major news stuff. We have bare ground along the driveway!
That brown stuff is bare ground. We haven't seen it since October last year. As you can see there is still a lot of the white stuff, AKA snow, but it is actually melting. I drove to Anchorage this weekend; from Big Lake south there are just a few patches of snow; none in Anchorage. Gosh! Golly! The ground, of course, is frozen after a few cm deep. But we are getting there. My shop door is clear; I can get in without ice axe and shovel. Double gosh and golly. And I got into my driveway today without engaging four-wheel drive. Triple gosh and golly. It happens every year; one would think one could come to expect it, but it is always a minor miracle.

Time flies while you tie flies

An absorbing way of waiting for the snow to melt is to tie some trout flies. So I went upstairs and fished up, so to speak, my fly-tying gear. I haven't done this for quite some time, so I was a tad clumsy at first, and even at second. However, we began to get some results eventually.
The little bench I built in Juneau holds most of my tools while I tie. You can see the vise on the right (I'm left-handed), the bobbin and assorted scissors, clips, and other strange devices. Not shown is the enormous collection of stuff you need to do a fly, all with exotic names -- dubbing, hackles, marabou feathers, peacock ditto, strange furs, dubbing, ad infinitum. Not to mention hooks in various sizes. And of course a book or two with the recipe for the fly. I have a very nice book, written for beginners like me, with lots of pictures; it's Skip Morris's Fly Tying Made Clear and Simple.

All in all, a pleasant way to spend your afternoon. And it reminds you that sooner or later the lakes will melt, and I can go fishing. I'll do some more on the subject, but just a little worn out right now.

Chasing rainbows, er, threads

And so, driveway out of the way, I can return to chasing threads in wood. I am making progress, I am glad to say. It may not look like it:
But we have a distinct thread to the left of the picture. The right side looks like a porcupine. So here is what I have learned. One, you need to turn down the right side of the cylinder, maybe 2-5mm. The shoulder gives you a reference point to start. Two, take your trusty lead pencil turning tool and use it to establish a passable pencil thread. If you mess it up, just sand it off and try again. Three, you need a tool rest with a square top. The rounded things supplied for wood turning work very badly, if at all, and this is because the chase must be horizontal. Four, any hesitation is fatal. If you stop you will make the chase into a form tool. Pretty sometimes, but useless. Five, when you have successfully done a pencil thread you have a very good idea of how fast to go. For my 2mm pitch, the whole thing takes one second to do a few cm of thread. Six, again a virtue of the pencil, just follow the pencil for the first try -- striking the thread, the chasers say. Seven, on subsequent passes it is easier, but you have to catch the thread just right. The turned-down section is a great help. Otherwise you will cut another thread and that is not easy to fix. Once the thread is deep enough the chase pulls itself along.

On my next try I munged up the start, but the last bit came out very nicely.
The pencil strikes again. I have a highly improvised rest -- a hex key (Allen) wrench clamped in the (metal turning) tool post. But it has a flat top. Mandatory, I think. Got that trick from the late Tubal Cain, Simple Workshop Devices. Mr Cain (T.D. Walshaw) did chasing on his trusty Myford screwcutting lathe, and started the thread by the simple expedient of setting the Myford up to screwcut. All he had to do was hold the chase! But, he said, it is much faster than doing it in the standard way. On subsequent passes he would chase in the usual manner, and the whole thing was done in a few minutes.

I am simultaneously debugging both my technique and the chase. Not advisable, but then nothing ventured, nothing cut. Also the material is far from satisfactory. It is lilac branchwood and far too green. So it chips out. I am also certain now that this can be done on the pole lathe. In fact it may be easier because the pole lathe does not rotate quite so fast. I have the Taig slowed down to the max. Or to the min, to be more exact. Another lesson is that the smaller the pitch, the easier it is to do the thread. That is because on a 2mm pitch the whole thing is done (or munged up) in one second, two at most. Slow speed good, small pitch better than coarse.

I need to try the pole lathe. This summer I will consider uprights so I can bring the lathe in come Fall. Meantime... My shop is a mess; all the outdoor tools are in it and I really have no room. But any day now the snow will melt. There are now bare ground patches on my driveway.

Tap tap and die die

All right, time to get back to cutting threads in wood. My chasing efforts are at a standstill; I need to get back to them but today, I took the snow shovel and managed to open the shop door enough to get in. I retrieved my tap-and-die box set that I bought some time ago from Garret Wade and had a go at cutting threads via commercial means. I must say, if you have but occasional threads to cut and some spare change, this is the way to go. It is not cheap. I had a look at Garret Wade yesterday; they are actually cheaper than they were a few years back; a set (tap and die) will set you back about $50 US. The kit comes in two parts, a tap and a die box. Let's look at the die box first; this is used to cut the bolt -- the male thread. I happen to have the 3/4" set, 19mm in reasonable units. The die box is a large piece of hardwood. It comes apart by loosening some screws, and we behold its innards:
So this guy consists of a threaded insert -- Aluminum by the looks of it -- and a cutter. The cutter is a square section bar about 5mm thick, filed (or more likely, milled) into a 60 deg triangular section. A V-gouge, in fact. It is sharp (although like all commercial gadgets it can use some attention) and it overhangs the threaded insert by an adjustable amount. It is held in by a brass fixture which can be loosened to allow adjustment. In the foreground a commercial 3/4" dowel with the first attempt to cut threads on it. It worked, sort of, but it wasn't very neat. It required inhuman amounts of force to get the cutter to cut. Oh, yes, there is another piece to this thing; a wooden block with a hole in it. It is used to guide the dowel for the first cut. Good idea. But once I have some thread cut, like two turns, I prefer to take the block off so I can see how the cutter is doing. The adjustment of the cutter is crucial. Took me a morning to learn, but eventually I got the hang of it:
Really it's just like any other tool. If it cuts a long, uninterrupted shaving, it is properly adjusted. If it's too far back, it won't cut at all. If it's too far forward, it will jam. So you adjust and re-adjust. Extra factors are the exact diameter of the wood , the wood itself, and no doubt the aspect of the Zodiac. No wooden cylinder is an exact cylinder. Metal, maybe. Above a lilac branch. I turned it to about 18mm ( a tad undersize) and it worked much better than at the nominal 19mm. But we have a screw, Houston. How about a nut, Houston?

Well, to make a nut we drill a hole and run the tap through it. But how big a hole? Can't drill it nominal (19mm) -- tap would just slide through. Enter the tapping equation:

Tap hole diameter = Nominal Diameter - Pitch.

Needless to say, the only information with the kit is the "Made in Taiwan" label. Boo to Garret Wade, who usually do better than this. A little work with calipers says the pitch is about 2mm so 19mm - 2mm = 17mm which is as close as makes no nevermind to 3/8". And I do have a 3/8" Forstner bit, so to the drill press we went. And then we ran the tap in.
As with any kind of tapping operation, the hard part is to get the tap square to the nut. Once you do about two turns, you're in (literally). Another view shows the tap handle and the whole setup:
The nut is held in a vise clamped to the table. When you are turning even a measly 19mm nut, the amount of torque required (note tommy bar on tap) is considerable. I actually split several nuts before coming up with the above setup.

And grand finale (music, Maestro, please): does it fit? Well...
... yes, it does. I admit to having done this before. The bigger the diameter the harder it is. So before you build your Olive Oil (or Grape) press, perhaps you should do a 12mm jobbie first, and work your way up. But it was a pleasant way to spend a breakup day. Too cold to go out, too muddy to walk! Cut threads instead.

Breakup, episode II

I am almost afraid to say it. Breakup seems to be here. I walked down Bery road today and beheld the following sight:
Bare ground! Haven't seen that since last fall. Could it be that breakup is really here? When I went out, the temperature was -5C so everything is frozen. But by 2PM it was +12C! Amazing. You could not really prove it by the state of my driveway, though, as the following image shows.
I am an avid thermometer-watcher (also barometer watcher; after all, I am a sometime meteorologist) and I have noticed the dramatic rise in temperature in the afternoon. So, being a trained scientist, I developed an hypothesis. (Those readers who think the "h" should be sounded may read a hypothesis. But Sir Isaac Newton wrote "an hypothesis" and so do I). To wit, my snowblowing troubles might be diminished if I blew snow in the afternoon, say around 2PM. Then the sun would melt the surface layer, and the snowblower would not rise up on its legs and try to ride over the crust. I hate do do strenous things in the afternoon, preferring the early morning for all exertions; but this seemed worth a try. So out came Horatio. To my never-ending surprise, my hypothesis was correct. The scientific method strikes again. I blew out the "loop" -- the place where I get the car headed out the driveway again -- with only minor troubles and no breaking up the crust with a shovel. One more bit of edging to go. Tomorrow's job.

Of course if you wait long enough, Mother Nature will do the job for you. But I like having the driveway clear, and it will clear up a lot faster if it's blown out. Less snow to melt for Ma Nature. Ma is definitely on her own schedule, and we mortals must adapt.

Maybe real soon now I can get back to making screws in wood.

Chasing threads, adventures and misadventures

It has been a hard day. I spent an hour and a half blowing snow and am not much further ahead. It would be great snow for making an igloo. It froze last night, and you can cut blocks from the stuff. But trying to blow it away is another matter. Well, such is life in Alaska; let us return to screw cutting. In this episode we have my adventures in thread chasing. We saw the chases under construction. Look like a saw and a chisel got together. Now, in principle, this is simple. Let's suppose you want to cut an outside thread. So you move the chase along the work so that it scratches the surface of the cylinder that you have previously turned. Ah, but at what speed do you move it? Why, at the speed that gives you the proper pitch. My learned books (and this article) say this takes some practice. It sure does. Very hard to find the right speed. It is fatal to stop or hesitate. It is also hard to cut to the right depth. This is called "striking the thread."

My first attempts at this operation were disastrous. In one morning, I converted half a dozen cylinders into porcupine look-alikes. Nothing even remotely like a thread. Eventually, I got an idea. I took an ordinary lead pencil and used it on the tool rest; and yes, I'm using the Taig. About 30 cm of snow between me and the shop right now. However, this would work on any lathe. In fact it would work better on a pole lathe because it doesen't rotate quite so fast.
Picture a bit blurry, sorry. But you move the pencil along the rest until you get a uniform pitch -- and the pitch you are looking for, in my case 4mm. When a thread varies in pitch along its way, or crosses over, it is said to be drunk. My first attempts weren't just drunk, they had the D.T.s! But if you, er, munge it up, no problem: take a piece of sandpaper and get rid of the pencil marks. Much better than making porcupines. Eventually I started getting decent pitches:
Now we have an idea of the traverse speed. The smaller the pitch the slower the traverse. You can verify this with the pencil trick. A 4mm pitch is really too large, but having filed my chases I must use them! So I turned up a bigger cylinder, did a few "pencil tries" and screwed, so to speak, my courage to the sticking point. Lady MacBeth would be proud of me.
And, by George and Lady MacB. we have struck a thread. The next job is to chase it. One must put the chase in exactly the set of grooves you have stuck, and traverse accordingly. At a 4mm pitch, it is a matter of seconds. I suspect you are looking at an apprentice porcupine. But we persevere. It's fun, too. The depth is crucial. You want to scratch at this point, not cut. Unfortunately at this point the work leaped out of the 4-jaw chuck so I have to recenter it. This is easy on metal but harder on wood, because wood compresses. Moral: when you chuck an irregular piece of wood, label it with the jaw of the lathe. I always label my jaws, but sometimes forget to label the wood with the corresponding jaw. Pole lathe users can disregard this counsel, on account of there are no chucks.

Stay tuned for the further adventures and misadventures of an apprentice screw chaser.