Sunday, February 24, 2013

Depthing the wheels

Once you have cut out your wheels (big gears) and pinions (little gears) the next step is to "depth" the wheels. This is clockmacker-speak for "getting the gears to mesh correctly." As cut and sanded, the wheels and pinions will almost certainly not mesh. Small errors in cutting the gears will magnify.

Now in a clock we have a huge gear reduction, possibly 3600 to one (that is the number of seconds in an hour). This huge reduction is accomplished in stages and that's why we have pinions and wheels. That is why a clock looks so complicated. Every wheel (lots of teeth) meshes with a much smaller pinion (few teeth). And we are dealing with wood, which even in its plywood incarnation is kind of recalcitrant. A clock put together in winter might not run in the summer because the change in humidity swells up the wood and the teeth jam. Brass is much more humidity-resistant and that's why we usually make wheels out of brass. We also make pinions out of steel.

But I am stuck with wood. I am not complaining! I chose the way myself. Now we have to live with it. Each wheel has a mating pinion. I'm following Mr Wilding's instructions and he as built an infinite number of clocks compared to me; this is my first clock. Anyway what Mr Wilding recommends I do.

So above I have very, very carefully drilled holes in the back "plate" (frame piece of the clock). The holes are just large enough to accomodate a finishing nail. I have cut off the head of the nail. And so begins a tedious odyssey. You spin say the pinion, the little gear at the top. At some point it will certainly jam. You look at it with a magnifying glass. If necessary with a jeweler's loupe. You determine what is wrong. In general if you can see ink lines in the gears it will jam. You carefully sand away these lines. It still may jam. You sand away some more. I use my swiss files and lady's fingernail abrasives, AKA nail files, very cheap. Let us be thankful for lady's long fingernails. So there we have one pair of wheel-pinions complete.

Very tedious. But watchmakers have the same problems, only at a much smaller scale. So I am grateful. I only have to  use a loupe occasionaly. I have a really nasty problem on the second wheel-pinion combo. Stay, as they say, tuned.

Friday, February 15, 2013

Sanding wheels on the clock

I continue my last post. Too tired last night to finish it. You will recall that I have to sand the wheels. So there are points where the linisher fails. I decided to make special blades for my Dremel jigsaw. It is an actual Dremel, by the way, and no knockoff; I bought it at the thrift store for $10. The problem with this jigsaw is that it uses pinned blades -- blades that have a cross-pin drilled through them. It will not accept ordinary scrollsaw blades. So we must overcome this. I cut a broken bandsaw blade into suitably sized pieces, and "blued" the ends. That is I stuck them into a propane torch flame until they turned blue. This softens them up so you can drill them.

Once you have drilled them you can silver-solder a pin into them. The pin was supplied by a cut-up safety pin. More than one use for a safety pin. Above we have the Dremel jigsaw. To the right, a proto-blade (ex-bandsaw). To the proto-blade I glued pieces of a cut-up nail file or emery board, sold at very cheap prices anywhere. (Used to buff your fingernails.) So I have a reciprocating sander. I can use this to sand the wheels. Furthermore the blade is at right angles to the wheel, at left. This lashup works like a charm. A little slow, but much better than too agressive. I ground the teeth off the bandsaw piece; I am trying to sand, not to saw. 

I also put a wooden table on top of the Dremel's steel table. This cuts down the noise and vibration by a whole lot. Today I got two wheels and two pinions sanded. This is clockspeak. The wheels are the big gears. The pinions are the little gears. A clock (except for the escape mechanism) is nothing more than a gearbox. Geared way up, too. That is why it has such different "gear" sizes.

Eventually the emery board gets all choked up with sawdust. You can rescue it with "sculpy," a modeling clay sold at craft supply stores. It removes sawdust. very well. But sooner or later I will have to cut out another emery board and glue it in.  Small price to pay. I am glad I built the linisher; it will be useful later. But my $10 Dremel is doing the job just fine right now.

And thanks to Carlo Croce,  q.g., Italian clockmaker extraordinary, for his suggestions on how to modify a Dremel jigsaw. Carlo has a web site well worth visting if you are interested in mechanical clocks. He even has an English version. Stubborn that I am,  I read it in Italian. Errm. What does comunque mean? Consult your handy online Italian-English dictionary. There is also a Forum; you may get to it via Carlo's website. But you have to interpret Italian. I love Italian. Such a lovely language. I wish I was better at it but I'm glad I can at least read it.

Thursday, February 14, 2013

Wooden Clock

The problem with making a wooden clock is the number of things that you have to make to get from part A to part B. So I now have cut all my wheels out on the bandsaw. Now I have to sand these things down to the lines. For this I built the linisher, Topsy by name. Topsy is almost there. What we have to do is find some hose clamps to tie her down.
I had no hose clamps so I used duct tape (the all-purpose Alaska Solution to all machanical problems) to hold the electric drill down and thus allow me to sand the wheels. And pinions. The pinions, being small gears, are a lot harder to sand than the big wheels.
In the pic above, I am sanding the winding ratchet gear. This is a gizmo that allows you to wind up your clock. The linisher worked to spec for this gear. But now we have to do the pinions. They are very small gears that mesh with larger gears. Alas, the linisher does not do them very well. One reason is that the belt flexes. So I need yet another sander.Or YAS if you want an acronym.

So I thought (based on an isnpirational YouTube video) that maybe I could use my $10 Dremel jigsaw. I have some boards made for buffing your fingernails. Useful little files, in fact. If I could adapt them to the Dremel jigsaw I might have something.

But the Dremel sander uses blades held in by pins. "Piolini " if you prefer Italian. So my idea was this. Put some pins into a piece of cut-off broken bansdsaw blade. Glue to this piece some cut-up nail-buffing files, sold at any store for peanuts. Would this work? Real problem is putting the pins in. Which brings up the problem of making holes for the pins to go through.  Also brings up the problem of what shall we use for pins?

The answer turns out to be quite simple. (a) use safety pins for pin material. (b) silver-solder these pins to the piece of broken bandsaw blade.  Drilling the bandsaw blades to accept the pins takes some doing. These are very, very small holes. Less than one millimeter. That is as small as I can drill without extreme measures. But first we must blue the bandsaw blade ends. You will not get a hole through a regular bandsaw blade without bluing it. This means softening it in a flame until it turns blue color. So when you have done all this here is the soldering jig:

Here we have a completed blade, left. The embryo blade is to the right. Note the modeling clay, AKA "Sculpy". Its purpose is to hold the pin still while you solder it. It is very difficult to ensure that the pins are at right angles to the blade. With the Sculpy you can make the pins plumb to the blade.

So we have made a blade of sorts. Now we have to glue abrasive to it, abrasive meaning nail files, so stay tuned for our next episode.

Monday, February 4, 2013

The linisher project

We now have cut out all the wheels for the clock. But now we have to sand them. For this, Mr. John Wilding MBE, FBHI, recommends that I use a sanding belt on my bandsaw. Well, his had one. My chances of finding such a belt for my bandsaw are somewhere between zero and nil. So I have decided to build a linisher myself. This is a narrow belt sander, usually upright. Very useful for many purposes, including knife-grinding. This is a Topsy project. She just growed, as they say.

I started out by gluing up plywood and making two wheels, thinking I would use a screw-and slot adjustment of the tension. I did not think of bearings. I turned up the shafts on the Taig. Put them into holes in the wood. Used a cut-down belt sander belt for the linisher belt. This arrangement did not work. Too much friction. So Topsy began her growth. I soon found I had to add a third wheel for tensioning. And I had to add a rubber band for (insufficient) tension. Furthermore the belt would slip; so I added a rubber tire on the rightmost wheel above. Cut it from a old bicycle inner tube.

I also had to make proper bearings. The thing now runs on brass bearings, bronze would be better but this is unobtainium in Alaska. Had to make the bearings, too. Then I had to remake the stand (a piece of 2x4above ) because it was too narrow and pinched things. So we got to v0.1.

Although held together by clamps this is a much better proposition. I of course have got to replace the clamps! And I have to make a table for it. And... it keeps growing.

However, the trial run worked.
The contraption is being driven by the ubiquitous battery drill. It spins. Topsy, as I call her as of now, is getting there.

But today our fabled snow splitter collapsed. Flimsy nails mostly. So today was spent on salvage. And shoveling snow. Live and learn.

Next the table, and a way of holding motive power in place. She grows.