Termination dust, 2015

I see I have already posted on this phenomenon before, because I have created a label for "termination dust." In order to save you the trouble of searching this blog for that label, I will repeat myself, as Walt Whitman did indeed say.

In the old days, when a prospector's claim ran out, he would start getting dust instead of nuggets in his pan (or whatever system he was using), and this was termination dust. Claim done. So nature gives us a similar signal" summer done.

Unfortunately my zoom feature has ceased. I fear my camera has therefore deceased too. Well, out on the back porch, we can just see dawn, and snow dust on the Chugach range. But there it is. The Fireweed has folded up. The birches turn yellow. Winter is upon us. Part of the fun of living in Alaska. Here in suburbia I can't go out and cut firewood. But we must accept change. The year wheels.

Dividing head woes

Things have been very awry. My clock wheels are in trouble. Fortunately they are acrylic, or I would be out a fortune. Problem is that while some of the teeth look fine, others have flat tops. After pondering this one for a while I finally came to the conclusion that the dividing head is running out. This means it isn't centered. It is wobbling. So let's check.

Observe my new elegant mini-dial indicator holder. It will hold both my Imperial supersensitive indicator (shown above) and a conventional DTI. It is being used to record the runout (wobble) on the wheel, which is is on a mandrel (shaft) held in a collet. These are my wonderful ER collets. They have essentially zero wobble.
 

 'Nother shot same thing, same results. Runout about .002" or about 4 "cents" (.04mm). Uh-oh. The wheel is quite acceptable for clockwork. Time to check the runout on the shaft of the dividing head. This is quite a production. The dividing head is mounted on the mill. This, except for the base, is made of non-ferrous metal, and the indicator base will not adhere. So I had left the vise on the mill. In it I clamped a piece of angle iron, aand the dial indicator will adhere to that!  So by now I had acquired a metric dial indicator, and checked the runout again. Horrors. A whole millimeter!
The runout is all in the shaft of the dividing head.

Then  I took the dividing head apart and checked its shaft. It needed no dail indicator to show it was bent. So I made a new one. I used my steady rest to hold things still. Here I am, parting offf the result. I claim a new method of parting off. I use my Dremel tool holder, one of the very fragile  cutoff wheels, and spin the lathe one way and the work i t'other. Got a nice clean part, and a very narrow kerf.

So the next thing was to do something about this. It is a very small dividing head, so my next idea was to add a new outboard support.  It is an aluminum block. Here it is under construction.

The results on divde head 2.0 are not encouraging. I measure the runout  on the new spindle:

It still comes to 30 cents. While better than a whole dollar it is not very good. Impasse. While I am figuring out what do do about this, I added a new feature to Cecil B. de Mille. Behold my Z-axis Digital Readout.

Just a super-cheap digital plastic caliper, a bit of angle aluminum, and some drill and tap, and now I know where my Z-axis is. Of course I can always use the dials. But the Count himself (on Sesame Street) would get confused  by the number of turns you made. And one turn off is a whole millimeter off. Worthwhile addition.

Big wheels on a small lathe

No matter how large a lathe you have, sooner or later you will come up with something too bigto turn. When I went to module 0.9 on the clock, I calculated the size of the biggest wheel and found I could swing it (that is, get it on the lathe without colliding with the bed). So I said, let us go ahead and do this thing with module 0.9. The following picture is the 50 tooth gears made so far. None of them are stellar. So we foresee problems ahead.

First thing was to cut the blanks out for the midsize wheels. I did this on the bandsaw. The first thing I did was to cut out masonite-type board slightly smaller than than the gear itself. When I put it on the lathe, it was very obvious that the regular toolpost was not going to reach to the rim and cut it. Impasse. Next morning I started designing a fixture that would move the toolpost -- and realized as I did I already had one, the compound slide. The Taig compound is very flimsy, so I usually don't use it unless I have to cut tapers. So up with the compound and success:

plus I have an extra 25 mm (1") by moving the tool to the outside groove.

So the last problem was to make a new dividing head plate. I did this my usual way, with my PostScript program. I used my optical center punch. Then off to the drill press. Just to make sure everything was centered, I used a fixture.

Then I put the dividing head back together and tried some more 50 tooth blanks.  None of them were stellar either. There is something wrong with the dividing head. But that will wait until the next episode.

Change of pace: this year's garden

One of the problems of living in suburbia is the lack of space to put in a garden. Another, for me, was the less than sterling health. But I seem to be unable to live without planting something. So this year, willy-nilly, I put a garden on the back porch.

Front to back, we have radishes, spinach, mesclun (lettuce mix), red leaf lettuce and tomatoes. We have aready picked some of them and they are delicious.

As you see the tomatoes are actually tomatoing. I am not sure they will ripen. But they are certainly happy, and that is what counts.

I suppose I am a farmer at heart.I like to grow things you can eat. Even if my farm is now the back porch, and wait til next year when I will get some more real estate. It is now container gardening time.

We will return to our regularly shceduled clockmaking drama in the next episode.

Life at module 0.9

In the last episode, we nade some lantern pinions. Measurement revealed that they were actually module 0.9. So this is really a  blessing. Since I am making my own cutters, the larger module will be easier to work with. So I am now embarking on the process of cutting the wheels. The first problem is to make the cutter.  I use Dremel 3mm tool shanks from expended Dremel tool cutters. Cheap, and they are good steel. they can be hardened and tempered. I am making a fly cutter, a one-point cutting tool.

Now a fly cutter does not actually cut teeth. What it does is cut the space between teeth. A clock tooth is supposed to have a cycloidal profile. This is the profile generated by a circle rolling on another circle. Yuk. However, this is approximated by a straight cut with a "rounded  over" circular radius at the tip. The radius is something like 1.7 mm at module 0.9.

So as a first task I made a button gauge.

I turned down a piece of steel to the proper radius, say 1.7 mm. I am too tired to go consult my notes in the shop. I drilled two holes the proper distance apart. This was done on the mill, you could never hit it by eye. The button gauge will be used see if I am on target with the radius. There is the problem of depth of cut, but if I overdo this I can always grind it off. Off to the mill.

Here we have an expended Dremel shaft put into a homemade fixture, a piece of square stock with a setscrew to hold it in place. The fixture is clamped in the mill vise.

I have available 3mm, 2mm, and 1mm. end mills. These are diameters. Hmm. If I were to cut 1.7 radius I would need a 3.4 mm cutter. Unicorn. Uncomfortable. But the 3mm guy will go 1.5 mm aand for now that will do. It is quite difficult to center up the cutter. But above you see it taking shape. So I did this. Now we heat it up red hot and quench. This will harden the steel.

I use my handy furnace and water-quench, and then temper, a difficult job on a piece smaller than your little fingernail.

Having done this, we take a test cut on a leftover blank we happen to have. The diameter is completly off, we just want to see if the cutter works at all.

So I mount this random blank on the dividing head and cut a few teeth. The diameter is wacky. But it does work -- i.e. it cuts teeth. Spacing all wrong of course.

Next step is to turn up a proper blank on the lathe. I cut them out on the bandsaw. The scrollsaw would be better, but it melts the plastic so the bandsaw wins.

Now we can cut teeth properly. I did a whole bunch of them. There are so many errors you can make. You can forget to tighten the dividing head, for instance. This will chew the blank. You can forget to loosen the dividing head, which will mean slippage in the gear train. Maybe I should loctite the worm. But I don't want to do this yet.

Anyway, at the end of several days work,  I came up with some wheels.

The leftmost wheel is complete chowder, as Tom Lipton would say. As we go left to right, we see gradual improvement, as I correct my mistakes, so the rightmost wheel is almost usable. But there are two problems. The tooth profile is off. Also the spacing is irregular. The tooth widths vary. This is a problem with my homemade dividing plate. In the next episode we del with these problems.

The saga of the lantern pinions

In a clock, the gears that convert the movement of the pendulum to the movement of the hands are of two types. If the gear  has 12 teeth or less it is called a pinion. If it has more than that, it is called a wheel. The Isaacs clock has 8 toothed gears for the pinions and other numbers for the wheels. Pinions are small fiddly things, about 6mm diameter. That's about 1/4" for the metrically challenged. Now there are several ways of doing pinions. First is to buy a commercial pinion cutter. Messrs. Thornton in England will sell you one, at what I consider an exorbitant price, 40 quid or about $80. Second, make tour own pinion cutter. I am really challenged here, because my mill is a real micro. The largest collet it will take is 3.2 mm (1/8") so the  7mm diameter of the hole in Messrs. Thornton's cutters is far too big for my tiny Proxxon mill. Second, make your own cutter. I looked a lot into this and they are quite a complex problem -- again because I have such a tiny mill. I will deal with this some other day. I can do it, I think, but I will have to rescale a lot of things.

The third way is to make lantern pinions and this is what I did. Essentially a lantern pinion is a very small hamster cage. It is two circles for the side of the cage, and 8 bars to the cage. Eight bars work out conveniently to 45 degrees at a side.

So I made up a wheel divided into 45 degree increments. A production,  but possible. I then used my aformentioned Dremel tool holder to drill the 8 holes. Simple, eh? Not really. First I had to make a mandrel, a shaft that fits into my "crocodile," the ER-16 collet on my Taig. I threaded it US 4-40 because that is the smallest tap and die set I own, about 2.4 mm. Then I had to make a special nut to fit the 4-40 thread and not interfere with the boring of the holes. A standard 4-40 nut is too big. The diameter of the hamster cage is 6.1 mm at module 0.6.

So now we turn up a bunch of hamster cage circles to the proper diameter, which is about 12mm. This can be done en masse, four sides at once. Then I laboriously cut up some music wire into cage bars. Regardless of its name, music wire has nothing to do with music, and worse, it is often called piano wire, although it has little or nothing to do with pianos.

The first result is shown above. It is a valid lantern pinion. It is sitting on top of a ski wax container. I use the ski wax on bandsaw blades and it really helps.

Now I made up an index stop out of an old saw blade and a broken Dremel mini-drill. I have lots of those, they are are very easy to break. The ones I am using are about 0.7 mm but unfortunately the wire is 0,77 mm.
The index stop is saw blade attached to a magnet., super-glued to the saw blade. I works.

And fortunately, looking through my supplies, I found a wire (from Michael's) same gauge as the music wire, slightly less stiff, and far less expensive. And much more obtainable. I have bought out Lowe's supply.

So here is the final mise en scene (forgive the lack of a grave accent). These are the tools I used to make 9 lantern pinions. I should only need 7, but better safe than sorry. There are pliers, of course. Then is my Archimedes drill. This has a piece of music wire in it, which is used as a drill/reamer to bring the holes in the cages to final size. It was quite a feat to grind that thing properly so that it would actually drill.

 There is an 8mm wrench that belongs to the mill. I use it to cinch up the pin vise, the invaluable object on the right, which holds the wire while you get it through the holes. Sitting in the pin vise is the last of the hamster cages.

When it was all over I measured the diameter of the pins in the cage. It was supposed to be 6.11 mm and came out to 7.7mm. Ouch! This is a major blunder. A real Bozo, as Tom Lipton would say. However I think it is a blessing disguised as a blunder. I worked out what the module actually is, and is 0.9 instead of 0.6. I think this module will be much easier to work with. Of course I will be into a redesign of the clock because the spacings will be different from the plans. But since I can calculate all of this, the redesign will not be too bad a deal. I can still swing the biggest wheel on the Taig. Stay tuned.

A bookcase for the shop

It ocurred to me that it would be an excellent idea to have a bookcase in the shop. I have some books to which I often refer. Notice that I did not end a sentence with a preposition. Notice that it sounds clumsy to modern ears. Anyway,  I was inspired by Paul Seller's work. If you search for him, you will find everything. But Paul's YouTube videos deal with hand tools only. Just my ticket. So I went to Home Depot  (by accident, because I was looking for somehing else) and found a nice piece of cedar, sold as fencing and very cheap. About $1.69 as I recall. I decided I would use it as a bookcase and as a box for my dividing head. I lopped off what I needed for the case and that left me with some cedar. I planed it off, an excellent cardio exercise. So I want a dovetail case.

 I realized ex post facto that I should have done this backwards. You see above I am cutting pins in the uprights, Should have cut the tails instead. Simply a matter of appearance, joint is the same. One of Mr Seller's most interesting ideas is that of the "knife wall" and it did manage that correctly. When it came to putting it together it was another thing, I erred. Still, it came out all right. Not perfect. But 'twill suffice. Hand tools only for this thing.

 

So now it holds my essential references, and I am happy with that.

Back to the clock,  but that was a pleasant interlude.Coming next: making lantern pinions for the clock,