Divide and conquer

OK, I confess. What I am really trying to do is build a clock from the ground up. As with anything else, building a clock is no mean feat. It also rapidly becomes an obsession. So I am obsessed. I do not think this is grounds for a lawsuit. Anyway, the big thing about a clock is gear-cutting. There are several requirements for this. You need two perpendicular axes. On one of them a cutter is revolved, preferably by power. On the other, the would-be gear is held. On this latter you must have an indexer of some kind, i.e. a gizmo that will turn the (proto)gear by a precise amount. In a previous post I chronicled the making of the latter gizmo, the dividing plate. The gizmo allows me to divide a circle into 60 parts. By skipping holes I could also do 30 parts. In fact, any of the factors of 60, and now you know why they made you study factoring in school. Clock gears go from 120 or so teeth all the way down to 6. A clock, you see, is just a big gearbox. But you cannot shift the gears, unlike an automobile.

So in our last episode I had made the dividing plate. Had I about $300 to spare I could have bought a spin indexer to do the same job. But no. We did a dividing plate by hand (previous post).  So I turned up an arbor from a piece of scrap steel. An arbor in machinistspeak is simply an axle. There it is on the four-jaw chuck, a pain to set up but it runs really really true.  This held my victim, a failure from the dividing plate episode. Much too small to be a dividing plate. Next, I  arranged my Dremel (knock-off) device on to the vertical slide on the lathe. Major project. Too many things to adjust. I have blogged on this contraption before, so see previous posts.

This needs some overhauling. Once the DSO (Dremel Shaped Object is bolted in I cannot adjust it except with the vertical slide, and it has extremely limited travel, 50 mm or so. Not enough. This is why most people do this on a mill. But a (small) mill is about $500 plus shipping, almost as much as the mill itself. And again, I have no space for a mill. But lashup though it may be, I have the two required perpendicular axes. And it cost much less than the mill, i.e. zero.

I have no cutter yet. This is work in progress. In its stead (thak you Richard, for pointing out my error. I said "staid" before),  I put an abrasive cut-off wheel on the dremel. I also arranged a spring-loaded detent for the divider plate. So I am really not cutting gears yet. But the whole two-axis lashup arrangement is working! I cut some remarkably gear-like slots in the sacrificial victim! I was a bit worried about wobble, but none was perceptible.

The classical material for clock gears is brass, sometimes steel. But brass is like Unobtainium in Alaska. Small pieces, at a hobby store, maybe. Big pieces, no. So I am doing all this in plastic. Plastic is everywhere. On dismantling an expired (battery) clock I found plastic gears everywhere. So if they can do it so can I. My  plastic is found. I think it is a piece of refrigerator. So I can experiment all day long. Just as well. Winter is here. Lots of time to experiment.

It snows in Alaska

One of the more surprising facts of Alaska is that it does not snow that much. Not here, anyway. If I lived in Cordova that might be false, but no. I am in Willow. We had 12 cm of snow on the official snow pole. But last night in came down. I awoke this morning to find 29 cm on the OSP. That stands for Official Snow Pole. It is a broken ski pole. To this, via epoxy,  I affixed a large nail that allows me to sink it in the ground. I have marked it in 10 cm intervals. So, the OSP reports 29 cm. I record its readings daily. Usually zero this time of year. So 12 to 29 is some 17 cm of snow. Convert it yourself; I refuse to deal with King Henry's thumb width units.

Anyway time to clea the driveway.  John and Fluffy went out and played in the snow. Fluffy threatened to throw snowballs at John. John, armed with mechanical contrivances, had the upper hand, for all he had to do was turn the chute of Horatio the snowblower in her direction and she would be deluged. But Fluffy is brave. She handled the snowblower like a pro.

 
John had more than his share too.

He plowed a trail around the house, most useful. I pleaded flu, but at least I went out for moral support and very glad I didn't have to do it myself.

Chalupy is now accessible. Very important in winter. More snow in the offing. We will deal with it.

Incidentally all the snowblower's problems were solved with a new sparkplug. Moral, from lawnmowers on up: change your sparkplug once a year at least. 

Dremel attachment, the sequel

In our last episode we saw how I went about converting a chainsaw sharpening attachment into a vertical spindle for the Taig. But you will remember that the thing fouled the DSO (Dremel Shaped Object)/ What we needed were some spacers. Some careful measurement convinced me that 6.5 mm would be enough. I found a nice piece of scrap rod a little over 13mm long. Great. Now we have to center-drill it so it will act as a spacer. Of course it will need longer screws. Fortunately I save every screw that comes across my path.  But the real problem is center-drilling the spacers. Now the best way to do this is on the Taig, but Mr Taig was busy with other jobs. Furthermore the self-centering three-jaw chuck's jaws are shot. So I did it on the drill press. I made a fixture (a device to hold things down while you work on them). A simple wood block. Drill a hole through it, tight fit on the round piece, and slit the hole with a saw.

  

Clamp it in a vise. The slit makes the wood close around the steel rod and holds it fast.  Then you can e.g. drill it, which I did, all the way through. Fortunalely the hole was started by a previous project so I didn't have to center it. Then I sawed the spacer in half with a hacksaw, a marvellous tool. Use the same block to do the sawing. Guides the saw.  At the end of the day I had to roughly equal pieces. Trim up with a file, still on the block. At the end of the day I had two spacers.For the record the spacers are steel 6.3 mm (1/4") hardware store stuff.

You can just see the spacers. Now I have a spindle at right angles to the lathe axis, marvellous.

What I really want to do is cut clock gears. So for this I need a dividing plate and this is my next project. We will see how it goes.  I will also need gear cutters. I will have to make these. This is Alaska. We do have Home depot, and Lowe's, but we do not have machinist's supply houses. Got to order from afar, and pay shipping costs too. So I will make my own cutters. They must fit a Dremel shaft. I intend to start out with plastic gears.  Dremel will certainly cut plastic! But your high-precision  quartz clock uses plastic (probably lexan) gears so maybe I can cut one too.

I have also, quite accidentally, got the beginning of an ornamental lathe, but that's a separate post. Still need a dividing plate. Stay tuned.

A vertical spindle for the Taig lathe

Ah, what to post. I have been very busy, but as usual at this time of year I can't tell you about it. So let's look at the Dremel atachment for the Taig lathe. Nice and neutral, nobody's getting one of these for Christmas.

Milling on my Taig lathe is a comprehensive nuisance.  I do have the Taig vertical milling attachment.  But the cross-feed screw has a very limited travel. So I have been toying for a long time with adding a vertical milling spindle. A lot of things came together this afternoon. An article in Popular Mechanics, a reprint. A lot of watching videos on watchmaking, a fascinating subject. Need a magnifying glass!  All the reading I have done on ornamental lathes. Lots of stuff.

So a long time ago I bought an attachment for the Dremel. I don't own such a thing but I have a knock-off, made in Asia. Good for them. The attachment purported to let you sharpen chainsaws, a subject of great interest to me. Dull chainsaws are dangerous. Even sharp ones are risky, but less so. This attachment , as far as I am concerned, was a waste of money. It consisted of a bracket and a plastic gizmo that screws on to the nose of your DSO (Dremel-Shaped Object). You held the bracket so's it lined up with the bar, then used rotary grinders to sharpen the teeth. But hand-held. Waste of time. You cannot hand-hold these things worth spit. I have discoursed before on this subject. Get a proper jig, or buy a chain saw grinder. I did both. But the Dremel nose and the bracket I kept.

Today I thought, "hey, if attached this bracket to a piece of 1/4" (6mm) bar with some holes drilled into it, I could mount the whole thing on the Taig milling attachment! So after some work this afternoon, we are here.

Behold the Taig lathe with vertical milling attachment. Behold also the 6mm bar. It sticks up and fouls the DSO. But really the bracket is inadequate. The DSO won't fit.  A matter of about 3mm. So I will have to make some spacers. This will allow the DSO to screw into the plastic fitting at the bottom. This may turn into a major project. But if I can do it, then I have a vertical spindle for the Taig.  Maybe I could even cut gears, at least in Brass or  Aluminum or plastic.  Then I could make a clock. Of course I would need dividing  plates. Next topic, I suppose.

Miracles with SuperGlue

I have this project. Unfortunately I cannot tell you why I have it or what its ultimate destiny may be. This is because what I am making could be for you! Keeping this blog going in the pre-Christmas months is a major headache. However, I can tell you this. I am making bearings. I have drilled out some steel rod to 3.15 mm which is some RGU. Now I have to cut a slot in the rod. I must mill this slot. I have the Taig lathe (on which I turned the bearings). I also have the vertical milling attachment. I refuse to buy the Taig mill. For one thing it costs $600. For another I have no place to put it! So we must make do with what we have.

For those of you who do not know the difference between a lathe and a mill: in the lathe the work rotates. The cutter stays put. So you turn objects of rotational symmetry, like cylinders. A mill works backwards. The cutter rotates and the work stays put. Aye, and there's the rub. Keeping the work put seems to be 99% of milling. So I have this cylinder, drilled out; I want to cut a slot in it along the long axis. Conventional wisdom says put I the cylinder in a V-block. Clamp it down. Yes, but my V-block clamp fouls. It hits the lathe, the chuck, everything. Can't do it. What now?

So there is a solution. Use super-glue! I actually super-glued the cylinder to the V-block. Then I clamped the V-block onto my home-built milling table. The aluminum clamper is starting to bend; must replace it with steel. No matter. It worked. I move the whole milling table up and down with its feedscrew. I am using a Taig milling cutter, about 1.6 mm wide. The Milling cutter is held by a Taig collet and I must say this is the first time I have found the Taig collets useful. They usually are either too small or too large.  Anyway, note the slips of paper between the clamping fixtures. These keep things from slipping and are very effective. Thanks to Myfordboy for that tip. See his blog, cited off this one.  Great source of information.

So I cut my slot. A bit too deep, but I can deal with that. Another use for my leadscrew, when I get it done.  Really have to hand it to superglue. In the end, superglue can be undone with heat. Just heat up with a butane torch.  Modern adhesives are a lifesaver.

Chasing the elusive thread

I knew I had a label for it. Screw chasing, that's what it was. Took forever to find it though. So today's post returns us to March and April of last year. When summer comes I move outdoors so nothing got done since then. Well, I watched  lot of thread-chasing videos on YouTube and I must say I admire the dexterity of these people, not to mention the fact that they put their knowledge out on the net for all to see. Generous to a fault. Anyway, you will recall that this label deals with cutting threads in wood. The methods range from ancient Greek techniques (cut thread with chisel) to wood taps and dies and finally chasing on a lathe. Since I want to use my Polecat this is not a trivial undertaking.

You will also recall I am cutting a 4mm pitch thread. This is very large. Most of the people on You Tube are (a) using powered lathes and (b) cutting something like 16 TPI or 1.6mm pitches. So you might say I am behind the power curve, since the smaller the pitch the easier to chase. However, we press on. We have evolved an intermediate technique. It is somewhere between the Greeks and the modern chasers. So we start out in Greek style, wrapping a piece of paper marked off in 4mm lines. It must be offset when you wrap it by one interval or you will cut circles.

Tape the paper down to your cylinder really well. else it will slip and make hash out of your efforts. Now, just like the Greeks, take your mini-dozuki saw and saw out the lines, rotating the lathe by hand. Do not try to treadle.

You do not have to saw very deep but you have to saw very carefully indeed. You must hold the saw along the lines of the spiral. Now we want to deepen the groove. For this I find the skew chisel is just the ticket, held vertically for a change.

It is important that the tool be at center height. Nice thing about having the work between centers is that you can rotate it at will. Thus we clean up small mistakes in the sawing. We get the groove as deep as we think it needs to be. So that the next tool has a path to follow. Next we really start chasing the thread.

Here is my one-point chasing tool which I cobbled up from an old piece of steel. It has a 60 deg. point. Modeled on a machine lathe thread-cutting tool. It also has some side relief. Probably not enough. Still experimenting. But we still do not treadle. We apply the tool and start forming the thread, also deepening the groove. Turn by hand.

When you get the groove deep enough you will find you can actually treadle; the tool will follow the groove all by itself. Not only that, the multi-tooth chase actually works! See previous posts. But you must treadle very slowly. This is hard to do. The temptation to bash the treadle down is overwhelming. Resist it. Any machinist knows that to cut a thread you put the lathe in backgear and take the slowest speed you have. I have no backgear, it's all my leg. It is all too easy to have the tool jump out of the groove, or dig in.

The above shots were staged for the blog. When I was working this out I had no thoughts of taking pictures. But at the end of the day I had cut a quite respectable thread on the left end of the turning.

There are problems. For one thing the cylinder has a big crack in it, making things difficult. For another it chips. I think this is a problem with the paper guideliner. Lines not exacty spaced. I can fix this. It is also a problem with my one-point chaser, I think. Need more side relief, or is that side rake? But I can now say I chased a thread on a pole lathe. Stay tuned, as usual.

And at last we have snow on the ground. Not much, about 2cm. Enough to ski on! I was so tired of walking.

Steady part 2.

Still on the subject of steady rests for turning long whippy pieces. Now a lathe will turn to about .02 mm or a "thou," .001 of the width of Henry VIII's thumb. What a remarkable choice of a unit. Still, in those days the King's word was the law and we have not progessed much beyond that. Anyway, when you are turning long thin pieces the whip or spring in the piece far exceeds the accuracy of the cut of the lathe. If your lathe is good to .02 mm the thing will spring a whole mm so your accuracy is gone.

So I am trying to turn the threads off of a 1/4" threaded rod. My whole objective, as I related before is to put a leadscrew on the Taig lathe to allow me  precision adjustment along the bed. Taig uses a rack-and-pinion arrangement; cheap but inaccurate. But a 1/4 (6mm) rod is very whippy. I would rather use something around 18mm but I can't fit that through the bore of the Taig. So in this case we need steadies, and you might want (or not, but I will give it to you anyway) to see the completed arrangement.
 
We have both a fixed steady rest, which I described before, and a traveling steady bolted to the carriage. Both of these arrangements need refining, but they work. The traveling steady is a casting supplied by the Chalupy foundry, AKA John, but I did the pattern. And poorly. The more work you put into a pattern (wood) the less metal you have to move. Lesson learned.

The real problem in these rests is to machine the slots for the crews that hold these things down. In fact, the whole problem of machining metal is holding the work. The actual machining is easy, if only the work will stay put. So after many trials, unseemly language, and agony I came up with something that worked.

Here it is. The Taig has been fitted with the vertical milling attachment. An end mill sits in the 3-jaw chuck. An aluminum bar and some long screws provide vertical steadiness. Two pieces of steel square, barely visible, are held by clamps to my horizontal table. They keep the work form rotating around in the table. I wish I had an end mill exactly the width of the slot, but I broke it. You are not supposed to hold an end mill in a chuck but needs must when the Devil drives, as they say. You should use collets. But none of the Taig collets will hold my end mills. So into the chuck it goes.

 I finally got the blasted screw turned down. But alas, at last minute something went wrong and the hole in the mounting to pass the turned-down portion went wayward. I am in to re-making the mounting. Grrr.

After all this precision work it was comic relief to get Polecat, my mini-pole lathe (bungee lathe, actually) running  again.

It is nice. No motor. No fussing.  Immune to power failures. Excellent cardio workout. Just turn the thing! Made some improvements.

Polecat is doing a tool handle, of course. That's why I built it. Never can have enough tool handles. The handle happens to be for an Ulu. Whose? Ah, I won't tell.  Eat your heart out.