Small shepherd's sundial

Some time ago, I made a simple wooden shepherd's sundial.  It's crude and doesn't work well, but I set it on a lanyard and occasionally use it.  When I decided to use it recently, my wife asked for a small one as a necklace.  Commissioned artwork time!

Since I wanted the sundial to be stylish as well as functional, I thought a bit about materials.  I ended up with a simple design that uses 3/8" copper tubing.  It's the same stuff that you can get at the hardware store for various plumbing jobs, but it's small enough for the task.  I traced out the hour lines using a short python script, and printed them out for use as a guide.

The gnomon is held in a steel cylinder with a slight lip to retain it inside the copper tubing, which has a matching (reverse) lip bored in the end.  You slide the cylinder in from the bottom of the sundial.  Boring the copper was a bit of a problem until I got the boring bit set properly.  I also ended up bursting through the side of the first cylinder because I didn't correctly account for the thickness of the tubing. 

I cut the tubing with a jeweler's saw and filed it to final shape for the noon curve.   The cylinder has two drillings: an axial drilling for the hanging loop and a radial drilling for the gnomon.  The hanging loop is just a piece of brass wire bent into a loop at the top.  I thought of soldering it in place, but decided not to.  I hammered the bottom end of the wire into a small rivet, so the loop is free to turn. 

Here is a trial assembly.

I spent considerable time polishing the copper, the pin, and the cylinder.  The machining was not too arduous, though it did take a few tries, but the engraving was much more tricky.

Here's the final product.

I did not use a watchmaker's square graver (too unwieldy on the round surface) nor the more usual round graver (difficult to get it to bite consistently) to do the engraving.  After a bit of trial on a scrap piece of copper tubing, I found that a very small screwdriver that I had previously sharpened to a narrow cutting blade worked much better for engraving.

To keep everything aligned, I taped the printout to the surface of the copper, and cut through the paper.  This got the copper marked in roughly the right places.  Then I removed the paper and finished the engraving under the microscope.  This took about an hour, and was a bit nerve-wracking because every slip-up is visible.  I'm not too proud of how the engraving came out -- many slips, wiggles, and other awful mishaps are visible if you look closely.  However, it doesn't look embarrassingly bad if you don't use a microscope. 

The sundial certainly looks nice enough on its own, but I am not sure how practical the shiny surface will be in use.  It's cloudy now, which might be for the best!

Fixing a violin bow ferrule

The ferrule on my son's violin bow snapped open.  This is the little metal piece near the end of the frog...  You can see the split along the edge.  I'm holding the two pieces together in this picture.

This not being a particularly expensive bow, I decided to try my hand at repairing it.  I am not a luthier -- any more than I am a watchmaker or clockmaker; that doesn't stop me -- and this is not a usual repair...  That said, it's not particularly difficult either.  I was inspired by the instructions on this page.

These are the parts that need to be removed to access the ferrule.

 

The idea is that ferrules are typically soldered together from two pieces: a flat piece and a round piece.  This video explains the process, which reminds me of many jewelry soldering tasks.

But since this bow was not that expensive, I think the ferrule was assembled as one piece.  From looking inside the break, it looked like the ferrule was brass plated with something shiny.  It is slightly magnetic, so perhaps it's stainless steel? 

In any case, I can solder brass with a little flux!  So apply flux wherever you want solder... and don't put it where you don't!

The task is basically a soldering job and a jewelry job.  For that, I like to use fairly soft, lead-free silver solder.  It's easy enough to slice off a small chip to use with a chisel.

Bind the works up with soft iron wire.  This holds the ferrule together as you solder, and gives you a handle that is far from the flame!

If you're careful, you can plant the solder chip in the blob of flux.  Then, when you heat the joint, the flux melts, and then the solder follows the flux into the joint.  Be very careful to apply heat slowly, so that the flux doesn't splatter and knock the solder away!  Also, if you overheat the joint, the flux will burn away, leaving oxidization everywhere, and then the solder won't stick to the joint.  Worse, it will probably stick somewhere else...

I didn't photograph the soldering process itself because I didn't have enough hands free.  Once the soldering is done, there is some scaling, oxidization, and flux.

I like to dissolve most of the flux in isopropyl alcohol.

Then you can file away the excess scaling and solder (gently!)...

Try the fit of the ferrule on the frog. 

File until it slides on with some friction, but not too much.  It's difficult to describe what you're after, but it's very easy to feel what "too tight" feels like.  I also interleave the job of polishing with the job of fitting, since polishing the inside of the ferrule adjusts the fit to the frog.  Because the solder made a bit of a fillet, which I wanted to retain, I also filed the frog a little bit.  You wouldn't want to do this to an expensive bow, but this bow had a plastic frog, and didn't seem to mind the offense.

To start the polishing, I start with sandpaper.  Things were clean enough that I could start to sand with 600 grit

... and then move to 1500 grit

... and finally polish all surfaces.

I like to use premade polishing paste in a stick.  Even though it's intended to be used on a powered buffing wheel, I just scrape the stick onto a piece of fabric and polish by hand.  You have better control of the polishing of small parts that way.

Keep trying the fit of the ferrule on the frog as you polish, until it fits perfectly and is polished.

Slide the ferrule onto the bow hair.  Make sure it's oriented in the right direction!

This bow has the hair anchored by a screw...  Slide the cover on...

Slide the ferrule on..

And press the spreader in place.  The spreader may be a bit tighter than before, since the solder joint takes up some space.  Don't force it!  I did force, and was rewarded with a split solder joint.  I had to start back at the beginning!  If it doesn't fit, carefully file the spreader so that it does....

And finish the job by reassembling the frog.

Antiques and heirlooms

Among amateur watch repairers, it is good advice refuse to work on antiques or valuable heirlooms.  Doing so without sufficient experience can lead to frustration!  Old watches also have non-standard parts and other oddities that can trip up the unsuspecting would-be repairer.  I have followed this advice until recently... and ended up in a bit of an adventure.

What tempted me down this path was an antique heirloom watch that was in very poor shape.

It was apparently my great grandmother's watch.  It is quite pretty, but when I received it, it had not been well kept by its owner.  Furthermore, it had been to some very poor watchmakers!  Slowly, over the course of three years, I made a number of repairs, none too difficult:

1. I replaced the missing glass with an acrylic face.
2. The case wouldn't close because it was slightly out of round... I put it back into the round, so the case opens and closes correctly.
3. I remade a case screw that someone had snapped the head in half (!). There are marks on the plate where the screwdriver skidded off after snapping the screw, so clearly way too much force was involved.  Ouch!
4. The winding stem that was acting up, because a brake was tensioned incorrectly.
5. I put the hairspring back in order because it was twisted badly.
6. Finally, recently, I took the movement apart and cleaned it.  This was completely uneventful.

It now runs reliably, but gains about 5 minutes per day.  That's terrible, of course.  But given that I don't have a replacement hairspring and given the age of the watch, it's well within what I'm willing to tolerate.

I had a very different experience -- and it's not over -- with a watch from my wife's family.

This watch wouldn't run, but didn't have anything visibly wrong with it.  Upon disassembly, I found that the lever fork cock was ever so slightly bent and was pinning the fork down.  Since it couldn't move very well, that kept the train stuck.  That wasn't the only problem...

As I was reassembling the balance, I was a bit less careful than I should have been.  I noticed the balance was not able to turn freely in both directions.  The balance was simply on the wrong side of the fork, and needed to be carefully lifted over the fork.  Unfortunately,  I couldn't visualize what was wrong.  Instead of the correct move, I gave the balance a sound push the other way.  That was not a good plan, and I really did know better!  Disaster!  The impulse pallet jewel was shattered!

After carefully sizing the missing pallet (seems to be about 19/1000"), I realized that it would be useful to make the pallet out of blued steel.  It should have nearly the same characteristics, and it should "just work."  (I also ordered a ruby impulse pallet, but I'm not confident of my measurements...)

It took five tries to make and install the impulse pallet, because I lost the first three pallets I made, and although the fourth worked, it was very poorly made.  The fifth looks nice enough and seems to be working. 

Of course, the first step was to disassemble the balance.  I removed the old pallet by heating the roller table with a soldering iron with a fine tip at roughly 250 degrees F.  Using a needle, I cracked off all the old shellac.

First, I trued up the end of a 0.5mm blued steel rod, using an arkansas slip.

After truing, I rounded and burnished the end.  Next, under the microscope, and on a soft piece of wood, I ground a flat surface using the arkansas slip.  In the picture below, the flat is visible as the slight smear at the end of the rod.  (The flat is about 1 mm long.)

This made the rod into a D shape.  I kept grinding the flat until the rod barely entered the hole in the roller table.  Then, I burnished the flat surface.

Unfortunately, the rod was too large to fit the slot in the lever fork.

So, I ground a fine taper to the rod by hand, by eye, under the microscope until the rod would just barely bind in the lever fork as I rotated it with the tip in the fork.

Then I switched to a steel burnisher to smooth the surface of the rod.  After burnishing, the rod freely fit the lever fork, with the base of the taper still fitting the roller table.

To cut the pallet off the rod, it's important to cut it to the precise length.  Since I ended up making five pallets, I was able to zero in on the correct length by comparing with an earlier attempt.  But in any case, I reversed the rod in the pin vise, and then used a narrow file as a saw to slice off the pallet.

Once again, I switched back to the arkansas slip to true the end, and then polished it with the burnisher.  Even though this cut end is completely invisible, this was an important step because the cutting raised burrs.  Burnishing removed those burrs.

OK, now the pallet was small!  It's the apparent "grain of sand" on the left of the frame in the balance cock in the picture below.

Getting the impulse pallet into the hole in the roller table was... irritating.  The pallet is slippery by design, and rounded... which means that holding it too tightly (or gripping the wrong surface) with tweezers will launch it across the room.  I lost three attempts irretrievably and lost another one for a very long time.  Eventually I got it pressed in place.

To anchor the pallet, I gripped the balance in surgical clamps and applied shellac.

Someone before me was way too liberal with the shellac and glued together several turns of the hairspring.  I was able to knock them apart, but if it impacts timing, I may have to immerse the spring in alcohol.  I'm loathe to do that because the spring has a nice overcoil and is very, very delicate!

Here is the balance reassembled with the new impulse pin installed in the roller table.

And a zoom-in:

 
But the balance reassembly did not entirely go well the last time...  I bumped the attachment point with the tweezers, and snapped the spring at the balance attachment point.  Previously, I had thought it nice that there was a removable clamp that made removing the balance easy.  However, that clamp was installed very permanently onto the hairspring.  It took a good two hours to remove the old pin (brass, extremely tightly fit; I think it was staked in place at the factory!), fashion a new pin (I used soft copper, and much longer, since I wanted be able to get it out in the future if needed), and get everything back to working order.  As wooden clockmaker Clayton Boyer says, "Mistakes take a lot of time. I spend some of my best woodworking time making them."  Yeah, I agree.

Still, after all that, the watch still would not run.  What!?!  No visible trouble... actually, not.  I had never worked with a watch with an overcoiled hairspring.  It can happen that the overcoil turn can foul on both the balance cock and the main turns of the spring.  That was the problem.  A very slight touch on the spring attachment point fixed the overcoil's path, and the watch sprung to life!

The movement is now running, which is a relief!  It sounds different from the other movements I've repaired, because it's quite a bit lower frequency (around 2 Hz) than other movements of the same size (typically 4-6 Hz).  Assuming it all goes back together, I wonder if it will keep reasonable time?

One final thing, though.  The winding works for this watch is not the usual Swiss mechanism.  It's a bit simplified, which seems elegant at first.  Here it is when correctly assembled.

However, should the stem get loose and you simply try to reinsert it, you will likely knock the cylinder gear assembly off its retaining spring.  This is rather subtle.  In the picture below, the lower retaining spring is supposed to be running in the cylindrical groove right below it.  All you need to do to repair it is slip the stem back in, and push the spring down gently.  It reseats easily, and then you can carefully withdraw the stem, leaving everything in place.

This process is extremely annoying, because although fixing it takes mere seconds, to access this mechanism you have to uncase the movement, dismantle the hands, and dismantle the dial.  Reassembling the movement into the case involves reinserting the stem, which has a tendency of knocking the winding mechanism out of order... so you need to back up, disassemble everything and try again...

Violin sound pin setting tool

The sound pin in Zachary's violin was inadvertently knocked over.  There's a tool for fixing this problem, and it is not expensive.  However, it was also not available on short notice, so I made one.

The tool is a 1/8" steel rod set in a handle of rosewood.  To make the tip, I hammered the end of the rod into a spade shape, hardened it, and then ground it to a sharp flat blade.  I then bent the rod to fit the shape of the violin, which is a standard 4/4 size.  Afterwards, I polished the rod, oiled it slightly, and set it in the handle.  The handle was a short segment of a hard rose cane I had taken during pruning, and was shaped on the belt sander.

To use the tool, stab the sharp end into the sound pin (grainwise), carefully thread the pin and tool through the F-hole, and then carefully upright the pin just below the treble foot of the bridge. This took me a few tries, but it wasn't too demanding.  Just make sure the bridge is already mostly in place with the strings just barely tightened before you begin, otherwise uprighting the bridge will surely topple the sound pin. 

Clock 4 pendulum pivot

In an effort to reduce the pendulum pivot friction for clock 4, I have decided to try setting the pivots on metal points rather than wood.  The points and matching cups are cut from brass.

While a little hard to see, the pins mount in holes drilled in the end of the pendulum's hook-shaped protrusion.  Once mounted, I marked where they sat on the hanger, and drilled holes to receive the cups.  It sounds more complicated than it is; here is a zoom-in of the installation.

In the process of installing the pins, I snapped off the pendulum's hook.  So that is now gluing.  Once it's dry, I'll be able to tell if this helps to reduce the pendulum's running friction.

Update: after drying, for the unloaded pendulum, I get a median of 71 full periods for the amplitude to halve.  That puts the unloaded Q = 320, which is a little bit better than before.

Saxaphone ligature screw

Edwin's saxaphone ligature takes two 6-32 screws.  One of them broke, so I made a replacement.  I started with 1/2" diameter steel rod.  I think it was zinc plated, but that wasn't too critical; whatever plating was originally there was removed.

I started by turning the portion to be threaded to 1/8".  Since the length wasn't too critical, I just used the good screw to figure the length.

I threaded the end by hand.  (I could have used a geometric die, but the setup would have been longer...)

Once threaded, I turned the shoulder that separates the threaded portion from the handle.

The shoulder actually tapers a bit, which I did with the graver.

The handle is a rounded ball, which I shaped with the graver after using a parting tool to remove most of the waste.

Here is the part next to the broken screw after parting.

I removed the leftover spigot by reversing the screw in the lathe -- good thing I have an 1/8" collet.

Now the handle is ready for final shaping.

Since I had to remove lots of material, I figured I could either spend time with a file or the bench grinder.  The bench grinder seemed like the better option (it may not have been any faster, actually).  I gripped the part in a pin vice so that I was securely in hand.

I ground both flats with numerous breaks to dunk in cool water...

After polishing, hardening, tempering, and final polishing, here is the final product in place.

The handle is a little wider than the original, but it does the job.