Contributions to LibriVox

I have been contributing my voice to public domain audiobooks on Librivox as a bit of a hobby. As one would expect, my bent is toward science and math, and one full recording I made, ready for consumption, is the eighth lecture on General Dynamics by Max Planck. Hear about space-time as only a contemporary of the theory can tell it!

A much longer recording of a 400-page book by Rouse Ball on the History of Mathematics is in progress. I picked up a lot of math and physics from reading both of these books. He goes, as many of these writers do, from antiquity to “modern times”, which for him end at around the year 1890, the decade of the book’s publication.

Replacing pedals on my moped

You might recall my Tomos Targa LX, which is sometimes in need of some special attention, includng yesterday when the pedals and cranks finally came in the mail. I had to order from the States, and there was an outer packaging that contained a note saying that Canada Post received the package in damaged condition. Well, two solid chrome pedal cranks, a crankshaft, and two pedals are not necessarily breakable, and all the parts seemed to be there.

The cranks came without lock pins, so I had to take them off the old ones. After removing the bolts and washers, a fair bit of hammering was required to persuade the lock pins to come loose while not damaging them. The pedals were installed and everything fit nicely. The remains of the sticky packaging tape was removed with acetone, and now the cranks have a shiny new appearance.

Getting a new book bag and the use of rivet guns

Some professionals have briefcases, I use a backpack, which I sometimes call a book-bag. I have been partial to the ones with wheels so that it is useful regardless of whether I decide to travel to work by car or moped.

While I was in Boston (Cambridge, actually) last week, I purchased for about $110US, such a book-bag (J-World) after a previous one of mine expired (really, one of its plastic fasteners broke making backpacking much more difficult), and three days after I returned home, the straps pulled on the material on the back panel above the straps, and the material above the straps separated from the backpack. Not an immediate danger, but a sign of trouble ahead. Living in Canada, going back to a shop in Massachusetts wasn’t really worth it, so I decided its fate otherwise.

I could toss it, but I am loathe to do that, since there is a lot of other things about its construction which make it a good find, such as the fact that the nylon shell covers a hard plastic shell across the top, rear and bottom of the book-bag. But I decided on taking it upon myself to do a repair job. So I went to Canadian Tire and bought some rivets and a pack of rivet washers.

The thick part you see in the diagram above is the rivet, and is the part that will end up in the pieces joined. The thin part is the mandrel. The mandrel extends all the way up the inside of the rivet. The “shank” is the thick part extending from the collar to some distance up the rivet (I believe that is where the break point is of the mandrel). The “gauge” is the rivet’s thickness.

I already had a rivet gun which I use rarely, so I went on You Tube to re-teach myself the use of a rivet gun. What I was riveting was plastic to cloth, using 5mm (3/16″) gauge rivets with a 12 mm (0.5″) shank. I only had the choice between short and long shanks. The washers were to be applied to both sides of the work. Of course, the diameters of the openings in the washers had to match the gauge of the rivet. Applying the washers to both sides amounted to riveting metal to metal with the plastic and cloth sandwiched in the middle. I thought that would be a way of riveting soft material with the least amount of damage.

The “handle area” of the bag. The material (where the rivets now are) became separated from underneath the plastic cover; no doubt due to the pulling of the shoulder straps. I was able to re-insert it easily since the platic handle area was only secured by 4 Phillips screws which were easily accessed from inside the bag.

The first thing I had to do was tuck the separated material back into where it belonged. A small section of material under the plastic cover worked free and was difficult to put back. That is, until I discovered that the handle area was secured by four screws accessible from the inside.

Once that was put away, I had to drill four holes through the material and plastic. But I just couldn’t drill a 3/16″ hole first time out. I found the drill bit too thick, and had to first resort to a thin bit (say 3/32″) at first, then another that was slightly thicker (like say 9/64″) before finally settling on 13/64″, just a shade larger than the hole size I wanted. After drilling, the hole on the plastic had to be cleaned with an exacto blade so that the surface was made flat and free of drilling debris.

With the hole now prepared, it was time for the rivet. The “pointy” end of the rivet points to the outside of the book bag, with the shank (the thick part) inserted into the hole through a rivet washer. While doing all this, make sure that the back compartment of the book bag is completely unzipped so you can also insert another washer on the inside of the book bag where the shank protrudes. I was able to hold the washer with one hand while squeezing the rivet with the other. If you find this too clumsy, get a friend to hold the washer on the inside while you concentrate on squeezing the rivet gun with both hands on the other side.

As you can see in the picture, the rivets are not exactly placed evenly or symmetrically. I was just aiming for survival mode, and in my own rough and sloppy way, I liked the result. That material isn’t going anywhere, and now the plastic backing is being used to handle the pressure from the shoulder straps. I placed another four rivets underneath the straps, but being careful not to disrupt any stitchings, especially those which held the straps to the book-bag.