Saturday, August 27, 2016

An interlude on the Kenai

We went down to the Kenai river the other day, at the invitation to my daughter's boss Jeff, who has a lovely house on the river. The house is quite the impressive structure. I view it as a rustic palazzo. The big beams are timber-framed.

There is a fishing dock provided for your fishing pleasure. Complete with running water from a tap, so you can wash out your catch. You fish with a couple of meters of line with any old rod and reel. Jeff provided bait-casting reels, which I hate. I caught nothing.

Day and night the Kenai flows by. It is most relaxing. Soothing. Here's looking upstream. You can see a few houses. They will be very expensive. It is not a poor man's paradise.

Looking downsteam.There are a few houses, but I left them out on purpose.

 Somtimes quiet kayaks go by. Less often powerboats. I prefer, of course, the kayaks. They seem to fit right in with this environment.

I didn't catch any fish, as I said,. Jeff, of course, can catch fish anywhere.

We ate this guy for dinner. My daughter has a video of Jeff filleting this salmon. When she sends it to me, I'll see if I can post it. He does it in well under 5 minutes.

We ate very well. Jeff's palazzo has smokers, grills, ovens... the complete works. It was a wonderful interlude.

Wednesday, August 3, 2016

A dividing plate for the dividing head

If you look back on the archives (under the label "DividingHed" (misspell) you will see my homemade dividing head, made out of a printer salvage and some (literally) bedstead scraps. The way a dividing head works is based on a worm and gear. For each turn of the worm, the gear advances one tooth. I happen to have a 75 tooth gear. So if you had a 75 tooth gear to cut, life would be easy: one turn per tooth. In real life not all gears have 75 teeth. Sometimes more, sometimes less. So you have full turns or no full turns plus a fraction. The fraction of a turn is supplied by a dividing plate. It is a circle full of a bunch of holes that give you the fraction. I carefully worked out the holes needed by my clock and concluded I could get away with 50 and  40 hole plates. Commercial dividing heads come supplied with all kinds of plates with a wide variety of holes.

The first step in making one of these plates is to run my PostScript program that lays out the plate. I could have used a CAD program but I am afraid that their conversion to print format will distort my plate. That done, I glue the template on to a Lexxan circle. Now the fun begins.

Above I am using my optical center punch (Veritas) to centerpunch each hole. Very tedious work. Next to this is a box of very tiny Morse drill bits. By hand, with an Archimides drill I will go through each hole. Also very tedious. This gives me a pilot hole. Now we can get going.

 Using still a very small drill -- about 1mm -- we drill each hole a bit larger, and so on till the last size, around 4mm. For this kind of work opti-visors are really wonderful. See below.

Next job is to mount the plate on the dividing head. After all that work, this is easy.

This dividing plate has worked extremely well, and revealed a design flaw in the head itself. Deal with that later! Meanwhile I have an escape wheel to cut, shown below.

The escape wheel is not really a gear. It is a starfish-shaped wheel that regulates the rate at which the clock ticks. So the article says I should use a slitting saw but nobody makes one small enough for my mill. I use a Dremel abrasive disk instead. This is about half a millimeter thick. Bit thick,  but the scape wheel came out very nicely.