Archive for July, 2009

Pseudoscope

Tuesday, July 28th, 2009

Next up on the Calvacade of Learning Experiences!  (I thought “Calvacade of Failure” had a nice ring to it, but… optimism, please.)

A pseudoscope is a device that flips the line of sight of your eyes; that is, the line of sight of your right eye is transposed with that of your left eye, and vice versa.  The purpose of pseudoscopes was to help figure out how people process depth information.  Supposedly, the actual visual input being reconciled with the expected input results in some convex shapes being seen as concave, flipped depth values for objects in close proximity, and other oddities.

Unfortunately, it didn’t work for me.

Rather than purchase a $750 pseudoscope, I followed the instructions here, which result in a rather more economical $10 pseudoscope.

Pseudoscope Parts

Pseudoscope Parts

The above picture shows the parts I started with.  Nitpickily observant readers will note that the mirrors are too small for the instructions given at the link.  This is because these were the closest size available at the store.  As I discovered, optical devices require a bit more precision than “whatever they had at the store”, and so I later purchased the correctly sized mirrors online.  Financially observant readers will now note that this device cost rather more than the expected $10.

A bit of measuring and assembly later:

Pseudoscope

Pseudoscope

In the picture above, your eyes should be placed at middle left, and the field of view extends to the right.  The logic behind the mirror placement is evident.

As I said, this doesn’t work for me.  I spent an hour or so focussing it, rather like a coincidence rangefinder, moving the two images together, and then looking at different objects under different conditions.  Inside, outside, dark, or light, with a long or short focal distance, my brain resolutely refused to be tricked.  The only oddity I noticed was the path distance added by the pseudoscope made me misjudge how close nearby objects were.

I can think of a few reasons why this didn’t work for me.  I am reasonably sure I got the focus right, so this probably is not it.  The first possibility is that I needed still larger mirrors to completely cover my field of view, and that there was enough reference information left unreflected by the mirrors that my brain was not misled.  The other possibility is that it did not work for me because I am about 70% left eye dominant, which both mucks up the positioning of the mirrors and puts another reference point into the equation that my brain was processing.  This too may have been enough information to prevent the illusion for taking effect.

In any event, I’ve spent enough time on it, and so it will go on the shelf of interesting ideas that didn’t pan out.

Signal Cam 1

Monday, July 27th, 2009

So, what *have* I been doing?

The actual answer, “experiencing defeat on several project fronts”, is a bit pessimistic sounding.  Let’s replace that with: “learning more than I thought I would about widely variant fields.”

First up:

The right-hand turn signal in my (old) car has never held itself in place when I move the signal stalk, requiring me to hold the signal stalk firmly upward preparatory to making the turn.  While not a terrible problem unto itself, the car has manual steering, requiring several turns of the wheel to make said turn.  As my right hand is not equipped with a 360 degree rotator cuff, I need to take my left hand off of the signal as I begin the turn, possibly confusing those behind me.  (Bonus points for needing to downshift at the same time.)

Let’s find out what is causing the problem.

All together now: first, disconnect the battery.

This is the much-weathered horn cover on the steering column.  Note: extremely fake woodgrain dash (factory!) and the extreme absence of airbag.  This latter is important, as I lack the gumption to muck about with airbag-equipped steering columns, preferring to keep my screwdrivers on the outside of my sinuses.

steering wheel trim ring

A bit of prying, and the cover’s spring clips give.

horn ring

Horn Ring

This is minimal corrosion for those of us in the land of salt and snow.   Any work you can do without a propane torch or extractors is almost blessed.

The protruding ring is the “horn ring”.  It moves in and out, and when it moves in, it makes contact and the horn sounds.  It is important to have disconnected the battery at this point, else you irritate the neighbors sounding the horn at intervals.  Disconnect the cable at center, and undo the three bolts that hold the steering wheel on.

Steering Column "Can"

Steering Column "Can"

The “can” is mostly a spacer, but is held on quite tightly.  Undo the nut (lots of force – it is a single point of failure for the steering wheel).  You will note that the can doesn’t come off.  This is because it is held on the column by a splined shaft under the nut.  This, too, is difficult to remove, without…

Steering Wheel Puller

Steering Wheel Puller

… this facehugger-looking implement.  It is basically a gear puller; the threaded shaft at middle pushes against the splined shaft that the nut was on, and it pulls the can off using the splined shaft as a hardpoint to push against.

Oops.  The threaded shaft is pointed and harder than the car.  Note divot in steering shaft.  Evidence of sloppy work, though not as sloppy as that done by whoever put all of the screwdriver gauges around the edge in the picture below.

Signal Cam

Signal Cam

Aaand there’s the problem.  The nylon assembly at left is in the “right turn” position.  The barbed bit in the red circle is supposed to catch on the greasy part behind it, but doesn’t.  The green arrow points at a crack in the nylon, about 1/32″ deep.  That’s all it takes.

I now need to find a replacement, and to figure out how to remove the original.

Sippican Cottage Footstool

Friday, July 17th, 2009

I mentioned Sippican Cottage Furniture the other day.  Here’s why:

stool-front-web

Sippican Cottage Super Ten Fingers Stepper

That top step that you are looking at is tiger maple, finished appropriately.  It changes color a bit as the light changes, and the photograph doesn’t lie.  It is that pretty under bright light.

Another view:

stool-ortho-web

If you look closely, you will see that there is some wear on the stool.  Sippican Cottage makes “slightly distressed” furniture, a look that I do not prefer but have to admit looks good here.

I purchased this as a gift for a friend a while ago, but had to take a few pictures before giving it to her.  It is good to remember what can be done by those who are (much) more skilled than you are, to have something to aspire to.  I also really wanted to see that maple up close.  Now to find a source for it.

16 inch combination square

Wednesday, July 15th, 2009

While I have been working on things, you wouldn’t necessarily know it to look at this site.  One project is waiting on parts, one is stalled while I make a design decision,and one is stalled pending me figuring out what is wrong with a circuit.

The desk is coming along but has hit the point where you realize that your careful measurements and plans ran afoul of your ability and materials.  The below tool is one of my proudest acquisitions:

square

This is a Craftsman 16″ combination square.  It’s a 90″ square, 45″ try angle, 16″ steel ruler, level, and has a scribe tucked into the “grip” below the level.  It is a metalworker’s tool (as indicated by the scribe) that is useful to woodworkers.  For some reason, I consider this to be a very “grownup” tool.  My father has one, and it was never used for measuring by we children.  Wooden freebie rulers from local political campaigns and hardware stores were for the kids.  (I don’t know who the town supervisor is of my hometown, but I’ll forever remember the name of the politician who gave out that ruler, probably 20 years ago.)  In hindsight, dad was probably worried about us damaging the level or losing the ruler.  It is well made, tough, and the ruler, being steel, has square, undented ends, unlike the aforementioned wooden rulers.

In any case, I was happy when I finally purchased one several years ago.  It sits well in the hand, a product of many decades of product evolution.  Amazingly, it is still available for less than $20. I am astonished at the level of precision available for this price.  I am not a machinist; I do not require thousandths of an inch tolerance and do not know if this square provides it (I doubt it).  The level of finish offered in a tool that today costs as much as a pretty good steak would make it suitable for those at the highest point of their profession a few generations ago.  I had a discussion with a friend a while ago, and we realized that possession of an inexpensive modern micrometer, available today for $10 or so, would be worth a small fortune 150 years ago.  (Note: my 1902 Sears catalog does not seem to  have the pages that would contain precision instruments.  More’s the pity.)

I hear the response, “And?  Many new things would have been impressive long ago.”  I suppose, that when I look at this square, I see the history of the tool: wooden blocks, then carefully chosen and put together wood squares, made of hard wood, which you can’t get wet, then brass, rough iron, heavy and subject to temperature variations and tarnish, steel, and finally this aluminum tool.  While I am impressed by currently new technologies, I have a similar well of fascination for the amount of power that can be found in the average suburban basement.  Metallurgy, machining technologies, theoretical science, engineering, and the simple evolution of use all come together in an inexpensive item, available to just about everyone.  Thinking further on it, the ability to measure accurately figures in no small role in these developments, as well.  The more tool power available to the individual, the more development we can have, I think.

There is, however, a temptation posed by this square.  No matter how precisely you measure when woodworking, something will not fit.  The drill bit wanders a little, or is shunted a little aside by a knot, or you put it in at 93 degrees instead of 90.  The wood is sniped a bit at the end.  The jigsaw blade cut just off the perpendicular.  The plane caught on something.  You made all of your measurements from a slightly crooked reference.  Skill and good tool maintenance can help avoid most of these, but error adds up when measuring and fitting.  The owner of Sippican Cottage Furniture explains it better than I could here, but the gist of it is:  use the actual workpiece involved as the reference whenever possible.  Use the same reference for all of the same parts.  That way you only have one step to mess up, instead of chaining errors together.  The precision offered by the combination square made you think you could work  the wood like you could the paper on which you did your design work.

The above comments may or may not be an explanation of the issues I am having with my desk project.

Wherein I shave legs

Friday, July 10th, 2009

legs

Desk legs.  What did you think I meant?

(That’s a little Stanley hand plane on top.)