I have an oval picture for which I would like to make a frame. I can
draw the oval
As I see it there would be two parts in cutting the oval.
----- The oval cut that would eventually frame the picture.
----- The rabbet cut to hold the picture.
I have the following tools available to me:
1. Table saw (I have no idea how this could be used)
2. Standard size non plunge router with router table.
3. Dremmel with spiral cut bit and other router bits.
4. Jig saw.
5. Drill press with brad point and Forstner bits.
Can I get suggestions making the cutout for the picture.
Finishing the outside edges is obvious.
Major axis length (longest "diameter")
Minor axis length (shortest "diameter")
One more tool:
Analytic Geometry :)
Let 2a = major axis
let 2b = minor axis
There will be two foci (on the major axis)
The distance from the center to either focus is sqrt(a^2 - b^2)
The equation, if you want to plot an ellipse is
x^2/a^2 + y^2/b^2 = 1
Or, if you want to construct an ellipse:
push a pin into each of the foci
tie a string to each pin so that if you pull the string taut with a
pencil point, the pencil point will just touch a point at a distance b
from the center on the perpendicular bisector of a line between the two
It sounds a lot more complicated than it really is :)
Once you've drawn it, you can freehand rout the opening - and can then
use a rabbet bit to cut for the glass and photo.
FWIW - this project begs for a spindle sander. ;-)
I detested that class.
Prof was a Yugoslav, didn't have a great command of English. He had been a
partisan and his throat had been cut ear to ear; no idea if that affected
his speech but he was next to impossible to understand. It was the only
class I *ever* had to repeat.
Bummer. I can sympathize because my freshman physics class was a Korean
who had a similar handicap, and who made up for it by screaming his
lectures. I dropped the course after a week and restarted the following
quarter with a different prof, along with all the folks who'd stuck it
out and failed the course.
The guy who taught my Calculus and Analytic Geometry class, by contrast,
was clear, soft-spoken, and wrote everything on the blackboard as he
lectured. He wrote with his right hand and erased with his left as he
went, with pauses as he walked back to the left side of the board. It
would have been humorous if I hadn't been in a permanent panic to get
things into my notes before they disappeared. :)
Just having the youngest out of college, I know that taking notes in
class today can be as simple as hitting a button and letting the
recording device/laptop tape the lecture.
I can't help but think that letting technology do it for you probably
skips a vital link in the synapses that the process of writing it down
completes. I was thinking about that the other day when responding to
the thread on width, length, etc.
Botany prof drew pictures of plant cell structures on a blackboard and
students were required to handcopy them to a notebook that was part of
the course grade ....and today, 45 years later, those pictures I copied
from that blackboard are still vivid in my mind.
Also had a Korean grad student that taught an advanced math course full
of words like 'vector-value', 'differential', etc. that he couldn't
pronounce in an understandable manner to anyone ... a brilliant guy, but
he cost most of us a grade point or two.
One of the best teachers I ever had was my analytical geometry teacher
in high school. I had many more in college but he was the best.
As for technology in the class room while there are negatives, there are
all so some strong positives. If I have a computer in physical
chemistry I may have a better understanding of how the various equation
Of course you go to school to learn what you do not know, and to learn
They're becoming forgotten. Slide rules put man on the moon.
Back in HS and college, the classes like Physics and Chem had a
half bushel basket by the door with school slide rules for the
kids without their own.
Same mathematical functions as a computer, but these days the computer
is _much_ faster.
That wasn't always the case, even with electronic digital computers.
When I was in the Army we routinely beat "Freddie" FADAC (Field
Artillery Digital Automatic Computer) with our slide rules in the Fire
Direction Centers ... in combat we seldom used "Freddie" to actually
fire missions, just to check our slide rule results, if we didn't have
to wait on it.
It wasn't a matter of arithmetic trust, FADAC was just too damn slow.
Reminds me of my state PE exams.
Knew they gave a lot of partial credit and you needed an 80 to pass.
During a 2 day exam, never completely solved a math question.
Posted a note at the top of every answer sheet that went something
* = Plug in values and turn crank.
Would set up the equations to solve a problem, then it was "*" time.
I passed the exams.
After all, I wasn't there to take a slide rule exam, but rather
One guy, an older gentleman, pulled out his drafting board, some
triangles, a scale and provided graphical solutions.
Have no idea if he passed the exams.
Back then, computers were big clunkers that were kept in huge
And it was inconcievable to those who ran them that micros were ever
going to achieve that kind of performance. Now we bitch about how slow
our machine is when it is several times faster than an '80s supercomputer.
When I was in High School in the late 50's I paid 25 dollars for a cheap
slide rule. There was no way I could have afforded the expensive ones.
Today when you go to flea markets or antique stores you can pick up the
most expensive for 5 or 10 dollars/ with case.
My favorite slide rule was the circular slide rule. For some spectra
conversion in IR or UV you could make the calculation on the circular
slide rule faster that any calculator today.
My Post, log-log-desi-trig complete with carrying case was less than
$15 when I got it while still in high school.
Had several inverse as well as folded scales which allowed you to fly
thru the calculations.
Never did figure out how to use the "pencil & eraser" functioin.<G>
Still have that little beauty someplace.
Got one of my Dad's cast off K&E's in HS, but don't remember the model.
You're right, I think I paid $20+ for the one I used in college, but
damn that was expensive!
... that's back when I routinely found it necessary to cash bank
"counter drafts" (remember those?) for 50 cents at the student center
two or three times a week.
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