Wednesday, March 30, 2011

first attempt at converting a picture

this was an attempt to convert this picture
I think I need to tweak the interconnect between the pieces.

Thursday, March 24, 2011

4 and 5 point spirals

Here is four points.
Here is a five point.
Here is a close up of one of the bobbins to show how the string winds up.

Wednesday, March 23, 2011

Monday, March 21, 2011


This is a fractal called the Cesaro curve. This one has a turn of 90 degrees so it just draws a checkerboard.

Sunday, March 20, 2011

More early 4ballo shots

Basic Stamp program

At first I was just programming the Basic Stamp board to draw pictures. I very soon ran into limitations with that. This board only has 128 bytes of program space so the program had to be very short. Also i needed floating point math and trig functions for some of the things I wanted to draw. I added serial in and out lines to the board so I could talk to it from the PC. Then I just use the board as a driver for the motors and do all the calculating of the picture in the PC. I plan to replace the Basic Stamp board with an Arduino so I can put all the routines in the board and not need a computer connected to draw pictures.
Here is the program I ended up with in the board to talk to the computer. This lets me send a character, 0 through 8 to the board to move the pen one step in any of 8 directions. 0 moves it up, 1 moves it up and to the right, 2 moves it to the right, etc. Then I right programs in Quick Basic to draw my pictures.

' {$STAMP BS1}
' {$PBASIC 1.0}
' left stepper motor connected to P6 and P7
' right one connected TO P3 and P4
' both motors move cw one turn and then ccw one turn
'ccw on left motor winds it up
'cw on right motor winds it up
'00 01 11 10 00 turns cw

SYMBOL counter2 = W1
SYMBOL counter1 = W0
SYMBOL left_real = B10 'phase of the motor, 1,2,3,4
SYMBOL right_real = B11
SYMBOL accumulator = B9
SYMBOL left_grey = B8 'grey code of the motor, 0,1,3,2
SYMBOL right_grey = B7
SYMBOL left_dir = B6 '1 for cw, -1 for ccw
SYMBOL right_dir = B5
SYMBOL speed = B4

speed = 0 'speed is how long to wait between steps
DIRS = 254 'set all pins but P0 to outputs
left_real = 1
right_real = 1

'pause 2 seconds to give time to position motors
PAUSE 2000

PINS = 0
SEROUT 1, N2400, ("START",13)

SERIN 0, N2400, #counter2

BRANCH counter2, (up, up_right, right, down_right, down, down_left, left, up_left)
SEROUT 1, N2400, (#counter2, 13)
GOTO start

left_dir=-1 ' wind up left motor
right_dir = 1 'wind up right motor
GOSUB move
GOTO start

left_dir = 0 'don't move left motor
right_dir = 1 'wind up right motor
GOSUB move
GOTO start

left_dir = 1 'unwind left motor
right_dir = 1 ' wind up right motor
GOSUB move
GOTO start

left_dir = 1 'unwind left motor
right_dir = 0  'don't move right motor
GOSUB move
GOTO start

left_dir = 1  'unwind left motor
right_dir = -1  'unwind right motor
GOSUB move
GOTO start

left_dir = 0  'don't move left motor
right_dir = -1  'unwind right motor
GOSUB move
GOTO start

left_dir = -1  'wind up left motor
right_dir = -1  'wind up right motor
GOSUB move
GOTO start

left_dir = -1  'wind up left motor
right_dir = 0  'don't move right motor
GOSUB move
GOTO start

'GOTO start


left_real = left_real + left_dir
IF left_real < 5 THEN left1
IF left_real > 0 THEN left2
left_real = 4
IF left_real <> 1 THEN left3
left_grey = 0
IF left_real <> 2 THEN left4
left_grey = 1
IF left_real <> 3 THEN left5
left_grey = 3
IF left_real <>4 THEN left6
left_grey = 2

right_real=right_real + right_dir
IF right_real < 5 THEN right1
IF right_real > 0 THEN right2
right_real = 4
IF right_real <> 1 THEN right3
right_grey = 0
IF right_real <> 2 THEN right4
right_grey = 1
IF right_real <> 3 THEN right5
right_grey = 3
IF right_real <>4 THEN right6
right_grey = 2

accumulator = left_grey * 8 + right_grey
accumulator = accumulator * 8
PINS = accumulator
PAUSE speed
SEROUT 1, N2400, (#counter2, 13)


some details.

The white plotting area of the white board is about 22" by 34".
I first tried using a board about a yard long with the motors about the even with the edge of the white area.
I don't have any good photos yet, just some poor cell phone camera shots. I never took one of just the pen holder. It is made from KNEX.
I will be showing better pictures and maybe drawings of things later.
This is a lousy shot of the Basic Stamp board. There is one connector for each motor and one with three wires for serial communications.

Here are a couple shots showing how I glued sewing machine bobbins to stepper motors to wind the fish line to.
This is very blurry shot of one of the driver boards. I will have more details of those to follow although I have seen some circuits I would like to replace them with.
At first I just sat the board on the edge of a card table with the white board leaning up against the leg of the table. That very soon showed some serious problems so I built a frame to hold everything together. I built the top of the frame that holds the board with the motors longer so I could put some cuphooks at the ends to guide the string to the bobbins. This made the string wind much more evenly. That was the cause of the gaps in the picture on the first post. Here is what it looked like.
It still had a couple problems. The steps in the upper part of the board are less accurate than the steps in the lower part just due to the geometry of the thing. Also the pen has some friction to the board and this made the lines drawn going down not at accurate. That is why the upper circle in this picture has kind of a lump to the left. By the way this is a polar plot of several different phases of standing waves.
I do need to give credit to some of my picture ideas to Bruce Shapiro at This one is similar to one he calls 4ballo drawn by Sisyphus III.
To help solve these two problems I moved the board to the bottom of the legs of the frame and added the weight of a couple of dead AA batteries to the pen.

Saturday, March 19, 2011

some more tries.

Here are some more things i tried.

It is fairly repeatable but the circles aren't too circular.

Thursday, March 17, 2011

The beginning.

I started building a white board plotter.
I've been thinking about it for years and finally put some hardware together.
I reused a Basic Stamp BS1 project board that I had used to build a POV pinewood derby car.
I also used some stepper motor driver boards that I had built for a project my son was doing.

Here was an early attempt to draw a spiral.