Tuesday, December 13, 2011

AS220 Labs

I adapted some code that AS220 Labs posted for a drawbot they made.
It worked.
http://www.as220.org/labs/drawbot/

Monday, August 8, 2011

not quite working

Didn't quite work right. I think I have to work on getting the weight that I use with the pen just right. Not enough and it sticks like this. Too much and it skips steps and gets out of place.
Here is a link to the code I used.
http://dl.dropbox.com/u/37661946/fourballo.pde


back to it

I dug the doodler out this week and started working with it again. I had to fix some parts that got broke when it was put into storage.

I am trying to figure out how to post the code. Maybe dropbox.com or hackaday?

Thursday, April 21, 2011

answers to some code requests

some readers asked about the code.
Christopher, i am not sending it Gcode. I send it a single character followed by a carriage return.
The character is a digit 0 through 7. 0 means move up one step, 1 means up and to the right one step, 2 means move right one step, etc. everything is then calculated in a quickbasic program and sent through the serial port. now i have replaced the basic stamp board with the Arduino so now all the code is internal to it and it can run without the PC connected. i am having some problems with that setup though. when it gets toward the top of the board the steppers slip some steps and it gets lost as to where it really is. I think possibly because I am taking Vin and ground from the connector on the Arduino and the motors draw about 750 ma I am getting too much drop across that connection. I may change the driver from a unipolar design that grounds one end of the coil or the other while supplying power to the center to an H bridge driver that supplies power to one end and ground to the other and switches both to change the steps. That should supply the same amount of magnetic force while using half the current.
Here is the code to draw several pictures one after the other in quickbasic.

'WHITE BOARD PLOTTER TESTS
CLS
PI = 3.141593
GOSUB WBPSETUP


'SCREEN 12 '640 * 480 graphics



'OPEN "COM1:2400,N,8,1" FOR RANDOM AS #1
OPEN "COM1:2400,N,8,1,CD0,CS0,DS0,OP0,RS,TB2048,RB2048" FOR RANDOM AS #1
'OPEN "COM1:2400,N,8,1,RS,TB2048" FOR RANDOM AS #1


'GOTO FOURBALLO
'GOTO CESARO4


START:

HEADING = 0
CENTERX = 0
CENTERY = 0
LENGTH = 0
X = CENTERX
Y = CENTERY
FIRSTLOOP:
LENGTH = LENGTH + .3

HEADING = HEADING + 2.08

X = COS(HEADING) * LENGTH + X
Y = SIN(HEADING) * LENGTH + Y
GOSUB WBPMOVE
IF LENGTH < 18 GOTO FIRSTLOOP

FOURBALLO:
HEADING = 0
CENTERX = 0
CENTERY = 0
SIZE = 5
PHASES = 72

X = SIZE: Y = 0: GOSUB WBPMOVE
INPUT "ERASE THE BOARD AND PRESS ENTER "; N$

FOR HEADING = 0 TO (PHASES * 2 * PI) STEP (.02)
MOVCIRC = HEADING / PHASES
R = SIZE
R1 = COS(HEADING * 2)
R2 = SIN(HEADING + MOVCIRC)
R = R + R1 * R2 * SIZE
X = COS(HEADING) * R + CENTERX
Y = CENTERY + SIN(HEADING) * R
GOSUB WBPMOVE
NEXT
X = SIZE: Y = 0: GOSUB WBPMOVE
INPUT " PRESS ENTER "; N$

CESARO4:
CSIDE = 7.5
CSTAGE = 0
SIDE = CSIDE * .453 ^ CSTAGE
X = 0
Y = -(CSIDE / 3)
GOSUB WBPMOVE
INPUT "PRESS ENTER"; N$

FOR CSTAGE = 0 TO 7
SIDE = CSIDE * .453 ^ CSTAGE
FOR CUBE = 1 TO 4
STAGE = CSTAGE
GOSUB SPIKE
HEADING = HEADING + PI / 2
NEXT CUBE
HEADING = HEADING - PI / 2
NEXT CSTAGE
GOTO CESARODONE

SPIKE:
IF STAGE = 0 THEN GOSUB FORWARD: GOTO DONE
STAGE = STAGE - 1
GOSUB SPIKE
HEADING = HEADING + (84 / 180 * PI)
GOSUB SPIKE
HEADING = HEADING - (168 / 180 * PI)
GOSUB SPIKE
HEADING = HEADING + (84 / 180 * PI)
GOSUB SPIKE
STAGE = STAGE + 1

DONE:
RETURN

FORWARD:
X = X + SIDE * SIN(HEADING)
Y = Y + SIDE * COS(HEADING)
GOSUB WBPMOVE
RETURN

CESARODONE:
X = 0: Y = 0: GOSUB WBPMOVE

CLOSE
END

WBPMOVE:

WBPX = X
WBPY = Y
WBPOLDX = WBPXNOW
WBPOLDY = WBPYNOW
WBPXDELTA = WBPX - WBPXNOW
WBPYDELTA = WBPY - WBPYNOW
IF ABS(WBPXDELTA) < (WBPSTEPSIZE) AND ABS(WBPYDELTA) < (WBPSTEPSIZE) THEN GOTO WBPMOVEDONE

WBPXDIR = SGN(WBPXDELTA)
WBPYDIR = SGN(WBPYDELTA)

IF ABS(WBPYDELTA) > ABS(WBPXDELTA) THEN GOTO WBPYBIGGER

WBPXBIGGER:
FOR WBPX = WBPXNOW TO X STEP (WBPXDIR * .01)
WBPY = Y - ((X - WBPX) / WBPXDELTA) * WBPYDELTA
GOSUB WBPTRYSTEPPING
NEXT WBPX
GOTO WBPXFINISH

WBPXFINISH:
GOSUB WBPTRYSTEPPING
IF ABS(X - WBPXNOW) > WBPSTEPSIZE OR ABS(Y - WBPYNOW) > WBPSTEPSIZE THEN GOTO WBPXFINISH
GOTO WBPMOVEDONE

WBPYBIGGER:
FOR WBPY = WBPYNOW TO Y STEP (WBPYDIR * .01)
WBPX = X - ((Y - WBPY) / WBPYDELTA) * WBPXDELTA
GOSUB WBPTRYSTEPPING
NEXT WBPY

WBPYFINISH:
GOSUB WBPTRYSTEPPING
IF ABS(X - WBPXNOW) > WBPSTEPSIZE OR ABS(Y - WBPYNOW) > WBPSTEPSIZE THEN GOTO WBPYFINISH
GOTO WBPMOVEDONE

WBPTRYSTEPPING:
'try stepping in each direction and see which way gets closer to x,y

'TRY STEPPING 0
WBPLEFTTRY = WBPLEFT - WBPSTEPSIZE
WBPRIGHTTRY = WBPRIGHT - WBPSTEPSIZE
GOSUB WBPTRYDIST
WBPTRY(0) = SQR((WBPXDIFF * WBPXDIFF) + (WBPYDIFF * WBPYDIFF))

'TRY STEPPING 1
WBPLEFTTRY = WBPLEFT
WBPRIGHTTRY = WBPRIGHT - WBPSTEPSIZE
GOSUB WBPTRYDIST
WBPTRY(1) = SQR((WBPXDIFF * WBPXDIFF) + (WBPYDIFF * WBPYDIFF))

'TRY STEPPING 2
WBPLEFTTRY = WBPLEFT + WBPSTEPSIZE
WBPRIGHTTRY = WBPRIGHT - WBPSTEPSIZE
GOSUB WBPTRYDIST
WBPTRY(2) = SQR((WBPXDIFF * WBPXDIFF) + (WBPYDIFF * WBPYDIFF))

'TRY STEPPING 3
WBPLEFTTRY = WBPLEFT + WBPSTEPSIZE
WBPRIGHTTRY = WBPRIGHT
GOSUB WBPTRYDIST
WBPTRY(3) = SQR((WBPXDIFF * WBPXDIFF) + (WBPYDIFF * WBPYDIFF))

'TRY STEPPING 4
WBPLEFTTRY = WBPLEFT + WBPSTEPSIZE
WBPRIGHTTRY = WBPRIGHT + WBPSTEPSIZE
GOSUB WBPTRYDIST
WBPTRY(4) = SQR((WBPXDIFF * WBPXDIFF) + (WBPYDIFF * WBPYDIFF))

'TRY STEPPING 5
WBPLEFTTRY = WBPLEFT
WBPRIGHTTRY = WBPRIGHT + WBPSTEPSIZE
GOSUB WBPTRYDIST
WBPTRY(5) = SQR((WBPXDIFF * WBPXDIFF) + (WBPYDIFF * WBPYDIFF))

'TRY STEPPING 6
WBPLEFTTRY = WBPLEFT - WBPSTEPSIZE
WBPRIGHTTRY = WBPRIGHT + WBPSTEPSIZE
GOSUB WBPTRYDIST
WBPTRY(6) = SQR((WBPXDIFF * WBPXDIFF) + (WBPYDIFF * WBPYDIFF))

'TRY STEPPING 7
WBPLEFTTRY = WBPLEFT - WBPSTEPSIZE
WBPRIGHTTRY = WBPRIGHT
GOSUB WBPTRYDIST
WBPTRY(7) = SQR((WBPXDIFF * WBPXDIFF) + (WBPYDIFF * WBPYDIFF))

WBPTEMP = 0
IF WBPTRY(1) < WBPTRY(WBPTEMP) THEN WBPTEMP = 1
IF WBPTRY(2) < WBPTRY(WBPTEMP) THEN WBPTEMP = 2
IF WBPTRY(3) < WBPTRY(WBPTEMP) THEN WBPTEMP = 3
IF WBPTRY(4) < WBPTRY(WBPTEMP) THEN WBPTEMP = 4
IF WBPTRY(5) < WBPTRY(WBPTEMP) THEN WBPTEMP = 5
IF WBPTRY(6) < WBPTRY(WBPTEMP) THEN WBPTEMP = 6
IF WBPTRY(7) < WBPTRY(WBPTEMP) THEN WBPTEMP = 7
ON (WBPTEMP + 1) GOSUB WBP0, WBP1, WBP2, WBP3, WBP4, WBP5, WBP6, WBP7
FOR WBPZ = 1 TO 6000: NEXT

'CALCULATE WHERE THE PEN IS NOW
WBPS = (WBPLEFT + WBPRIGHT + WBPBASE) / 2
WBPAREA = SQR(WBPS * (WBPS - WBPLEFT) * (WBPS - WBPRIGHT) * (WBPS - WBPBASE))
'VERTICAL DISTANCE FROM SPOOLS DOWN TO THE PEN IS
WBPHEIGHT = (WBPAREA * 2) / WBPBASE
WBPWIDTH = SQR((WBPLEFT * WBPLEFT) - (WBPHEIGHT * WBPHEIGHT))

WBPXNOW = WBPWIDTH - WBPCENTERWIDTH
WBPYNOW = WBPCENTERHEIGHT - WBPHEIGHT

RETURN

GOTO WBPMOVE

WBPTRYDIST:
WBPTRYS = (WBPLEFTTRY + WBPRIGHTTRY + WBPBASE) / 2
WBPTRYAREA = SQR(WBPTRYS * (WBPTRYS - WBPLEFTTRY) * (WBPTRYS - WBPRIGHTTRY) * (WBPTRYS - WBPBASE))
'VERTICAL DISTANCE FROM SPOOLS DOWN TO THE PEN IS
WBPTRYHEIGHT = (WBPTRYAREA * 2) / WBPBASE
WBPTRYWIDTH = SQR((WBPLEFTTRY * WBPLEFTTRY) - (WBPTRYHEIGHT * WBPTRYHEIGHT))

WBPXTRY = WBPTRYWIDTH - WBPCENTERWIDTH
WBPYTRY = WBPCENTERHEIGHT - WBPTRYHEIGHT
WBPXDIFF = WBPX - WBPXTRY
WBPYDIFF = WBPY - WBPYTRY

RETURN

WBPMOVEDONE:

'THE SEMIPERIMETER IS THE DISTANCE BETWEEN THE SPOOLS PLUS
'THE LENGTH OF EACH STRING DIVIDED BY TWO
'THE AREA OF THE TRIANGLE IS THE SQUARE ROOT OF
'THE SEMIPERIMETER TIMES THE DIFFERENCE BETWEEN THE
'SEMIPERIMETER AND EACH SIDE
'WBPLEFT = LENGTH OF LEFT STRING
'WBPRIGHT = LENGTH OF RIGHT STRING
'WBPBASE = DISTANCE BETWEEN SPOOLS

WBPS = (WBPLEFT + WBPRIGHT + WBPBASE) / 2
WBPAREA = SQR(WBPS * (WBPS - WBPLEFT) * (WBPS - WBPRIGHT) * (WBPS - WBPBASE))
'VERTICAL DISTANCE FROM SPOOLS DOWN TO THE PEN IS
WBPHEIGHT = (WBPAREA * 2) / WBPBASE
WBPWIDTH = SQR((WBPLEFT * WBPLEFT) - (WBPHEIGHT * WBPHEIGHT))

WBPXNOW = WBPWIDTH - WBPCENTERWIDTH
WBPYNOW = WBPCENTERHEIGHT - WBPHEIGHT
'FOR WBPZ = 1 TO 10000: NEXT

RETURN

WBP0:
PRINT #1, 0
WBPLEFT = WBPLEFT - (WBPSTEPSIZE)
WBPRIGHT = WBPRIGHT - (WBPSTEPSIZE)
RETURN

WBP1:
PRINT #1, 1
WBPRIGHT = WBPRIGHT - (WBPSTEPSIZE)
RETURN

WBP2:
PRINT #1, 2
WBPLEFT = WBPLEFT + (WBPSTEPSIZE)
WBPRIGHT = WBPRIGHT - (WBPSTEPSIZE)
RETURN

WBP3:
PRINT #1, 3
WBPLEFT = WBPLEFT + (WBPSTEPSIZE)
RETURN

WBP4:
PRINT #1, 4
WBPLEFT = WBPLEFT + (WBPSTEPSIZE)
WBPRIGHT = WBPRIGHT + (WBPSTEPSIZE)
RETURN

WBP5:
PRINT #1, 5
WBPRIGHT = WBPRIGHT + (WBPSTEPSIZE)
RETURN

WBP6:
PRINT #1, 6
WBPLEFT = WBPLEFT - (WBPSTEPSIZE)
WBPRIGHT = WBPRIGHT + (WBPSTEPSIZE)
RETURN

WBP7:
PRINT #1, 7
WBPLEFT = WBPLEFT - (WBPSTEPSIZE)
RETURN


WBPSETUP:

'48 STEPS IS ONE TURN OF THE MOTOR
'20 TURNS IS ABOUT TWO FEET
'468 STEPS IS ABOUT 12 INCHES, 39 STEPS PER INCH
'THE WHITE PART OF THE BOARD IS 34.5 INCHES WIDE * 22.5 INCHES TALL
'THE CENTER OF THE SPOOLS ARE 33.875 INCHES APART
'THE CENTER OF THE SPOOLS ARE ABOUT .75 INCHES ABOVE THE BOARD
'IF BOTH STRINGS ARE 24 INCHES LONG
'THE PEN IS ABOUT 16.5 INCHES BELOW THE TOP OF THE BOARD
'THE SEMIPERIMETER IS THE DISTANCE BETWEEN THE SPOOLS PLUS
'THE LENGTH OF EACH STRING DIVIDED BY TWO
'THE AREA OF THE TRIANGLE IS THE SQUARE ROOT OF
'THE SEMIPERIMETER TIMES THE DIFFERENCE BETWEEN THE
'SEMIPERIMETER AND EACH SIDE
'WBPLEFT = LENGTH OF LEFT STRING
'WBPRIGHT = LENGTH OF RIGHT STRING
'WBPBASE = DISTANCE BETWEEN SPOOLS
'WBPS=(WBPLEFT + WBPRIGHT + WBPBASE)/2
'WBPAREA = SQR(WBPS*(WBPS-WBPLEFT)*(WBPS-WBPRIGHT)*(WBPS-WBPBASE))
'VERTICAL DISTANCE FROM SPOOLS DOWN TO THE PEN IS
'WBPHEIGHT = (WBPAREA*2)/WBPBASE
'WBPBASE = 33.875
'50.5 INCHES BETWEEN THE CUPHOOKS
'32 INCHES FROM THE LEFT HOOK TO THE CENTER OF THE BOARD

WBPSTEPSIZE = 11.125 / 500


PRINT "POSITION THE PEN AT THE CENTER OF THE BOARD."
INPUT "PRESS ENTER"; N$

INPUT "ENTER THE LENGTH OF THE LEFT STRING "; WBPLEFT
'WBPLEFT = 28.5
INPUT "ENTER THE LENGTH OF THE RIGHT STRING "; WBPRIGHT
'WBPRIGHT = 27.75
'INPUT "ENTER THE DISTANCE BETWEEN SPOOL CENTERS "; WBPBASE
'WBPBASE = 33.875
WBPBASE = 50.5
'INPUT "ENTER THE HEIGHT OF THE WHITE AREA "; WBPTALL
WBPTALL = 22.5
'INPUT "ENTER THE WIDTH OF THE WHITE AREA "; WBPWIDE
WBPWIDE = 34.5
WBPS = (WBPLEFT + WBPRIGHT + WBPBASE) / 2
WBPAREA = SQR(WBPS * (WBPS - WBPLEFT) * (WBPS - WBPRIGHT) * (WBPS - WBPBASE))
WBPHEIGHT = (WBPAREA * 2) / WBPBASE
WBPCENTERHEIGHT = WBPHEIGHT
PRINT "WBPCENTERHEIGHT="; WBPCENTERHEIGHT
WBPCENTERWIDTH = SQR((WBPLEFT * WBPLEFT) - (WBPCENTERHEIGHT * WBPCENTERHEIGHT))

PRINT "WBPCENTERWIDTH="; WBPCENTERWIDTH

RETURN

Wednesday, April 13, 2011

Arduino

Last week I converted the doodler to use an Arduino.
There is a bit of a learning curve to converting my programming from quickbasic to the Arduino language which is a form of C.
It runs a lot faster this way but I think it is too fast. I will add some delay and see if it works better. I displayed it at a homeschool talent night and got some good comments. They allowed dads to bring projects too.

doodler formulas

Here are some of the formulas I use to calculate where to draw.

doodler formulas

I need to figure out where the pen is.
I keep track of how long each string is with each step it takes.
I also know the distance between the cuphooks the strings go over.
That defines a triangle.
There is a neat formula for calculating the area of a triangle.
Add up all three sides, that is the perimeter. Half of that is the semi-perimeter.
Find the difference between each side and the semi-perimeter.
Multiply those three differences times each other and times the semi-perimeter.
Take the square root of that and you have the area.
Once you have the area you can figure out the height of the triangle, (area*2)/base=height.

WBPLEFT is the length of the left string.
WBPRIGHT is the length of the right string.
WBPBASE is the distance between the cuphooks.
WBPS is the semi-perimeter.
WBPS = (WBPLEFT + WBPRIGHT + WBPBASE) / 2
WBPAREA = SQR(WBPS * (WBPS - WBPLEFT) * (WBPS - WBPRIGHT) * (WBPS - WBPBASE))
WBPHEIGHT is the distance down from the cuphooks to the pen.
WBPHEIGHT = (WBPAREA * 2) / WBPBASE
WBPWIDTH is the distance from the left hook to the pen.
WBPWIDTH = SQR((WBPLEFT * WBPLEFT) - (WBPHEIGHT * WBPHEIGHT))
The center of my board is 0,0 so this calculates X and Y for where the pen is.
Units is inches.
WBPXNOW = WBPWIDTH - WBPCENTERWIDTH
WBPYNOW = WBPCENTERHEIGHT - WBPHEIGHT
WBPCENTERWIDTH is the distance from the left hook to the center of the board.
WBPHEIGHT is the distance from the hooks down to the center of the board.

Tuesday, April 12, 2011

some one elses idea

here is a link to a similar idea someone is doing with spray paint.
http://geekphysical.blogspot.com/2011/02/giant-printer.html

Friday, April 1, 2011

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

Cesaro



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
'0000000

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)

start:
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

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

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

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

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

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

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

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

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


'GOTO start
END

move:

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

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

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

RETURN

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 taomc.com. This one is similar to one he calls 4ballo drawn by Sisyphus III.
http://www.taomc.com/art_machines/sisyphus/sisiii/4ballo1_800.JPG
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.