this one looks great! can you share the schematic?
No schematic available, these photos should help
For convenience, left photo has been mirrored (flip horizontal)
Whats a tantalum capacitor used for? what is its advantage or difference from the conventional electrolytic one?
The capacitor removes noise
Tantalum electrolytic capacitors have more Farads per grams, you can use standard ones
hey kas!
my project is almost done....but the cube falls off. This happens since the grippers are slightly off centered....i mean the grippers hold the cube off-centered. Me and my project partners are not being able to figure out how to correct this. I am going to give a last try tomorrow by shifting the grippers closer to each other almost so as they touch each other. Will that work out?
P.S:
Project submission is on 16th 
Hi dd5665
Your wrist servo's are not mounted symetric, this may have an impact on alignment
Also make sure that boards are perpendicular
I enclose a pdf for the two boards (also available in eps, dxf, ai)
Important: dimensions are OK for a 57mm Rubik's cube
Let me know if it helps
SupportV2.pdf (50 KB)
Hey kas!
Thanx a lot for that drawing. We aligned the grippers near-perfectly. Somehow.
Theres another problem now. We were using an indian clone called induinoX. I dont knw why but after scanning 4 sides of the cube. The message arduino not responding shows up in the console window.
I tried reducing the baud rate of serial communication in both cube mover.ino as well as in the python script to 9600 but it still doesnot work.
Probably not enough juice for the Arduino
try checking with a DVM
How do you power the board ??
I dont know why but after scanning 4 sides of the cube...
Seems that you get problems when the BACK wrist servo starts playing
My guess:
At some point, this servo may be blocked fully CW or CCW and sucks current
try moving the servo arm by one or two steps
No the grippers dont get stuck or anything.
When i press scan cube button. it scans the faces one by one but after scanning foursides, when its about to scan the up face. It gives the error.
I power the board using the PC USB
when its about to scan the up face. It gives the error
That's when the BACK wrist servo is energized
Try changing back wrist servo
I power the board using the PC USB
=500 mA only 
you get processor brownout
You need a 2 amps wall adapter
Google for brownout servo arduino
no i power the servo using a separate SMPS (one used in desktop pcs)
only arduino using the usb
Make sure Arduino and servo grounds are connected
possible bad servo
is your back wrist servo moving normally for scan #5 (top face) ??
try permuting servo
Do you get error message when running with servo's power OFF ??
Arduino and servo grounds are connected.
I tried the test button. this time the grippers move perfectly for all moves. I think the serial communication gets garbled messages?
can that happen? my baud rate is now 9600...should i try and decrease it?
also, what is the front 2 scan function? why should we scan the front face twice?
I think the serial communication gets garbled messages?
You may get noise, check for loose connections
can that happen?
On my bot, communication is rock solid
my baud rate is now 9600...should i try and decrease it?
No
what is the front 2 scan function? why should we scan the front face twice?
This function moves back cube to original position, no scan performed
do not compare ur robot with mine. Yours is like factory made. I wish i could intern with you for 2-3 years. 
Yours is like factory made
CNC helps producing clean designs 
Again, if you get errors when scanning Top face, Back wrist servo is the designated culprit (or connection to it)
my back pinch and rotate servos are faulty i know. I have to show my professors this way tomorrow. I'll replace the servos later on and check.
I'm studying your codes for tomorrow's presentation.
I have given your name on our thesis. 
I'm studying your codes for tomorrow's presentation
Good luck ;D let us know the outcome
Time to sleep now 
Everyone loved the robot!
I got a new arduino uno from a friend. I'll hook it up tomorrow and see if the arduino not responding problem is fixed.
Everyone loved the robot!
.
Hey kas!
I have around a month's time to fix the robot completely to solve it. I will be leaving my college after a month. Today i showed the robot to our head of department and he was so impressed by it (he is a very hard-to-impress man). I want to gift our robot to our college's department. Can you help me diagnose the problem. I tried replacing the arduino with another one (this one is the official arduino uno) but the problem still persists.
Arduino not responding after 4th scan
I have around a month's time to fix the robot completely to solve it. I will be leaving my college after a month
That plenty of time
Please answer ALL questions
I tried the test button. this time the grippers move perfectly for all moves
Uninstall the cube
run "Scan colors"
2) Do you still have communication problems when the cube is removed (reduced servo's load)
If you still get the error message:
Disconnect all four servo's (remove plugs from shield) and run "Scan colors"
You should see debugging info in your Python shell
http://127.0.0.1:8081/?connect1
b'<HTML><BODY>\r\nDone!\r\n</BODY></HTML>\r\n'
b'OKb\r\n'
http://127.0.0.1:8081/?scanB
b'<HTML><BODY>\r\nDone!\r\n</BODY></HTML>\r\n'
b'OKl\r\n'
http://127.0.0.1:8081/?scanL
b'<HTML><BODY>\r\nDone!\r\n</BODY></HTML>\r\n'
b'OKf\r\n'
http://127.0.0.1:8081/?scanF
b'<HTML><BODY>\r\nDone!\r\n</BODY></HTML>\r\n'
b'OKr\r\n'
http://127.0.0.1:8081/?scanR
b'<HTML><BODY>\r\nDone!\r\n</BODY></HTML>\r\n'
b'OKu\r\n'
http://127.0.0.1:8081/?scanU
b'<HTML><BODY>\r\nDone!\r\n</BODY></HTML>\r\n'
b'OKd\r\n'
http://127.0.0.1:8081/?scanD
b'<HTML><BODY>\r\nDone!\r\n</BODY></HTML>\r\n'
b'OKg\r\n'
...........
Re-connect the two FRONT servo's only (camera side)
Run "Scan colors" again
4) Are the two servo's running OK ??
5) Do you see debug info as per above ??
Re-connect the BACK pinch servo (only BACK wrist servo is left disconnected)
Run "Scan colors" again
6) Are the three servo's running OK ??
7) Do you see debug info as per above ??
Let me have your answers
To be continued ...