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Erratic Printing/Lift Servo
12-28-2017, 01:43 PM
Post: #1
Erratic Printing/Lift Servo
Hi. A couple of ongoing issues. The lift servo is working very erratically. I followed the set up positioning video - and one “spline” left and right when it didn’t work well. Also started with the servo moved to slightly different positions by hand - and various power on start up positions.

Added picture.. (it always drags/draws the line from the the starting position to the text).

Secondly, when cleaning the board the lift servo is erratically active, lifting the eraser from the board at odd, random moments. I would have thought the lift servo would be inactive for the entire wipe/clean process.

Help gratefully appreciated.

Colin


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12-28-2017, 06:12 PM (This post was last modified: 12-28-2017 06:14 PM by JohnQ.)
Post: #2
RE: Erratic Printing/Lift Servo
Looks like the lifting servo is slightly dis-adjusted. Try to unscrew it and rotate a little bit. What worked for me: during the stand by, the lifting servo is a little bit off the aluminium pipe (photo attached) and the wiper servo completely perpedicular to the glass. If the servos are set like that when the iboardbot is waiting for commands, it should wipe and draw properly.
   


Regarding your second comment: this is strange. You are right, the lifting servo should be inactive while wiping. Just a quick question: is the lifting servo making noise (3 buzzes) when the iboardbot gets connected to internet? Just double checking that both servos are not swapped.

Try this: the Arduino code allows to use the i2C port on the Brain shield as another servo port. Connect the lifting servo as indicated in the photos below (and see how it goes)
       
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12-28-2017, 06:56 PM
Post: #3
RE: Erratic Printing/Lift Servo
[quote='JohnQ' pid='3184' dateline='1514484769']
Looks like the lifting servo is slightly dis-adjusted. Try to unscrew it and rotate a little bit. What worked for me: during the stand by, the lifting servo is a little bit off the aluminium pipe (photo attached) and the wiper servo completely perpedicular to the glass. If the servos are set like that when the iboardbot is waiting for commands, it should wipe and draw properly.



Regarding your second comment: this is strange. You are right, the lifting servo should be inactive while wiping. Just a quick question: is the lifting servo making noise (3 buzzes) when the iboardbot gets connected to internet? Just double checking that both servos are not swapped.

Try this: the Arduino code allows to use the i2C port on the Brain shield as another servo port. Connect the lifting servo as indicated in the photos below (and see how it goes)



Thanks. Lifting servo does the 3 “buzzes” and moves about a bit. It’s in the position shown in your pics. It doesn’t move out (toward the glass) when the first move happens,but then sometimes does move (can go all the way perpendicular to the board). Tried the alternative servo placement.

Very odd. Doesn’t seem to be a faulty servo - but could it be?
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12-29-2017, 09:40 AM
Post: #4
RE: Erratic Printing/Lift Servo
The position of the horn of the servo is dictated by the internal potentiometer. It is very unlikely that that potentiometer is faulty but might happen

Have you tried Colin, to connect the lifting servo to the i2c port as John indicated and the servo behaved in the same way? If so: we can blame the servo. If you got the STEM kit you should have another servo (MG90) around. Swap servos (temporary) as see if the new servo works properly. If that is the case, please let us know at: info@jjrobots.com and we will send you a replacement ;-)
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