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 HELP.. Pen arm will not drop to plot on some designs
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By: dnewman (offline) on Sunday, April 17 2011 @ 09:58 AM PDT  
dnewman

Ahhh.... the servo isn't turning down either. That could be a wiring issue (not connected to the
correct row of pins) or a servo problem. Please double check the figure in the assembly guide to ensure proper orientation and positioning of the servo wiring connector to the EBB board.

I'd provide more details, but I have to run off right now.

Dan


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By: linuxwrangler (offline) on Sunday, April 17 2011 @ 10:02 AM PDT  
linuxwrangler

Have you tried the "manual control" option in the egg-bot extension? I would try repeatedly raising and lowering the pen and then observe/report. This will allow you to hear if the servo is trying to work, to watch to see if it is stuck on something, etc. without the distraction/noise of the other motors. The result of that test may help narrow the list of possible issues.


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By: Windell (offline) on Sunday, April 17 2011 @ 10:14 AM PDT  
Windell

This is sounding more and more like a mechanical issue. There's really no way for the software to respond correctly part of the time and not part of the time. If communication to the EBB were lost, plotting would stop altogether.

The video doesn't show the servo motor, nor the flexure hinge working, but it looks like it plots correctly at one *end* of the egg, rather than at some random locations. This also suggests mechanical issues. As far as I can tell, there isn't any sound either, so it's hard to tell when the servo is moving or not.

One thing that I can see in the video is that the servo cable is *way too tight* -- like it could be pulling the servo at one end of travel. Pull more of the cable to the "inside" of the chassis, so that it can move freely. I can think of several ways that this could potentially cause the setup to not work.

Once you've got that fixed, try to see where the servo isn't moving at all. With a "sacrificial" egg (or a piece of masking tape applied...) try using manual control to raise and lower the pen, with the pen arm at different locations. See if you can find any relation between when it doesn't work and where the pen arm is.


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By: dnewman (offline) on Sunday, April 17 2011 @ 10:16 AM PDT  
dnewman

Also, what values are you using for the pen up and pen down settings in the Eggbot Control's "Setup" tab?

If you are using values near the extremes of travel for the servo then that may be a concern. The servo should be able to travel 0 - 100% but if you have it near those extremes -- near 0 or near 100% -- and there are problems, then that would seem to suggest an issue with your particular servo. A work around would be to go through the "centering the servo horn" procedure again to make sure that it is well centered and you can use values in the 30 - 70% range rather than at the extremes.

Dan


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By: Anonymous: C Krueger () on Sunday, April 17 2011 @ 10:34 AM PDT  
Anonymous: C Krueger

It looks like the servo raising value was set at 100% and that caused the issue. I set it back down to 70% and it is working.

Thank you all for your help.





       
   
By: dnewman (offline) on Sunday, April 17 2011 @ 11:58 AM PDT  
dnewman

Great! Glad to hear that things are now working for you. I'm now curious to try this on my Eggbot so that I can better understand the issue. Might be worth adding to the troubleshooting wiki page.

Dan


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