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By: Anonymous: Eggplant! () on Sunday, October 10 2010 @ 08:24 AM PDT (Read 5747 times)  
Anonymous: Eggplant!

I've assembled my Egg-Bot! During testing, it seems that pen up/down are reversed. Obviously this will be an issue! I checked over the build docs a few times to make sure I didn't get anything backwards. It *looks* fine to me. Any suggestions?

I'm testing via the Inkscape plug-in on Vista. Python is borked on my Mac at the moment... cannot find the serial module. Once I get that figured out, I'll test there as well.

Inkscape: 0.48
Win USB driver: 1.0
EB Ext: 2.0.0r1

I snapped a few pics of my bot's arm assembly:

Arm assembly (front)
Arm assembly (back)
EiBot board connection





       
   
By: dnewman (offline) on Sunday, October 10 2010 @ 10:47 AM PDT  
dnewman

Quote by: Eggplant!


I'm testing via the Inkscape plug-in on Vista. Python is borked on my Mac at the moment... cannot find the serial module. Once I get that figured out, I'll test there as well.



Got to /Applications/Inkscape.app/Contents/Resources/extensions/ and check the permissions on
the directory named "serial". E.g., from a terminal window do

% cd /Applications/Inkscape.app/Contents/Resources/extensions/
% ls -ld serial
drwxr-xr-x 15 501 501 510 Oct 5 00:05 serial
%

Make sure that it is "r-x" and "r-x" for group and world (the right most two sets of perms in that output.)

Indeed, you can do

% sudo chmod a+rx serial

and that will ensure that the permissions include r (read) and x (execute) for owner, group, and world for that directory. (For a directory, "execute" means "list contents of".)

You can also do this with the GUI but it involves a right mouse click on the Inkscape folder so that you can elect to see the folder's contents which OS X will otherwise hide from you.

I mention the above as there was a brief period in which the Mac Inkscape installed didn't set the permissions quite correctly on that directory. In that case, depending upon what sort of permissions you allow your mortal users to run with, you might get a runtime error about an inability to "import serial". I suppose it's possible that if you picked up an installer package early, they you got that problem. It was fixed on 5 October.

Oh, and if you don't have a serial directory there, then just how did you install the eggbot software?
Manually?

Dan


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By: EmbeddedMan (offline) on Sunday, October 10 2010 @ 10:59 AM PDT  
EmbeddedMan

A really quick fix for any axis that seems like it is backwards is to swap two of its wires. Each motor connects with four wires. Swap either 1 and 2, or 3 and 4. Then it will run the other way!

(Obviously, getting it to work right according to the instructions is way better, but if you just want to test, this is quick.)

*Brian


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By: dnewman (offline) on Sunday, October 10 2010 @ 11:01 AM PDT  
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Quote by: EmbeddedMan

A really quick fix for any axis that seems like it is backwards is to swap two of its wires. Each motor connects with four wires. Swap either 1 and 2, or 3 and 4. Then it will run the other way!

(Obviously, getting it to work right according to the instructions is way better, but if you just want to test, this is quick.)

*Brian



But this is the pen lift servo with three wires. Isn't the height to lift based on the width of a periodic pulse?

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By: dnewman (offline) on Sunday, October 10 2010 @ 11:05 AM PDT  
dnewman

Quote by: Eggplant!

I've assembled my Egg-Bot! During testing, it seems that pen up/down are reversed. Obviously this will be an issue! I checked over the build docs a few times to make sure I didn't get anything backwards. It *looks* fine to me. Any suggestions?



P.S. It looks to me like your servo is mounted correctly. Had it been on the wrong side of the proximal pen arm then you would get a reversal I believe. (A rotate the servo counter clockwise to lift the pen arm would then be a rotate clockwise, lowering the pen arm.) So, I myself don't have any good advice on this front. But then, I'm a software guy.

So, speaking of software, you do have the pen up position value LARGER than the pen down position value in the "Setup" tab of the Eggbot Control extension, correct? The software doesn't check to see if the down position exceeds the up position. When down < up, then you will think that it is lowering the pen when doing a pen up relative to the pen down position which is now higher than then pen up position.

Dan


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By: Windell (offline) on Sunday, October 10 2010 @ 11:34 AM PDT  
Windell

So, speaking of software, you do have the pen up position value LARGER than the pen down position value in the "Setup" tab of the Eggbot Control extension, correct?


I'm very curious about this too.

The software should allow you to set the pen-up position to be lower than the pen-down position. So, it's possible that it's set up like this when it shouldn't be. Or, if the servo itself somehow has its position backwards-- due to internal miswiring --you can use this feature of the software to correct for it.

IF the motor is backwards,it would be the first case I've heard. However, if there are a significant number of other cases where servos are wired backwards inside, we should probably provide a simple "reverse servo motor" checkbox in the extension, like we do for the steppers.


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By: EmbeddedMan (offline) on Sunday, October 10 2010 @ 01:08 PM PDT  
EmbeddedMan

Quote by: dnewman

Quote by: EmbeddedMan

A really quick fix for any axis that seems like it is backwards is to swap two of its wires. Each motor connects with four wires. Swap either 1 and 2, or 3 and 4. Then it will run the other way!

(Obviously, getting it to work right according to the instructions is way better, but if you just want to test, this is quick.)

*Brian



But this is the pen lift servo with three wires. Isn't the height to lift based on the width of a periodic pulse?

Dan



Ooops. Sorry. Quite right - I was thinking the stepper motors. And yes, you are correct about the servo. There isn't a way in hardware to easily swap directions for it.

*Brian


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By: Anonymous: Eggplant! () on Sunday, October 10 2010 @ 03:24 PM PDT  
Anonymous: Eggplant!


So, speaking of software, you do have the pen up position value LARGER than the pen down position value in the "Setup" tab of the Eggbot Control extension, correct?
Dan[/p]



...forehead slap!

I'm a maroon. Everything is fine. Thanks for the help guys!





       
   
By: dnewman (offline) on Sunday, October 10 2010 @ 06:38 PM PDT  
dnewman

Quote by: Eggplant!


Everything is fine. Thanks for the help guys!



Glad to hear that the servo issue is resolved. Did you get things working on your Mac as well. That is, did you resolve the issue with Python and the pySerial library? If you used the Eggbot Mac installer then that library should have been installed for you, albeit with the wrong permissions if you had the installer package from 5 October. The problem was corrected later that same day or the very next day at the latest.

Dan


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By: Anonymous: Eggplant! () on Sunday, October 10 2010 @ 06:54 PM PDT  
Anonymous: Eggplant!

Yes it works on the Mac now too It appears I had the faulty installer.

Thanks!





       
   
By: mtbf0 (offline) on Sunday, October 10 2010 @ 07:48 PM PDT  
mtbf0

i, too, am a maroon. just a slightly different variety. installed the medial pen arm backwards and had to set the pen up lower than the pen down. of course, when i tried to print something, the servo was banging the piece the egg motor is mounted on. a helpful bystander pointed out that it was obvious from the picture on the box that i had it wrong.

it's not as if i haven't built emsl kits before. i learned from the meggy to follow the directions with care.

need patience. why was there none in the kit?


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By: Windell (offline) on Monday, October 11 2010 @ 12:00 PM PDT  
Windell

Quote by: Eggplant!

Yes it works on the Mac now too It appears I had the faulty installer.

My apologies for posting that faulty installer in the first place. Oops!Oops!Oops!

(And, thank you again, Dan, for pointing out the error!)


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