Eggbot Troubleshooting

If you are having difficulty with your first plots, don't panic: there are a couple of minor "setup" issues which may occur with some stepper motors. And, as you have likely seen in photos, the Eggbot produces very precise plots. By observing some basic guidelines, you can achieve the same results. And, if the pointers below do not cover your situation, be sure to search these wiki pages and avail yourself of the other support resources.

• Stair steps in plotted lines, jerky pen or egg motion
• Loud or whining stepper motors
• As soon as I plot, the pen arm swings to one end or the other of my egg and stays there
• Mirrored text
• Upside down text
• Circles plot like ellipses
• Closed figures plot open, the ends do not meet in my plots
• Plots run of the top or bottom of my egg
• I cannot get my plots framed the way I want them
• Plots do not center correctly
• "Paste in Place" results in a bitmap copy (OS X)
• "Paste in Place" doesn't paste back to the same location (OS X)
• Clicking "Apply" in the Eggbot Control extension does nothing (Windows XP)
• Additional sources of help

Stair steps

Loud stepper motors

Does your plot appear to have "stair steps" or jagged lines? Are the stepper motors loud or whining? You likely need to adjust the "Current Adjust" control on the EBB board with a small screwdriver. This is a physical control -- a potentiometer -- on the EBB circuit board mounted to your Eggbot chassis. The control is labelled "CUR ADJ" on the board. If the current is too strong or too weak you may see (or hear) these symptoms. The current increases as you rotate the control counter-clockwise (CCW). Starting with the control turned all the way clockwise (CW), both motors should be very weak. As you increase the current -- turning the control with a small screw driver CCW -- you should be able to feel the motors increasingly resist moving by your hand. The ideal setting is one that provides smooth, relatively low-noise moves from the stepper motors, but has enough torque that the pen arm is not "floppy". Often, this is about half way CCW, maybe a little less. More current, while increasing the motors torque, leads to jerky moves, with position errors (e.g., stair steps).

NOTE: the stepper motors are the two large, metal encased motors which mount to the Eggbot's chassis. One rotates the egg while the other rotates the proximal pen arm. The smaller, plastic encased motor which raises and lowers the distal pen arm is a "servo motor". It's behavior is not controlled by the current adjustment.

As soon as I plot, the pen arm swings to one end or the other of my egg and stays there

If, when you start a plot, the pen arm swings to one extreme end or the other of your egg and stays there, then you may need to adjust the current to your stepper motors. See stair steps above for help on adjusting the stepper motor current.

It is also possible that you are plotting a drawing whose vertical coordinates are outside of the expected range for y-coordinate values. Check to make sure that your Inkscape drawing page does not have an excessive height. Use the "Document Properties" item of the File menu to check the drawing's height. A drawing height in excess of 1000 pixels is suspect. Even heights of 1000 pixels or less still may require care in framing. See framing and pen centering for assistance with framing. Also, make sure that you are using v2.1 or later of the Eggbot Control extension. It supports arbitrary y-coordinate range offsets. With v2.0 and earlier, the y-coordinate values cannot stray far outside of the range [0, 1000].

Mirrored text

If your text appears "mirrored" (e.g., inverted from left to right) then first check the assembly directions to ensure that you have wired the egg motor correctly. Check that the ordering of the colored wires matches the picture. if they do not, then correct their ordering and try replotting. If you are sure that they are wired correctly, then everything is still okay: some stepper motors are just backwards. From the Eggbot Control extension, check (or uncheck) the "Reverse motion of Motor 2 (egg)" checkbox on the "Options" tab. Next, click the "Apply" button to save this setting. Now, plot your test again. If things are still reversed, then make sure that your change to the setting took effect. If there is still an issue, then perhaps you need to instead or also change the "Reverse motion of Motor 1 (pen)" setting. Note that after doing an upgrade of the Eggbot extensions, it is possible for this setting to be lost. In that case, simply set it again and save it with the "Apply" button.

Upside down text

Is your text plotting upside down? First, let us be clear: the (vertical) top of your Inkscape drawing should correspond to the pole of your egg closest to the egg motor and headstock. With this orientation in mind, if your text is plotting upside down then change the "Reverse direction of Motor 1 (egg)" setting. This setting is under the "Options" tab of the Eggbot Control extension. After changing the setting, click the "Apply" button to save your setting. Note that after doing an upgrade of the Eggbot extensions, it is possible for this setting to be lost. In that case, simply set it again and save it with the "Apply" button.

Circles look elliptical

Are your circles or other figures looking squashed? This can be expected once you realize that the Eggbot doesn't attempt to do any special transformations on your drawings when it plots them. Consequently, there are two immediate sources of distortion when plotting your drawings. First, the horizontal component of line segments become physically shorter as they approach either pole of your egg or sphere. This is a consequence of the diminishing circumference of your egg or sphere as the poles are approached. A second effect comes into play when plotting on non-spherical, eillipsoidal objects such as eggs which are longer from pole to pole than they are wide. This means that a single step of the pen arm produces a longer stroke than a single step of the egg motor. As such, a vertical line in your Inkscape drawing can produce a longer stroke than a horizontal line of the same length. The net result is that objects will appear horizontally flattened when drawn on eggs.

To counter this effect, try horizontally stretching your drawing by upwards of 150%. To do this

• Use the "Select All in All Layers" item of Inskcape's Edit menu.
• Then, under the Object menu, choose the "Transform" item.
• In the sub-window which appears on the right edge of the Inkscape window, select the "Scale" tab.
• Set the horizontal scale factor to 150% and the vertical to 100%; ensure that the "Scale proportionally" box is not checked.
• Click the "Apply" button.

Ends don't meet in plots

When the ends of figures do not line up, this strongly suggests an alignment or slippage problem with. To check the alignment, rotate your egg with the motors disengaged and see if there is any perceptible wobble. It's important that the egg be well centered in the egg cups, otherwise, the egg may precess a bit as it is rotated. Sometimes it helps to lift the Eggbot up and sight down the long axis of the egg as you turn it. As regards slippage, the egg needs to be held in tightly by the tailstock spring. That spring should be compressed around two-thirds or more (but not fully compressed). See improving precision for many more tips on alignment and other factors which will influence the quality of your plots.

Plots run off the top or bottom of my egg

I cannot get my plots framed the way I want them

Plots do not center correctly

If you are having difficulty with framing or centering, see framing and pen centering.

"Paste in place" results in a bitmap copy (OS X)

"Paste in place" doesn't place the object in its original location (OS X)

On Macs, if your "Paste" or "Paste in Place" operations are resulting in bitmaps being imported into your Inkscape drawing, then you need to change your X11 preferences. X11 is the windowing system which Inkscape uses to manage its windows. If you click on any running Inkscape window, you will see in the Apple menu bar along the top of your computer screen the menu item "X11". Click on the X11 menu and select the "Preferences" item. In the resulting popup "X11 Preferences" window, select the "Pasteboard" tab. Next, unset the item "Update Pasteboard when CLIPBOARD changes".

Another symptom of this problem is that the "Paste in Place" operation does not paste the copied object back to its original location; instead it appears elsewhere on your drawing page. Furthermore, you can check to see if a bitmap was pasted by looking at the "Edit" menu. If the "Undo" item indicates that an "import" was done, then a bitmap was imported.

Clicking "Apply" in the Eggbot Control extension does nothing (Windows XP)

If nothing happens and no error or warning message is displayed when you click the "Apply" button in the Eggbot Control extension, then you may be experiencing an Inkscape bug. Try running an extension from the "Render" category of the Extensions menu. If still nothing happens, then it would appear that something is wrong with Inkscape on your system and it cannot successfully run extensions. With Inskscape 0.48 on Windows XP, there have been reports to the Inkscape team of such problems. It appears that falling back to Inkscape 0.47 fixes the problem.