Solidoodle 3-two questions (Page 1 of 2)

This video shows how before the printing starts, the filament is retracted instead of extruded! Any ideas what's causing this? Only Skeinforge slicing does this. Any idea how to fix it? Here is also the G-code (the first few lines):

G90
G21
M106
M113 S1.0
M108 S28.13
G1 X68.439 Y62.77 Z0.15 F4500.0
G1 F9000.0
G1 E2.5
G1 F4500.0
M101
G1 X91.73 Y62.77 Z0.15 F1687.5 E4.6281
G1 X91.73 Y87.23 Z0.15 F1687.5 E6.8629
G1 X67.27 Y87.23 Z0.15 F1687.5 E9.0978
G1 X67.27 Y62.77 Z0.15 F1687.5 E11.3327
G1 X68.439 Y62.77 Z0.15 F1687.5 E11.4394
G1 F9000.0
G1 E8.9394
G1 F1687.5
M103
G1 X75.73 Y72.399 Z0.15 F4500.0
G1 F9000.0
G1 E11.4394
G1 F4500.0
G92 E0
M101
G1 X75.73 Y78.77 Z0.15 F1687.5 E0.5821
G1 X83.27 Y78.77 Z0.15 F1687.5 E1.271
G1 X83.27 Y71.23 Z0.15 F1687.5 E1.96
G1 X75.73 Y71.23 Z0.15 F1687.5 E2.6489
G1 X75.73 Y72.399 Z0.15 F1687.5 E2.7557
G1 F9000.0
G1 E2.4047
G1 F1687.5
...

Yea, Slic3r just makes a complete mess and so I am forced to use Skeinforge. Here is the difference between the two. I don't even know what Slic3r is making. Skeinforge "makes" the part but with very bad quality. For me it doesn't matter; I am just trying to make the printer work properly. Hopefully someone can help.

Thanks a lot Ian for your response. I switched to using Slic3r instead of Skeinforge because nothing seemed to able able to fix the over extrusion. I am pleased with the build quality using Slic3r and I adjusted the Z-tab to work with Slic3r (Skeinforge didn't seem to be that sensitive to the Z-tab; it did a pretty good job at sticking the first layer without much hassle.) I will continue tweaking the printer and optimizing it to work with Slic3r.

Do you know how I can make the printer print in the center of the print bed? Centering the object in Repetier doesn't seem to do it.

Ian, you rock!!! That did it.

'should' they is a long mechanical discussion with many opinions

But by design, in the printer, yes, the Idler Pulleys are 'free floating'....

After the new found joy of calibrating the printer and using Slic3r I decided to print a part.

Attempt A: I printed the part on its bottom. The print quality is good but the part was brittle (the layers sheered off like graphite).

Attemp B (see attached photos): I printed the part on its side. The part is stronger but the print quality went down.

My questions are:

1) In both attempts the dimensions were off. How do I fix that? Is the flow rate tutorial good enough or are there other things I need to check? http://wiki.solidoodle.com/flow-rate

2) In the Attempt B, the print quality went down--namely, there were unclosed areas (gaps)--how do I fix that? Will the X-Y calibration tutorial solve this? (I calibrated the X-Y axes three time already over the past week, so I am wondering if there is something else I should look into.)

Of course, I am also planning to experiment with different infill values and patterns to get stronger structures, but I would appreciate it if you can guide me in regard to the above two questions. And over all I am pretty happy with the printer.

Is that the top or bottom of the part?  It might be under extruding, which would give you perimeters that are too thin, or the settings might be right but the extruder is having trouble feeding.   What is your speed set to?  Try slowing it down and see if the gaps close up.  A calibration cube might turn out right because it has to run slow to let the plastic cool.  The when you run an actual print it goes faster, and might be too fast for the extruder to keep up.

It might be having trouble keeping up if there is a partial clog, there is filament dust in the gear teeth, or the speeds are high.  The filament might be getting too hot too high up inside the black barrel, in which case putting a fan on the barrel can help. 

Depending on how the print is oriented on the platform, Y backlash can keep the fill from reaching the perimeters, but looking at the spaces between lines in the solid fill I would think there is under-extrusion.

Do you have any other colors?  Black in general has a reputation for being problematic, either low quality or more finicky about what temperature you use.  Plastic is colored by adding pigments to an off-white base resin, so a dark, opaque color like black requires more additives than other colors.  If you don't have another color to by compare, you could try doing some small cubes and run a variety of temperatures from 190-205 and see if you get better results at any point.

Natural would give you the best baseline since that should be ABS and nothing else.  It is off-white, not to be confused with White filament which probably has titanium dioxide in it for color.

There's no power button.  I plug mine into a power strip and use its switch instead.

Thank you both for the tips about the power button.

The printer is doing a fairly good job but I am still getting not smooth walls (full of ABS "droplets", it's like the layers are not perfectly stationed on top of each other?) Do you know how I can get smoother walls printed?

Yeah, I should have said 433MHz remote