Extruder won't run during testing

So I have completed most of my Prusa build, everything seems to be working fine. I'm getting ready to calibrate it, so I loaded up printrun/pronterface and did some experimenting. I can move the X,Y, and Z axes just fine. When I push the "extrude" button, my extruder motor DOES turn briefly. I can set the extrude length to 100 mm and the extruder runs for a little while, as expected.
So next I did a "dry run" by printing a calibration cube without any filament loaded. My X,Y,and Z axes behave exactly as expected, and my hot-end heats up, but my extruder wheel never turns during the run. If I halt it, and click the "extrude" button again, the extruder turns. Is there some configuration option I might be missing that would prevent my extruder from running during an actual print session from printrun? I created the calibration cube myself using openSCAD, and just exported it to STL, and then loaded it up in printrun. The Gcode file was generated without problems, and the movements of the X,Y, and Z axes all looked correct.

As a side-note, I tried using the RepRap java host, but I'm getting errors. I read a blurb on the mendel-parts forum that the Gen6 electronics doesn't currently work with RepRap host. Is this true? I'm using the SPrinter firmware on my Gen6 board.

You have to activate Dimension in Skeinforge AND clicking Extrude 100mm and it runs longer is hardly calibrating your printer.

REMOVE the hot end, put a mark on the filament and then Extrude 100mm, put a second mark on the filament and measure the distance between the two marks. If it is not 100mm then calculate the factor and adjust your E_STEPS_PER_MM by exactly this factor, compile, upload and repeat the test.

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

Maybe I wasn't clear... the extruder doesn't run AT ALL during the print run. I haven't even started calibrating yet because the extruder motor won't run. However, it DOES run when I click the extrude button.

Can you explain "You have to activate Dimension in Skeinforge" in more detail? Could this be why my extruder doesn't run during a print run?

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macphyter
Can you explain "You have to activate Dimension in Skeinforge" in more detail?

Select the Skeinforge - Carve - Dimension tab. Activate by checking the activate checkbox!

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macphyter
Could this be why my extruder doesn't run during a print run?

YES!

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

Thanks for the tip... I went to "Craft" -> "Dimension" and checked the box to activate dimension, but for some reason I'm still not getting any extrusion during the print run. Is there anything else I can check?

Did you calibrate your extruder as Bob described and then set your firmware steps per mm accordingly? If not, your e steps per mm might be too small for you to see the extruder moving. Look in the g-code file that you generated and you sould see G1 commands with E codes in it. What E numbers do you see? In SF 40 and later, it's based on feed length so the numbers will be very small. You didn't mention what electronics and firmware you're using but some of them are set to steps per mm based on ength of extruded filament which would be too small.

brnrd-
Thanks for your advice. I opened the G-code file, and discovered that instead of "E" values, the GCodes contain "F" values for the extruder. I don't know how that happened, but I suspect there's some configuration for multiple extruders going on or something. Does anyone know why I'd be getting "F" instead of "E" for the extruder? I think that explains why I can control the extruder from the printrun GUI button, but running a print won't extrude.

I might have to edit my GCode file by hand and replace all the "F"s with "E"s just so I can print a test run.

OK, PROBLEM SOLVED!!

I read the G-Code docs and learned that the "F" is for the acceleration value. Then I realized that I was loading the previously generated G-Code file that was built before I activated the "Dimension" module. Once I loaded the STL file and re-generated the G-Code, the "E" values showed up. How embarrassing!

Now I can go run my first test print and see some actual plastic.

I am having the exact same problem as the others above, however, I am just using Slic3r, which is built in to printerface to generate my g-code. Does anyone know what has to be changed to fix it? I would switch over to using skeinforge, but I already have everything calibrated to working with the default Slic3r settings.

Disregard the last post, fixed my problem by changing the board's firmware to Repetier and the issue has been fixed.