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Extruder problems demonstrated on video

Posted by mattuwattu 
Extruder problems demonstrated on video
April 25, 2011 04:52PM

I am pressing on and making good progress ( with help from you guys n gals!). I have fully functional x y z and the machine happlily follows the gcode paths in thsoe directions.

I have got my extruder kind of working although i have had to revert to older versions of software .... More on that later.

When i say the extruder kind of works, i mean that in the RepRap host software if i manually extrude it will do so. Ie on the extruder tab, clicking extrude will do exactly that.

However, when i try to plot a part the extruder exhibits some strange behaviour - it feeds but then withdraws the same amount. Overall i get no filament feed through the extuder. To see what i mean take a look at this:


Anyone had similar experiences?

Re: Extruder problems demonstrated on video
April 28, 2011 07:02PM
You've got to enable the "dimension" plugin in skienforge.

What's happening (if you check your g-code) is that every movement command specifies a relative amount to extrude. If your firmware isn't set up for that (it's expecting an explicit G92 (IIRC) to reset the value of the E axis to 0 again at the end of each layer) then you'll get the behavior you've described.

Look at the "E" values given on your "G1" commands in your g-code. They're all small, and proportional to the distance traveled. You want them to be progressively larger, and increasing by the distance traveled each time. Then at the end of each layer, you'll see a "G92" (IIRC) and it starts at zero again.

The difference is that in one mode, it starts at zero (by issuing a "G92 E0") at the start of each layer. In the other mode, it starts at zero at the begining of each move. (The "Teacup" firmware be default has "E always relative" which means it starts at zero every time you move.)

I'm building it with Baling Wire
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