Teacup - extruding too fast when going around corners

I have a Prusa Mendel with Gen7 electronics, using the Teacup firmware. Everything works beautifully when driving the printer manually from Pronterface.

When trying to print a part though, the extrusion speed is way too high when going around corners. Along longer straight lines, it is adequate (minor tweaking to be done, but generally speaking it's OK). My x-steps, y-steps and e-steps are set up properly, as I can check when extruding manually. Filament and nozzle diameters set in Slic3r are OK.

The attachment shows the skirt of the part I'm trying to print; the points show the coordinates defined in the G-code file. The over-extrusion happens in those areas where the points are close to each other.

Is this a firmware issue, that the calculation of the proper extrusion speed could somehow be off?

Oliver

Might as well post a picture of what happens. You can clearly see how the extrusion is about right along the straights, and too much in the corners.

Oliver

Is it possible you have compiled to default to relative E movements, but generate G-code for absolute ones? Your G-code should have G82 or G83 to set the right thing.

Also, have a look for LOOKAHEAD. Brand new to Teacup, currently only in the Gen7 branch.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

I had Teacup compiled without E_ABSOLUTE defined, and there was no M82 command in the g-code, only a G90.

Will report back with results ...

Oliver

Ok, now it interprets the absolute E coordinates correctly. But now it extrudes way too slowly ... the E steps are set right, since driving it manually with Pronterface gives the correct length of filament extruded. The filament settings in Slic3r are also correct, as far as I'm aware.

Anyway, setting the extrusion multiplier to 2 I get something resembling the part I wanted to print ;-)

Oliver

Quote
Raketenolli
Anyway, setting the extrusion multiplier to 2 I get something resembling the part I wanted to print ;-)

If you extrude 100mm via Pronterface and the motor pulls in 100mm of filament then your problem is probably the wrong filament diameter set in your slicer program, e.g. you have 3mm set but are using 1.75mm filament!

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

I set the Slic3r to a filament diameter of 3 mm, and that's what I'm using. Looking at the g-code, and calculating the resulting extrusion diameter from the length of the path traveled (from X and Y coordinates) and the filament length to be extruded (from E coordinates), I get about 0.32 mm, which makes sense since I'm using a 0.35 mm nozzle and have layer height set to 0.28 mm.

Oliver