Skeinforge: Tuning advice for newbie?

I finally got a pool of filament delivered and to play with.

After some try and errors, I finally got a water tight Minimug printed on the 5th trial. But still it is flawed.

Picture 1: [picasaweb.google.com]
Picture 2: [picasaweb.google.com]

So as you can see the circle has a bulge, it is where each layer start and ends. I suspect my extruder oozes hence causing this...?

On the other hand, is there any more complicated "benchmark" / "test" object that I could print to identify other potential issue?

One trick that worked well for me was to stretch the filament a bit. Work out the plastic flow rate that matches your nozzle size and head speed, then stretch it just a bit. I have a 0.6 mm nozzle, which extrudes roughly a 0.7 mm filament into free air due to die swell (check Nophead's blog for some info on that subject); I found I got best results when I set my head speed and extruder speed for a 0.5 mm filament, which requires a bit of stretching.

Also, you can try messing with oozebane in Skeinforge, but I found my firmware is a bit too slow; all the extra short moves were slowing things down too much on my machine, causing too much plastic in the corners.

Wade

Is there a big pause when it starts a new layer?

It looks like the end of the path has too much plastic and the start of the path has too little. The extruder is probably switched off and on while z moves up a layer, but that is normally so fast that there is no time for much ooze.

There is a benchmark object here [www.thingiverse.com] although I haven't tried it myself yet.

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[www.hydraraptor.blogspot.com]

Thanks. Seems a short pause when the movement stopped but before the extruder is turned off is causing the issue. I need to fix the response time of the M103 command.

Thanks for the idea.

What machine are you using?

I had exactly the same with a Repstrap (CNC machine with an exruder). The CNC software turned out to always have considerable axis delays when issuing M functions so I have had to pursue a different method.

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Regards

Ian