First Printout - Beginners Questions

Thanks to nophead for this wonderful machine. It's real fun to see it work for the first time.

As an absolute beginner I got some questions, I hope You won't smile about them.
I added the first print. There were some mistakes as You can see.
The second one was better, without any changes to the printer.
But there is a problem with the first layer on the left side. The left border seems flowing away.
Furthermore is a Little V mistake in the middle of the object in the last layer as I marked it with a red line.
Do You have an idea, what I can do for improvement.

What about the printers speed? Do I have to do some modifications or is speed fixed in the g-code?
Why does the fan start, when the printjob is finished. Is it not necessary while printing?

Best regards from Germany
Ulli

I only recently got my mendel 90 up and running so I'm a beginner as well, but in my experience there's a lot of things that can go wrong with the first layer so I can't really answer that. But an all purpose fix for me has just been to lower print speed. Which you do by going into skeinforge -> speed -> feed rate and flow rate. From what I've read, you shouldln't stray to far from the 1:1 proportion between the two. As for the fan, the default end.gcode for me turned the fan on after the print was finished, possibly to cool the piece faster so you don't have to wait so long to detach the piece from the print bed. You can change it by going to alterations and changing end.gcode. I've actually gotten a lot better prints leaving the fan on during prints, and I believe a lot of people recommend it for lower temperature plastics like PLA as overheating gets to be a problem with small islands and large minimum layer times.

Your first layer on the left side is most likely a bed level and z height problem. To make sure your bed is level measure the skirt (outline) from the print to see if it matches the layer height (0.3mm). If it is consistantly the same number all the way around your bed is level and you will just need to adjust the zheight in marlin but it looks like your bed isn't level.

It's a little too hard for me to see what the V problem is but it doesn't look terrible to me.

You can adjust speed in skeinforge as mention previously.

The fan turns on at the end to cool the hotend faster and limit the ooze the comes out of the hotend at the end of the print. If you added the fan at the back to cool the bed it would also turn on at the end of the print to cool the bed faster.

Cheers,

Thanks for Your hints.
As You suggested to improve the bed levelling, I tried to get a GCode for the clamp.stl.
As descripted in Nopheads manuel I installed Skeinforce.
The I tried to produce a G-Code. It seemed to work, but there is a mistake with speed.
Ooze free start is correct, but after then speed is much too low. From the start point to the printing position Mendel90 moves at say 1mm/sec.
The Skeinforce-text is attached.
Regards
Ulli

Silly mistake. As in former threads to be found the correct profile for skeinforce is ABS for printing PLA.
Now it works.
Just one layer is not ok. Do You have an idea why?

Looks pretty the same problem as I had printing out my clamp.

Nophead gave some hints. incoherent filament