Print on Flashforge Creator Pro is rough in spots

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I'm using a Flashforge Creator Pro and PLA filament to create the object found here: http://www.thingiverse.com/thing:825780. I've been using both supports and a raft. You can see from the pictures that the top prints really well but the bottom turns out rough. I'm fairly new to 3D printing, so I'm not sure which things to alter to prevent this. Does anyone have any suggestions for what might be causing this?

Edit: if it helps to know, I am printing with 10% infill.

My guess is that you're printing too hot, the bottom layers are smaller and print faster, which may not be leaving time to cool for the next layer. Try slowing down your printing and/or lowering your temperature.

Also, you should expect some roughness on overhangs, but it shouldn't be as bad as you're experiencing.

Thanks! I did manage to get this printed on a Makerbot Replicator 2, which didn't seem to have any issues, but this is really good to know for future prints. I'm still getting used to the Flashforge and the differences between it and the Makerbot.

I agree with Djprinter. You're printing it with a higher temperature. I suggest reducing your temperature while printing, or give some time to allow your model to cool down before printing the next layer to avoid rough spots. Slow printing also helps so that you can have the details of your model printed perfectly.

try printing two side by side.

basically the layers aren't cooling enough. The best solution is to add active cooling ducts to the print head. For pla it's pretty much essential. I also find it realy helps with abs as well.
Hell mine's always switched on (hmm, maybe that's the issue I have with taulman stuff - have to fit an on/off switch and find out)

The temperature you print at has a minor effect - what actually matters is how fast you can cool the hot plastic.
It's not quite the same thing.

But basically the bottom of a sphere is always going to be rough if you can't cool the layers properly. There's a thrad around somewhere where I've got comparison pics with and without the cooling duct.
It's a significant difference.