Print issue: irregular layers

Hello board!

Very new to 3D printing.

We got a TAZ 4 at my place of work, a hospital. The intention is to print volume rendered ct scans in 3d to help orthopaedic surgeons plan their surgeries more effectively before hand.

We’re getting a strange issue with some prints, almost anything with finer detail and I cant find anything similiar in my various searches. I’ve attached an image as it’s quite hard to describe. The print is meant to be a hollow cube with smooth edges that can be used to test bridging and calibration but obviously with it printing as shown in the picture below it is proving we have an issue.
This is the thingiverse page for the object: http://www.thingiverse.com/thing:30171

We also get a fair amount of blobbing and the occasional missed layer. I’m starting to think our nozzle is somehow clogged even though the whole set up is less than a month old.

Anyone know how best i can diagnose the issue?

The print pictured was done at 15mm/s at a 0.2 layer height but it has occured at all speeds i’ve tried it at and at all layer heights.
20150804_143720.jpg

Your starting layer is too close, you are overextruding significantly and your retraction settings seem to be off. If this is pla you might also have a cooling fan issue. Back the nozzle hight away from the print bed until the initial layer looks less lumpy. Then measure your filament 3 places and take the average and enter that into your slicer for the filament width. You will probably find your filament is wider than the current setting. Increase your retraction amount a bit to get rid of the stringy bits. If you aren’t running a cooling fan and that is pla, add one. There is a guide on how to do so in the ohai kit documents.

Thanks for the input. I’ll try everything you mentioned and get back to you.