Configuration Print with Prusa - need help

I am having some difficulties configuring my first prusa. The first few layers look great but then it gets sloppy as can be seen in the attached picture. I've decreased the layer height to 0.34 mm which seemed to improve things from the initial setting of 0.4 mm. However going smaller than 0.34 hasn't seemed to make a difference.

Any thoughts on how I should proceed? I will happily post more info if needed.

Using PLA 3mm
nozzle diameter: 0.5mm
filament diameter 3 mm

I have seen that happen with thin walled objects if they become detached from the bed during the build. They start to warp and the corner lifts. That causes the wall to be pressed against the nozzle and it then gets pushed to the side because the thin wall has little strength. Once that happens a wave develops and it get worse each layer,

Is it the case the corners are lifting during the build?

If so I would reduce the height of the test. As long has the lower layers are correct and the correct thickness I would move on to a solid cube. If that doesn't stick review what you are building on. Blue tape, heated glass ?

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The PLA is actually adhering very well to the heated glass. Corners are not lifting at all. Should I just move on then?

Thanks.
Ben

It looks like the plastic has stopped flowing and you end up printing with just the ooze for a few layers. I would guess that it is caused by a jam in the hotend or slipping hobbed bolt.

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Does it look like this sometimes? It starts out really good, then gets worse and worse layer by layer. Really helpful site, the art of 3d print failure on flickr.

[www.flickr.com]

Fixed it with cooling/slowing down. I feel like every printer should have a fan. Fans are the reason commercial printers works as good as they do. If you don't have a fan, just slow down the print to allow the PLA to cool, maybe try 10mm/s or 5mm/s. Each layer might take 30-60 seconds depending on the print. Its okay if your test box takes 20-30 minute to print, just make sure that the plastic is being put in place in the right amount and at the right place.

It took me several months to learn this. Its better to get it working slow and have a success than to do everything fast and have a box of failures. Start slow, get it working, then pick up the slack by changing one thing at a time and keeping track of your settings. Slic3r will work if you measure your filament, calibrate the machine, and allow for cooling, and it works really great. I print with an extrusion multiplier of 1. Make sure you check your filament with calipers in several places, then average the values. I've checked filament in 10 or more spots to get a good average. A set of micrometers on amazon are pretty cheap, $10. It will measure your filament to 1/10,000 of an inch. Maybe its overkill, maybe not. No filament is perfectly round and 3mm. Its usually off a little off. My filament is 2.8mm. This is why they sell it by weight, not by length.

Good luck!