Small perimeters are getting "dragged."

I’ve looked through the forums, but haven’t found an answer to my problem. I’m using Repetier V1.0.4, Slic3r, PLA, and a taped bed. I started plotting the 5mm Calibration Cube (Thx to MCroucher), hoping to refine my settings. After numerous attempts, I’m now plotting it over and over, just trying to determine if ANYTHING I do affects the print.

I’ve uploaded four images:

Image 1 shows the last seven attempts. The main problem I’m encountering (A) is that the top two steps become completely rounded. Image 2 shows a close-up. The arrow indicates the direction of travel, and you can see that it appears the layers are getting “dragged.” Image 3 is a close-up from another angle.
So, what have I tried? I’ve tried:

• Modifying the heat in 2 degree increments between 190 and 205 degrees.
• Speeding up the travel 300% (100mm/s) for small perimeters that take less than 30 seconds.
• Slowing down the travel by 70% (10mm/s) for small perimeters that take less than 30 seconds.
• Having the fan come on for the top two “steps.”

None of these appeared to affect the quality. Would printing the external perimeters first possibly help? Would turning the fan on continuously possibly help?

Image 4 shows problem (B)—holes in top surfaces. I tried adjusting the number of solid top layers all the way to 7, but don’t really know if this setting affects just the top-most layers in the entire model, or the top-most layers of each step.

Finally, back in Image 1, you can see problem (C), which appears to be support material that was added erroneously. I’ve only seen this happen once, which makes it seem all the more odd.

Any suggestions for what I might try next. To solve problem (A) or (B)? Thanks, in advance, for your help.

 

Being PLA it looks like you need to cool the plastic more. Also for a small object like this try turning down your speed

 

Mike -

Thanks for your prompt reply. So, in the last two of my original bullet points, I thought I was trying just what you're suggesting. How are you suggesting that cooling the plastic, and adjusting the speed, should be done? Thanks, again, for your help.

 

Mike is absolutely right. Especially for this model and PLA the fan should be on for all except the first few layers. Those defects are classic autocooling setting problems. You need to play around with and understand the autocooling settings. For that print the fan max should be 100%. You might want to try even slower than 10mm/s for the short time layers. I'm used to Slic3r so I don't know how autocooling is configured in other slicers. If a layer takes too short a time to print and is not cooled enough you get those melted and dragged sections. The worst case is when the nozzle hits a turned up section and knocks the print off the bed.

 

I would recommend making a seperate configuration for these changes called something like "Small PLA"

In your slicer configuration settings > filament settings tab> Cooling > have the Keep fan always on enabled. You could probably set the min and max to 100

Under print settings > Speed > Speed for print moves > make sure all the perimeters and infil settings are 30 or less.

 

Oh, yeah, Baby! Per your suggestions, I slowed the travel for everything down to 10mm/s, turned the fan on 100%, and even placed a second fan to blow directly on the printer. Worked like a charm. Thanks, VERY much, for your help.

I can hardly wait until I get to that point where I know enough about how the print responds to various settings to be able to solve problems by "gut feeling." I was also thinking it'd be an excellent idea to post a series of dual pictures—one showing a problem, the 2nd showing the problem fixed + an explanation of what was done to solve it. Could be a very handy reference.

Thanks, again!

 

That sounds like a great idea. It could be the go-to page for common problems. Every time someone makes a thread with a problem like this that's been solved their photos could be added to a chart with the problems and solutions.

 

The following link would be helpful.

http://reprap.org/wiki/Print_Troubleshooting_Pictorial_Guide

 

Extremely helpful. Thank you.