3D Printing Warping Prone Parts

I’ve owned a Da Vinci Pro 1.0 for about a year now.  And I have noticed that like any other printer, the settings are crucial.  And I hope that this will help other owners.  And maybe owners of other machines as well.

3D Printing with ABS can be problematic from time to time.  ABS really shines when it comes to versatility.  Not only is it an easily accessible filament, but it is strong.  However, that strength doesn’t come without weakness.  And ABS has quite a few weaknesses.

First off, the sharpness of the print will not be as high as with other plastics. Due to the properties of the plastic, it just doesn’t lend itself well to printing high detail models.  But it excels at simpler ones.  This coupled with it’s strengths and it’s ability to be chemically bonded to itself with acetone make it a suitable plastic for creating enclosures.  And in electronics, we always need enclosures.

Secondly, ABS tends to warp.  And warping is exaggerated by larger parts with more mass. To break it down, if it is large, or flat, or has sharp corners, you will likely experience warping.  Or in the event that you do not experience warping, you may experience layer separation.

The root cause of the problem is that ABS tends to shrink as it cools.  So whether or not you’re able to make it stick to the build plate, you’re likely going to have some type of distortion.

This effect can be minimized to a degree, but will always be present.  A heated build surface is a must.  As is an enclosed build area.  These two items will help “keep the heat in”, and that will help the layers cool at a more uniform level.  But this isn’t a complete solution.  Even if you print slow, you may have problems with curling, or warping.

Below is an example of a warping prone part.  It’s large, it’s flat, and it would normally have sharp edges.  But I have designed this part to minimize warping.  Let me explain.

The first thing we need to address is mass.  Now this part was originally part of a larger piece.  That larger piece added a lot of height and mass to the model.  The problem with that is that with each layer you’re going to add a slight amount of additional “pull” to the piece.  Which over time, and increasing layers, can worsen the effect of shrinkage.

The next item we will look at is sharp corners.  There is no getting around it, sharp corners are like a magnet for warping.  Some people try to add “shields”, so to speak, around the corners to help maintain an even temperature.  However, I’ve had little luck with this approach.  What I have had luck with is “Mouse Ears.”  By adding a mouse ear to corners, I have found it does two things.  First, it turns a sharp corner into a round corner.  And secondly, it helps to tack the part down to the build surface, preventing it from peeling up.  An example of a Mouse Ear is here:

Another thing that we must discuss is build settings, specifically build speed.  The fact is, the faster you print the more warping you’ll likely get.  Warping happens as the piece cools. But the solution I have found is to allow the part a little time to cool down to the temperature of the heated bed before applying the next layer.  I do this by adjusting only my “Normal” Shell setting on the printer.  This slows the speed on the Outer Shells to 5mm/s.  This means that the shells take a much longer time to print.  Allowing the rest of the previous layer’s temperature to normalize.  See below:

How does this help?  Well, honestly I had experience ZERO warping on the part shown above with this setting.  However, it does substantially increase build time.  How much longer?  Well (and bear in mind the software’s estimates are never correct, they over state the time) with 20mm/s setting it is estimated to take about 3hrs.  With the 5mm/s setting it is estimated to take 5:40 hrs.  That is almost twice as long.  In reality, the part would likely take about 1:30-2 hours to print with the 20mm/s setting, and approximately 4hrs to print with the 5mm/s setting at 20% infill.  So there is a significant increase in time. But I have experience zero warping with this setting.

But there is one more disadvantage to using this setting that I’ve noticed.  At the place where the print nozzle starts (the Da Vinci has a tendency to start from the same spot for many layers in a row) there may be spots that are ‘missed’.  That is to say that they didn’t get filled in with plastic.  I believe this has to the do with the extrude ratio and the extraction.  I haven’t had a chance to experiment with those settings.  But I plan on testing in the future.

I hope this helps someone else with their print settings on the Da Vinci Pro 1.0 printer.