MakerBot Industries

Too cool! Too cool!

Even when you’ve got Skeinforge totally dialed in there can be other potential problems with getting a perfect print. ¹  A drafty room, cold ambient temperature, or too much moisture can all cause problems.  Just as cold and wet conditions can lead to suboptimal prints, so can too much heat.  If a layer is still molten and gooey when the next layer is laid down on top of it, the lower layer can get squished or pulled out of place.  Through the use of judicious cooling, you can ensure you don’t have a problem with a molten lower layer.

Besides the Thing-O-Matic’s built-in fan, there have been a number of extruder cooling mechanisms:

• The Ducted Cooling Fan by Iwo
• Around-the-Nozzle Cooling Ring by scanlime
• HYPERVENTILATOR! by ScribbleJ

ScribbleJ’s version, while perhaps the most labor intensive, is easily the most well documented and entertaining to read.  If you haven’t already checked it out, some of those pictures are priceless.

For more information and ideas on fighting the gooey layer problem, check out Bothacker’s work with Skeinforge’s Cool function and Tesla893′s idea of printing multiple copies of parts at once.

1. Photo courtesy of Piero…assente fino a domani [↩]

PLA Pawn temperature tests

Above are twelve nearly-consecutive print-tests of Cliff Biffle’s pawn.  Once I pulled the black ABS filament out, I inserted the clear PLA, and ran it until it looked reasonably clear.  However, you can see how the plastruder was still clearing out the remaining black ABS for the first three prints.  Here are the relevant Skeinforge settings for the above pawn prints:

• The entire top row was printed way too hot – at 230 degrees Celsius.  Each print looks essentially identical, except for the variation in their coloring.  The bases are very well defined – but the “stem” of  each is slightly warped.  This is likely the result of the layers not having sufficient time too cool before the next layer is deposited.  Molten PLA holds its heat longer and stays gooier longer than ABS, so it is more prone to having layers pushed around slightly when a layer is put on top of it.  The little globe at the top of the pawn is droopy and doesn’t look very spherical.  Overall, these pieces could be acceptable as playing pieces, but I’ve seen some amazing prints in PLA and I want better for my 3D printer.
• For the middle row I tried lowering the temperature and experimented with Skeinforge’s “Cool” feature.  Notes on these prints, left to right, follow.
  • The far left pawn printed at 190 degrees Celsius and with the “Cool” feature set to 20 seconds.  The “Cool” setting made the extruder trace over the perimeter of the layer until it had spent a total of 20 seconds at that layer.  If you look closely at the picture, you’ll notice there appears to be a slight gouge out of the spherical part of the pawn.  I believe the gouge was created as the extruder essentially tore bits of plastic off the layer.  That said, this print has two other interesting qualities.  First, this pawn is significantly whiter than all other prints.  I believe this was caused by the “Cool” feature being set so high.  Secondly, aside from the gouge this pawn turned out better than any other print.
  • The next pawn over was printed at 190 degrees Celsius with “Cool” set to 10 seconds.  This print is slightly less opaque than the prior and has much larger gouges throughout the model.  This was one of the most unsuccessful prints.
  • The next pawn over to the right was printed at 190 degrees Celsius with “Cool” set to 5 seconds.  I canceled this print part way through because it was evident the stem of the print was badly mangled.  However, it was slightly more clear than the prior prints.
  • The last pawn to the right in the middle row was printed at 195 degrees Celsius with “Cool” set to 5 seconds.  This pawn’s stem was also mangled and the entire model deformed.
• The bottom row contains three prints with the “Cool” feature set to 1 second.  I’m not sure this helped at all.
  • The far left pawn was printed at 195 degrees Celsius.  I didn’t see much of an appreciable difference between this model and the ones printed at 220 degrees Celsius.
  • The middle pawn was printed at 187 degrees Celsius.  I didn’t see an appreciable difference from the prior print.
  • The far right pawn was printed at 210 degrees Celsius.  I didn’t see any appreciable difference from the prior two prints or any of the prints at 230 degrees.

I’m not sure how to proceed with testing.  The one print that looked the best, except for gouges, was the one printed at 190 degrees Celsius with “Cool” set to 20 degrees.  One potential issue with Cool set so high is that this print took more than 27 minutes versus about 7 minutes when Cool was set to 1 second.  I suspect any of these print settings might be acceptable for larger objects, allowing the rest of the layer to cool sufficiently to support the next layer.  However, I’m more concerned with dialing in the quality for smaller objects – if I can print those I should be able to print nearly anything.

Do you print successfully with PLA on your Cupcake?  What settings do you think are the most important?  What suggestions could you offer to help others?

Also, one additional photo of the same pawns as above, but with the flash on my phone turned off.  This might help seeing some of the details.

PLA pawn tests - no flash

Tesla893 shows off his simple trick for printing quality small parts. When printing very small or narrow parts, the lower layers don’t get enough time to cool and solidify before the next layer is placed down. This causes squishing and sliding of layers. One effective method of reducing this problem is through the use of Skeinforge’s “Cool” setting. The Cool setting allows you to specify a minimum time the printer will spend working on a given layer – ensuring that your small parts have enough time to cool before the next layer is put down.

Tesla893′s trick is to print multiple small parts at once. Sure, you might have a little more stringing between parts to account for, but the printer is forced to spend more time between each individual small area given them all time to cool.

Update: The video appears to be removed for some reason.  It would have just shown you that Tesla893 was printing multiple copies at once.