Tag Archives: thin layer

Hi Rez Printing Problems

Posted on by
The stuff nightmares are made of: 1/4 of Disney's head

The stuff nightmares are made of: 1/4 of Disney's head

Earlier I had wondered about some of the challenges facing high resolution printing.  Specifically, I had suggested that a lower resolution would be better for overhangs, speed, and (after the suggestion of Erik) interlayer adhesion.

It looks like Dave Durant has a proof of concept with 1/4 of Disney’s head. 1  The layer height is unbelievably small – but as he points out:

Even smallish overhangs seem to be far harder to print at this layer height. I tried to print this one several times and it always went pear shaped as it got close to his chin, which is a pretty agressive overhang. Serious blobbage. :(

This certainly seems to demonstrate the flip side of my hypothesis – that thin layers are not good for printing overhangs.  I’ve been printing with a layer height of about 0.33mm.  This seems to give me enough resolution and overhang printability to make whatever I’ve needed so far.  However, I think it also gives us a reason to have several different configurations for a MakerBot for each kind of plastic:

  1. Thin layer printing
  2. Good overhang printing
  3. High speed/thick layer printing
  4. Printing small holes?

What other kinds of profiles would you suggest?

  1. Dave – your Flickr account says all rights reserved.  Obviously, I’m attributing this to you.  If you would like me to remove the picture, I will do so. [↩]

PLA versus ABS, initial thoughts

Posted on by

I’ve yet to print something big as I am still working out some of the black ABS specks from the extruder.  Of the things I have printed so far, it looks like the PLA feels more brittle than the ABS.  ABS will flex slightly when pressure is applied, whereas PLA seems to resist until it snaps.  I like that I’m not wasting PLA by building rafts any more, now that the raft option is turned off in Skeinforge.

PLA takes a little longer to cool which has a few effects on a build.  If the layer underneath is still molten and saggy, the layer on top will sag too.  When an ABS part is done printing you’re basically ready to remove it.  I find that a PLA object can still be a little soft for as much as 15-30 seconds after a build.

I’m loosing finer details on prints.  I just reprinted the toy fire truck swivel.  It turned out really nice except for the actual swivel part.  Unlike the ABS model where the swivel snapped off immediately, the PLA model’s swivel was pretty solid (once it cooled and hardened).  However, it came out too thin!  As I watched it print, the PLA was so warm that it just stretched back during parts of the print – meaning the extruder nozzle made the full circuit, but the plastic stretched a little and pulled back closer to it’s last position.  Uh, that may not sound like the clearest example.

Suffice it to say that small round details such as the swivel didn’t turn out very well.  Which is pretty odd since similar small round detailed parts on the teapot did turn out well.  I suppose part of the reason is the swivel was one small round part where the next hot layer was set down on the prior still hot layer, unlike on the teapot where the thin round spout would be drawn, then the body, then the thin round part for the handle and back over the body – so that by the time the next thin layer was set down the prior layer had cooled.